To investigate the role of HbA1c in postpartum reclassification of gestational diabetes (GDM) we studied 364 women with GDM attending the postpartum reclassification assessment of their glucose tolerance status. A 75-g oral glucose tolerance test (OGTT) was performed and HbA1c was determined. Diabetes was diagnosed in 12 (3.3%), 7 (1.9%) and 2 (0.6%) women according to the fasting plasma glucose (FPG) and/or the 2-hour OGTT, the FPG alone and HbA1c levels, respectively. The sensitivity and specificity for HbA1c to diagnose diabetes was 16.7% and 100%, respectively, for FPG and OGTT criteria. The combination of a cutoff value of 5.5% for HbA1c and FPG allowed us to identify 95.1% of women with any kind of glucose intolerance. We conclude that in the early postpartum period, the cutoff of 6.5% for HbA1c alone has low sensitivity for the diagnosis of diabetes compared with OGTT, but the combination of FPG and HbA1c at a lower cutoff value is very useful to identify women with any kind of glucose intolerance.
© 2012 The Authors BJOG An International Journal of Obstetrics and Gynaecology © 2012 RCOG.