Metformin
updated
Metformin is an established treatment for type 2 diabetes. The D grade here applies to healthy-human longevity: aging-oriented trials report null, unfavorable, and preliminary positive functional or biomarker results, but none shows longer life in metabolically healthy people.
biguanide glucose-lowering drug
- US tablets contain metformin hydrochloride, whose mass differs from the free base
- The current immediate-release label covers type 2 diabetes, not healthy aging
- UKPDS outcome benefits apply to newly diagnosed type 2 diabetes
- Direct aging studies use different populations and endpoints and have mixed results
- The label carries a boxed warning for metformin-associated lactic acidosis
What exactly is metformin?
Metformin is a small-molecule biguanide. The free base is PubChem CID 4091, while US tablets supply metformin hydrochloride, CID 14219. Their formula and molecular mass differ because the hydrochloride includes the salt. Immediate-release, extended-release, liquid, and fixed-combination products also need product-specific exposure and labeling.
| Record | Formula | Molecular weight |
|---|---|---|
| Metformin free base, CID 4091 | C4H11N5 | 129.16 |
| Metformin hydrochloride, CID 14219 | C4H12ClN5 | 165.62 |
PubChem CID 4091 · free base identity
NIH chemical identity record
PubChem Compound Summary for CID 4091, metformin.
The free-base record identifies metformin as C4H11N5 with molecular weight 129.16 and InChIKey XZWYZXLIPXDOLR-UHFFFAOYSA-N.
Read the original sourcePubChem CID 14219 · hydrochloride drug substance
NIH chemical identity record
PubChem Compound Summary for CID 14219, metformin hydrochloride.
The hydrochloride record identifies C4H12ClN5 with molecular weight 165.62 and InChIKey OETHQSJEHLVLGH-UHFFFAOYSA-N. A hydrochloride tablet strength and a free-base molecular mass are not the same identity field.
Read the original sourceDailyMed · type 2 diabetes label, revised April 2026
FDA drug label
DailyMed. Metformin hydrochloride immediate-release tablets, revised April 2026.
The label indicates immediate-release metformin hydrochloride tablets as an adjunct to diet and exercise for glycemic control in adults and children age ten and older with type 2 diabetes. It does not list healthy aging, lifespan, healthspan, dementia prevention, or muscle gain as an indication.
- Metformin lowers hepatic glucose production, reduces intestinal glucose absorption, and improves insulin sensitivity without stimulating insulin secretion.
- The boxed warning concerns metformin-associated lactic acidosis, including fatal postmarketing cases.
- Common reactions include diarrhea, nausea or vomiting, flatulence, asthenia, indigestion, abdominal discomfort, and headache.
- Participants / model
- Adults and pediatric patients age ten and older with type 2 diabetes
- Treatment
- Immediate-release oral metformin hydrochloride under label-specific renal and clinical monitoring
- Study design
- Current regulated product information
What does the D grade mean if metformin is an established medicine?
The grade covers healthy-human longevity, not diabetes care. The current immediate-release label covers glycemic control in adults and children age ten and older with type 2 diabetes. It has no indication for lifespan extension, broad healthspan, dementia prevention, or improving exercise adaptation.
DailyMed · type 2 diabetes label, revised April 2026
FDA drug label
DailyMed. Metformin hydrochloride immediate-release tablets, revised April 2026.
The label indicates immediate-release metformin hydrochloride tablets as an adjunct to diet and exercise for glycemic control in adults and children age ten and older with type 2 diabetes. It does not list healthy aging, lifespan, healthspan, dementia prevention, or muscle gain as an indication.
- Metformin lowers hepatic glucose production, reduces intestinal glucose absorption, and improves insulin sensitivity without stimulating insulin secretion.
- The boxed warning concerns metformin-associated lactic acidosis, including fatal postmarketing cases.
- Common reactions include diarrhea, nausea or vomiting, flatulence, asthenia, indigestion, abdominal discomfort, and headache.
- Participants / model
- Adults and pediatric patients age ten and older with type 2 diabetes
- Treatment
- Immediate-release oral metformin hydrochloride under label-specific renal and clinical monitoring
- Study design
- Current regulated product information
753 people with new type 2 diabetes · median 10.7 years
Randomized controlled trial
UK Prospective Diabetes Study Group. Lancet. 1998. PMID 9742977.
Among 753 overweight people with newly diagnosed type 2 diabetes, 342 were allocated intensive control with metformin and 411 conventional diet-based care for a median 10.7 years. Relative risk fell 32% for any diabetes-related endpoint, 42% for diabetes-related death, and 36% for all-cause mortality versus conventional care.
- The supplementary add-on comparison in 537 people already on maximum sulfonylurea found a 96% higher diabetes-related-death risk with early metformin addition versus continuing sulfonylurea alone.
- The paper also reported fewer diabetes-related endpoints in a combined main and supplementary analysis, so the adverse add-on signal was not a simple overall verdict.
- Participants / model
- 753 overweight people with newly diagnosed type 2 diabetes in the main randomized comparison
- Treatment
- Protocol-titrated metformin intensive-control policy versus conventional diet-based policy
- Follow-up
- Median 10.7 years
- Study design
- Randomized controlled comparison within UKPDS, plus a separate supplementary randomized add-on analysis
These are diabetes-treatment outcomes in a selected metabolic-disease population, not a healthy-user longevity trial.
Read the original sourceRandomized-strategy follow-up · diabetes mortality benefit persisted
Post-trial randomized-strategy follow-up
Adler AI et al. Lancet. 2024. PMID 38772405.
Extended linkage follow-up found that the original early metformin strategy in newly diagnosed type 2 diabetes retained relative risk reductions of 20% for death from any cause and 31% for myocardial infarction versus conventional glycemic control. The corresponding absolute risk reductions were 4.9% and 6.2%.
- Participants / model
- Surviving UKPDS participants followed through linked UK health records
- Treatment
- Original randomized early intensive metformin strategy versus conventional glycemic control
- Follow-up
- Individual follow-up from baseline up to 42 years; extended monitoring up to 24 years after trial end
- Study design
- Intention-to-treat post-trial follow-up of the original randomized strategy
Post-trial treatment was no longer controlled. The result remains specific to early diabetes care, not prophylactic use in healthy people.
Read the original sourceHow does metformin lower glucose?
The label describes reduced hepatic glucose production, reduced intestinal glucose absorption, and improved peripheral insulin sensitivity without stimulating insulin secretion. Those actions explain glucose lowering. They do not establish slower aging, and broader pathway claims need their own direct outcome evidence.
DailyMed · type 2 diabetes label, revised April 2026
FDA drug label
DailyMed. Metformin hydrochloride immediate-release tablets, revised April 2026.
The label indicates immediate-release metformin hydrochloride tablets as an adjunct to diet and exercise for glycemic control in adults and children age ten and older with type 2 diabetes. It does not list healthy aging, lifespan, healthspan, dementia prevention, or muscle gain as an indication.
- Metformin lowers hepatic glucose production, reduces intestinal glucose absorption, and improves insulin sensitivity without stimulating insulin secretion.
- The boxed warning concerns metformin-associated lactic acidosis, including fatal postmarketing cases.
- Common reactions include diarrhea, nausea or vomiting, flatulence, asthenia, indigestion, abdominal discomfort, and headache.
- Participants / model
- Adults and pediatric patients age ten and older with type 2 diabetes
- Treatment
- Immediate-release oral metformin hydrochloride under label-specific renal and clinical monitoring
- Study design
- Current regulated product information
What did UKPDS show?
