Quantifying fluctuation in glucose levels to identify early changes in glucose homeostasis in cystic fibrosis

Abstract

BackgroundCystic fibrosis related diabetes (CFRD) is associated with increased morbidity in CF. Variability in physiological systems is associated with dysfunctional homeostasis. We examined whether fluctuation in glucose is a marker of CFRD or “pre-diabetes”. MethodsUsing a machine learning approach, we compared glucose IQR to current diagnostic criteria in a review of continuous glucose monitoring data. ResultsAnalysis was performed on 248 studies from 142 children. Calculated IQR (cIQR) was increased between children with CFRD, normal glucose homeostasis and indeterminate status (p<0.0001) and impaired glucose tolerance (p<0.05, Kruskal–Wallis test). In subjects who developed CFRD (n=20), cIQR increased between baseline and diagnosis (1.4mmol/L versus 2.4mmol/L, p<0.0001, Wilcoxon test). Area under the curve for CFRD on the basis of cIQR was 0.865 (p<0.0001). Neither episodes of hypoglycaemia nor cIQR at baseline predicted CFRD. ConclusionsGlucose fluctuation on CGMS can be quantified by calculating the IQR. This information may improve early recognition of abnormal glucose homeostasis.