Effect of metformin on patients with impaired glucose tolerance.

AIMS: To evaluate the effect of metformin on glucose metabolism, insulin sensitivity and rate of conversion diabetes in people with impaired glucose tolerance (IGT). METHODS: Seventy subjects with IGT were randomized under double-blind conditions to receive either placebo (n = 37) or metformin (n = 33) at a dosage of 250 mg three times daily for a duration of 12 months. Glycaemic control, plasma insulin and other biochemical indexes were assessed before and after 3, 6 and 12 months. RESULT: At 12 months the conversion rate to diabetes was 16.2% in the placebo group compared to 3.0% for the metformin group (P = 0.011). Of subjects treated with metformin for 12 months, 84.9% became normoglycaemic compared to 51.4% of those receiving the placebo. Significant improvements in fasting glucose, glucose tolerance and insulin sensitivity were found at 12 months and at intermediate clinic assessments. CONCLUSIONS: Metformin can improve glucose metabolism in IGT patients and may be a treatment option in their management of IGT subjects.