In overweight people with newly diagnosed type 2 diabetes, the original randomized metformin strategy reduced diabetes-related endpoints and mortality versus conventional care over a median 10.7 years. Extended follow-up reported persistent all-cause mortality and myocardial-infarction benefits. That is valuable diabetes evidence in a defined disease population, not proof of prophylactic longevity in healthy users.
| Analysis | Population and follow-up | Key result |
|---|---|---|
| UKPDS 34 | 753 overweight people with new type 2 diabetes; median 10.7 years | 32% lower any diabetes endpoint; 42% lower diabetes death; 36% lower all-cause death |
| UKPDS 91 | Post-trial follow-up of original randomized strategy | 20% lower all-cause death; 31% lower myocardial infarction |
753 people with new type 2 diabetes · median 10.7 years
Randomized controlled trial
UK Prospective Diabetes Study Group. Lancet. 1998. PMID 9742977.
Among 753 overweight people with newly diagnosed type 2 diabetes, 342 were allocated intensive control with metformin and 411 conventional diet-based care for a median 10.7 years. Relative risk fell 32% for any diabetes-related endpoint, 42% for diabetes-related death, and 36% for all-cause mortality versus conventional care.
- The supplementary add-on comparison in 537 people already on maximum sulfonylurea found a 96% higher diabetes-related-death risk with early metformin addition versus continuing sulfonylurea alone.
- The paper also reported fewer diabetes-related endpoints in a combined main and supplementary analysis, so the adverse add-on signal was not a simple overall verdict.
- Participants / model
- 753 overweight people with newly diagnosed type 2 diabetes in the main randomized comparison
- Treatment
- Protocol-titrated metformin intensive-control policy versus conventional diet-based policy
- Follow-up
- Median 10.7 years
- Study design
- Randomized controlled comparison within UKPDS, plus a separate supplementary randomized add-on analysis
These are diabetes-treatment outcomes in a selected metabolic-disease population, not a healthy-user longevity trial.
Read the original sourceRandomized-strategy follow-up · diabetes mortality benefit persisted
Post-trial randomized-strategy follow-up
Adler AI et al. Lancet. 2024. PMID 38772405.
Extended linkage follow-up found that the original early metformin strategy in newly diagnosed type 2 diabetes retained relative risk reductions of 20% for death from any cause and 31% for myocardial infarction versus conventional glycemic control. The corresponding absolute risk reductions were 4.9% and 6.2%.
- Participants / model
- Surviving UKPDS participants followed through linked UK health records
- Treatment
- Original randomized early intensive metformin strategy versus conventional glycemic control
- Follow-up
- Individual follow-up from baseline up to 42 years; extended monitoring up to 24 years after trial end
- Study design
- Intention-to-treat post-trial follow-up of the original randomized strategy
Post-trial treatment was no longer controlled. The result remains specific to early diabetes care, not prophylactic use in healthy people.
Read the original sourceHas metformin been shown to extend human lifespan?
No randomized trial in the cited evidence showed lifespan extension in metabolically healthy people. In the long-term DPP/DPPOS prevention cohort, metformin did not reduce all-cause mortality versus placebo over a median 21 years, HR 0.99. UKPDS mortality benefit occurred in newly diagnosed type 2 diabetes. Different populations prevent either result from answering the healthy-user lifespan claim.
3,234 high-risk adults · no mortality reduction over median 21 years
Long-term follow-up of randomized prevention trial
Lee CG et al. Diabetes Care. 2021. PMID 34697033.
Among 3,234 adults at high risk for type 2 diabetes originally randomized to metformin, lifestyle, or placebo, 453 deaths occurred over a median 21 years. Compared with placebo, metformin did not reduce all-cause mortality, HR 0.99, cancer mortality, HR 1.04, or cardiovascular mortality, HR 1.08.
- Participants / model
- 3,234 adults at high risk for type 2 diabetes
- Treatment
- Original masked metformin, lifestyle, or placebo assignment; later unmasked continuation and cross-over exposure occurred
- Follow-up
- Median 21 years
- Study design
- Long-term observational follow-up by original randomized group with blinded cause-of-death adjudication
After the masked phase, lifestyle was offered broadly and metformin use occurred outside original groups. This is a prevention cohort with metabolic risk, not a metabolically healthy lifespan trial.
Read the original source753 people with new type 2 diabetes · median 10.7 years
Randomized controlled trial
UK Prospective Diabetes Study Group. Lancet. 1998. PMID 9742977.
Among 753 overweight people with newly diagnosed type 2 diabetes, 342 were allocated intensive control with metformin and 411 conventional diet-based care for a median 10.7 years. Relative risk fell 32% for any diabetes-related endpoint, 42% for diabetes-related death, and 36% for all-cause mortality versus conventional care.
- The supplementary add-on comparison in 537 people already on maximum sulfonylurea found a 96% higher diabetes-related-death risk with early metformin addition versus continuing sulfonylurea alone.
- The paper also reported fewer diabetes-related endpoints in a combined main and supplementary analysis, so the adverse add-on signal was not a simple overall verdict.
- Participants / model
- 753 overweight people with newly diagnosed type 2 diabetes in the main randomized comparison
- Treatment
- Protocol-titrated metformin intensive-control policy versus conventional diet-based policy
- Follow-up
- Median 10.7 years
- Study design
- Randomized controlled comparison within UKPDS, plus a separate supplementary randomized add-on analysis
These are diabetes-treatment outcomes in a selected metabolic-disease population, not a healthy-user longevity trial.
Read the original sourceRandomized-strategy follow-up · diabetes mortality benefit persisted
Post-trial randomized-strategy follow-up
Adler AI et al. Lancet. 2024. PMID 38772405.
Extended linkage follow-up found that the original early metformin strategy in newly diagnosed type 2 diabetes retained relative risk reductions of 20% for death from any cause and 31% for myocardial infarction versus conventional glycemic control. The corresponding absolute risk reductions were 4.9% and 6.2%.
- Participants / model
- Surviving UKPDS participants followed through linked UK health records
- Treatment
- Original randomized early intensive metformin strategy versus conventional glycemic control
- Follow-up
- Individual follow-up from baseline up to 42 years; extended monitoring up to 24 years after trial end
- Study design
- Intention-to-treat post-trial follow-up of the original randomized strategy
Post-trial treatment was no longer controlled. The result remains specific to early diabetes care, not prophylactic use in healthy people.
Read the original sourceHealthy-aging evidence · no completed lifespan trial
PubMed and ClinicalTrials.gov records
PubMed and ClinicalTrials.gov records for metformin, healthy aging, and lifespan.
The cited ClinicalTrials.gov records include no completed trial of lifespan extension in metabolically healthy people. In the long-term prevention evidence, DPP/DPPOS found no mortality benefit.
- The cited Russian-language and Russian-affiliation records include one rat sarcopenia paper, three other mouse lifespan papers, and a review; none is a human efficacy trial.
- The cited Chinese-language and China-affiliation records include 42 mostly preclinical or review titles and one 32-man observational epigenetic-age study.
- A 243-patient Chinese-language retrospective geriatric diabetes safety report, PMID 19080232, does not answer healthy-aging efficacy or supersede the current label.
Did metformin improve resistance-training gains in MASTERS?
Among the 94 older adults who completed MASTERS, placebo produced larger lean-body-mass and thigh-muscle gains than metformin during 14 weeks of supervised resistance training. The published correction replaced a relative-strength table row but did not change the muscle-mass conclusion.
109 randomized, 94 completed · hypertrophy blunted
Randomized controlled trial
Walton RG et al. Aging Cell. 2019. PMID 31557380; PMCID PMC6826125.
