H6PD and diabetes mellitus: The level of cytosolic enzymes like glucose-6-phosphate dehydrogenase (G6PDH), glutamate dehydrogenase (GDH) and mitochondrial enzyme succinate dehydrogenase (SDH) is reduced in individuals with diabetes, where G6PDH plays a vital role in antioxidant defense against oxidative stress by the production of NADPH [75] while GDH and SDH are involved in insulin secretion [76,77].