Renal function trajectories before and during the COVID-19 pandemic in Japanese individuals with type 1 diabetes: a post-hoc analysis of the multicenter retrospective investigation by the IPRA-CKD study group.

The coronavirus disease 2019 (COVID-19) pandemic and associated lifestyle changes have affected metabolic status in individuals with diabetes. The impact of these changes on renal function in individuals with type 1 diabetes (T1D) remains unclear. We performed a post-hoc analysis of a multicenter retrospective cohort study (the IPRA-CKD study) including 190 Japanese individuals with T1D who were not receiving sodium-glucose cotransporter 2 inhibitors. Participants were recruited between June 2022 and July 2023, and longitudinal data over a consecutive 60-month period preceding enrollment were extracted at 6-month intervals and divided into periods before and during the pandemic. Annual rates of estimated glomerular filtration rate (eGFR) decline were compared between the periods before and during the COVID-19 pandemic using a linear mixed-effects model. The eGFR decline was not accelerated during the pandemic compared with before the pandemic; the estimated eGFR slopes were -1.54 ± 0.28 mL/min/1.73 m2/year before the pandemic and -1.05 ± 0.22 mL/min/1.73 m2/year during the pandemic (p = 0.27). Glycemic control was preserved during the pandemic, despite small but significant increases in body weight, blood pressure, and insulin dose. Exploratory subgroup analyses suggested a less steep eGFR decline during the pandemic among participants with body mass index ≥25 kg/m2 or those receiving renin-angiotensin system inhibitors; however, these findings should be interpreted as hypothesis-generating. In this multicenter cohort of individuals with T1D, the COVID-19 pandemic was not associated with accelerated eGFR decline overall.Clinical Trial Registry (CTR) registration: UMIN-CTR000047441.