Can we really diagnose diabetes during pregnancy?

Objective: To identify the accuracy of diagnosing postpartum diabetes and glucose intolerance using antepartum glycosylated hemoglobin (HbA1c) and fasting glucose values.

Study Design: A retrospective Hawaiian cohort of women with gestational diabetes during 2004-2011 were evaluated. Antepartum HbA1c and postpartum 75-g glucose tolerance tests were obtained.

Results: An antepartum HbA1c value of ≥6.5% had a 45.7% sensitivity, a 96% specificity and a 40% positive predictive value (PPV) for predicting postpartum diabetes. An antepartum HbA1c value of ≥6.5% had a 6.6% sensitivity, a 94.2% specificity and a 27% PPV for predicting postpartum impaired glucose tolerance. An antepartum HbA1c value of ≥6.5% had a 10.3% sensitivity, a 95.7% specificity and a 33.3% PPV for predicting postpartum impaired fasting glucoses.

Conclusion: We could not demonstrate a clinically useful PPV for diagnosing postpartum diabetes or glucose intolerance using an antepartum elevated HbA1c value of ≥6.5% or a fasting glucose level of ≥90 mg/dL.