Randomised controlled trialindependent cross-checkabstract only checked★ key study I-ODD-01 in-depth review
Metformin in overweight type 2 diabetes (UKPDS 34)
Effect of intensive blood-glucose control with metformin on complications in overweight patients with type 2 diabetes (UKPDS 34). UK Prospective Diabetes Study (UKPDS) Group.
Overview
UKPDS Group. Lancet 1998 · PMID 9742977
Metformin reduced deaths from any cause by about a third over 10 years.
Does the study support the specific claim? No · Methodological quality: moderate
Plain-language summary
Study explained simply
- What did the researchers want to find out?
Intensive control with metformin in overweight type 2 diabetes
- How was the study done?
RCT within UKPDS (UKPDS 34)
- How many people, animals or samples were studied?
753 (main comparison); Overweight newly diagnosed type 2 diabetes, mean age 53
- What was actually found?
Mortality -36%.
- How large was the observed effect?
RR reduction 36% (9-55)
- What do the results mean in everyday life?
Metformin is protective.
- What are the study's limitations?
Small arms; Open-label; Conflicting supplementary result
- What does it say about Elawady's specific claim?
- Do the results apply to Germany and Europe?
UK.
- What can explicitly not be concluded from this study?
Effects in non-overweight patients.
Scientific in-depth review
1. Full reference
- Authors
- UKPDS Group
- Journal
- Lancet
- Year
- 1998
- Identifier
- PMID 9742977
- Verification
- verified – PubMed efetch 2026-10-25 (this agent)
- Retracted
- no
- Corrections
ErratumIn: Lancet 1998 Nov 7;352(9139):1558
- Extent checked
- abstract only
- Conflicts of interest and funding
not stated in abstract
2. Research question
Intensive control with metformin in overweight type 2 diabetes
3. Study design and population
- Study design
- Randomised controlled trial – RCT within UKPDS (UKPDS 34)
- Population
Overweight newly diagnosed type 2 diabetes, mean age 53
- Country
UK
- Period
Median 10.7 years
- Sample size
753 (main comparison)
- Inclusion and exclusion criteria
As described in the abstract; details not available in abstract.
4. Methods and endpoints
- Exposure / intervention
Metformin
- Comparator
Conventional diet policy
- Endpoints
Any diabetes-related endpoint, diabetes-related death, all-cause mortality
- Statistical methods
Intention to treat
5. Actual results
- Results
HbA1c 7.4% vs 8.0%. Any diabetes endpoint -32% (13-47); diabetes-related death -42% (9-63); all-cause mortality -36% (9-55). Metformin better than SU/insulin for any endpoint, mortality, stroke. Early metformin added to SU: diabetes-related death +96% (2-275) in supplementary trial, not confirmed in combined epidemiological analysis.
- Absolute risks
not reported
- Authors' conclusion
Metformin decreases diabetes-related endpoints in overweight patients with less weight gain and hypoglycaemia; may be first-line.
6. Strengths
- Long RCT
7. Weaknesses
- Small arms
- Open-label
- Conflicting supplementary result
8. Risk of bias
- Orienting tool
- RoB 2
- Type of assessment
- simplified assessment (abstract only)
- Full formal assessment
- no
- Overall risk of bias
- some concerns
- Rationale
Small sample; open-label.
9. Assessment of the statistical interpretation
Wide CIs.
10. Relevance to the specific claim
Contradicts C-ODD-01, C-ODD-06; supports C-INS-11.
11. Independent contrary findings
Supplementary SU+metformin finding.
12. Transferability to Germany and Europe
UK.
13. Overall methodological judgement
Foundation of metformin first-line use.
| Multidimensional assessment | |
|---|---|
| Authenticity of the source | verified |
| Methodological quality | moderate |
| Risk of bias | some concerns |
| Precision of results | moderate |
| Directness | direct |
| Reproducibility | partly replicated |
| Consistency with the overall evidence | mixed |
| Regional transferability | high |
| Adequacy of the interpretation (by the archive) | not applicable |
14. Open questions
None beyond those stated.
15. Linked fact checks
- Archive conclusion: insulin is indispensable in type 1 diabetes; in type 2 diabetes, evidence supports caution with intensive dosing, prioritising metformin, weight loss and dietary change before insulin escalation, and aiming for moderate rather than near-normal HbA1c; this is not the same as rejecting insulin. – Studies supporting the claim
- Metformin (Glucophage) disrupts normal metabolism and causes lactic acidosis (automatically, by blocking the Cori cycle). – Studies contradicting or limiting the claim
- Every major class of glucose-lowering drug (metformin, sulfonylureas, thiazolidinediones, DPP-4 inhibitors, SGLT2 inhibitors, GLP-1 agonists) carries a documented signal of serious harm in the peer-reviewed literature. – Studies contradicting or limiting the claim
- Glucose-lowering drugs are net harmful and belong among the 'forbidden' items; dapagliflozin (Forxiga) is among the 'dirtiest' drugs and kills the brain; leg amputations happen only to people taking diabetes drugs and insulin. – Studies contradicting or limiting the claim
- Long-term metformin lowers vitamin B12 and increases B12 deficiency (de Jager RCT: -19%, +7.2 percentage points deficiency over 4.3 years; DPPOS confirms). – Studies with mixed or unclear results
- Sulfonylureas cause more myocardial infarctions, strokes and deaths than metformin (21% higher in 253,690 veterans). – Studies supporting the claim