MC4R and type 2 diabetes mellitus: Since genetic variations have occurred for the development of obesity and diabetes, genome-wide associations studies (GWA) have highlighted various genes, e.g., the melanocortin-4 receptor (MC4R) gene for obesity [70] and peroxisome proliferator-activated receptor gamma (PPARG) gene [71] and islet potassium voltage-gated channel subfamily J member 11 (KCNJ11) gene [72] for T2D.