MASTERS randomized 109 generally healthy adults age 65 and older; 94 completed and were analyzed after a two-week drug ramp plus 14 weeks of supervised progressive resistance training. Placebo produced larger gains in lean body mass, thigh muscle mass, thigh muscle area, and muscle density than metformin.
- The trial used 1,700 mg per day after a one-week titration.
- Strength gains trended lower with metformin but did not reach statistical significance.
- Fifteen randomized participants discontinued, including six because of adverse events.
- Participants / model
- 109 randomized generally healthy adults age 65 and older; 94 completers analyzed
- Treatment
- Metformin titrated to 1,700 mg per day or placebo plus supervised resistance training
- Follow-up
- Two-week drug-only ramp followed by 14 weeks of training
- Study design
- Multicenter randomized double-blind placebo-controlled trial
This trial tested adaptation to a structured exercise program, not lifespan or treatment of sarcopenia.
Read the original sourceCorrection · relative-strength row replaced
Published correction
Aging Cell. 2020. PMID 32141718; PMCID PMC7059173.
The corrigendum replaces an incorrect relative-strength row in Table 2 and updates related supporting information. The corrected relative-strength comparison was p=.30. It does not retract or alter the reported lean-body-mass or thigh-muscle-mass conclusion.
- Study design
- Correction notice tied to the original randomized trial
Does metformin add physical-function benefit to lifestyle training?
In DEMFOS, intensive lifestyle improved physical performance among 114 older adults with obesity. Adding metformin changed the score by 0.1 points versus lifestyle plus placebo, 95% CI -1.2 to 1.4, p=.92.
114 older adults with obesity · no added physical-function gain
Randomized controlled trial
Armamento-Villareal R et al. Lancet Healthy Longevity. 2026. PMID 42532077.
DEMFOS randomized 114 adults age 65 to 85 with obesity to intensive lifestyle plus metformin, intensive lifestyle plus placebo, or healthy-lifestyle education plus metformin. At six months, adding metformin to intensive lifestyle changed the physical-performance score by only 0.1 points versus intensive lifestyle plus placebo, 95% CI -1.2 to 1.4, p=.92.
- Participants / model
- 114 older adults with obesity; 101 men and 13 women
- Treatment
- Intensive weight-management and exercise intervention with metformin or placebo, plus a healthy-lifestyle education and metformin comparator
- Follow-up
- Six months
- Study design
- Randomized placebo-controlled trial with intention-to-treat primary analysis
Intensive lifestyle outperformed education plus metformin, but metformin did not add physical-function benefit to intensive lifestyle. The mostly male sample narrows generalization.
Read the original sourceDid MET-PREVENT improve walking speed in frail older adults?
The four-month adjusted walking-speed difference was 0.001 m/s, p=.96. Metformin recipients also had more recorded adverse events and hospital admissions: 108 versus 77 events and 12 of 35 versus 3 of 36 admitted. The death in the metformin group was judged unrelated.
72 frail or prefrail older adults · walking-speed endpoint null
Randomized controlled trial
Witham MD et al. Lancet Healthy Longevity. 2025. PMID 40147475.
Seventy-two adults age 65 or older with probable sarcopenia and physical prefrailty or frailty were randomized for four months. The adjusted between-group difference in four-meter walk speed was 0.001 m/s, 95% CI -0.06 to 0.06, p=.96.
- Metformin recipients had 108 adverse events among 35 exposed participants versus 77 among 36 placebo recipients.
- Hospital admissions occurred in 12 of 35 versus 3 of 36.
- One death in the metformin group was judged unrelated to study treatment.
- Participants / model
- 72 older adults, mean age 80.4, with probable sarcopenia and physical prefrailty or frailty
- Treatment
- Metformin 500 mg three times daily or placebo
- Follow-up
- Four months
- Study design
- Double-blind randomized placebo-controlled trial; ISRCTN29932357
The authors concluded that metformin did not improve walking speed and was poorly tolerated in this population.
Read the original sourceWhat did the newer two-year frailty trial find?
The July 2026 preprint reported a favorable deficit-accumulation frailty-index change, but not a matching Fried-phenotype benefit once metformin-related weight loss was removed from that score. It randomized 145 people, four declined before dosing, and 141 entered the analysis. The study did not measure lifespan.
| Measure | Result | Limit |
|---|---|---|
| Deficit-accumulation frailty index | -0.006 per year versus placebo, p=.0222 | Positive clinical composite in a preprint |
| Fried phenotype, year one | Worsened by 0.72 points per year versus placebo | Weight loss counted as a frailty component |
| Fried phenotype without weight loss | No between-group difference | Does not confirm the positive index result |
| Blood epigenetic clocks | Two clocks changed favorably | Surrogate biomarkers |
145 randomized, 141 treated · mixed frailty outcomes
Randomized trial preprint
Espinoza SE et al. medRxiv. 2026. PMID 42620010.
In older adults with glucose intolerance, 145 were randomized and four declined before taking study drug, leaving 141 in the analysis. Over two years, the deficit-accumulation frailty index improved by 0.006 per year versus placebo, p=.0222. The Fried phenotype worsened in year one because weight loss counted as a frailty component; after removing that component, there was no between-group difference.
- Metformin produced greater weight loss, -5.7 versus -2.3 kg, p=.0002.
- PC-Horvath2 and PC-Hannum blood clocks changed in a favorable direction.
- This July 2026 preprint had not completed journal peer review.
- Participants / model
- 145 randomized nonfrail or prefrail adults with glucose intolerance; 141 received study drug and entered the analysis
- Treatment
- Metformin titrated as tolerated or placebo
- Follow-up
- Two years
- Study design
- Single-site randomized double-blind placebo-controlled trial reported as a preprint
- Funding
- US National Institute on Aging grant 1R01AG052697-01A1
The two frailty measures did not tell the same story, and epigenetic clocks remain surrogate biomarkers rather than lifespan outcomes.
Read the original sourceNCT02570672 · 141 started, 125 completed
Clinical trial registry with results
ClinicalTrials.gov. NCT02570672.
The registry lists 141 actual participants who started, 70 metformin and 71 placebo; 58 and 67 completed. Both deficit-accumulation frailty index and Fried phenotype are registered primary outcomes. Results were first posted in August 2025.
- Participants / model
- 141 adults age 65 to 90 with prediabetes who began study treatment
- Treatment
- Metformin titrated to 1,000 mg twice daily as tolerated or placebo
- Follow-up
- Two years
- Study design
- Completed phase 2 randomized quadruple-masked parallel trial
The registry count of 141 excludes the four people whom the preprint says were randomized but declined before taking study medication.
Read the original sourceDo the biomarker trials prove slower aging?
Results are mixed, and none is a validated substitute for living longer or avoiding disability. METFORAGING found no primary PhenoAge difference in 35 per-protocol completers with well-controlled HIV. A 2026 North Indian prediabetes trial reported larger telomere length, telomerase activity, and SIRT1 expression, while a small Chinese diabetes study found an observational epigenetic-clock association.
| Study | Population | Finding | What the result does not measure |
|---|---|---|---|
| METFORAGING | 40 randomized adults with HIV; 35 analyzed | Primary PhenoAge difference -1.02 years, p=.627 | Under-enrolled per-protocol pilot |
| North India trial | 127 adults with prediabetes; 112 completed | Telomere and related biomarkers increased | 24 weeks, no clinical aging endpoint |
| Chinese PLA study | 32 older men with type 2 diabetes | Two clock measures associated with metformin use | 16 versus 16, nonrandomized |
40 randomized, 35 analyzed · primary PhenoAge endpoint null
Randomized pilot trial
Marcelo-Calvo C et al. EClinicalMedicine. 2026. PMID 42023167; PMCID PMC13098334.
