The Effects of Exenatide on Post-Meal Sugar Peaks and Vascular Health in Obese/Pre-Diabetic Young Adults

The primary aim of this study is to evaluate the effect of exenatide on daily glycemic excursions obtained by continuous glucose monitoring system (CGMS). The CGMS summary parameters that we are most interested in include: * The percent of glucose values above 140 mg/dl and/or AUC of glucose values above 140 mg/dl * AUC of glucose values over 100 mg/dl during three days * Maximal meal-related glucose excursions * Three-day mean glucose (including low readings - below 100 mg/dl) Secondary Study Endpoints: Secondary endpoints will include: * glucose tolerance status as assessed by OGTT * Vascular function scores as assessed by PAT, FMD and step test. * Biochemical markers of vascular health, including inflammatory markers, markers of oxidative stress and microalbuminuria. * Changes in BMI