Methods for Measuring Insulin Sensitivity

INCLUSION CRITERIA: Normal Volunteers: Adults between the ages of 21 and 55 in good general health with no significant underlying illnesses, on no medication, and a normal body mass index (20-26 kg/m(2)). Obese Subjects: Adults between the ages of 21 and 55 in good general health with no significant underlying illnesses, on no medication, and a body mass index between 30 and 35 kg/m(2). Hypertensive Subjects: Adults between the ages of 21 and 55 in good general health except for mild to moderate hypertension (blood pressure between 140/95 and 170/109 off medication), on no medication except for antihypertensive agents. Subjects will be taken off all antihypertensive drugs for at least one week prior to study. If a subjects blood pressure exceeds 180/110 on three determinations over a period of at least 15 minutes, the subject will be withdrawn from the study and appropriate antihypertensive therapy resumed. Diabetic Subjects: Adults between the ages of 21 and 65 in good general health except for non-insulin dependent diabetes mellitus controlled with oral hypoglycemic agents. Subjects on no other medications. If fasting blood glucose exceeds 300 mg/dl, the subject will be withdrawn from the study and appropriate therapy resumed. EXCLUSION CRITERIA: Pregnancy, liver disease, pulmonary disease, end-organ damage such as renal insufficiency, coronary artery disease, heart failure, peripheral vascular disease, proliferative retinopathy, diabetic neuropathy, or HIV infection.