Danazol induces resistance to both insulin and glucagon in young women

Abstract

1. Danazol elevates plasma insulin, plasma glucagon and serum low-density lipoprotein concentrations and reduces the serum high-density lipoprotein concentration. 2. Associations between these disturbances were studied in 17 women receiving danazol therapy for endometriosis. Eleven women underwent intravenous glucose tolerance tests with measurement of plasma glucose, insulin, C-peptide and glucagon concentrations and modelling analysis of intravenous glucose tolerance test concentration profiles. Six women underwent glucagon sensitivity tests. Serum concentrations of lipids and lipoproteins were measured in all cases. 3. Danazol reduced the fasting plasma glucose and insulin concentrations, but markedly raised the fasting plasma glucagon concentration. The insulin and C-peptide responses to the intravenous glucose tolerance test were increased twofold and the net decrement in glucagon concentration was increased tenfold. The glucose response to the intravenous glucose tolerance test was unaffected. Insulin sensitivity was reduced by 55%. Both first-phase plasma insulin responsiveness and net first-phase pancreatic insulin secretion were increased; insulin half-life was prolonged. The glucose response to the glucagon sensitivity test was reduced on treatment. The calculated low-density lipoprotein cholesterol level rose by 20%, whereas high-density lipoprotein cholesterol level fell by 47%. None of these changes in serum lipoprotein levels correlated with changes in insulin metabolism. In general, metabolic changes normalized after 3 months. 4. Danazol increases the sensitivity of pancreatic insulin and glucagon secretion to glucose. Danazol-induced insulin and glucagon resistance could be due to receptor down-regulation resulting from hypersecretion of insulin and glucagon.