Abstract

Objective: To examine whether diabetes is a risk factor for hospitalization with pneumonia and to assess the impact of HbA_1c level on such risk.

Research Design and Methods: In this population-based case-control study we identified patients with a first-time pneumonia-related hospitalization between 1997 and 2005, using health care databases in Northern Denmark. For each case, ten sex- and age-matched population controls were selected from Denmark's Civil Registration System. We used conditional logistic regression to compute relative risk (RR) for pneumonia-related hospitalization among persons with and without diabetes, controlling for potential confounding factors.

Results: The study included 34,239 patients with a pneumonia-related hospitalization and 342,390 population controls. The adjusted RR for pneumonia-related hospitalization among persons with diabetes was 1.26 (95% confidence interval (CI) 1.21-1.31) compared with nondiabetic individuals. The adjusted RR was 4.43 (95% CI 3.40-5.77) for persons with type 1 diabetes and 1.23 (95% CI 1.19-1.28) for persons with type 2 diabetes. Diabetes duration ≥10 years increased the risk of a pneumonia-related hospitalization (adjusted RR 1.37; 95% CI 1.28-1.47). Compared with persons without diabetes, the adjusted RR was 1.22 (95% CI 1.14-1.30) for diabetic persons whose HbA_1c level was <7%, and 1.60 (95% CI 1.44-1.76) for diabetic persons whose HbA_1c level was ≥9%.

Conclusions: Type 1 and type 2 diabetes are risk factors for a pneumonia-related hospitalization. Poor long-term glycemic control among patients with diabetes clearly increases the risk of hospitalization with pneumonia.