Long-term treatment study of global standard dose metformin in Japanese patients with type 2 diabetes mellitus

In 169 Japanese patients with type 2 diabetes mellitus with blood glucose levels that were inadequately controlled with diet and exercise therapy alone, or with diet and exercise therapy plus a sulfonylurea (SU) drug, we evaluated the safety and efficacy of global standard dose metformin given up to a maximum daily dose of 2250 mg for 54 weeks. The changes in HbA1c from baseline to the final evaluation visit were −1.32 ± 0.76% for metformin monotherapy and −1.29 ± 0.81% for metformin plus SU, both significantly lower than baseline. The incidences of adverse events and adverse drug reactions were 91.1% (154/169 patients) and 67.5% (114/169 patients), respectively. The most common adverse events were gastrointestinal symptoms, and most of the gastrointestinal symptoms were considered by investigators to be related to metformin treatment. An increased blood lactic acid level was observed in three subjects (1.8%); however, no clinical symptoms were reported, and there was no increase in mean lactic acid concentration throughout the evaluation period. Symptoms of hypoglycemia were reported in 16 patients, all receiving metformin plus SU, but none received metformin monotherapy. There was a decrease in mean body weight. Global standard dose metformin may be useful for maintaining good blood glucose control over the long term in the treatment of type 2 diabetes mellitus in Japanese patients.