Use of Glycated Hemoglobin and Waist Circumference for Diabetic Screening in Women With a History of Gestational Diabetes

Objective: Although their risk of type 2 diabetes is markedly increased, women with prior gestational diabetes mellitus (GDM) do not receive appropriate testing following their pregnancy. Identifying a less burdensome testing method might increase postpartum testing rates. Our objective was to examine the adequacy of glycated hemoglobin (A1C) and waist circumference (WC) measurements to detect impaired glucose metabolism among women with prior GDM. Methods: The analysis included 178 women who had GDM between 2003 and 2010. WC and A1C were measured, and a 75g 2h-OGTT was performed. Pre-diabetes was defined as a fasting plasma glucose (FPG) >= 5.6 and < 7.0 mmol/L or a 2-hour plasma glucose (2h-PG) >= 7.8 and < 11.0 mmol/L, and type 2 diabetes was defined as a FPG >= 7.0 mmol/L and/or a 2h-PG >= 11.1 mmol/L. Sensitivity and specificity analyses were performed. Results: The mean age of subjects was 36.4 +/- 4.8 years, and testing occurred at a mean 3.5 +/- 1.9 years following delivery. Combining A1C >= 5.7% and WC >= 88 cm to detect pre-diabetes had a sensitivity of 76% and specificity of 62%, and to detect type 2 diabetes it had a sensitivity of 91% and specificity of 34%. Compared with women who had A1C and WC within the normal range, women with A1C >= 5.7% and WC >= 88 cm were more likely to have type 2 diabetes (OR 4.4; 95% CI 2.0 to 9.9). Conclusion: These analyses suggest that the combination of A1C and WC could represent a sensitive test for pre-diabetes and type 2 diabetes in the years following a pregnancy complicated by GDM. Further validation of this testing method is required.