INS and obesity due to melanocortin 4 receptor deficiency: Furthermore, in the group with obesity, a significant correlation was found between the erythrocyte and insulin value after 2 h of OGTT (p = 0.04, r = 0.4), while HGB correlated with glucose and insulin after 2 h of OGTT (p = 0.018, r = 0.45; p = 0.04, r = 0.44, respectively).