REN and glucose metabolism disease: Notable new findings of this study include the following: (i) RASi relieved Tac-induced glucose metabolism disorder; (ii) RASi mitigated Tac-induced β-cell dysfunction by promoting the imbalance of β-cell proliferation and apoptosis; (iii) RASi alleviated Tac-induced vascular dysfunction in dorsal pancreatic arteries and pancreatic hypoxia; (iv) Tac activated RAS by promoting renin expression and secretion, which is in turn caused by vascular dysfunction in renal arteries and the ensuing kidney hypoperfusion and hypoxia.