Is early postpartum HbA1c an appropriate risk predictor after pregnancy with gestational diabetes mellitus?
Compared to the 2-h oral glucose tolerance test (OGTT), the assessment of HbA1c was proposed as a less time-consuming alternative to detect pathologies in carbohydrate metabolism. This report aims to assess the predictive accuracy of HbA1c to detect alterations in glucose disposition early after gestational diabetes mellitus (GDM) pregnancy. A detailed metabolic characterization was performed in 77 women with previous GDM (pGDM) and 41 controls 3–6 month after delivery: 3-h OGTT, frequently sampled intravenous glucose tolerance test. Follow-up examinations of pGDMs were performed up to 10 years. HbA1c (venous samples, HPLC) was assessed at baseline as well as during the follow-up period (475 patient contacts). Moderate associations were observed between HbA1c and measurements of plasma glucose during the OGTT at the baseline examination: The strongest correlation was found for FPG (r = 0.40, p < 0.001), decreasing after ingestion. No associations were detected between HbA1c and OGTT dynamics of insulin or C-peptide. Moreover, baseline HbA1c showed only modest correlation with insulin sensitivity (r = −0.25, p = 0.010) and disposition index (r = −0.26, p = 0.007). A linear model including fasting as well as post-load glucose levels was not improved by HbA1c. However, pGDM females with overt diabetes manifestation during the follow-up period showed more pronounced increasing HbA1c in contrast to females remaining normal glucose tolerant or developing prediabetes. It is suggested that the performance of HbA1c assessed early after delivery is inferior to the OGTT for the detection of early alterations in glucose metabolism. However, an increase in HbA1c levels could be used as an indicator of risk for diabetes manifestation.
KeywordsHbA1c Gestational diabetes mellitus Oral glucose tolerance test Postpartum risk stratification Impaired fasting glucose Impaired glucose tolerance
We acknowledge to Mrs. Astrid Hofer, Study Nurse, Medical University of Vienna, Department of Internal Medicine III, Mr. Thomas Prikoszovich, MD, Medical University of Vienna, Department of Internal Medicine III, and Mrs. Anita Thomas, Bsc, Department of Internal Medicine III, for helping with data assessment. The study was supported by the Austrian Science Fund (P14515-MED) to AKW.
Conflict of interest
Christian S. Göbl, Latife Bozkurt, Rajashri Yarragudi, Andrea Tura, Giovanni Pacini and Alexandra Kautzky-Willer declare they have no conflict of interest.
Statement of Human and Animal Rights
All procedures followed were in accordance with the ethical standards of the Ethics Committee of the Medical University of Vienna and with the Helsinki Declaration of 1975, as revised in 2008 (5).
Statement of Informed consent
Informed consent was obtained from all patients for being included in the study.
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