NKX6-1 and obesity due to melanocortin 4 receptor deficiency: To analyze the effects of obesity on β-cell dedifferentiation with NKX6.1 inactivation, non-diabetic samples were divided into four groups according to the BMI standards for Asians special BMI: < 23 (normal), 23–25 (overweight), 25–30 (obesity), ≥30 (over-obesity).