What role does MC4R play in blood sugar?

MC4R (melanocortin 4 receptor) is a key regulator of energy balance and appetite in the hypothalamus. Its primary role is controlling food intake and energy expenditure. Regarding blood sugar, MC4R acts indirectly: impaired MC4R signaling (e.g., due to mutations) can lead to hyperphagia and obesity, which in turn promote insulin resistance and elevated blood glucose. There is also evidence that MC4R directly modulates insulin secretion and hepatic glucose production, but these effects are less well-established in humans than its appetite-regulating function. GWAS studies link MC4R variants to obesity and type 2 diabetes risk, but the direct effect on fasting glucose is weak. Single SNP results from consumer DNA tests have no clinical utility for blood sugar management. Evidence: mechanistic, moderate human support.