Introduction: Use of continuous glucose monitoring (CGM) as a diagnostic tool for cystic fibrosis-related diabetes (CFRD) is receiving increasing attention. We aimed to: i) describe the glucose profile by CGM in CF patients >10 years of age; ii) compare CGM and oral glucose tolerance test (OGTT) results; and iii) evaluate lung function and nutritional status changes over the previous year.
Methods: Prospective study of CF patients aged ≥10 years. OGTT and CGM (Ipro2TM) were performed between November 2012 and May 2014. Changes in BMISDS and percent forced expiratory volume in 1s (%FEV1) in the year preceding both tests were assessed. Patients with exacerbations treated with steroids, GH, immunosuppression, or insulinised or transplanted were excluded. ROC curve (compared to the gold standard OGTT) was used to determine optimal glycaemic cut-offs for detecting clinical changes. Analysis using STATA Statistical Software.
Results: Twenty-one patients: (43% males); mean age 16 years. Genotype: 38% homozygous F508del, 38% heterozygous F508del, and 24% other mutations. In CGM: average max glucose 191 mg/dl (178201), average min glucose 59 mg/dl (47.566.5), average time >140 mg/dl: 5%. Nine patients presented glucose values <60 mg/dl and six >200 mg/dl (three with greater than one peak). Two patients had fasting blood glucose (FBG) >126 mg/dl. Abnormal tolerance glucose (ATG) was defined as postprandial CGM time >140 mg/dl ≥4.5% or FBG CGM time >30% between 100 and 126 mg/dl; and CFRD glucose was defined as >200 mg/dl greater than one peak or FBG levels >126 mg/dl. The ATG patients on CGM had a variation of BMI and FEV1 greater (−0.1 SDS and −4.5% respectively) than the normal CGM patients (+0.05 SDS and −1%). Four (36.3%) of the 11 patients with normal OGTT had normal CGM with a variation of +0.05 BMISDS vs 7 (63.7%) who had ATG CGM with a variation of −0.18 BMISDS. Nevertheless, in these patients, there were no differences in lung function.
Conclusions: i) CGM is a useful tool for diagnosing and managing carbohydrate metabolism in patients with CF. ii) CGM reveals early glucose tolerance abnormalities that remain undiagnosed by OGTT screening and are correlated with clinical abnormalities.
01 Oct 2015 - 03 Oct 2015