Gestational diabetes: comparision of the carpenter and the coustan thresholds with the new thresholds of Turkish women and implications of variations in diagnostic criteria

Abstract

Objective: To find optimal 100-g 3-h oral glucose tolerance test (OGTT) threshold levels for diagnosis of gestational diabetes (GDM) in Turkish pregnant women. Methods: This study was conducted with 808 women screened for GDM between 24–28 weeks of gestation using the 1-h 50-g glucose challenge test (GCT) with a subsequent 3-h 100-g OGTT for confirmation if screen was positive. The glucose values obtained were analysed by both the Carpenter and Coustan (C&C criteria) and National Diabetes Data Group (NDDG) criteria for the diagnosis of GDM and IGT. Optimal OGTT cutoff values for Turkish population were calculated by ROC curve analysis. Results: The new diagnostic criteria, based on the result of the 100-g OGTT obtained from the healthy pregnant women, were 82.5, 171.5, 151.5, and 111.5 mg/dl at 0, 1, 2, and 3 h. The prevalence of GDM was 15.7% by the new criteria, 8.1% by C&C criteria, and 5.6% by the NDDG criteria. According to new criteria, 7.7% of infants of diabetic mothers had macrosomia. This ratio was 2.6% for non diabetic women. Conclusions: Ethnic differences, enviromental factors and nutritional habits may effect development of GDM. Application of some pre-determined nomograms to all races and ethnic groups can lead errors.