Anders Hammerich Riis

OBJECTIVE: To examine whether diabetes is a risk factor for hospitalization with pneumonia and to assess the impact of A1C 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, 10 sex- and age-matched population control subjects were selected from Denmark's Civil Registration System. We used conditional logistic regression to compute relative risk (RR) for pneumonia-related hospitalization among subjects 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 control subjects. The adjusted RR for pneumonia-related hospitalization among subjects with diabetes was 1.26 (95% CI 1.21-1.31) compared with nondiabetic individuals. The adjusted RR was 4.43 (3.40-5.77) for subjects with type 1 diabetes and 1.23 (1.19-1.28) for subjects with type 2 diabetes. Diabetes duration >or=10 years increased the risk of a pneumonia-related hospitalization (1.37 [1.28-1.47]). Compared with subjects without diabetes, the adjusted RR was 1.22 (1.14-1.30) for diabetic subjects whose A1C level was <7% and 1.60 (1.44-1.76) for diabetic subjects whose A1C level was >or=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.