Evidence check: MC4R in the context of blood sugar

The MC4R gene (melanocortin 4 receptor) is primarily involved in appetite regulation and energy balance. Variants in MC4R are strongly linked to obesity (both monogenic and common forms). The connection to blood sugar is indirect: obesity often leads to insulin resistance and impaired glucose metabolism. Some GWAS have found modest associations between MC4R variants and fasting glucose or type 2 diabetes risk, but these effects are small and often confounded by BMI. Evidence is moderate (human-observational/GWAS), not strong enough for clinical recommendations. Blood sugar management should focus on lifestyle and established risk factors.