Association between metformin use and cervical cancer risk in women with diabetes in Japan: a retrospective cohort study

Abstract

Background This study aimed to evaluate the association between metformin use and the risk of cervical cancer in women with diabetes compared to dipeptidyl peptidase-4 inhibitors (DPP-4is), using a new-user active-comparator design.

Methods We analyzed data from the JMDC claims database for new users of metformin or DPP-4i between 2010–2022 who were women. Propensity score overlap-weighting was applied to adjust for differences in age, complications, comorbidities, and other anti-diabetic medications. Kaplan–Meier curves and Cox proportional hazards models were used to compare cervical cancer incidence between the metformin and DPP-4i groups.

Results A total of 31,269 eligible individuals were identified, comprising 11,466 metformin users and 19,803 DPP-4i users. Cervical cancer occurred in 11 women (34.0/100,000 person-years) from the metformin group and 34 (59.0/100,000 person-years) in the DPP-4i group. Metformin use was associated with a lower risk of cervical cancer in our unadjusted Kaplan–Meier analysis (P = 0.058), and multivariable-adjusted Cox model (hazard ratio, 0.49; 95% CI, 0.22–1.09; P = 0.082), although neither difference was statistically significant.

Conclusions Our findings did not show a statistically significant association between metformin use and cervical cancer incidence. However, this study’s limited sample size precluded definitive conclusions.