The goal of this research study is to study the effect of testosterone or estrogen on blood sugar control and fat metabolism. Changes in hormone levels with age may affect risk factors for heart disease such as diabetes. Diabetes is a glandular condition associated with lack of the hormone insulin or an insensitivity to it resulting in problems with blood sugar control and fat metabolism. The effect of commonly used hormonal supplements such as testosterone by older adults on insulin and body composition is not well understood. In this study, the role of testosterone and estrogen on your ability to control blood sugar and your body composition will be assessed.

We plan to study 60 subjects. All of these subjects will be healthy older men between the ages of 60-85 years old who are not on testosterone therapy. Subjects that are screened who have any clinically significant abnormalities detected on their screening physical exam or laboratory testing (e.g. PSA > 4), who have a history of prostate cancer, polycythemia, or who cannot take testosterone will not be included.

If a subject is eligible to participate after initial screening, that subject will take medications to adjust their hormone levels and have tests performed that measure insulin sensitivity and adiposity before and after these hormone medications. The outcomes that will be measured are: 1) insulin sensitivity, 2) hormone levels (total and free testosterone levels, sex hormone-binding globulin levels) and 3) body composition and abdominal adiposity.