Is type 2 diabetes a different disease in obese and nonobese patients?
OBJECTIVE
The main purpose of this work was to study the possible differences in insulin secretion in a large group of type 2 diabetic patients in relation to diabetes duration, obesity, and the presence of secondary failure after treatment with oral hypoglycemic agents.


METHODS
There were 147 nonobese and 215 obese type 2 diabetic 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-peptide concentrations, as the mean of the three postprandial increments above the premeal value.


RESULTS
Basal C-peptide concentrations were significantly higher in obese than nonobese patients of both groups. The mean of meal-stimulated C-peptide concentrations was also significantly higher in obese than nonobese patients with good glycemic control, but not in the secondary failure groups. In nonobese and obese patients considered separately, a significant negative correlation between the mean of daily blood glucose and meal-stimulated C-peptide was observed (r=-0.705 and r=-0.679, respectively, P < 0.001) and the residual beta-cell function was significantly correlated with the known duration of diabetes and metabolic control, but not with BMI, in both groups.


CONCLUSIONS
On average, obese diabetic subjects showed higher meal-stimulated C-peptide than nonobese subjects only in well-controlled 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 minor role, thus showing that type 2 diabetes is the same disease in obese and nonobese patients.
Department of Internal Medicine, University of Genoa, Italy.
R
R
Prando
V
V
Cheli
P
P
Melga
R
R
Giusti
E
E
Ciuchi
P
P
Odetti
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D001786:Blood Glucose / Q000378:metabolism*; D015992:Body Mass Index; D002096:C-Peptide / Q000097:blood / Q000378:metabolism; D003430:Cross-Sectional Studies; D003920:Diabetes Mellitus / Q000145:classification / Q000188:drug therapy / Q000503:physiopathology*; D003924:Diabetes Mellitus, Type 2 / Q000145:classification* / Q000188:drug therapy / Q000503:physiopathology*; D005260:Female; D006801:Humans; D007004:Hypoglycemic Agents / Q000627:therapeutic use; D007328:Insulin / Q000097:blood / Q000378:metabolism; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D009765:Obesity; D019518:Postprandial Period
D001786:Blood Glucose; D002096:C-Peptide; D007004:Hypoglycemic Agents; D007328:Insulin