• Mean change in insulin sensitivity from baseline to Month 9.
  

• Mean change, baseline to Month 9, in body weight and composition, Body Mass Index (BMI), lipid profile, fasting glucose; blood pressure; safety evaluations (adverse events) during study.
  

Topiramate is not approved for the treatment of obesity. This double-blind, placebo controlled study investigates the effect of topiramate on insulin sensitivity in overweight or obese patients with Type 2 Diabetes. After a screening phase, patients are randomized to receive either topiramate (96 milligrams[mg] twice daily) or placebo for 9 months in the double-blind phase. After 9 months, patients have the option to continue in the open-label phase and receive treatment with topiramate for 1 year. Patients in the placebo group then receive topiramate with dosage increasing gradually to 96 mg twice daily, with the option of increasing to 256 mg twice daily. Patients in the topiramate group continue with the maintenance dose received during the double-blind phase, with the option of increasing to 256 mg twice daily. Assessments of effectiveness made monthly include insulin sensitivity, body composition (as measured by computed tomography [CT]), body weight and Body Mass Index (BMI), waist and hip circumferences, fasting lipid profile, fasting glucose and hemoglobin type A1c (HbA1c) levels, and blood pressure. Safety evaluations, including incidence of adverse events, clinical laboratory results, vital signs, and electrocardiograms [ECGs]), are performed throughout the study. The study hypothesis is that topiramate will improve insulin sensitivity in type 2 diabetic patients and will be well tolerated. Patients will be randomized to receive 192 mg/day (96mg twice daily) of topiramate, or placebo, per mouth for 9 months, with an option of topiramate treatment increasing to 256mg/day both groups during the extension period of 1 year.