Impact of Covid-19 on rates of gestational diabetes in a North American pandemic epicenter

Aims We assessed the impact of Covid-19 on gestational diabetes rates in Quebec, the pandemic epicenter of Canada. Methods We conducted a population-based study of 569,686 deliveries in Quebec between 2014 and 2021. We measured gestational diabetes rates in wave 1 (March 1, 2020-August 22, 2020) and wave 2 (August 23, 2020-March 31, 2021), compared with the prepandemic period. We used interrupted time series regression to assess changes in gestational diabetes rates during each wave, and log-binomial regression models to estimate adjusted risk ratios (RR) and 95% confidence intervals (CI) for the association of the pandemic with gestational diabetes. We identified the types of patients that contributed to the change in gestational diabetes rates using Kitagawa's decomposition. Results Gestational diabetes rates were higher during the first (13.2 per 100 deliveries) and second waves (14.3 per 100 deliveries) than during the prepandemic period (12.4 per 100 deliveries). Risk of gestational diabetes increased both in wave 1 (RR 1.05, 95% CI 1.02-1.09) and wave 2 (RR 1.14, 95% CI 1.10-1.18), compared with the prepandemic period. However, most of the increase in gestational diabetes rates was driven by low-risk women without Covid-19 infections who were socioeconomically advantaged, had no comorbidity, and were 25-34 years of age. Conclusions Gestational diabetes rates increased during the pandemic, mainly among women traditionally at low risk of hyperglycemia who did not have Covid-19 infections. Sudden widespread changes in screening or lifestyle can have a large impact on gestational diabetes rates in a population.