The purpose of this study is to compare the vascular effects of two commonly used diabetes medications, rosiglitazone and glyburide in type 2 diabetic patients.

Rosiglitazone and glyburide are two commonly used diabetic medications that have both been shown to be effective in controlling blood glucose levels. Since they work in different ways, they may have different effects on the health of the blood vessels. This study will assess which medication is better at improving the health of the arteries separate from the blood glucose lowering effects. Artery health will be assessed non-invasively by ultrasound. Certain markers of atherosclerosis found in the blood will also be measured.

Inclusion Criteria:

• Age 25-75 years
• Type 2 diabetes mellitus for less than or equal to 10 years
• Pre-screening HbA1c > 6.5 %
• Screening 110 mg/dl < fasting plasma glucose < 240 mg/dl after 2 weeks of metformin 500 mg twice daily (b.i.d.)

Exclusion Criteria:

• Thiazolidinedione or sulfonylurea use in previous 30 days (may undergo washout period of 30 days)
• Known contraindications to use of thiazolidinedione or sulfonylurea
• Female patients must be postmenopausal, surgically sterile, or using adequate contraception
• Uncontrolled hyperlipidemia according to American Heart Association (AHA) guidelines
• Subcutaneous insulin use
• Elevated liver enzymes (2.5 times the upper limit of the reference range)
• Serum creatinine >160 mmol/l
• Anemia (Hb <11 g/dl for men or <10 g/dl for women)
• Body mass index (BMI) <22 or >42 kg/m2
• History of ketoacidosis
• Angina/New York Health Academy class III/IV cardiac insufficiency
• Electrocardiographic evidence of marked left ventricular hypertrophy
• Uncontrolled hypertension according to AHA guidelines
• Hemoglobinopathy

6-months

Small sample size; unbalanced sex distribution between groups