Every study we read on this question

Trials in people (10)

• 10.7-year trial in 753 overweight adults with diabetes: metformin lowered risk of death
  Randomized trial1998753 peoplePoints to benefit
• 4-month trial in 72 frail older adults: metformin did not change walking speed
  Randomized trial202572 peopleNo difference
• Trial in 1830 adults at diabetes risk: no clear change in walking on metformin
  Randomized trial20241,830 peopleNo difference
• 12-week trial in 53 older adults: metformin blunted fitness gains from exercise training
  Randomized trial201953 peoplePoints to harm
• Trial in men, 29 to 45: metformin did not clearly change biological age test
  Randomized trial2025No difference
• Trial in 105 pregnant women without diabetes: metformin did not change placenta aging signs
  Randomized trial2025105 peopleNo difference
• Two small trials in people with HIV: blood cell age clocks fell with metformin
  Randomized trial2024Points to benefit
• A trial in 20 healthy older adults: metformin lessened muscle shrinkage during bed rest
  Randomized trial202320 peoplePoints to benefit
• 2-week trial in 16 healthy older adults found mixed muscle energy results with metformin
  Randomized trial202216 peopleMixed
• 14-week trial in 47 older adults found mixed results for metformin during strength training
  Randomized trial202047 peopleMixed

Population studies (8)

• Study of 31177 memory-clinic patients: metformin went with slower decline in thinking
  Population study: followed a group202631,177 peoplePoints to benefit
• Study of 4278 Scottish adults: stopping metformin in kidney disease went with lower survival
  Population study: followed a group20254,278 peoplePoints to benefit
• Study of 373 adults found no clear link between metformin gut bacteria and memory
  Population study: followed a group2024373 peopleNo difference
• Study of 188983 older adults with diabetes: closer pill-taking went with lower death risk
  Population study: cases vs controls2023188,983 peoplePoints to benefit
• Study of 4851 Swedes with esophageal cancer: metformin use went with lower death risk
  Population study: followed a group20234,851 peoplePoints to benefit
• Study of 20314 UK adults: metformin use showed no clear link to better thinking
  Population study: one-time survey202220,314 peopleNo difference
• Study of ovaries in mice and women: metformin use went with less immune activity
  Population study: followed a group202027 peoplePoints to benefit
• Study of 4038 people with diabetes and kidney disease: metformin went with lower death
  Population study: followed a group20194,038 peoplePoints to benefit

Animal and cell (3)

• In mice given a drug that speeds aging signs, metformin countered some aging markers
  Animal study2022Points to benefit
• In worms and lab-grown human cells, metformin given late in life shortened lifespan
  Animal study2020Points to harm
• In middle-aged male mice, 0.1% metformin in food extended lifespan; 1% was toxic
  Animal study2013Points to benefit

Reviews (3)

• Pooled review: in diabetes, metformin was linked to lower liver cancer risk
  Pooled review (meta-analysis)2022Points to benefit
• Pooled review of 53 studies: diabetics on metformin had lower death risk than non-diabetics
  Pooled review (meta-analysis)2017Points to benefit
• Pooled review of 204 studies: fewer heart deaths with metformin, little clear evidence otherwise
  Pooled review (meta-analysis)2016Mixed

Opinion (2)

• Review of metformin use beyond diabetes, including aging, with trials planned
  Opinion or narrative review2022No direction
• Review of the case for metformin as an anti-aging drug
  Opinion or narrative review2019No direction