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Home › Research › What the research found › Every row

Every row of the evidence table

One row per finding: what was tested, which way the result went, and how the study was built. The answer by area, and where the studies disagree, are on the main page.

Every row

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Area All 382 Care, carers and services 140 Medicines 85 Genes (not modifiable) 35 All modifiable factors together 27 Diet and supplements 23 Exercise and activity 21 Sleep, mood and social life 19 Hearing and vision 8 Alcohol, tobacco and cannabis 6 Infection and vaccination 5 Heart and metabolic health 4 Injury, delirium and falls 4 Environment 3 Cognitive activity 2
Question Both Prevention 190 Treatment 192
Direction Any Benefit 144 Harm 105 No effect 38 Mixed 37 No direction reported 58
Design Any meta-analysis 57 randomised trial 44 phase 3 trial 15 systematic review 9 phase 2 trial 10 cohort study 136 phase 1 trial 2 cross-sectional study 31 case-control study 14 modelling study 20 regulatory decision 7 company announcement 1 coverage determination 1 None 35
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Showing 5 of 382 rows for Metformin / antidiabetic. One row per study per exposure: a study that tested two different things appears twice, once for each.

Scroll the table sideways to see every column.

Research and outcomes, 5 rows. Every row links to its source.
Exposure Question Direction Outcome measured Design People Effect size, as the source reported it Source
Metformin / antidiabetic Medicines Prevention Benefit
why

Heterogeneity was near-total (I-squared 98.9%) and the estimate went to null in people newly diagnosed with diabetes (HR 1.01), which is where prevalent-user bias would be smallest.

 Incident dementia meta-analysis 3,463,100 HR 0.76 (95% CI 0.65-0.91) vs non-users overall; HR 1.01 (0.81-1.27) in newly diagnosed diabetes Diabetes, Obesity and Metabolism 2025
✓ Peer-reviewed PMID 39780315
Metformin / antidiabetic Medicines Prevention No effect
why

Designed around new diabetes diagnoses with a landmark analysis and a one-year lag, which removes the prevalent-user advantage that inflates metformin's apparent benefit in the pooled cohorts.

 Incident dementia cohort study 34,700 Adjusted HR 1.05 (95% CI 0.96-1.15), no association Journal of Internal Medicine 2024
✓ Peer-reviewed PMID 37747779
Metformin / antidiabetic Medicines Prevention Benefit
why

Comparator is other oral antidiabetic drugs, not no treatment.

 All-cause dementia and Parkinson's disease cohort study 358,862 All-cause dementia aHR 0.79 (95% CI 0.69-0.90) for SGLT2 inhibitor vs other oral antidiabetic drugs Neurology 2024
✓ Peer-reviewed PMID 39292986
Metformin / antidiabetic Medicines Prevention Mixed
why

The split inside this one paper is the finding: the 41 observational studies show large benefits (SGLT2i OR 0.56, GLP-1RA OR 0.58) while the 23 randomised trials show no difference. When design and result disagree this cleanly, the trials are the ones to believe.

 Incident dementia meta-analysis 3,462,926 Observational: SGLT2i OR 0.56 (95% CI 0.45-0.69), GLP-1RA OR 0.58 (0.46-0.73) vs non-users; RCTs: no difference Alzheimer's Research & Therapy 2024
✓ Peer-reviewed PMID 39716328
Metformin / antidiabetic Medicines Prevention Benefit
why

The exposure actually studied is STOPPING metformin early, which carried 21% higher dementia incidence than staying on it. Read as indirect support for metformin, not as a trial of it.

 Incident dementia cohort study 41,346 HR 1.21 (95% CI 1.12-1.30) for dementia after early metformin termination JAMA Network Open 2023
✓ Peer-reviewed PMID 37878309

How this table was built, and where it is weak →