The purpose of this study is to determine whether atazanavir use is of influence on the endothelial dysfunction associated with type 2 diabetes mellitus.

Inclusion Criteria (most important):

• 18 - 70 years
• type 2 diabetes mellitus treated with diet, oral medication and/or insulin
• BMI of 18 to 35
• determinants of renal and hepatic function within twice the upper limit of normal range, abnormalities in lipid profile permitted

Exclusion Criteria (most important):

• history of smoking within past year
• history of or current abuse of drugs, alcohol or solvents
• current use of antihypertensive, cardiac or other vasoactive medication
• clinical evidence of cardiac or pulmonary disease