The adrenal steroid, dehydroepiandrosterone (DHEA), has been shown to be therapeutic to genetically diabetic mice of the C57BL/KsJ db/db genotype when fed in the diet at a concentration of 0.4%. One of the most striking effects in this murine model of diabetes mellitus is the almost total prevention of atrophy and degeneration of the pancreatic islets of Langerhans. This study proposes to examine two major parameters by which to further evaluate the nature of this observation: the pancreatic content of the three major islet hormones, insulin, glucagon, and somatostatin; and, the relative volume densities and positional arrangements of the islet and islet cell types responsible for the biosynthesis and secretion of these hormones, the beta, alpha, and delta cells, respectively. Groups of 8 Bks db/db males and their normal litter-mates will be fed 0.4% DHEA in the diet for periods of 0, 2, 6, 12, and 18 weeks. At each time point, animals will be killed and pancreatic extracts will be prepared in acid ethanol and the hormone content assayed using radioimmunoassay. Halves of the same pancreas will be fixed in Bouin's solution and processed by routine histological methods for the immunocytochemical localization of insulin, glucagon and somatostatin using the peroxidase-antiperoxidase method. Sections through the entire pancreas at 140 micrometer intervals will be analyzed for the islet and alpha, beta, and delta cell volume densities using a digitizing tablet with cursor, and graphics and statistical analyses will be generated using statistal analysis programs on a Tandy 1000, 256K, double disk drive personal computer. Graphics will be generated using the Student's t-test, and variances resulting from interactions of genotype, diet, and length of time on diet will be analyzed using analysis of variance. The progress of the diabetes syndrome will be monitored by taking body weights and plasma glucose samples weekly.