HbA1c as a predictor of diabetes after gestational diabetes mellitus.
We wanted to investigate third-trimester HbA1c as a predictor of diabetes after gestational diabetes mellitus (GDM).



Women with GDM were followed up prospectively for five years from pregnancy to detect the development of diabetes. The ability of HbA1c to predict diabetes was evaluated with receiver-operating characteristic (ROC) curves and logistic regression analysis.



By five years, 73 of 196 women had been diagnosed with diabetes. An optimal cut-off point for HbA1c of 36mmol/mol (5.4%) could predict diabetes with 45% sensitivity and 92% specificity. For HbA1c ≥39mmol/mol (≥5.7%), sensitivity, specificity, and positive predictive value were 30%, 97%, and 91%, respectively. In logistic regression analysis, adjusting for the diagnostic glucose concentration during pregnancy, HbA1c levels in the upper quartile (≥36mmol/mol) were associated with a 5.5-fold increased risk of diabetes.



Third-trimester HbA1c levels in the pre-diabetes range revealed women with post-partum diabetes with high specificity and high positive predictive value. HbA1c testing could be used as a strategy to select high-risk women for lifestyle interventions aimed at prevention of diabetes starting during pregnancy. The results should encourage further validation in other populations using new diagnostic criteria for GDM.
Department of Clinical Sciences Malmö, Lund University, SE-205 02 Malmö, Sweden; Department of Obstetrics and Gynaecology, Office for Healthcare "Kryh", SE-271 82 Ystad, Sweden. Electronic address: rickard.claesson@med.lu.se.
Rickard
R
Claesson
Department of Clinical Sciences Malmö, Lund University, SE-205 02 Malmö, Sweden; Department of Obstetrics and Gynaecology, Office for Healthcare "Sund", SE-251 87 Helsingborg, Sweden. Electronic address: claes.ignell@med.lu.se.
Claes
C
Ignell
Department of Clinical Sciences Malmö, Lund University, SE-205 02 Malmö, Sweden; Department of Endocrinology, Skåne University Hospital, SE-205 02 Malmö, Sweden. Electronic address: nael.shaat@med.lu.se.
Nael
N
Shaat
Department of Clinical Sciences Malmö, Lund University, SE-205 02 Malmö, Sweden; Department of Endocrinology, Skåne University Hospital, SE-205 02 Malmö, Sweden. Electronic address: kerstin.berntorp@med.lu.se.
Kerstin
K
Berntorp
D019540:Area Under Curve; D015415:Biomarkers / Q000097:blood; D001786:Blood Glucose / Q000378:metabolism; D003920:Diabetes Mellitus / Q000097:blood / Q000175:diagnosis / Q000209:etiology*; D016640:Diabetes, Gestational / Q000097:blood* / Q000175:diagnosis; D005260:Female; D005500:Follow-Up Studies; D005951:Glucose Tolerance Test; D006442:Glycated Hemoglobin / Q000378:metabolism*; D006801:Humans; D016015:Logistic Models; D016017:Odds Ratio; D011237:Predictive Value of Tests; D011247:Pregnancy; D011263:Pregnancy Trimester, Third / Q000097:blood; D011446:Prospective Studies; D012372:ROC Curve; D015203:Reproducibility of Results; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors
D015415:Biomarkers; D001786:Blood Glucose; D006442:Glycated Hemoglobin; C517652:hemoglobin A1c protein, human
Gestational diabetes; HbA1c; OGTT; Post-partum diabetes; Prediction