Universal HbA1c Measurement in Early Pregnancy to Detect Type 2 Diabetes Reduces Ethnic Disparities in Antenatal Diabetes Screening: A Population-Based Observational Study.
In response to the type 2 diabetes epidemic, measuring HbA1c with the first-antenatal blood screen was recently recommended in NZ. This would enable prompt treatment of women with unrecognised type 2 diabetes, who may otherwise go undetected until the gestational diabetes (GDM) screen. We compare inter-ethnic antenatal screening practices to examine whether the HbA1c test would be accessed by ethnicities most at risk of diabetes, and we determined the prevalence of unrecognised type 2 diabetes and prediabetes in our pregnant population. This is an observational study of pregnancies in Christchurch NZ during 2008-2010. Utilising electronic databases, we matched maternal characteristics to first-antenatal bloods, HbA1c, and GDM screens (glucose challenge tests and oral glucose tolerance tests). Overall uptake of the first-antenatal bloods versus GDM screening was 83.1% and 53.8% respectively in 11,580 pregnancies. GDM screening was lowest in Māori 39.3%, incidence proportion ratio (IPR) 0.77 (0.71, 0.84) compared with Europeans. By including HbA1c with the first-antenatal bloods, the number screened for diabetes increases by 28.5% in Europeans, 40.0% in Māori, 28.1% in Pacific People, and 26.7% in 'Others' (majority of Asian descent). The combined prevalence of unrecognised type 2 diabetes and prediabetes by NZ criteria, HbA1c ≥5.9% (41mmol/mol), was 2.1% in Europeans, Māori 4.7% IPR 2.59 (1.71, 3.93), Pacific People 9.5% IPR 4.76 (3.10, 7.30), and 'Others' 6.2% IPR 2.99 (2.19, 4.07). Applying these prevalence data to 2013 NZ national births data, routine antenatal HbA1c testing could have identified type 2 diabetes in 0.44% and prediabetes in 3.96% of women. Routine HbA1c measurement in early pregnancy is an ideal screening opportunity, particularly benefitting vulnerable groups, reducing ethnic disparities in antenatal diabetes screening. This approach is likely to have world-wide relevance and applicability. Further research is underway to establish whether, as for type 2 diabetes, prompt treatment of prediabetes improves pregnancy and neonatal outcomes.
Department of Obstetrics and Gynaecology, University of Otago, Christchurch Women's Hospital, Christchurch, New Zealand.
R C E
RC
Hughes
Biostatistics and Computational Biology Unit, University of Otago, Christchurch School of Medicine, Christchurch, New Zealand.
J
J
Williman
Department of Obstetrics and Gynaecology, University of Otago, Christchurch Women's Hospital, Christchurch, New Zealand.
J E
JE
Gullam
D000328:Adult; D003924:Diabetes Mellitus, Type 2 / Q000175:diagnosis* / Q000208:ethnology; D016640:Diabetes, Gestational / Q000175:diagnosis* / Q000208:ethnology; D042241:Early Diagnosis; D005260:Female; D005951:Glucose Tolerance Test; D006442:Glycated Hemoglobin / Q000032:analysis*; D006801:Humans; D008403:Mass Screening; D009520:New Zealand / Q000208:ethnology; D011247:Pregnancy; D011296:Prenatal Diagnosis / Q000379:methods*; D015995:Prevalence; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D055815:Young Adult
D006442:Glycated Hemoglobin