INS and obesity due to melanocortin 4 receptor deficiency: Since patients undergoing hemi pancreatectomy for donation to a relative with type 1 diabetes showed normal 24-h glucose profiles [16], and deterioration of insulin secretion and glucose tolerance one year later [16] with an increased risk of developing T2D only in the presence of obesity and insulin resistance [17], the contribution of the decreased beta-cell mass to the onset of T2D appeared as a subject of debate [6,7].