Insulin secretion to glucose infusion in gestational diabetes subjects with differing DNA polymorphisms flanking the insulin gene.

Glucose-stimulated insulin secretion was assessed in relation to the DNA polymorphism flanking the insulin gene in 16 women who had had gestational diabetes. When not pregnant they were studied by a Constant Glucose Infusion for 1 hr with Model Assessment (CIGMA). The patients with either heterozygous 1/3 alleles or homozygous 1/1 or 3/3 alleles in the 5' flanking region of the insulin gene had similar plasma insulin and C-peptide concentrations and similar estimates of beta-cell function. This suggests that the large DNA insert (Class 3 allele) near the insulin gene does not directly affect insulin secretion. The association of polymorphisms with Type 2 diabetes may be due to linkage disequilibrium with other disease-related alleles.