Association Between Metformin Use and Risk of Lung Cancer in Patients With Type 2 Diabetes: A Systematic Review and Meta‐Analysis
Mehdi Karimi, Farnaz Hooshmand, Kiana Mohammadian, Seyed Morteza Ali Pourfaraji, Masoud MortezazadehABSTRACT
Background and Aim
Lung cancer remains one of the leading causes of cancer‐related mortality worldwide. Type 2 diabetes mellitus (T2DM), the most prevalent endocrine disorder, is commonly managed with Metformin, an antidiabetic medication that has demonstrated potential anticancer properties. This meta‐analysis aimed to discover the association between Metformin use and the risk of lung cancer in patients with T2DM.
Methods
A comprehensive search of online databases was conducted up to January 1, 2026, to identify relevant observational studies. After screening, appropriate data were extracted. Meta‐analyses utilized the most fully adjusted hazard ratio (HR) with corresponding 95% confidence intervals (CI) as the effect measures. All statistical analyses were performed using R Statistical Software.
Results
The pooled analysis of 29 observational studies showed a significant reduction in lung cancer risk among Metformin users compared with nonusers (HR: 0.85, 95% CI: [0.77–0.94], p = 0.002). Subgroup analyses revealed significant associations in cohort studies (HR: 0.79, 95% CI: [0.70–0.89], p < 0.01) and in studies conducted in Asia (HR: 0.82, 95% CI: [0.68–0.99], p = 0.04). Extended Metformin use (> 3 years) was associated with a significant reduction in lung cancer risk (HR: 0.87, 95% CI: [0.79–0.95]; p < 0.01), whereas no significant effect was observed for shorter durations.
Conclusion
This meta‐analysis indicated a potential protective effect of Metformin use in individuals with T2DM against lung cancer, with a significant risk reduction observed, particularly among long‐term users and in Asian populations. The significant associations identified in cohort studies and in extended‐duration use underscore metformin's promise in lung cancer prevention.