A case of glucocorticoid-induced diabetes in which the efficacy between sitagliptin and metformin was compared

To date, promising strategies for treating glucocorticoid (GC)-induced diabetes with antidiabetic drugs have not been established. We herein report the case of a woman with GC-induced diabetes in which we compared the efficacy of two kinds of orally administered antidiabetic drugs sitagliptin and metformin by continuous glucose monitoring (CGM) and meal-challenge test (MCT). As a result, CGM showed that daily fluctuation of blood glucose levels was reduced during administration of metformin but not during administration of sitagliptin. On the other hand, MCT showed that administration of metformin reduced plasma glucose levels accompanied by the decrease of plasma insulin levels and the increase of plasma glucagon levels, whereas administration of sitagliptin had little effects on these parameters. This case is the first report to compare the efficacy between sitagliptin and metformin in glucose homeostasis by CGM and MCT in a patient with GC-induced diabetes.