Diabetes mellitus in patients with cystic fibrosis: the impact of diabetes mellitus on pulmonary function and clinical outcome.

In this multicenter study, the impact of CF-related diabetes mellitus (CFRD) on pulmonary function and clinical outcome has been investigated. To better characterize the relationship between insulin deficiency and clinical outcome we prospectively followed a group of 56 CF patients, 28 with CFRD (group 1) and 28 without diabetes (group 2) for 5 years. The clinical course of the patients was registered at each center. Data included were mortality, pulmonary function, body mass index, in-patient treatment, and CF-typical and diabetes typical complications. At the end of the study nearly twice the number of patients had died in group 1 as compared to group 2, however due to the low patient number this did not reach statistical significance. In patients with diabetes FEV1 and FVC declined significantly over the five year study period, whereas patients without diabetes did not show a significant decline during the study period. Retinopathy, nephropathy, and neuropathy were only observed in diabetic patients. In conclusion, the data presented in this prospective, multicenter study give evidence that insulin deficiency leads to a direct decline in pulmonary function suggesting a cause and effect relationship between insulin deficiency and lung disease.