We will recruit 1132 healthy, non-diabetic individuals (546 men, 586 women), age range 18-65, and body mass index (3 subgroups: nonobese, overweight and obese). We need to recruit more women than men because triglyceride and glucose levels are lower in women than men. Therefore a larger number of women are needed to see an effect. In 3 outpatient visits to the Clinical Center, participants will have body fat analyses, an electrocardiogram, an oral glucose tolerance test, questionnaires about sleep and stress and an intravenous glucose tolerance test. This study has the potential to provide significant insight and lead to the development of programs that help decrease diabetes and cardiovascular risk in blacks.