Objective The aim of this study was to evaluate any association between metformin use and oncological outcomes of cervical cancer in patients with type 2 diabetes mellitus (DM).

Methods We retrospectively identified 248 patients with cervical cancer with type 2 DM who received primary treatment between 2004 and 2015. The clinicopathological characteristics and oncological outcomes were collected and analyzed. The patients were then separated into metformin use (n = 118) or non–metformin use (n = 130) groups.

Results With a median follow-up of 2.85 years, patients who were given metformin had lower recurrence rate than patients who did not receive metformin (P = 0.011). The 5-year disease-free survival (DFS) and overall survival (OS) were 81.55% and 93.27% in the metformin use group, and 65.06% and 86.82% for the non–metformin use group, respectively. In multivariate analysis, non–metformin use (hazard ratio [HR], 1.89; P = 0.037), baseline hypertension (HR, 2.52; P = 0.005), and stage (HR for stage II vs I, 3.48; HR for stage III vs I, 6.45; P = 0.01) were independent adverse prognostic factors for DFS, whereas the statistically significant independent prognostic factors for OS were age (HR for age >65 vs ≤50, 3.86; P = 0.044) and stage (HR for stage III-IVA vs I-II, 3.45; P = 0.007).

Conclusions Our findings demonstrate that metformin use is associated with improved DFS, but not in OS in patients with cervical cancer with type 2 DM. Further large-scale and long-term follow-up studies are warranted to confirm the antitumor effects of metformin.