Comparison of gastrointestinal adverse events with different doses of metformin in the treatment of elderly people with type 2 diabetes.

ABSTRACT

WHAT IS KNOWN AND OBJECTIVE: Gastrointestinal discomfort is the most common adverse event of metformin treatment for type 2 diabetes, especially in elderly patients. The aim of this study was to compare gastrointestinal adverse events resulting from different doses of metformin used for the treatment of elderly people with type 2 diabetes. METHODS: A total of 361 elderly patients with newly diagnosed diabetes were randomly divided into three groups metformin 1000 mg/d (N = 120), metformin 1500 mg/d (N = 121) and metformin 2000 mg/d (N = 120). Glycaemic control and gastrointestinal adverse events (abdominal pain, diarrhoea, nausea, vomiting, bloating and anorexia) were assessed and compared among the three groups after 12 weeks of treatment. RESULTS AND DISCUSSION: At baseline, there was no significant difference in gastrointestinal symptoms among the three groups. After 12 weeks of treatment with metformin, the change in HbA1c level was -0.7%, -0.9% and -1.0% for the 1000 mg/d, 1500 mg/d and 2000 mg/d groups, respectively (P < .0001). There was no significant difference in gastrointestinal adverse events among the three groups after treatment with metformin. In total, 62 people (17.2%) could not tolerate the adverse effects of metformin, and most of them stopped treatment in the first 4 weeks. Logistic regression analysis shows that female sex (OR = 2.660, 95%CI 1.692-4.183, P < .0001) and the concurrent use of organic cation transporter 1-inhibiting drugs (OR = 1.874, 95%CI 1.076-3.265, P = .027) are independent risk factors for adverse events. WHAT IS NEW AND CONCLUSIONS: Our data demonstrate that metformin doses of 1000 mg/d-2000 mg/d have similar adverse events but that 2000 mg/d of metformin yields the best glycaemic control in elderly people with diabetes. If elderly people can tolerate 1000 mg/d of metformin, we could gradually increase the dose to 2000 mg/d to achieve better glycaemic control.