IS TYPE-2 DIABETES A DIFFERENT DISEASE IN OBESE AND NONOBESE PATIENTS

OBJECTIVE - The main purpose of this work was to study the possible di fferences in insulin secretion in a large group of type 2 diabetic pat ients in relation to diabetes duration, obesity, and the presence of s econdary failure after treatment with oral hypoglycemic agents. RESEAR CH DESIGN AND METHODS - There were 147 nonobese and 215 obese type 2 d iabetic subjects, aged 35-80 years, investigated in a cross-sectional descriptive study. Subjects were grouped according to whether glycemic control was good (mean blood glucose <8.5 mmol/l) or poor. beta-Cell function was assessed by measuring meal-stimulated insulin and C-pepti de concentrations, as the mean of the three postprandial increments ab ove the premeal value. RESULTS - Basal C-peptide concentrations were s ignificantly higher in obese than nonobese patients of both groups. Th e mean of meal-stimulated C-peptide concentrations was also significan tly higher in obese than nonobese patients with good glycemic control, but not in the secondary failure groups. In nonobese and obese patien ts considered separately, a significant negative correlation between t he mean of daily blood glucose and meal-stimulated C-peptide was obser ved (r = -0.705 and r = -0.679, respectively, P < 0.001) and the resid ual beta-cell function was significantly correlated with the known dur ation of diabetes and metabolic control, but not with BMI, in both gro ups. CONCLUSIONS - On average, obese diabetic subjects showed higher m eal-stimulated C-peptide than nonobese subjects only in well-controlle d groups. In both obese and nonobese patients, an inverse association between meal-stimulated insulin secretion and duration of diabetes was observed. In obese patients, as in nonobese patients, the lower beta- cell function seems likely to be the major pathogenetic factor in the appearance of secondary failure, while being overweight plays only a m inor role, thus showing that type 2 diabetes is the same disease in ob ese and nonobese patients.