Associations between gestational diabetes mellitus and elevated HbA_1c early postpartum in a multi-ethnic population

To investigate the prevalence of elevated HbA_1c 14 weeks postpartum in different ethnic groups and in women with and without gestational diabetes mellitus (GDM) in the index pregnancy and to explore demographic and biological factors from early pregnancy associated with elevated HbA_1c (HbA_1c ≥5.7% (≥39mmol/mol)) postpartum.

From a cohort study in Oslo, Norway, we included 570 pregnant women, examined in gestational week 15, 28, and 14 weeks postpartum. The association between elevated HbA_1c and demographic and biological factors were assessed by logistic regression analyses.

The prevalence of elevated HbA_1c postpartum was 23% in the total population, 15% among Western Europeans and 28% among women with ethnic minority background (p<0.01). In ethnic minorities elevated HbA_1c was found in 39% of women with recent GDM diagnosed by the World Health Organization 2013 criteria and in 21% of women without GDM (p<0.01), compared to 22% and 13% in Western Europeans (p=0.11). We found independent associations between elevated HbA_1c and ethnic minority background (OR 2.0, 95% CI 1.27, 3.18), and GDM (OR 2.04, 95% CI 1.35, 3.10) (p<0.01).

The prevalence of elevated HbA_1c postpartum was 23%, and significantly higher among women with ethnic minority background irrespective of GDM.