There is increasing evidence that inflammation plays a role in progression and destabilization of atherosclerotic plaque. FDG-PET can visualize activated metabolic activity of inflammatory cells. It is possible that FDG-PET can detect atherosclerotic plaque inflammation and that FDG-PET can monitor the effect of pioglitazone on plaque inflammation.

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.

Inclusion Criteria:

• Subjects between the ages of 35 and 85 years
• Subjects with impaired glucose tolerance and type 2 diabetes, who had atherosclerosis detected by carotid ultrasound and/or CT
• Subjects who had vascular FDG uptake by FDG-PET

Exclusion Criteria:

• Subjects with insulin treatment
• Subjects with uncontrolled diabetes, hypertension, symptomatic coronary artery disease, symptomatic cerebrovascular disease
• Subjects taking more than three antidiabetic medications
• Subjects taking anti-platelet, statins, antidiabetic agents, thiazolidinediones (TZDs) within 8 weeks prior to randomization
• Subjects with cardiac failure (New York Heart Association Class > III) or left ventricular dysfunction (LVEF < 40%)
• Subjects with systemic disorders such as active inflammatory, liver, renal, hematopoietic, and malignant disease