SHORT CYCLES OF VERY-LOW-CALORIE DIET IN THE THERAPY OF OBESE TYPE-II DIABETES-MELLITUS

Very Low Calorie Diet (VLCD) is known to induce not only weight loss, but also an improvement of metabolic control, in obese type II diabetics. In order to evaluate the therapeutical efficacy of cycles of VLCD shorter than those previously described, 29 obese type II diabetics and 31 obese nondiabetic subjects were entered as inpatients and prescribed a 450 kcal/day diet for 15 days. Metabolic results obtained were similar to those achieved with longer cycles of VLCD, showing that 15 days are sufficient to induce a BMI decrease in diabetic (BMI from 35.3+/-4.8 to 33.3+/-4.6 after VLCD) and nondiabetic patients (BMI from 40.5+/-7.4 to 38.1+/-7.2 after VLCD), a desired fall of blood glucose levels and the decrease of daily insulin needs in insulin-treated patients. Glucagon tests were performed before and after VLCD in order to study possible modifications of insulin secretion. Although we did not observe any significant increase of C-peptide basal or peak levels (nM/ml) either in diabetic (basal levels before VLDC: 1.2+/-0.4 and peak levels 2.4+/-0.7; basal after VLCD 1.23+/-0.6 and peak 2.6+/-0.7) and nondiabetic patients (basal levels before VLDC 1.0+/-0.3 and peak levels 2.5+/-0.4; basal after VLCD 0.9+/-0.3 and peak 2.4+/-0.6). The rise of the C-peptide/glycemia ratio is an index of an improvement of insulin biological activity, which could be partly responsible for the therapeutical effects of VLCD. In 5 diabetics and 5 obese nondiabetics, insulin receptor number was determined on circulating lymphomonocytes at the beginning and at the end of VLCD. The improvement of insulin sensitivity in diabetic patients after VLCD, which was previously described, does not seem to depend upon an increase in the number or affinity of insulin receptors, and therefore should be mostly ascribed to possible modifications at a post-receptorial level.