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

Aims To examine whether women with an HbA(1c) of 41-49mmol/mol (5.9-6.6%) at diagnosis of gestational diabetes are higher risk than women with an HbA(1c) of<41mmol/mol (5.9%) and whether pregnancy outcomes are improved if treated at<24weeks' gestation. MethodsThis was an observational study of women with gestational diabetes diagnosed by early HbA(1c) screening or subsequent oral glucose tolerance test at<34weeks' gestation who delivered at National Women's Health, Auckland, from July 2012 to June 2014. Data were extracted from the hospital database. Women with HbA(1c) 41-49mmol/mol (5.9-6.6%) were divided into those seen<24weeks (Early, n=134) and those seen24weeks (Later, n=151). Those with HbA(1c)<41mmol/mol (5.9%) were labelled Other GDM (n=661). ResultsThe 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. ConclusionsAn HbA(1c) of 41-49mmol/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 HbA(1c)41mmol/mol (5.9%).