Differences in Hemoglobin A1c during Pregnancy between Non-Hispanic Black versus White Women with Prepregnancy Diabetes

Objective: The objective of this was to determine whether the change in hemoglobin A1c (HbA1c) from early to late pregnancy differs between non-Hispanic Black and White women with prepregnancy diabetes.

Study design: A retrospective analysis was performed from an integrated prenatal and diabetes care program from 2012 to 2016. We compared HbA1c as a continuous measure and secondarily, HbA1c <6.5%, cross-sectionally, and longitudinally in early (approximately 10 weeks) and late (approximately 31 weeks) pregnancies. Linear and logistic regression were used and adjusted for age, body mass index, White diabetes class, medication use, diabetes type, gestational age at baseline HbA1c measurement, and baseline hemoglobin.

Results: Among 296 non-Hispanic Black (35%) and White pregnant women (65%) with prepregnancy diabetes (39% type 1 and 61% type 2), Black women were more likely to experience increased community-level social determinants of health as measured by the Social Vulnerability Index (SVI) and were less likely to have type 1 diabetes and have more severe diabetes versus White women (p < 0.05). Black women had higher mean HbA1c (7.8 vs. 7.4%; beta: 0.75; 95% confidence interval [CI]: 0.30-1.19) and were less likely to have HbA1c < 6.5% at 10 weeks compared with White women (24 vs. 35%; adjusted odds ratio: 0.45; 95% CI: 0.24-0.81) but not after adjusting for SVI. At 31 weeks, both groups had similar mean HbA1c (both 6.5%) and were equally as likely to have HbA1c < 6.5% (57 vs. 54%). From early to late pregnancy, Black women had a higher percentage decrease in HbA1c (1.3 vs. 0.9%; beta = 0.63; 95% CI: 0.27-0.99) and were equally as likely to have an improvement or stable HbA1C < 6.5% from 10 to 31 weeks, with both groups having a similar mean HbA1c (6.5%) at 31 weeks.

Conclusion: Despite experiencing greater community-level social determinants of health, Black women with pregestational diabetes had a larger reduction in HbA1c and were able to equally achieve the target of HbA1c < 6.5% by late pregnancy compared with White women as part of an integrated diabetes and prenatal care program.

Key points: · An integrated diabetes and pregnancy care program may decrease racial and ethnic disparities in glycemic control.. · Black women had a larger reduction in HbA1c versus White women.. · Black women were able to equally achieve the target of HbA1c < 6.5% by late pregnancy versus White women..