A nationwide, population-based cohort study published in the Endocrine Practice evaluated the long-term association between SARS-CoV-2 infection and incident prediabetes and type 2 diabetes. The study included 599,744 adults with a positive COVID-19 test and 4,485,145 adults with a negative test between January 1 and December 31, 2020. 

Participants had no prior SARS-CoV-2 infection or diagnosis of prediabetes or type 2 diabetes at baseline. Propensity score matching was used to control for confounding, and time-to-event analyses were performed using Kaplan–Meier and Cox proportional hazards models.

Among 5,084,889 individuals followed for a median of 2.6 years (maximum follow-up 5 years), confirmed SARS-CoV-2 infection was associated with increased risk of prediabetes (HR 1.23; 95% CI 1.21–1.25) and type 2 diabetes (HR 1.40; 95% CI 1.37–1.43) compared with uninfected individuals. The highest risk was observed within the first month following infection (prediabetes HR 1.87; 95% CI 1.75–1.98; type 2 diabetes HR 1.87; 95% CI 1.79–1.96). Although attenuated, elevated risk remained significant during follow-up extending up to five years (prediabetes HR 1.23; 95% CI 1.20–1.27; type 2 diabetes HR 1.48; 95% CI 1.43–1.53).

SARS-CoV-2 infection was associated with an increased risk of incident prediabetes and type 2 diabetes compared with no documented infection.

The risk was highest during the first month after infection and remained elevated over follow-up. These findings indicate a persistent association, though causality cannot be established from observational data.

Limitations included potential diagnostic misclassification, inability to account for reinfections or time-varying exposures, lack of variant-specific analysis, residual confounding, and possible exposure misclassification during follow-up.