Pre-pandemic diabetes and risk of long COVID: longitudinal evidence

To examine whether pre-pandemic diabetes is associated with an increased risk of Long COVID in a nationally representative UK cohort. We conducted a prospective cohort analysis using data from the UK Household Longitudinal Study. A total of 11,669 adults aged ≥ 16 years were followed from Wave 10 (2018-19) to Wave 14 (2022-23). The primary exposure, pre-pandemic diabetes, was defined at baseline (Wave 10) based on self-report of a doctor diagnosis. The primary outcome, Long COVID, was assessed at follow-up (Wave 14) and defined as self-reported symptoms lasting more than 12 weeks after a COVID-19 infection that could not be explained by another cause. Modified Poisson regression models with robust standard errors were used to estimate relative risks of Long COVID associated with pre-pandemic diabetes. Predictive margins were then calculated to obtain adjusted probabilities. At follow-up, 1,076 participants (9.2%) reported Long COVID. In the unadjusted model, participants with pre-pandemic diabetes had a 36% higher risk of Long COVID compared with those without diabetes (RR = 1.36, 95% CI: 1.09-1.69, p = 0.006). After adjusting for age and sex, the relative risk increased to 1.43 (95% CI: 1.15-1.79, p = 0.002). In the fully adjusted model, which controlled for age, sex, ethnicity, education, income satisfaction, smoking, and other long-standing illness, the relative risk of Long COVID in participants with diabetes was 1.60 (95% CI: 1.27-2.02, p < 0.001). The adjusted predicted probability of long COVID was 14.4% (95% CI: 11.2-17.6) among those with diabetes, compared with 9.0% (95% CI: 8.5-9.5) among those without. In this nationally representative prospective cohort, pre-pandemic diabetes emerged as an independent risk factor for Long COVID. Enhanced surveillance and targeted support for individuals with diabetes may be warranted in Long COVID care strategies.