METFORAGING randomized 40 nondiabetic adults age 50 or older with well-controlled HIV; 35 who completed 96 weeks entered the per-protocol efficacy analysis. The adjusted PhenoAge acceleration difference was -1.02 years, 95% CI -5.30 to 3.26, p=.627, so its primary endpoint was null.
- Enrollment stopped at 40, below the protocol target of 60.
- Dosing started once daily; 11 of 19 metformin participants taking dolutegravir remained once daily because the interaction raises metformin exposure.
- Drug-free follow-up continued to week 144, beyond the primary week-96 report.
- Participants / model
- 40 randomized nondiabetic, virologically suppressed adults with HIV; 35 per-protocol completers
- Treatment
- Metformin 850 mg, usually increased from once to twice daily, or placebo
- Follow-up
- 96-week intervention endpoint with drug-free follow-up to week 144
- Study design
- Single-center randomized double-blind placebo-controlled pilot trial
- Funding
- Instituto de Salud Carlos III and European Union sources stated in the article
The HIV population, under-enrollment, per-protocol analysis, and dolutegravir exposure split limit transfer to healthy aging.
Read the original source127 randomized, 112 completed · biomarkers increased
Randomized biomarker trial
Bhatt SP et al. Mechanisms of Ageing and Development. 2026. PMID 42692117.
In 127 North Indian adults age 30 to 60 with prediabetes, 112 completed 24 weeks. Metformin increased leukocyte telomere length, telomerase activity, and SIRT1 expression versus placebo. The abstract calls for validation of the marked telomere result in larger, longer studies.
- Participants / model
- 127 North Indian adults with prediabetes; 112 completed
- Treatment
- Metformin 500 mg twice daily or placebo, both with lifestyle counseling
- Follow-up
- 24 weeks
- Study design
- Participant-blind and outcome-assessor-blind randomized placebo-controlled trial
Telomere and gene-expression changes are biomarkers. The trial did not measure clinical healthspan or lifespan.
Read the original source32 older men with diabetes · observational association
Cross-sectional observational study
Li M et al. Frontiers in Genetics. 2022. PMID 36226195; PMCID PMC9548538.
The Chinese team compared 16 older men with type 2 diabetes who had taken stable metformin for at least five years with 16 who had not used it for five years. Horvath and Hannum clock measures were associated with slower epigenetic aging in the metformin group.
- Participants / model
- 32 Chinese men with type 2 diabetes, mean age 73.3
- Treatment
- Existing stable metformin use for at least five years versus no metformin use over that period
- Study design
- Small nonrandomized cross-sectional comparison
- Funding
- National Key Research and Development Program of China
Long-term medication groups can differ in unmeasured ways. This association is not a treatment effect or clinical-aging outcome.
Read the original sourceHas metformin been shown to prevent dementia?
A 2026 DPPOS preprint found no significant difference in the overall distribution of cognitive syndromes, while adjusted dementia odds and one memory test favored original metformin assignment. The dementia estimate used few cases, the memory effect was small, and comparison groups later received metformin, so confirmation is needed.
1,483 assessed · overall syndrome distribution null, dementia odds signal
Long-term follow-up preprint
DPP Research Group. medRxiv. 2026. PMID 42620159.
Among 1,483 DPPOS participants assessed decades after initial randomization, overall cognitive-syndrome distributions did not differ by group. Adjusted dementia odds were lower after original metformin assignment versus placebo and lifestyle, while memory performance differed modestly, Cohen d=.1.
- Participants / model
- 1,483 DPPOS participants, median age 74, originally at high risk for type 2 diabetes
- Treatment
- Original metformin, placebo, or intensive-lifestyle assignment followed by long-term open-label and out-of-study exposure
- Follow-up
- Original randomization in 1996 to 1999; cognitive assessment in 2022 to 2024
- Study design
- Prospective long-term analysis by original randomized group, currently reported as a preprint
The overall syndrome distribution was null, dementia cases were limited, metformin crossed into comparison groups, and the report is a preprint without completed journal peer review.
Read the original sourceWhat safety risks matter outside diabetes treatment?
The immediate-release label has a boxed warning for metformin-associated lactic acidosis. Risk rises with renal impairment, interacting drugs, age over 65, iodinated contrast, surgery or restricted intake, hypoxic states, excessive alcohol, hepatic impairment, and mitochondrial disease. Gastrointestinal effects and reduced vitamin B12 are common practical limits.
Metformin is contraindicated below the label’s renal threshold and during acute or chronic metabolic acidosis. The label also flags drugs that reduce metformin clearance, carbonic-anhydrase inhibitors, and increased hypoglycemia risk when combined with insulin or an insulin secretagogue.
DailyMed · type 2 diabetes label, revised April 2026
FDA drug label
DailyMed. Metformin hydrochloride immediate-release tablets, revised April 2026.
The label indicates immediate-release metformin hydrochloride tablets as an adjunct to diet and exercise for glycemic control in adults and children age ten and older with type 2 diabetes. It does not list healthy aging, lifespan, healthspan, dementia prevention, or muscle gain as an indication.
- Metformin lowers hepatic glucose production, reduces intestinal glucose absorption, and improves insulin sensitivity without stimulating insulin secretion.
- The boxed warning concerns metformin-associated lactic acidosis, including fatal postmarketing cases.
- Common reactions include diarrhea, nausea or vomiting, flatulence, asthenia, indigestion, abdominal discomfort, and headache.
- Participants / model
- Adults and pediatric patients age ten and older with type 2 diabetes
- Treatment
- Immediate-release oral metformin hydrochloride under label-specific renal and clinical monitoring
- Study design
- Current regulated product information
72 frail or prefrail older adults · walking-speed endpoint null
Randomized controlled trial
Witham MD et al. Lancet Healthy Longevity. 2025. PMID 40147475.
Seventy-two adults age 65 or older with probable sarcopenia and physical prefrailty or frailty were randomized for four months. The adjusted between-group difference in four-meter walk speed was 0.001 m/s, 95% CI -0.06 to 0.06, p=.96.
- Metformin recipients had 108 adverse events among 35 exposed participants versus 77 among 36 placebo recipients.
- Hospital admissions occurred in 12 of 35 versus 3 of 36.
- One death in the metformin group was judged unrelated to study treatment.
- Participants / model
- 72 older adults, mean age 80.4, with probable sarcopenia and physical prefrailty or frailty
- Treatment
- Metformin 500 mg three times daily or placebo
- Follow-up
- Four months
- Study design
- Double-blind randomized placebo-controlled trial; ISRCTN29932357
The authors concluded that metformin did not improve walking speed and was poorly tolerated in this population.
Read the original sourceNCT02570672 · 141 started, 125 completed
Clinical trial registry with results
ClinicalTrials.gov. NCT02570672.
The registry lists 141 actual participants who started, 70 metformin and 71 placebo; 58 and 67 completed. Both deficit-accumulation frailty index and Fried phenotype are registered primary outcomes. Results were first posted in August 2025.
- Participants / model
- 141 adults age 65 to 90 with prediabetes who began study treatment
- Treatment
- Metformin titrated to 1,000 mg twice daily as tolerated or placebo
- Follow-up
- Two years
- Study design
- Completed phase 2 randomized quadruple-masked parallel trial
The registry count of 141 excludes the four people whom the preprint says were randomized but declined before taking study medication.
Read the original sourceWhich studies define the diabetes and aging results?
