Incretin Hypersecretion in Gestational Diabetes Mellitus

Context: Incretins are crucial stimulators of insulin secretion following food intake. Data on incretin secretion and action during pregnancy are sparse. Objective: The aim of the study was to investigate the incretin response during an oral glucose tolerance test (OGTT) in pregnant women with and without gestational diabetes mellitus (GDM). Design: We analyzed data from the ongoing observational PREG study (NCT 04270578). Setting: The study was conducted at the University Hospital Tubingen. Participants: We examined 167 women (33 with GDM) during gestational week 27 +/- 2.2. Intervention: Subjects underwent 5-point OGTT with a 75-g glucose load. Main outcome measures: We assessed insulin secretion and levels of total glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic peptide (GIP), glicentin, and glucagon during OGTT. Linear regression was used to analyze the relation of GLP-1 and glucose with insulin secretion and the association of incretin levels on birth outcome. Results: Insulin secretion was significantly lower in women with GDM (P< 0.001). Postload GLP-1 and GIP were similar to 20% higher in women with GDM (all P < 0.05) independent of age, body mass index, and gestational age. GLP-1 increase was associated with insulin secretion only in GDM, but not in normal glucose tolerance. Postprandial GLP-1 levels were negatively associated with birth weight. Conclusions: The more pronounced GLP-1 increase in women with GDM could be part of a compensatory mechanism counteracting GLP-1 resistance. Higher GLP-1 levels might be protective against fetal overgrowth.

Automated summary

This study aimed to investigate the incretin response during an oral glucose tolerance test (OGTT) in pregnant women. The results showed that insulin secretion was lower in women with gestational diabetes mellitus (GDM), but the increase in GLP-1 was only associated with insulin secretion in GDM women. Additionally, postprandial GLP-1 levels were negatively associated with birth weight.