The interaction of 2 diseases: diabetes mellitus and cystic fibrosis

We have reviewed the hospital records of 24 patients with cystic fibrosis-associated diabetes, and 2 groups of CF patients (1 with normal and the other with abnormal oral glucose tolerance tests) who did not develop symptomatic fasting hyperglycemia, to define the clinical characteristics of the diabetes and to study its effects on the progression of the pulmonary disease, changes in sputum organisms, and mortality. Although maximum blood glucoses ranged from 322 to 1160 mg/dl with a median of 579 mg/dl, only 1 of 24 diabetic patients developed ketoacidosis. This patient developed diabetes 12 years prior to the diagnosis of CF and may have had type 1 diabetes. In contrast, hypoglycemia was frequent and 4 patients were hospitalized with serious neurologic manifestations. Two patients were found to have diabetic retinopathy, 1 with macular edema required laser photocoagulation to improve vision, and the other had multiple microaneurysms. CF-associated diabetes did not influence the deterioration of clinical scores, chest x-ray scores, pulmonary function tests, the number of hospital admissions, the type of organisms found in the sputum, or mortality rates. The development of diabetes in our CF patients was not related to the severity of pulmonary dysfunction, clinical, or chest x-ray scores. Thus, although the development of diabetes is an additional encumbrance upon the already therapeutically burdened existence of a CF patient, it does not appear to affect the course of the disease. Despite the demonstration of diabetic retinopathy in this study, most patients with CF-associated diabetes still do not live long enough to develop microvascular complications from the diabetes.