title: Hemoglobin A1c in early postpartum screening of women with gestational diabetes.
abstract: OBJECTIVE
  To assess the utility of hemoglobin A1c (HbA1c) in the early postpartum screening of women with gestational diabetes mellitus (GDM).
  
  
  METHODS
  Over a 3 years period, HbA1c estimations were undertaken in addition to and simultaneously with the traditional oral glucose tolerance test (OGTT), in 203 women with GDM as a part of early postpartum screening for dysglycaemia, at 6 wk post-partum. World Health Organization criteria was used for diagnosing diabetes: fasting blood glucose (FBG) ≥ 7.0 mmol/L and/or 2-h postprandial blood glucose (PPBG) ≥ 11.1 mmol/L and/or HbA1c ≥ 48 mmol/mol; and impaired glycaemiastate: impaired fasting glucose 6.1-6.9 mmol/L and/or impaired glucose tolerance 7.8-11.0 mmol/L and/or HbA1c: 42-47 mmol/mol.
  
  
  RESULTS
  Mean FBG, 2-h PPBG and HbA1c were 4.9 ± 0.7 mmol/L, 5.6 ± 2.0 mmol/L and 38 ± 5 mmol/mol respectively. FBG, 2-h PPBG and HbA1c detected 6 (3%), 7 (3.5%) and 11 (5.4%) cases of diabetes respectively, and 11 (5.4%), 25 (12.3%) and 23 (11.3%) cases of pre-diabetes state respectively. HbA1c values ≥ 48 mmol/mol (≥ 6.5%) showed a diagnostic sensitivity of 71.4% and specificity of 98.5% for diabetes in comparison to OGTT in receiver operating characteristics curve analysis. At HbA1c cut-off 44 mmol/mol, sensitivity and specificity were 100% and 92.3% respectively [area under the curve: 0.98 (95%CI: 0.96-1.00)]. Sensitivity and specificity for detecting high risk "impaired glycaemia" state [HbA1c 42 mmol/mol (6.0%)] were 28% and 80%, respectively.
  
  
  CONCLUSIONS
  HbA1c level ≥ 48 mmol/mol (≥ 6.5%) has reasonable sensitivity and high specificity in comparison to OGTT for early postpartum screening of diabetes in GDM. At 6(th) week postpartum screening, if FBG is normal and HbA1c < 44 mmol/mol OGTT is not recommended.
authors.affiliation: Mahesh V Katreddy, Joseph M Pappachan, Sarah E Taylor, Radha Indusekhar, Ananth U Nayak, the combined Antenatal Diabetes Clinic, University Hospital of North Staffordshire NHS Trust, Stoke on Trent ST4 6QG, United Kingdom.
authors.forename: Mahesh V
authors.initials: MV
authors.lastname: Katreddy
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Pappachan
authors.forename: Sarah E
authors.initials: SE
authors.lastname: Taylor
authors.forename: Alan M
authors.initials: AM
authors.lastname: Nevill
authors.forename: Radha
authors.initials: R
authors.lastname: Indusekhar
authors.forename: Ananth U
authors.initials: AU
authors.lastname: Nayak
keywords: Gestational diabetes mellitus; Glycated haemoglobin; Impaired glycaemia; Postpartum screening