Helicobacter pylori infection decreases metformin tolerance in patients with type 2 diabetes mellitus

This study assessed whether Helicobacter pylori infection could influence metformin tolerance in patients with type 2 diabetes mellitus. Demographic, anthropometric, ultrasound, and laboratory data were obtained from 415 metformin-naive patients with diabetes. H. pylori infection was assessed based on the (13)C-labeled urea breath test ((13)C-UBT). The study duration was 4 weeks, and all subjects started metformin from 500 mg/day to 1,500 mg/day progressively. Gastrointestinal side effects were assessed each week, and the metformin doses were adjusted by the compliance. Gastrointestinal side effects were compared between H. pylori-positive and -negative groups. According to the (13)C-UBT results, 220 patients were categorized as H. pylori negative versus 195 as H. pylori positive. At baseline, the scoring of gastrointestinal symptoms showed no statistical difference between the two groups. After 4 weeks, for gastrointestinal symptoms such as abdominal pain, nausea, bloating, and anorexia, the respective percentages in H. pylori-positive and -negative subjects were 44.6% versus 21.8% (P < 0.01), 20.0% versus 9.6% (P < 0.01), 47.7% versus 23.2% (P < 0.01), and 32.8% versus 12.3% (P < 0.01). The final metformin dose was 951.28 ± 661.1 mg in H. pylori-positive subjects, significantly less than that in H. pylori-negative subjects (1,209.09 ± 522.91 mg) (P < 0.01). On multivariate analysis, female gender, H. pylori infection, body mass index, triglycerides, age, and low-density lipoprotein-cholesterol were the independent parameters associated with any gastrointestinal symptoms. Patients with diabetes having H. pylori infection demonstrated more gastrointestinal side effects than those without H. pylori infection after taking metformin. Furthermore, female gender, H. pylori infection, body mass index, triglycerides, age, and low-density lipoprotein-cholesterol are independent determinants of metformin's side effects.