Inclusion Criteria:

• Males age 12 years and 0 days through 24 years and 364 days.
• Tanner stage 4 or 5.
• Accessible medical history and medications history.
• Willingness to fast and complete all clinical evaluations and specimen collection.
• Willingness and ability to give informed consent or assent with parental/legal guardian permission, where required.

Group 1: HIV-Negative Control Subject Specific Inclusion Criteria

• All subjects for Group 1 will be tested for HIV-1 to confirm negativity unless they have a documented negative antibody test within the last three months of study entry.
• Willingness and ability to give informed consent for HIV testing. Groups 2, 3, and 4: HIV-Positive Subject Specific Inclusion Criteria
• HIV-1 infection as documented by a positive result on any of the following licensed tests at any time: any antibody test confirmed by Western blot, HIV culture, plasma HIV-1 RNA PCR >1,000 copies/ml or HIV-1 DNA PCR.
• Horizontal HIV infection transmission (non-perinatal, non-transfusion acquired infection).
• Group 2: Currently not on ART and must never have received ART.
• Group 3: Currently on a NNRTI, non-PI containing regimen for three or more months, must never have received a total of more than six months of PI-containing regimen and at least one year must have passed since receipt of last PI-containing regimen.
• Group 4: Currently on a PI, non-NNRTI containing regimen for three or more months, must never have received a total of more than six months of NNRTI-containing regimen and at least one year must have passed since receipt of last NNRTI-containing regimen.

Exclusion Criteria:

• Transgender male to female (MTF) or female to male (FTM) youth
• Refusal to fast for the 8 hours before collection of laboratory specimen requiring fasting.
• Unable to obtain medical/medications history.
• History of anorexia or bulimia.
• Type I Diabetes Mellitus.
• Type II Diabetes Mellitus and cannot omit diabetes medication for the 48-hour period prior to laboratory specimen collection for oral glucose tolerance test (OGTT).
• Current use or use within the past 6 months of oxandrolone, nandrolone, oxymetholone, stanozolol, or any other synthetic anabolic/androgenic agents.
• Current use or use within the past 6 months of pharmacologic doses of growth hormone. Physiologic growth hormone replacement therapy is permitted, as long as dosages meet the following specifications:
• Adolescents in puberty - less than or equal to an equivalent of 0.1 mg/kg/day
• Adolescents past puberty - less than or equal to an equivalent of 0.025 mg/kg/day
• Current use or use within the past 6 months of pharmacologic doses of testosterone. Physiologic testosterone replacement therapy is permitted as long as dosages meet the following specifications:
• Injection - no more than 400 mg/month of testosterone enanthate
• Patch - no more than 5 mg/day (e.g. Testoderm, Androderm)
• Gel in pre-packaged doses - no more than 7.5 g/day of gel (e.g. Androgel, Testim)