[Novel aspects in the mechanisms of steroid diabetes and the regulation of hepatic glucose production by insulin and steroids].

Glucocorticoids are known to increase blood glucose levels, and an impairment of glucose tolerance is a common side effect of glucocorticoid therapy and a central feature of Cushing's disease. A major pathophysiological event in this process is an increased glucose production of the liver on the basis of glucocorticoid-induced insulin resistance resulting in an increment in hepatic gluconeogenesis. Both, glucocorticoids and insulin are known to affect the expression of the two gluconeogenic key enzymes, phosphoenolpyruvate-carboxykinase (PEPCK) and glucose-6-phosphatase (G6Pase). While glucocorticoids are known to stimulate the expression of the PEPCK- and G6Pase gene, insulin decreases hepatic glucose production through an inhibition of PEPCK- and G6Pase gene expression. Recently, considerable progress has been made in the understanding of the signal transduction involved in the glucocorticoid- and insulin-dependent regulation of hepatic gluconeogenesis. In this article, we will review the most recent advances and assemble the current knowledge into a clinically relevant pathophysiological model.