Women with an HbA1c of 41-49 mmol/mol (5.9-6.6%): a higher risk subgroup that may benefit from early pregnancy intervention

Diabet Med. 2016 Jan;33(1):25-31. doi: 10.1111/dme.12812. Epub 2015 Jun 15.

Abstract

Aims: To examine whether women with an HbA1c of 41-49 mmol/mol (5.9-6.6%) at diagnosis of gestational diabetes are higher risk than women with an HbA1c of < 41 mmol/mol (5.9%) and whether pregnancy outcomes are improved if treated at < 24 weeks' gestation.

Methods: This was an observational study of women with gestational diabetes diagnosed by early HbA1c screening or subsequent oral glucose tolerance test at < 34 weeks' gestation who delivered at National Women's Health, Auckland, from July 2012 to June 2014. Data were extracted from the hospital database. Women with HbA1c 41-49 mmol/mol (5.9-6.6%) were divided into those seen < 24 weeks (Early, n = 134) and those seen ≥ 24 weeks (Later, n = 151). Those with HbA1c < 41 mmol/mol (5.9%) were labelled Other GDM (n = 661).

Results: The Early and Later groups, compared with Other GDM, had more Polynesian and fewer (non-Indian) Asian women, higher BMI and more required medication (P < 0.001). More were smokers (P = 0.007, 0.02) and more had chronic hypertension (P < 0.001, 0.02). There were higher rates of adverse outcomes in the Later group than the Other GDM group (pre-eclampsia 8.0% vs. 2.4%, P = 0.001, preterm birth 16.6% vs. 8.2%, P = 0.002, neonatal admission 15.5% vs. 9.2%, P = 0.02). Outcomes were similar between the Early group and Other GDM group (pre-eclampsia 1.5% vs. 2.4%, P = 0.5, preterm birth 10.5% vs. 8.2% P = 0.4, neonatal admission 13.6% vs. 9.2%, P = 0.12). Comparing the Early and Later groups, the Early group had less pre-eclampsia, 1.5% vs. 8.0%, adjusted P = 0.03. Other outcomes were not statistically different.

Conclusions: An HbA1c of 41-49 mmol/mol (5.9-6.7%) identifies a higher-risk group of women with gestational diabetes. Overall, our data support early treatment of women with an HbA1c ≥ 41 mmol/mol (5.9%).

Publication types

  • Comparative Study
  • Observational Study

MeSH terms

  • Adult
  • Asian Continental Ancestry Group
  • Diabetes, Gestational / blood
  • Diabetes, Gestational / diagnosis*
  • Diabetes, Gestational / ethnology
  • Diabetes, Gestational / physiopathology
  • Diabetes, Gestational / therapy
  • Early Diagnosis
  • European Continental Ancestry Group
  • Female
  • Glycated Hemoglobin A / analysis*
  • Humans
  • Infant, Newborn
  • Infant, Newborn, Diseases / epidemiology
  • Infant, Newborn, Diseases / ethnology
  • Infant, Newborn, Diseases / etiology
  • Infant, Newborn, Diseases / prevention & control*
  • Intensive Care, Neonatal
  • Male
  • New Zealand / epidemiology
  • Oceanic Ancestry Group
  • Pre-Eclampsia / epidemiology
  • Pre-Eclampsia / ethnology
  • Pre-Eclampsia / etiology
  • Pre-Eclampsia / prevention & control*
  • Pregnancy
  • Pregnancy Trimester, Second
  • Pregnancy, High-Risk / blood*
  • Pregnancy, High-Risk / ethnology
  • Premature Birth / epidemiology
  • Premature Birth / etiology
  • Premature Birth / prevention & control*
  • Premature Birth / therapy
  • Prenatal Diagnosis
  • Risk Factors

Substances

  • Glycated Hemoglobin A
  • hemoglobin A1c protein, human