Cheung KS, et al. - In Helicobacter pylori-eradicated diabetic patients, researchers investigated the impact of metformin use on gastric cancer (GC) risk and its association with glycemic control. Findings revealed a lower GC risk in association with metformin use, in a duration- and dose-response manner, which was independent of hemoglobin A1c (HbA1c) level.

Methods

• All diabetic patients who were prescribed clarithromycin-based triple therapy for H. pylori infection from 2003-2012 were recruited using a hospital registry database in this territory-wide cohort study.
• Patients were observed from H. pylori therapy prescription until GC diagnosis, death, or end of study (December 2015).
• GC was diagnosed within first year of H. pylori therapy; prior history of GC or gastrectomy, and failure of eradication of infection all were included in exclusion criteria.
• Using Cox model with propensity score adjustment for covariates (age, sex, comorbidities, medications [including insulin], and time-weighted average HbA1c), they estimated the hazard ratio (HR) of GC with metformin (defined as ≥ 180-day use).
• Two-sided statistical tests were performed.

Results

• A median follow-up of 7.1 years (IQR, 4.7-9.8) was performed, during which GC development was noted in 37 (0.51%) of 7,266 diabetic patients at a median age of 76.4 years (IQR, 64.8-81.5 years).
• The investigators noted a reduced GC risk (adjusted HR: 0.49; 95% CI: 0.24-0.98) associated with metformin use.
• Findings suggested a trend towards a lower GC risk with increasing duration (P_trend=0.01) and dose of metformin (P_trend=0.02).
• HbA1c level was not identified as an independent risk factor for GC.