The utility of glucose area under the curve from the oral glucose tolerance test as a screening tool for cystic fibrosis-related diabetes.

BACKGROUND: Consistently abnormal glucose levels on oral glucose tolerance test (OGTT) are the most effective screening tool for cystic fibrosis-related diabetes (CFRD). However, some cystic fibrosis (CF) patients demonstrate abnormal glucose profiles not reaching levels required for CFRD diagnosis and are, therefore, left untreated. Since CFRD is associated with disease deterioration, early diagnosis and treatment are desirable. AIM: To explore the association between the area under the curve of glucose (G-AUC) obtained during a five-point 2-h standard OGTT and CF disease severity parameters. METHODS: All CF patients referred for an annual routine OGTT at the Hadassah CF Center between 2002 and 2018, were included. Disease severity parameters were correlated with the G-AUC. RESULTS: Two hundred forty-two OGTTs were performed in 81 patients (mean age 19.7 ± 9.0 years); 54% were normal, 14% showed impaired glucose tolerance (IGT), 5% had values in the indeterminate range (INDET), 11% had both IGT and INDET and 16% were diagnosed with CFRD. A gradual increase in mean G-AUC was observed among the groups. In multivariate regression models, G-AUC ≥ 295 mg h/dl was independently associated with an increased number of pulmonary exacerbations (PEx). Not all the patients having this value met the CFRD definition. CONCLUSION: Patients who do not fulfill the criteria for CFRD may have abnormal glucose metabolism identifiable by abnormally high G-AUC values, which may be associated with more PEx. The potential advantage of treating these patients with insulin and the subsequent reduction in PEx needs further investigation.

Increasing Vitamin D Serum Levels Is Associated With Reduced Pulmonary Exacerbations in Patients With Cystic Fibrosis.

CONTEXT: In 2012, The North American Cystic Fibrosis Foundation (NACFF) published new guidelines for the treatment of vitamin D deficiency in individuals with cystic fibrosis (CF). OBJECTIVE: The objectives of our study were to assess the efficacy of these guidelines, and to test the effect of increasing vitamin D dosage on pulmonary function and exacerbations. DESIGN: Pulmonary function tests and serum concentrations of 25-hydroxyvitamin D [25(OH)D] were measured 1 year before increasing vitamin D dosage according to the guidelines and at least 1 year later. In addition, days of hospitalization and pulmonary exacerbations were counted and an average per year (average number of days of hospitalization and average number of pulmonary exacerbations [PEA], respectively) was calculated. SETTING AND PARTICIPANTS: A total of 90 patients from The Cystic Fibrosis Clinic at Hadassah Mount-Scopus Hospital, Jerusalem, Israel. RESULTS: The mean serum concentration of vitamin D increased significantly from 20.97 ng/mL (52.34 nmol/L) at baseline to 25.41 ng/mL (63.42 nmol/L) at the end of follow-up (P < 0.001). The number of PEA decreased significantly from 2.79 ±â€Š3.96 to 2.15 ±â€Š2.91 (P = 0.007). The change in vitamin D levels was correlated with a decrease in PEA (correlation coefficient = -0.318, P = 0.002). CONCLUSIONS: The NACFF guidelines for management of vitamin D deficiency improve vitamin D levels in patients with CF but did not reach the normal values in most patients. The increase in vitamin D serum levels was, however, associated with a decrease in number of pulmonary exacerbations.