Glucagon-like peptide 1 (GLP-1) levels may be reduced in
type 2 diabetes, but whether a similar impairment exists in
gestational diabetes mellitus (GDM) has not been established. We studied this in a prospective cohort study of pregnant women (n = 144) during oral
glucose tolerance test (OGTT).
GLP-1,
glucose, and
insulin were sampled at 30-min intervals during a 2-h 75-g OGTT, and indices of insulin secretion and sensitivity were calculated. In a nested case-control study, women with GDM (n = 19) had 12% lower total
GLP-1 secretion area under the curve (AUC) compared with control subjects matched for age, ethnicity, and gestational age (n = 19), selected from within the lowest quartile of glucose120 min values in our cohort. GDM had lower
GLP-1 response in the first 30 min (19% lower GLP-130 min and 17% lower AUC0-30 min) after adjustment for possible confounders. Their
glucose levels began to diverge at 30 min of the OGTT with increasing
insulin levels, and by 120 min, their
insulin levels were three times higher. In a secondary cohort of 57 women that included "high-normal" glucose120 min values, low
GLP-1 AUC0-30 min was independently associated with lower indices of insulin secretion and sensitivity. In conclusion, we have observed that women with GDM have lower
GLP-1 response at 30 min of an OGTT and
hyperglycemia at 120 min despite significant
hyperinsulinemia.