1324-P: GLP-1 Hypersecretion in Gestational Diabetes

Background and Aims: Incretins are crucial for an adequate insulin secretion in response to ingestions of nutrients. In patients with diabetes, prediabetes or a specific genetic background, this incretin effect is blunted. Data on incretin secretion and action during pregnancy are scarce. Here we investigated the incretin response during an oral glucose tolerance test (OGTT) in pregnant women with and without gestational diabetes.

Methods: Pregnant women from the ongoing PREG study underwent 5-point OGTT with 75 g glucose. We measured plasma glucose, insulin and C-peptide at all time points and total GLP-1 at minute 0, 30 and 120. Indices of insulin secretion and GLP-1 increase were calculated from the difference at min 0 and 30. We used linear regression to analyze the relation of GLP-1 and glucose with insulin secretion.

Results: We examined 163 women during gestational week 26.8 (±2.0 SD), GDM was present in 30 (18.4%) women. Insulin secretion was significantly lower in women with GDM (p=0.04, adjusted for BMI, age, week of gestation, insulin sensitivity). GLP-1 levels increased after glucose intake with a peak at 30 min. GLP-1 levels at minute 30 and AUC_GLP-1 was significantly higher in women with GDM (by ∼20%, both p=0.03, adjusted for age, BMI and week of gestation). The GLP-1 increase was associated with insulin secretion only in GDM, but not in women with normal glucose tolerance. This association remained significant even after adjustment for increase of glucose and basal insulin levels (GDM group: p<0.001, non GDM: p=0.69).

Conclusion: Women with GDM had lower insulin secretion despite increased GLP-1 levels during OGTT. The more pronounced GLP-1 increase in women with GDM could be part of a compensatory mechanism counteracting GLP-1 resistance. In addition to incretin resistance, this phenomenon suggests a dysfunction of glucose stimulated insulin secretion.