Rural-urban disparities in pregestational and gestational diabetes in pregnancy: Serial, cross-sectional analysis of over 12 million pregnancies

Objective: To compare trends in pregestational (DM) and gestational diabetes (GDM) in pregnancy in rural and urban areas in the USA, because pregnant women living in rural areas face unique challenges that contribute to rural-urban disparities in adverse pregnancy outcomes. Design: Serial, cross-sectional analysis. Setting: US National Center for Health Statistics (NCHS) Natality Files from 2011 to 2019. Population: A total of 12 401 888 singleton live births to nulliparous women aged 15-44 years. Methods: We calculated the frequency (95% confidence interval [CI]) per 1000 live births, the mean annual percentage change (APC), and unadjusted and age-adjusted rate ratios (aRR) of DM and GDM in rural compared with urban maternal residence (reference) per the NCHS Urban-Rural Classification Scheme overall, and by delivery year, reported race and ethnicity, and US region (effect measure modification). Main outcome measures: The outcomes (modelled separately) were diagnoses of DM and GDM. Results: From 2011 to 2019, there were increases in both the frequency (per 1000 live births; mean APC, 95% CI per year) of DM and GDM in rural areas (DM: 7.6 to 10.4 per 1000 live births; APC 2.8%, 95% CI 2.2%-3.4%; and GDM: 41.4 to 58.7 per 1000 live births; APC 3.1%, 95% CI 2.6%-3.6%) and urban areas (DM: 6.1 to 8.4 per 1000 live births; APC 3.3%, 95% CI 2.2%- -4.4%; and GDM: 40.8 to 61.2 per 1000 live births; APC 3.9%, 95% CI 3.3%-4.6%). Individuals living in rural areas were at higher risk of DM (aRR 1.48, 95% CI 1.45%-1.51%) and GDM versus those in urban areas (aRR 1.17, 95% CI 1.16%-1.18%). The increased risk was similar each year for DM (interaction p = 0.8), but widened over time for GDM (interaction p < 0.01). The rural-urban disparity for DM was wider for individuals who identified as Hispanic race/ethnicity and in the South and West (interaction p < 0.01 for all); and for GDM the rural-urban disparity was generally wider for similar factors (i.e. Hispanic race/ethnicity, and in the South; interaction p < 0.05 for all). Conclusions: The frequency of DM and GDM increased in both rural and urban areas of the USA from 2011 to 2019 among nulliparous pregnant women. Significant rural-urban disparities existed for DM and GDM, and increased over time for GDM. These rural-urban disparities were generally worse among those of Hispanic race/ethnicity and in women who lived in the South. These findings have implications for delivering equitable diabetes care in pregnancy in rural US communities.