Human evidence spans diabetes outcomes, prevention mortality, exercise and frailty trials, and aging biomarkers. Population and endpoint differences matter: benefit in diabetes does not establish lifespan extension in metabolically healthy adults.
PubChem CID 4091 · free base identity
NIH chemical identity record
PubChem Compound Summary for CID 4091, metformin.
The free-base record identifies metformin as C4H11N5 with molecular weight 129.16 and InChIKey XZWYZXLIPXDOLR-UHFFFAOYSA-N.
Read the original sourcePubChem CID 14219 · hydrochloride drug substance
NIH chemical identity record
PubChem Compound Summary for CID 14219, metformin hydrochloride.
The hydrochloride record identifies C4H12ClN5 with molecular weight 165.62 and InChIKey OETHQSJEHLVLGH-UHFFFAOYSA-N. A hydrochloride tablet strength and a free-base molecular mass are not the same identity field.
Read the original sourceDailyMed · type 2 diabetes label, revised April 2026
FDA drug label
DailyMed. Metformin hydrochloride immediate-release tablets, revised April 2026.
The label indicates immediate-release metformin hydrochloride tablets as an adjunct to diet and exercise for glycemic control in adults and children age ten and older with type 2 diabetes. It does not list healthy aging, lifespan, healthspan, dementia prevention, or muscle gain as an indication.
- Metformin lowers hepatic glucose production, reduces intestinal glucose absorption, and improves insulin sensitivity without stimulating insulin secretion.
- The boxed warning concerns metformin-associated lactic acidosis, including fatal postmarketing cases.
- Common reactions include diarrhea, nausea or vomiting, flatulence, asthenia, indigestion, abdominal discomfort, and headache.
- Participants / model
- Adults and pediatric patients age ten and older with type 2 diabetes
- Treatment
- Immediate-release oral metformin hydrochloride under label-specific renal and clinical monitoring
- Study design
- Current regulated product information
753 people with new type 2 diabetes · median 10.7 years
Randomized controlled trial
UK Prospective Diabetes Study Group. Lancet. 1998. PMID 9742977.
Among 753 overweight people with newly diagnosed type 2 diabetes, 342 were allocated intensive control with metformin and 411 conventional diet-based care for a median 10.7 years. Relative risk fell 32% for any diabetes-related endpoint, 42% for diabetes-related death, and 36% for all-cause mortality versus conventional care.
- The supplementary add-on comparison in 537 people already on maximum sulfonylurea found a 96% higher diabetes-related-death risk with early metformin addition versus continuing sulfonylurea alone.
- The paper also reported fewer diabetes-related endpoints in a combined main and supplementary analysis, so the adverse add-on signal was not a simple overall verdict.
- Participants / model
- 753 overweight people with newly diagnosed type 2 diabetes in the main randomized comparison
- Treatment
- Protocol-titrated metformin intensive-control policy versus conventional diet-based policy
- Follow-up
- Median 10.7 years
- Study design
- Randomized controlled comparison within UKPDS, plus a separate supplementary randomized add-on analysis
These are diabetes-treatment outcomes in a selected metabolic-disease population, not a healthy-user longevity trial.
Read the original sourceRandomized-strategy follow-up · diabetes mortality benefit persisted
Post-trial randomized-strategy follow-up
Adler AI et al. Lancet. 2024. PMID 38772405.
Extended linkage follow-up found that the original early metformin strategy in newly diagnosed type 2 diabetes retained relative risk reductions of 20% for death from any cause and 31% for myocardial infarction versus conventional glycemic control. The corresponding absolute risk reductions were 4.9% and 6.2%.
- Participants / model
- Surviving UKPDS participants followed through linked UK health records
- Treatment
- Original randomized early intensive metformin strategy versus conventional glycemic control
- Follow-up
- Individual follow-up from baseline up to 42 years; extended monitoring up to 24 years after trial end
- Study design
- Intention-to-treat post-trial follow-up of the original randomized strategy
Post-trial treatment was no longer controlled. The result remains specific to early diabetes care, not prophylactic use in healthy people.
Read the original source3,234 high-risk adults · no mortality reduction over median 21 years
Long-term follow-up of randomized prevention trial
Lee CG et al. Diabetes Care. 2021. PMID 34697033.
Among 3,234 adults at high risk for type 2 diabetes originally randomized to metformin, lifestyle, or placebo, 453 deaths occurred over a median 21 years. Compared with placebo, metformin did not reduce all-cause mortality, HR 0.99, cancer mortality, HR 1.04, or cardiovascular mortality, HR 1.08.
- Participants / model
- 3,234 adults at high risk for type 2 diabetes
- Treatment
- Original masked metformin, lifestyle, or placebo assignment; later unmasked continuation and cross-over exposure occurred
- Follow-up
- Median 21 years
- Study design
- Long-term observational follow-up by original randomized group with blinded cause-of-death adjudication
After the masked phase, lifestyle was offered broadly and metformin use occurred outside original groups. This is a prevention cohort with metabolic risk, not a metabolically healthy lifespan trial.
Read the original source109 randomized, 94 completed · hypertrophy blunted
Randomized controlled trial
Walton RG et al. Aging Cell. 2019. PMID 31557380; PMCID PMC6826125.
MASTERS randomized 109 generally healthy adults age 65 and older; 94 completed and were analyzed after a two-week drug ramp plus 14 weeks of supervised progressive resistance training. Placebo produced larger gains in lean body mass, thigh muscle mass, thigh muscle area, and muscle density than metformin.
- The trial used 1,700 mg per day after a one-week titration.
- Strength gains trended lower with metformin but did not reach statistical significance.
- Fifteen randomized participants discontinued, including six because of adverse events.
- Participants / model
- 109 randomized generally healthy adults age 65 and older; 94 completers analyzed
- Treatment
- Metformin titrated to 1,700 mg per day or placebo plus supervised resistance training
- Follow-up
- Two-week drug-only ramp followed by 14 weeks of training
- Study design
- Multicenter randomized double-blind placebo-controlled trial
This trial tested adaptation to a structured exercise program, not lifespan or treatment of sarcopenia.
Read the original sourceCorrection · relative-strength row replaced
Published correction
Aging Cell. 2020. PMID 32141718; PMCID PMC7059173.
The corrigendum replaces an incorrect relative-strength row in Table 2 and updates related supporting information. The corrected relative-strength comparison was p=.30. It does not retract or alter the reported lean-body-mass or thigh-muscle-mass conclusion.
- Study design
- Correction notice tied to the original randomized trial
72 frail or prefrail older adults · walking-speed endpoint null
Randomized controlled trial
Witham MD et al. Lancet Healthy Longevity. 2025. PMID 40147475.
Seventy-two adults age 65 or older with probable sarcopenia and physical prefrailty or frailty were randomized for four months. The adjusted between-group difference in four-meter walk speed was 0.001 m/s, 95% CI -0.06 to 0.06, p=.96.
- Metformin recipients had 108 adverse events among 35 exposed participants versus 77 among 36 placebo recipients.
- Hospital admissions occurred in 12 of 35 versus 3 of 36.
- One death in the metformin group was judged unrelated to study treatment.
- Participants / model
- 72 older adults, mean age 80.4, with probable sarcopenia and physical prefrailty or frailty
- Treatment
- Metformin 500 mg three times daily or placebo
- Follow-up
- Four months
- Study design
- Double-blind randomized placebo-controlled trial; ISRCTN29932357
The authors concluded that metformin did not improve walking speed and was poorly tolerated in this population.
