INS and obesity due to melanocortin 4 receptor deficiency: Given that mitochondria are impacted by both obesity [24] and hypoxia [25, 26], we examined the metabolic effects of diet-induced obesity and sustained hypoxic exposure on whole body glucose disposal and insulin responsiveness, and mitochondrial function of the muscle and liver in C57BL/6J mice fed either a regular chow or high-fat diet and exposed to continuous or nocturnal hypoxia for two weeks.