Glucose tolerance in singleton, twin and triplet pregnancies.

BACKGROUND: Data regarding the effects of multifetal pregnancy on the incidence of gestational diabetes mellitus (GDM) are inconsistent and even conflicting. Twin pregnancies have been associated with no increase, a marginal increase or a higher incidence of gestational diabetes. In triplet pregnancies, these effects have not been investigated yet.

OBJECTIVES: To analyze the results of the glucose challenge and tolerance tests in singleton, twin and triplet pregnancies.

STUDY DESIGN: A retrospective database analysis of pregnant women with singletons, twins or triplets who had complete results of the 50 g glucose challenge test (GCT) and the 100 g oral glucose tolerance test (OGTT). The cohort included 12,382 singletons, 515 twins and 39 triplets.

RESULTS: There were significantly higher rates of abnormal GCTs in twins and triplets compared to singletons (45.4% and 33.3%, respectively vs. 13.7%, P<0.001 and P<0.05). Significantly higher rates of gestational diabetes in twins (10.1% vs. 2.9 %, P<0.001) and triplets (12.8% vs. 2.9%, P<0.05) compared to singletons were observed. Mean glucose levels after the GCT were higher in twins compared to singletons, and even more in triplets (108 mg/dL in singletons vs. 120 mg/dL in twins vs. 129 mg/dL in triplets, P<0.001).

CONCLUSIONS: Glucose intolerance is aggravated in multifetal pregnancies. The likelihood of an abnormal GCT and gestational diabetes is higher in twins and triplets compared to singletons.