Post-partum reclassification of glucose tolerance in women previously diagnosed with gestational diabetes mellitus

Aims To re-evaluate post-partum screening; fasting plasma glucose (FPG) vs. oral glucose tolerance test (OGTT) in Caucasian women with previous gestational diabetes mellitus (GDM). Methods Once breast-feeding had finished, an OGTT was performed in 120 women with previous GDM. They were classified according to World Health Organization (WHO) 1985 and American Diabetes Association (ADA) 1997 criteria. The kappa-statistic measure of agreement was used to compared both diagnostic categories. A receiver-operating characteristic (ROC) curve studied the FPG as a test to detect abnormal glucose tolerance. Results Identical diabetes prevalence (2%) but quite different intermediate categories (12% impaired glucose tolerance vs. 3% impaired fasting glucose) were observed with both criteria. The kappa-statistic (scaled from 0 to 1) was 0.38 (fair agreement), P = 0.000. The ROC curve area of the FPG was 0.65. Conclusions FPG is an unsatisfactory method of evaluating the glucose tolerance of Caucasian women with previous GDM. OGTT may be a better test for such a purpose.