1. Diabetes, Endocrinology, and Obesity Branch, National Institutes of Health, Bethesda, Maryland.
2. Department of Nutrition, National Institutes of Health, Bethesda, Maryland.
3. Department of Laboratory Medicine, Clinical Center, National Institutes of Health, Bethesda, Maryland.
4. Office of the Director, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland.