Dysregulation of autophagy activation induced by atorvastatin contributes to new-onset diabetes mellitus in western diet-fed mice

Background and aims The incidence of statin-induced new-onset diabetes (NOD) is increasing but its underlying mechanisms remain unclear. We aimed to investigate the effects of various doses of atorvastatin (ATO)-induced autophagy on the development of NOD. Methods and results The isolated rat islets and MIN6 cells-treated with ATO, exhibited impaired glucose-stimulated insulin secretion, reduced insulin content, and induced apoptosis. Additionally, autophagy was induced at all doses (in vitro: 5, 10, 20 μM; in vivo: 10, 15, 20 mg/kg) in ATO-treated MIN6 cells or western diet (WD)-fed mice. In contrast to normal glucose-tolerant mice administered a low-dose (10 mg/kg) ATO, those treated with high-doses (15 or 20 mg/kg) exhibited impaired glucose tolerance. Furthermore, high-dose ATO-treated mice showed decreased β-cell mass and increased apoptosis compared to that of vehicle-treated mice. We also observed that the number of vesicophagous cells in the pancreas of 20 mg/kg ATO-treated WD-fed mice was higher than in vehicle-treated WD-fed mice. Inhibiting autophagy using 3-methyladenine (3-MA) and siAtg5 improved glucose tolerance in vivo and in vitro by preventing apoptotic β-cell death and restoring insulin granules. Conclusion These results indicate that high doses of ATO induced hyperactivated autophagy in pancreatic cells, leading to impaired insulin storage, decreased cell viability, and reduced functional cell mass, ultimately resulting in NOD development.