Contribution of first trimester fasting plasma insulin levels to the incidence of glucose intolerance in later pregnancy: Tanaka women's clinic study.

Aims: To clarify risk factors predictive of glucose intolerance in later pregnancy.
Methods: We prospectively studied 509 pregnant women who visited the obstetrics clinic in Tokyo prior to week 13 of gestation, between September 2008 and January 2010. Biochemical parameters were measured in fasting plasma samples collected at week 8.0 ± 2.0 of gestation. A 50 g glucose challenge test (GCT) was performed between weeks 26 and 29: plasma glucose levels ≥ 7.8 mmol/l 1h after ingestion indicated a positive GCT. Logistic regression was performed, adjusting for relevant covariates.
Results: We identified 114 patients with positive GCTs, including 8 with gestational diabetes mellitus (GDM). After correcting for baseline body mass index, only the homeostasis model assessment of insulin resistance value remained a significant predictor of GCT positivity (OR 2.07; 1.21-3.55). We identified threshold values of fasting plasma glucose (FPG) ≥ 3.66 mmol/l and fasting plasma insulin (FPI) ≥ 36.69 pmol/l as indicative of a higher risk of positive GCT (OR 2.38; 1.49-3.80).
Conclusions: First trimester FPI levels improve the predictive ability of FPG level on subsequent GCT positivity.
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