Read the original source114 older adults with obesity · no added physical-function gain
Randomized controlled trial
Armamento-Villareal R et al. Lancet Healthy Longevity. 2026. PMID 42532077.
DEMFOS randomized 114 adults age 65 to 85 with obesity to intensive lifestyle plus metformin, intensive lifestyle plus placebo, or healthy-lifestyle education plus metformin. At six months, adding metformin to intensive lifestyle changed the physical-performance score by only 0.1 points versus intensive lifestyle plus placebo, 95% CI -1.2 to 1.4, p=.92.
- Participants / model
- 114 older adults with obesity; 101 men and 13 women
- Treatment
- Intensive weight-management and exercise intervention with metformin or placebo, plus a healthy-lifestyle education and metformin comparator
- Follow-up
- Six months
- Study design
- Randomized placebo-controlled trial with intention-to-treat primary analysis
Intensive lifestyle outperformed education plus metformin, but metformin did not add physical-function benefit to intensive lifestyle. The mostly male sample narrows generalization.
Read the original source145 randomized, 141 treated · mixed frailty outcomes
Randomized trial preprint
Espinoza SE et al. medRxiv. 2026. PMID 42620010.
In older adults with glucose intolerance, 145 were randomized and four declined before taking study drug, leaving 141 in the analysis. Over two years, the deficit-accumulation frailty index improved by 0.006 per year versus placebo, p=.0222. The Fried phenotype worsened in year one because weight loss counted as a frailty component; after removing that component, there was no between-group difference.
- Metformin produced greater weight loss, -5.7 versus -2.3 kg, p=.0002.
- PC-Horvath2 and PC-Hannum blood clocks changed in a favorable direction.
- This July 2026 preprint had not completed journal peer review.
- Participants / model
- 145 randomized nonfrail or prefrail adults with glucose intolerance; 141 received study drug and entered the analysis
- Treatment
- Metformin titrated as tolerated or placebo
- Follow-up
- Two years
- Study design
- Single-site randomized double-blind placebo-controlled trial reported as a preprint
- Funding
- US National Institute on Aging grant 1R01AG052697-01A1
The two frailty measures did not tell the same story, and epigenetic clocks remain surrogate biomarkers rather than lifespan outcomes.
Read the original sourceNCT02570672 · 141 started, 125 completed
Clinical trial registry with results
ClinicalTrials.gov. NCT02570672.
The registry lists 141 actual participants who started, 70 metformin and 71 placebo; 58 and 67 completed. Both deficit-accumulation frailty index and Fried phenotype are registered primary outcomes. Results were first posted in August 2025.
- Participants / model
- 141 adults age 65 to 90 with prediabetes who began study treatment
- Treatment
- Metformin titrated to 1,000 mg twice daily as tolerated or placebo
- Follow-up
- Two years
- Study design
- Completed phase 2 randomized quadruple-masked parallel trial
The registry count of 141 excludes the four people whom the preprint says were randomized but declined before taking study medication.
Read the original source40 randomized, 35 analyzed · primary PhenoAge endpoint null
Randomized pilot trial
Marcelo-Calvo C et al. EClinicalMedicine. 2026. PMID 42023167; PMCID PMC13098334.
METFORAGING randomized 40 nondiabetic adults age 50 or older with well-controlled HIV; 35 who completed 96 weeks entered the per-protocol efficacy analysis. The adjusted PhenoAge acceleration difference was -1.02 years, 95% CI -5.30 to 3.26, p=.627, so its primary endpoint was null.
- Enrollment stopped at 40, below the protocol target of 60.
- Dosing started once daily; 11 of 19 metformin participants taking dolutegravir remained once daily because the interaction raises metformin exposure.
- Drug-free follow-up continued to week 144, beyond the primary week-96 report.
- Participants / model
- 40 randomized nondiabetic, virologically suppressed adults with HIV; 35 per-protocol completers
- Treatment
- Metformin 850 mg, usually increased from once to twice daily, or placebo
- Follow-up
- 96-week intervention endpoint with drug-free follow-up to week 144
- Study design
- Single-center randomized double-blind placebo-controlled pilot trial
- Funding
- Instituto de Salud Carlos III and European Union sources stated in the article
The HIV population, under-enrollment, per-protocol analysis, and dolutegravir exposure split limit transfer to healthy aging.
Read the original source127 randomized, 112 completed · biomarkers increased
Randomized biomarker trial
Bhatt SP et al. Mechanisms of Ageing and Development. 2026. PMID 42692117.
In 127 North Indian adults age 30 to 60 with prediabetes, 112 completed 24 weeks. Metformin increased leukocyte telomere length, telomerase activity, and SIRT1 expression versus placebo. The abstract calls for validation of the marked telomere result in larger, longer studies.
- Participants / model
- 127 North Indian adults with prediabetes; 112 completed
- Treatment
- Metformin 500 mg twice daily or placebo, both with lifestyle counseling
- Follow-up
- 24 weeks
- Study design
- Participant-blind and outcome-assessor-blind randomized placebo-controlled trial
Telomere and gene-expression changes are biomarkers. The trial did not measure clinical healthspan or lifespan.
Read the original source32 older men with diabetes · observational association
Cross-sectional observational study
Li M et al. Frontiers in Genetics. 2022. PMID 36226195; PMCID PMC9548538.
The Chinese team compared 16 older men with type 2 diabetes who had taken stable metformin for at least five years with 16 who had not used it for five years. Horvath and Hannum clock measures were associated with slower epigenetic aging in the metformin group.
- Participants / model
- 32 Chinese men with type 2 diabetes, mean age 73.3
- Treatment
- Existing stable metformin use for at least five years versus no metformin use over that period
- Study design
- Small nonrandomized cross-sectional comparison
- Funding
- National Key Research and Development Program of China
Long-term medication groups can differ in unmeasured ways. This association is not a treatment effect or clinical-aging outcome.
Read the original source1,483 assessed · overall syndrome distribution null, dementia odds signal
Long-term follow-up preprint
DPP Research Group. medRxiv. 2026. PMID 42620159.
Among 1,483 DPPOS participants assessed decades after initial randomization, overall cognitive-syndrome distributions did not differ by group. Adjusted dementia odds were lower after original metformin assignment versus placebo and lifestyle, while memory performance differed modestly, Cohen d=.1.
- Participants / model
- 1,483 DPPOS participants, median age 74, originally at high risk for type 2 diabetes
- Treatment
- Original metformin, placebo, or intensive-lifestyle assignment followed by long-term open-label and out-of-study exposure
- Follow-up
- Original randomization in 1996 to 1999; cognitive assessment in 2022 to 2024
- Study design
- Prospective long-term analysis by original randomized group, currently reported as a preprint
The overall syndrome distribution was null, dementia cases were limited, metformin crossed into comparison groups, and the report is a preprint without completed journal peer review.
Read the original sourceHealthy-aging evidence · no completed lifespan trial
PubMed and ClinicalTrials.gov records
PubMed and ClinicalTrials.gov records for metformin, healthy aging, and lifespan.
The cited ClinicalTrials.gov records include no completed trial of lifespan extension in metabolically healthy people. In the long-term prevention evidence, DPP/DPPOS found no mortality benefit.
- The cited Russian-language and Russian-affiliation records include one rat sarcopenia paper, three other mouse lifespan papers, and a review; none is a human efficacy trial.
- The cited Chinese-language and China-affiliation records include 42 mostly preclinical or review titles and one 32-man observational epigenetic-age study.
- A 243-patient Chinese-language retrospective geriatric diabetes safety report, PMID 19080232, does not answer healthy-aging efficacy or supersede the current label.
