Long-Term Efficacy of Metformin Therapy in Nonobese Individuals With Type 2 Diabetes

Abstract

OBJECTIVE—The U.K. Prospective Diabetes Study (UKPDS) has demonstrated that metformin is as effective as sulfonylureas in obese subjects and is associated with less weight gain, fewer hypoglycemic episodes, and better cardiovascular outcomes. It is hence the pharmacological therapy of choice in this subgroup. However, a gap in our present knowledge is the long-term response to metformin in nonobese individuals. In this study, we compared metformin therapy in normal, overweight, and obese individuals with type 2 diabetes. RESEARCH DESIGN AND METHODS—A database of patients treated at a referral center in Sydney, Australia, were analyzed. Patients with type 2 diabetes and complete HbA1c (A1C) data and treated with metformin or sulfonylurea monotherapy for at least three visits before receiving dual oral therapy were included (n = 644). Analysis by BMI and the type of oral agent was performed. Individuals were categorized as normal, overweight, or obese (BMI <25, 25–29.9, and ≥30 kg/m2, respectively). RESULTS—There were no differences between the initial, follow-up, and last A1C between the three metformin-treated groups. The duration of successful glycemic control with metformin monotherapy in the normal and overweight individuals and their incidences of diabetes-related complications for the entire duration of follow-up were not inferior to those of the obese individuals. The nonobese patients performed better regardless of the type of oral hypoglycemic agent used. CONCLUSIONS—We conclude that metformin is at least as efficacious in normal and overweight individuals as it is in those who are obese. Our study provides evidence-based data to support metformin use in nonobese individuals with type 2 diabetes.