Carbohydrate metabolism impairment in children and adolescents with cystic fibrosis

Abstract

Introduction: Development of cystic fibrosis-related diabetes (CFRD) is associated with worsening of nutritional status and lung function, as well as increased mortality. The relevance of diagnosing the «pre-diabetic» status in these patients has not been addressed and the utility of HbA1c measurement in these patients is under discussion.

Aim: To study and characterise the different categories of carbohydrate metabolism impairment in paediatric patients with cystic fibrosis.

Patients and methods: A transversal study for characterisation of carbohydrate metabolism impairment according to clinical and anthropometric status and genetic background in 50 paediatric patients with cystic fibrosis (CF) was undertaken. Oral glucose tolerance tests (OGTT) for determination of glucose and insulin levels measurement and continuous subcutaneous glucose monitoring (CSGM) were performed.

Results: 6% of patients presented with CFRD, 26% impaired glucose tolerance, 10% an indeterminate glucose alteration and 2% impaired fasting glucose. The severity of glycaemic impairment correlated positively with age and negatively with standardised height (p < 0.05) with intergroup differences in HbA1c levels (p < 0.01), with the latter correlating with the duration of hyperglycaemia throughout CSGM. No intergroup differences in mutation prevalence, pulmonary function test, nutritional status or disease exacerbations in the previous year were found. The daily enzyme replacement dose correlated with the glucose area under the curve (AUC, p < 0.05) but not with insulin-AUC.

Conclusions: An older age and greater enzyme replacement need are correlated with more severe carbohydrate metabolism impairment and lower standardized height in paediatric CF patients, with HbA1c correlating with the duration of hyperglycaemia. The study of the full glucose/insulin AUCs throughout the OGTT affords no additional information compared to glucose determination at 120 min in these patients.

Keywords: Cystic fibrosis; Diabetes; Fibrosis quística; Glucose monitoring; Hiperglucemia; Hyperglycaemia; Monitorización glucémica.