Diabetes, Glycemic Control, and Risk of Infection Morbidity and Mortality: A Cohort Study

Abstract

Background: Diabetic patients have an elevated risk of infection, but the optimal level of glycemic control with the lowest infection risk remains unclear, especially among the elderly. We conducted a cohort study to investigate the relation between fasting plasma glucose (FPG) level and risk of infection-related morbidity and mortality. Methods: Data of participants from a community-based health screening program in Taiwan during 2005-2008 (n=118,645) were analyzed. Incidence of hospitalization for infection and infection-related death was ascertained from the National Health Insurance Database and National Death Registry. Cox proportional hazards regression modelling was used to estimate the hazard ratio (HR) between FPG and risk of infection, adjusting for major risk factors of infection. Separate analyses were also performed to evaluate the risk of hospitalization among the elderly (> 65 years). Findings: During a median follow-up of 8.13 years, 14,372 cases of hospitalization for infection and 422 infection-related deaths occurred. The incidence rate of hospitalization for any infection was 36.33 and 14.26 per 1,000 person-years among diabetics and non-diabetics in the total study population, but increased to 70.02 and 45.21 per 1,000 person-years in the elderly. In the Cox regression analysis, the adjusted HR comparing diabetics to non-diabetics was 1.59 (95% CI: 1.52-1.67) for any hospitalization for infection and 1.71 (95% CI: 1.36-2.16) for infection-related mortality. The hazard for infection morbidity and mortality was higher at both extremes ( 200 mg/dl ) of FPG. The above relations were consistently observed in older people, across different sites of infection, and remained unchanged in several sensitivity analyses. Interpretation: The U-shape association between glycemic control and infection risk suggested that very tight glucose control may not provide any additional benefits in risk reduction. In older adults, the absolute risk of infection associated with diabetes was high. Funding Statement: Taiwan Ministry of Science and Technology (MOST105-2628-B-002-025-MY3). Declaration of Interests: The authors declare that they have no competing interests. Ethics Approval Statement: The study was approved by the Research Ethics Committee of the National Taiwan University Hospital.