UNLABELLED

Diabetes is a common and severe complication of cystic fibrosis. If unrecognized, the condition not only causes deterioration of pulmonary function and failure to gain weight, but also a six-fold increase in mortality.

AIM

1. To evaluate the course of abnormal glucose tolerance and cystic fibrosis-related diabetes (CFRD), as well as the effects of treating these conditions in children with cystic fibrosis. 2. To analyze the association between the classes of mutations in both alleles of the CFTR gene and glucose intolerance.

MATERIALS AND METHODS

analysis was undertaken of the clinical records of 12 children (from the years 2002 to 2014), who were under the care of the Diabetes Outpatient Clinic at the Medical University of Warsaw and the Cystic Fibrosis Centre of the Institute of Mother and Child in Warsaw. The patients were divided into groups based on glucose tolerance categories in the Oral Glucose Tolerance Test (impaired glucose tolerance - IGT, cystic fibrosis related diabetes without fasting hyperglycemia - CFRD FH⁻ or with fasting hyperglycemia - CFRD FH⁺). The mean age of the children who were referred to the Diabetes Outpatient Clinic was 12.09 ± 3.57 years and the mean HbA1c at the baseline versus the end of the follow up was 6.16 ± 1,77% versus 6.03 ± 1.05%, respectively. We used the continuous glucose monitoring system (CGMS) for the diagnostics of 4 patients. The mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene were investigated in all the patients. All the children had mutations in at least one allele of the CFTR gene belonging to class I or II. Six (6/12) patients were homozygous, and 3 (3/12) patients heterozygous for the Phe508del (former F508del) mutation. Three children had other mutations (1717-1G>A/2183AA-G, R553X/3380delGAAG, G542X/2143delT).

RESULTS

In our study group we recognized impaired glucose tolerance (IGT) in 7 (7/12) patients and cystic fibrosis-related diabetes (CFRD) in 5 (5/12) patients; there were 4 patients with CFRD FH⁺ and 1 patient with CFRD FH⁻. During follow up we observed IGT deterioration of glucose tolerance towards CFRD FH⁻ in 4(4/7) patients. Eight (8/12) patients were on functional insulin therapy, five of them (5/8) used insulin pumps. The remaining patients (4 individuals - 4/12), who were in good condition and on a high-glycemic index product restricted diet, did not require insulin. In the group treated with insulin we observed improvement in BMI z-scores (from-1.14 to -0.70).

CONCLUSIONS

Glucose tolerance in children with cystic fibrosis deteriorates with age. Patients in a good condition and with good compliance to a low-glycemic index product diet, start insulin therapy later. Patients with a severe course of cystic fibrosis and diabetes require immediate insulin implementation. Insulin treatment improves their nutritional status. A continuous glucose monitoring system is a useful diagnostic tool which can be taken into account in therapeutic decisions. Prospective studies on the pediatric population with cystic fibrosis are needed in Poland for a better analysis of the associations between abnormal glucose tolerance, the class of mutation in the CFTR gene and the impact of glucose intolerance treatment on the clinical status of the patients.