With the advent of highly active anti-retroviral therapy(HAART), patients with HIV disease are developing a series of metabolic abnormalities including peripheral fat wasting, increase in truncal fat, high serum triglyceride levels, insulin(a hormone that controls blood sugar) resistance with an increased incidence of Type 2 Diabetes Mellitus and elevated blood pressure. The premise of this study is that abnormalities in the ability of fat and muscle tissue to respond to the hormone insulin may be the cause of the diabetes mellitus, high serum triglyceride levels and abnormal fat distribution. The purpose of the study is to assess how insulin resistant patients with HIV disease are and if their fat and muscle tissue are responding abnormally to insulin. This is done by administering insulin and taking small tissue samples of fat and muscle from the upper thigh and assessing how good insulin acts in these tissues.

Patients with HIV disease will be admitted into the study after undergoing a screening medical history and examination. Once patients qualify, they will have their insulin resistance measured as well as the response of their fat and muscle to insulin; blood levels of glucose (sugar), cholesterol and triglycerides will be measured; body fat will be assessed using radiological tests; a detailed medical history will be obtained to assess risk factors for developing this syndrome.

Patients who are found to be insulin resistant will be offered a trial of an insulin sensitizing agent, called Avandia, for 6-12 weeks. It is hoped that the Avandia will restore the body's ability to respond normally to insulin (as it does in patients with Diabetes) and perhaps improve the fat abnormalities as well. All the same measures will be performed at the end of the course of Avandia as were done at baseline.

Patients who are not insulin resistant will be asked to come back yearly to assess whether they develop insulin resistance over time. This study will continue to recruit patients over the next 3 years.

Inclusion Criteria:

• 18 years and older
• Diagnosis of HIV or AIDS

Exclusion Criteria:

• Positive pregnancy test
• Diagnosis of cancer
• Acute illness (patients can be enrolled once stable)
• Hemoglobin less than 7.0 g/dl or acute heart problems
• Renal function greater than creatinine 1.5 mg/dl
• Liver dysfunction 3 times normal
• Use of medications like glucocorticoids and birth control pills
• Untreated hypertension
• Diabetes mellitus