[Insulin response to food in obese women]

The effects of two standard meals (meal A: 20 g proteins, 20 g lipids, 80 g maltodextrin; meal B: meal A plus 52 g lipids) on insulin and C-peptide secretion and on plasma levels of glucose and free fatty acids (FFA) was studied in 12 obese women separated into two groups according to the onset of obesity. One group (n = 6) developed into obesity after puberty (OP), the other (n = 6) became obese after pregnancy (OG). Meals A.--In OP women, the maximum insulin response was reached at 30 min after meal (141.8 +/- 14.2 microU/ml) and insulinaemia fell to the basal values at 180 min; in OG women the insulin response was linear in the interval 30-150 min after meal. The maximum secretion of C-peptide occurred between 30 min and 90 min in OP and between 60 min and 120 min in OG; the secretion rate was similar in the two groups. Blood glucose levels returned to the basal values at 120 min after meal in OP and at 180 min in OG. FFA levels significantly decreased after meal in both groups (p less than 0.01 vs basal values). Meal B.--Insulin secretion was decreased at 30 min after meal in OP and at 150 min in OG and the levels of C-peptide was not modified in both groups. The glycaemic response was unchanged in OP, but was lower in OG women (p less than 0.02). These results show that OP women present stronger and more rapid insulin response to meals than the OG women; this conclusion is supported by the analysis of the secretion of C-peptide. Blood glucose levels return to basal values faster in OP than in OG women. The blood level of FFA after the standard meals A and B are normal both in OP and OG women.