Normal fasting plasma glucose levels during pregnancy: a hospital-based study

Abstract

Objective: Recently, the International Association of Diabetes and Pregnancy Study Groups have suggested new criteria for the diagnosis of gestational diabetes including a fasting glucose level of ≥92 mg/dL. We determined reference levels for normal fasting plasma glucose levels throughout pregnancy and evaluated the new normal cut-off for fasting glucose level.

Methods: Charts of patients who delivered in our hospital between June 2001 and June 2006 were reviewed. Women with pregestational diabetes, fasting glucose level >105mg/dL or delivery at <24 weeks were excluded. Fasting glucose levels were assessed in 11 time categories between three months prior and four months postpartum in 7946 women.

Results: Compared to preconception levels, fasting glucose levels decreased by a median of 3 mg/dL in the first trimester (81–78 mg/dL). During the third trimester a slight further glucose reduction was observed (median 76 mg/dL). After delivery fasting glucose levels increased sharply (84 mg/dL in the puerperium and 81 mg/dL by three months postpartum). Throughout pregnancy 5.2–9.0% of pregnant women had a fasting glucose level of ≥92 mg/dL ;ibcompared to 8.2% in the Hyperglycemia and Adverse Pregnancy Outcome (HAPO) study].

Conclusion: Fasting glucose levels decrease early in pregnancy with only slight further decrease later on. It seems that the same fasting glucose cut-off can be used throughout pregnancy for the diagnosis of gestational diabetes mellitus.