Poor glycaemic control linked with pneumonia mortality
The benefits of maintaining good glycaemic control in patients with diabetes are often discussed in terms of preventing the development and progression of complications. A recent paper from Denmark reminds us that poorly controlled diabetes can worsen prognosis in other disease areas.
Writing in Diabetes Care, Kornum and colleagues studied the relationship between hyperglycaemia and pneumonia outcomes.
The authors studied records from a cohort of 29,900 adult patients with a first-time admission for pneumonia, of whom 2,931 had type 2 diabetes. They obtained information on diabetes, comorbidity, lab findings (where available), pulmonary complications and bacteraemia.
The authors recorded the difference in outcomes between patients with type 2 diabetes and those without
and calculated the relative risk of pulmonary complications, bacteraemia and death in the first 90 days after admission. A sub-group analysis was performed to correlate hyperglycaemia at admission with the same outcomes.
The study found that patients with type 2 diabetes were no more likely to suffer pulmonary complications (except adult respiratory distress syndrome) or bacteraemia than those without the disease, but their risk of mortality increased. The relative risk of mortality was 19.9% compared with 15.1% for patients without type 2 diabetes at 30 days post discharge, and 27.0% compared with 21.6% at 90 days. These give mortality rate ratios of 1.16 (95% CI=1.07-1.27) and 1.10 (95% CI=1.02-1.18) respectively.
Further analysis of the patients with type 2 diabetes showed the risk of mortality to be skewed to those patients with hyperglycaemia at admission. High blood glucose at admission (>14.0mmol/l) was a predictor of increased risk of mortality in patients with type 2 diabetes, with a mortality rate ratio at 30 days of 1.46 (95% CI=1.01-2.12).
This risk was increased in those with previously undiagnosed diabetes and hyperglycaemia when admitted with pneumonia. For these patients the mortality rate ratio at 30 days was 1.91 (95% CI=1.40-2.61).
These findings support earlier studies. In 2005, Finlay et al reported worse outcomes for hyperglycaemic patients in a Canadian study of 2,471 patients admitted with community-acquired pneumonia, which included 279 patients with blood glucose >11.0mmol/l at presentation.1
The message to patients with diabetes is that good glycaemic control not only protects against long-term complications but also confers protection against death in the event of pneumonia. This study reinforces the importance to general practice of good coverage of pneumonia and flu vaccinations in patients with diabetes.
Kornum JB, Thomsen RW, Riis A et al. Type 2 diabetes and pneumonia outcomes; a population based study. Diabetes Care June 26, 2007 published online ahead of print.Reviewer
Dr Matthew Lockyer
GP, Suffolk and hospital practitioner in diabetic medicine