Disparities in type 2 diabetes incidence trends during the COVID-19 pandemic in Sweden: a register-based population study

BACKGROUND: The COVID-19 pandemic profoundly affected health care provision for chronic diseases, including type 2 diabetes. However, its effects on type 2 diabetes incidence remain poorly understood, particularly how they differ between population groups, which has not yet been examined in a Swedish context. We aimed to investigate trends in type 2 diabetes incidence in Sweden from 2016 to 2022, and to explore whether potential changes in type 2 diabetes incidence associated with the COVID-19 pandemic varied by sex, age, or migration status. METHODS: Quarterly incidence rates of new-onset type 2 diabetes were calculated from individual-level register data for a dynamic population consisting of all adults (age ≥ 18 years) in Sweden during 2016-2019 (pre-pandemic) and 2020-2022 (pandemic). Incidence rate ratios (IRRs) for each pandemic year were modelled in multivariable Poisson regression analysis using the pre-pandemic years as reference, adjusted for age, sex, migration status, season, and long-term annual trend. Stratified and interaction analyses were performed based on age, sex, and migration status. RESULTS: Overall, the incidence of type 2 diabetes showed an increasing underlying linear trend of 3.6% (IRR 1.036, 95% CI 1.028, 1.045) between 2016 and 2022. During the pandemic (2020-2022), the overall type 2 diabetes incidence decreased by 6% relative to the underlying linear trend (IRR 0.94, 95% CI 0.91, 0.97). The decrease was strongest in 2020 (IRR 0.90, 95% CI 0.87, 0.94) compared to 2021 (IRR 1.03, 95% CI 0.99, 1.06) and 2022 (IRR 0.95, 95% CI 0.91, 0.99). The decline in type 2 diabetes incidence in 2020 was most pronounced among individuals 65 years and older and in the native-born Swedish population. CONCLUSIONS: During the first year of the COVID-19 pandemic in Sweden, a decline in incidence of type 2 diabetes was observed that varied in magnitude by sex, age, and migration status. This finding may reflect differential but transient changes in health-seeking behaviour during the initial phases of the pandemic. Our results underscore the challenges of maintaining continuous health care for non-communicable diseases during a major health crisis in society, highlighting the need to ensure equitable access for vulnerable groups such as older persons.