Patients on highly active antiretroviral therapy (HAART) regimens develop potentially deleterious metabolic effects, including insulin resistance, dyslipidemia, osteopenia and osteoporosis, and hyperlactatemia. Changes in body fat distribution and bone metabolism are also documented. There is considerable evidence that protease inhibitors (PI) can induce insulin resistance and increase triglyceride and cholesterol levels. It is now also clear that both metabolic changes and fat distribution abnormalities occur in PI-naive patients treated with nucleoside analogue reverse transcriptase inhibitors (NRTIs). In addition to class specific effects, there is emerging evidence that there are differences within each class of drug in the nature and magnitude of metabolic effects. This study will examine the metabolic effects of HAART in young women.

Adolescent women aged 12 through 24 years will be recruited into each of 5 treatment strata: Stratum 1 - HIV uninfected; Stratum 2 - HIV infected but never had HAART; Stratum 3 - HIV infected on NNRTI regimen for 3 or more months and less than 2 weeks of PI therapy; Stratum 4 - HIV infected on PI regimen for 3 or more months and less than 2 weeks of NNRTI therapy; and Stratum 5 - HIV infected on NRTI-only regimen for 3 or more months and less than 2 weeks of PI or NNRTI therapy. Participants in the study will have one study visit conducted over 1 or 2 days. The study visit will include survey questionnaires, DEXA scanning, anthropometric measurements, and blood tests examining lactate, glucose, and lipid metabolism.