Studies and sources
PubChem CID 4091 · free base identity
NIH chemical identity record
PubChem Compound Summary for CID 4091, metformin.
The free-base record identifies metformin as C4H11N5 with molecular weight 129.16 and InChIKey XZWYZXLIPXDOLR-UHFFFAOYSA-N.
Read the original sourcePubChem CID 14219 · hydrochloride drug substance
NIH chemical identity record
PubChem Compound Summary for CID 14219, metformin hydrochloride.
The hydrochloride record identifies C4H12ClN5 with molecular weight 165.62 and InChIKey OETHQSJEHLVLGH-UHFFFAOYSA-N. A hydrochloride tablet strength and a free-base molecular mass are not the same identity field.
Read the original sourceDailyMed · type 2 diabetes label, revised April 2026
FDA drug label
DailyMed. Metformin hydrochloride immediate-release tablets, revised April 2026.
The label indicates immediate-release metformin hydrochloride tablets as an adjunct to diet and exercise for glycemic control in adults and children age ten and older with type 2 diabetes. It does not list healthy aging, lifespan, healthspan, dementia prevention, or muscle gain as an indication.
- Metformin lowers hepatic glucose production, reduces intestinal glucose absorption, and improves insulin sensitivity without stimulating insulin secretion.
- The boxed warning concerns metformin-associated lactic acidosis, including fatal postmarketing cases.
- Common reactions include diarrhea, nausea or vomiting, flatulence, asthenia, indigestion, abdominal discomfort, and headache.
- Participants / model
- Adults and pediatric patients age ten and older with type 2 diabetes
- Treatment
- Immediate-release oral metformin hydrochloride under label-specific renal and clinical monitoring
- Study design
- Current regulated product information
753 people with new type 2 diabetes · median 10.7 years
Randomized controlled trial
UK Prospective Diabetes Study Group. Lancet. 1998. PMID 9742977.
Among 753 overweight people with newly diagnosed type 2 diabetes, 342 were allocated intensive control with metformin and 411 conventional diet-based care for a median 10.7 years. Relative risk fell 32% for any diabetes-related endpoint, 42% for diabetes-related death, and 36% for all-cause mortality versus conventional care.
- The supplementary add-on comparison in 537 people already on maximum sulfonylurea found a 96% higher diabetes-related-death risk with early metformin addition versus continuing sulfonylurea alone.
- The paper also reported fewer diabetes-related endpoints in a combined main and supplementary analysis, so the adverse add-on signal was not a simple overall verdict.
- Participants / model
- 753 overweight people with newly diagnosed type 2 diabetes in the main randomized comparison
- Treatment
- Protocol-titrated metformin intensive-control policy versus conventional diet-based policy
- Follow-up
- Median 10.7 years
- Study design
- Randomized controlled comparison within UKPDS, plus a separate supplementary randomized add-on analysis
These are diabetes-treatment outcomes in a selected metabolic-disease population, not a healthy-user longevity trial.
Read the original sourceRandomized-strategy follow-up · diabetes mortality benefit persisted
Post-trial randomized-strategy follow-up
Adler AI et al. Lancet. 2024. PMID 38772405.
Extended linkage follow-up found that the original early metformin strategy in newly diagnosed type 2 diabetes retained relative risk reductions of 20% for death from any cause and 31% for myocardial infarction versus conventional glycemic control. The corresponding absolute risk reductions were 4.9% and 6.2%.
- Participants / model
- Surviving UKPDS participants followed through linked UK health records
- Treatment
- Original randomized early intensive metformin strategy versus conventional glycemic control
- Follow-up
- Individual follow-up from baseline up to 42 years; extended monitoring up to 24 years after trial end
- Study design
- Intention-to-treat post-trial follow-up of the original randomized strategy
Post-trial treatment was no longer controlled. The result remains specific to early diabetes care, not prophylactic use in healthy people.
Read the original source3,234 high-risk adults · no mortality reduction over median 21 years
Long-term follow-up of randomized prevention trial
Lee CG et al. Diabetes Care. 2021. PMID 34697033.
Among 3,234 adults at high risk for type 2 diabetes originally randomized to metformin, lifestyle, or placebo, 453 deaths occurred over a median 21 years. Compared with placebo, metformin did not reduce all-cause mortality, HR 0.99, cancer mortality, HR 1.04, or cardiovascular mortality, HR 1.08.
- Participants / model
- 3,234 adults at high risk for type 2 diabetes
- Treatment
- Original masked metformin, lifestyle, or placebo assignment; later unmasked continuation and cross-over exposure occurred
- Follow-up
- Median 21 years
- Study design
- Long-term observational follow-up by original randomized group with blinded cause-of-death adjudication
After the masked phase, lifestyle was offered broadly and metformin use occurred outside original groups. This is a prevention cohort with metabolic risk, not a metabolically healthy lifespan trial.
Read the original source109 randomized, 94 completed · hypertrophy blunted
Randomized controlled trial
Walton RG et al. Aging Cell. 2019. PMID 31557380; PMCID PMC6826125.
MASTERS randomized 109 generally healthy adults age 65 and older; 94 completed and were analyzed after a two-week drug ramp plus 14 weeks of supervised progressive resistance training. Placebo produced larger gains in lean body mass, thigh muscle mass, thigh muscle area, and muscle density than metformin.
- The trial used 1,700 mg per day after a one-week titration.
- Strength gains trended lower with metformin but did not reach statistical significance.
- Fifteen randomized participants discontinued, including six because of adverse events.
- Participants / model
- 109 randomized generally healthy adults age 65 and older; 94 completers analyzed
- Treatment
- Metformin titrated to 1,700 mg per day or placebo plus supervised resistance training
- Follow-up
- Two-week drug-only ramp followed by 14 weeks of training
- Study design
- Multicenter randomized double-blind placebo-controlled trial
This trial tested adaptation to a structured exercise program, not lifespan or treatment of sarcopenia.
Read the original sourceCorrection · relative-strength row replaced
Published correction
Aging Cell. 2020. PMID 32141718; PMCID PMC7059173.
The corrigendum replaces an incorrect relative-strength row in Table 2 and updates related supporting information. The corrected relative-strength comparison was p=.30. It does not retract or alter the reported lean-body-mass or thigh-muscle-mass conclusion.
- Study design
- Correction notice tied to the original randomized trial
72 frail or prefrail older adults · walking-speed endpoint null
Randomized controlled trial
Witham MD et al. Lancet Healthy Longevity. 2025. PMID 40147475.
Seventy-two adults age 65 or older with probable sarcopenia and physical prefrailty or frailty were randomized for four months. The adjusted between-group difference in four-meter walk speed was 0.001 m/s, 95% CI -0.06 to 0.06, p=.96.
- Metformin recipients had 108 adverse events among 35 exposed participants versus 77 among 36 placebo recipients.
- Hospital admissions occurred in 12 of 35 versus 3 of 36.
- One death in the metformin group was judged unrelated to study treatment.
- Participants / model
- 72 older adults, mean age 80.4, with probable sarcopenia and physical prefrailty or frailty
- Treatment
- Metformin 500 mg three times daily or placebo
- Follow-up
- Four months
- Study design
- Double-blind randomized placebo-controlled trial; ISRCTN29932357
The authors concluded that metformin did not improve walking speed and was poorly tolerated in this population.
Read the original source114 older adults with obesity · no added physical-function gain
Randomized controlled trial
Armamento-Villareal R et al. Lancet Healthy Longevity. 2026. PMID 42532077.
