MCU and Hyperglycemia: Mitochondrial calcium uniporter (MCU) is the pore-forming subunit of the Ca2+ uniporter ion channel located on the mitochondrial inner membrane that mediates Ca2+ uptake into the matrix, regulating cytoplasmic Ca2+ signalling.9, –11 MCU is essential for glucose-induced increases in adenosine triphosphate (ATP) concentration in pancreatic β-cells,12 and its knockdown reduces agonist- and depolarization-induced mitochondrial Ca2+ sequestration, ATP production, and d-glucose-stimulated insulin secretion.13 However, the role of MCU in hyperglycaemia-induced EC dysfunction has not been explored.