Effects of Testosterone Gel on Carbohydrate and Lipid Metabolism In Elderly Obese Men

A. HYPOTHESES: In older men low testosterone levels, abdominal obesity and elevated fasting insulin who are at risk for the cardiovascular complications such as heart attack and stroke. 1. Supplemental testosterone will decrease abdominal adipose tissue and hepatic fat) and appendicular fat and intramyocellular lipid in peripheral muscles (IMCL). 2. Supplemental testosterone will improve insulin sensitivity by: 1. Decreasing hepatic glucose output (HGO), a measure of central insulin resistance 2. increasing peipheral glucose disposal (Rd), a measure of periperal insuln sensiivity 3. . Improving peripheral glucose disposal (Rd) by reducing IMCL 4. Increasing appendicular skeletal muscle mass B. OBJECTIVES: 1. Primary Objective: To determine the effects of supplemental testosterone to achieve testosterone levels in the upper normal physiologic range on central adipose tissue (abdominal and hepatic fat) and peripheral skeletal muscle fat (appendicular fat and IMCL). 2. Secondary Objectives: To determine the effects of supplemental testosterone to achieve testosterone levels in the upper normal physiologic range:on central insulin sensitivity ( hepatic glucose output ([HGO]) and peripheral insulin sensitivity (glucose disposal (Rd) Results of this study will provide greater understanding whether androgen therapy enhances insulin sensitivity by decreasing HGO, improving peripheral Rd and if these desired effects are achieved, whether they are due to reductions in abdominal fat or liver lipid, IMCL or effects of augmenting muscle mass per se. Results will generate hypotheses to investigate cellular and molecular mechanisms of androgen effects in persons at risk for the Metabolic Syndrome.