DEMFOS randomized 114 adults age 65 to 85 with obesity to intensive lifestyle plus metformin, intensive lifestyle plus placebo, or healthy-lifestyle education plus metformin. At six months, adding metformin to intensive lifestyle changed the physical-performance score by only 0.1 points versus intensive lifestyle plus placebo, 95% CI -1.2 to 1.4, p=.92.
- Participants / model
- 114 older adults with obesity; 101 men and 13 women
- Treatment
- Intensive weight-management and exercise intervention with metformin or placebo, plus a healthy-lifestyle education and metformin comparator
- Follow-up
- Six months
- Study design
- Randomized placebo-controlled trial with intention-to-treat primary analysis
Intensive lifestyle outperformed education plus metformin, but metformin did not add physical-function benefit to intensive lifestyle. The mostly male sample narrows generalization.
Read the original source145 randomized, 141 treated · mixed frailty outcomes
Randomized trial preprint
Espinoza SE et al. medRxiv. 2026. PMID 42620010.
In older adults with glucose intolerance, 145 were randomized and four declined before taking study drug, leaving 141 in the analysis. Over two years, the deficit-accumulation frailty index improved by 0.006 per year versus placebo, p=.0222. The Fried phenotype worsened in year one because weight loss counted as a frailty component; after removing that component, there was no between-group difference.
- Metformin produced greater weight loss, -5.7 versus -2.3 kg, p=.0002.
- PC-Horvath2 and PC-Hannum blood clocks changed in a favorable direction.
- This July 2026 preprint had not completed journal peer review.
- Participants / model
- 145 randomized nonfrail or prefrail adults with glucose intolerance; 141 received study drug and entered the analysis
- Treatment
- Metformin titrated as tolerated or placebo
- Follow-up
- Two years
- Study design
- Single-site randomized double-blind placebo-controlled trial reported as a preprint
- Funding
- US National Institute on Aging grant 1R01AG052697-01A1
The two frailty measures did not tell the same story, and epigenetic clocks remain surrogate biomarkers rather than lifespan outcomes.
Read the original sourceNCT02570672 · 141 started, 125 completed
Clinical trial registry with results
ClinicalTrials.gov. NCT02570672.
The registry lists 141 actual participants who started, 70 metformin and 71 placebo; 58 and 67 completed. Both deficit-accumulation frailty index and Fried phenotype are registered primary outcomes. Results were first posted in August 2025.
- Participants / model
- 141 adults age 65 to 90 with prediabetes who began study treatment
- Treatment
- Metformin titrated to 1,000 mg twice daily as tolerated or placebo
- Follow-up
- Two years
- Study design
- Completed phase 2 randomized quadruple-masked parallel trial
The registry count of 141 excludes the four people whom the preprint says were randomized but declined before taking study medication.
Read the original source40 randomized, 35 analyzed · primary PhenoAge endpoint null
Randomized pilot trial
Marcelo-Calvo C et al. EClinicalMedicine. 2026. PMID 42023167; PMCID PMC13098334.
METFORAGING randomized 40 nondiabetic adults age 50 or older with well-controlled HIV; 35 who completed 96 weeks entered the per-protocol efficacy analysis. The adjusted PhenoAge acceleration difference was -1.02 years, 95% CI -5.30 to 3.26, p=.627, so its primary endpoint was null.
- Enrollment stopped at 40, below the protocol target of 60.
- Dosing started once daily; 11 of 19 metformin participants taking dolutegravir remained once daily because the interaction raises metformin exposure.
- Drug-free follow-up continued to week 144, beyond the primary week-96 report.
- Participants / model
- 40 randomized nondiabetic, virologically suppressed adults with HIV; 35 per-protocol completers
- Treatment
- Metformin 850 mg, usually increased from once to twice daily, or placebo
- Follow-up
- 96-week intervention endpoint with drug-free follow-up to week 144
- Study design
- Single-center randomized double-blind placebo-controlled pilot trial
- Funding
- Instituto de Salud Carlos III and European Union sources stated in the article
The HIV population, under-enrollment, per-protocol analysis, and dolutegravir exposure split limit transfer to healthy aging.
Read the original source127 randomized, 112 completed · biomarkers increased
Randomized biomarker trial
Bhatt SP et al. Mechanisms of Ageing and Development. 2026. PMID 42692117.
In 127 North Indian adults age 30 to 60 with prediabetes, 112 completed 24 weeks. Metformin increased leukocyte telomere length, telomerase activity, and SIRT1 expression versus placebo. The abstract calls for validation of the marked telomere result in larger, longer studies.
- Participants / model
- 127 North Indian adults with prediabetes; 112 completed
- Treatment
- Metformin 500 mg twice daily or placebo, both with lifestyle counseling
- Follow-up
- 24 weeks
- Study design
- Participant-blind and outcome-assessor-blind randomized placebo-controlled trial
Telomere and gene-expression changes are biomarkers. The trial did not measure clinical healthspan or lifespan.
Read the original source32 older men with diabetes · observational association
Cross-sectional observational study
Li M et al. Frontiers in Genetics. 2022. PMID 36226195; PMCID PMC9548538.
The Chinese team compared 16 older men with type 2 diabetes who had taken stable metformin for at least five years with 16 who had not used it for five years. Horvath and Hannum clock measures were associated with slower epigenetic aging in the metformin group.
- Participants / model
- 32 Chinese men with type 2 diabetes, mean age 73.3
- Treatment
- Existing stable metformin use for at least five years versus no metformin use over that period
- Study design
- Small nonrandomized cross-sectional comparison
- Funding
- National Key Research and Development Program of China
Long-term medication groups can differ in unmeasured ways. This association is not a treatment effect or clinical-aging outcome.
Read the original source1,483 assessed · overall syndrome distribution null, dementia odds signal
Long-term follow-up preprint
DPP Research Group. medRxiv. 2026. PMID 42620159.
Among 1,483 DPPOS participants assessed decades after initial randomization, overall cognitive-syndrome distributions did not differ by group. Adjusted dementia odds were lower after original metformin assignment versus placebo and lifestyle, while memory performance differed modestly, Cohen d=.1.
- Participants / model
- 1,483 DPPOS participants, median age 74, originally at high risk for type 2 diabetes
- Treatment
- Original metformin, placebo, or intensive-lifestyle assignment followed by long-term open-label and out-of-study exposure
- Follow-up
- Original randomization in 1996 to 1999; cognitive assessment in 2022 to 2024
- Study design
- Prospective long-term analysis by original randomized group, currently reported as a preprint
The overall syndrome distribution was null, dementia cases were limited, metformin crossed into comparison groups, and the report is a preprint without completed journal peer review.
Read the original sourceHealthy-aging evidence · no completed lifespan trial
PubMed and ClinicalTrials.gov records
PubMed and ClinicalTrials.gov records for metformin, healthy aging, and lifespan.
The cited ClinicalTrials.gov records include no completed trial of lifespan extension in metabolically healthy people. In the long-term prevention evidence, DPP/DPPOS found no mortality benefit.
- The cited Russian-language and Russian-affiliation records include one rat sarcopenia paper, three other mouse lifespan papers, and a review; none is a human efficacy trial.
- The cited Chinese-language and China-affiliation records include 42 mostly preclinical or review titles and one 32-man observational epigenetic-age study.
- A 243-patient Chinese-language retrospective geriatric diabetes safety report, PMID 19080232, does not answer healthy-aging efficacy or supersede the current label.
Why is Metformin in D tier?
D concerns healthy-human lifespan and healthspan, not metformin treatment for type 2 diabetes. Diabetes outcomes, a frailty-index preprint, and short-term biomarker changes have not shown longer life in metabolically healthy users.