Atherosclerotic patients with impaired glucose tolerance and type 2 diabetes will undergo the FDG-PET/CT imaging at baseline and again following 4 months after treatment. Patients who meet eligibility criteria will be titrated up to a maximum of 30 mg/day pioglitazone or 4 mg/day glimepiride. Physical examinations will be done at baseline, 4 months, and 12 months. During study, subjects will have body weight, and vital signs (HR, BP, etc) assessed as well as waist circumference. Laboratory assessments will be done at each baseline, 4 month.