Question 4 Quelles stratégies diagnostiques et thérapeutiques des troubles du métabolisme glucidique au cours de la mucoviscidose? Stratégies diagnostiques et thérapeutiques des troubles du métabolisme glucidique au cours de la mucoviscidose

[Endocrine complications of cystic fibrosis in childhood]

Since the 20 last years, the median age of survival has dramatically improved in children suffering from cystic fibrosis and complications such as growth retardation, pubertal delay and low bone mineral density are now more often than not observed in affected adolescents. The severity of the disease and the poor nutritional status due to pancreatic insufficiency and malabsorption are commonly implicated but recent data suggest that the disease could also play a role though the alteration of the chlore chanel (CFTR). Furthermore an increase prevalence of glucose intolerance and diabetes due to the progressive β cells destruction is observed in these children that make the life sometimes difficult for these adolescents already affected by an heavy chronic disease. The monitoring of the children should thus now become pluridisciplinary and include regular clinical evaluation of height and pubertal status, mineral bone density by DEXA and OGTT every two years since 10 years of age. Therefore, in addition to the standard treatment of cystic fibrosis is now added the vitamin D supplementation, the subcutaneous insulin therapy and may be the growth hormone that could be a new therapeutic demonstrating beneficial effects in these chronic disease. However further studies need to be performed to improve the management of these new endocrine complications more and more frequent in children and adolescents suffering from cystic fibrosis.

[Value of continuous glucose monitoring in screening for diabetes in cystic fibrosis]

AIMS

In the past few years, survival has increased for people with cystic fibrosis (CF). Diabetes is an important complication of CF caused by pancreatic insufficiency, which reduces insulin secretion. Because of increased longevity of patients with CF, the prevalence of CF-related diabetes (CFRD) has increased. CFRD is associated with increased mortality and morbidity. Several studies have reported a decline in nutritional and pulmonary status 2-4 years before the diagnosis of CFRD. The introduction of insulin treatment can produce clinical improvement in weight and lung function. The oral glucose tolerance test is currently the reference method in screening for CFRD, but the current definition of diabetes based on the 2-h post-load plasma glucose level may not be the most accurate method for early detection of glucose tolerance abnormalities in CF. The continuous glucose monitoring system (CGMS) has been described as a useful tool for early detection of hyperglycemia in the CF patient. We tested the CGMS in CF patients with unexplained alteration of their general status. The aim of this study was to assess the value of the CGMS in this population.

METHODS

An annual OGTT (following World Health Organization recommendations) was conducted as a screening test to identify CFRD in patients aged over 10 years or patients aged under 10 years with a poorer clinical status. The CGMS was performed in patients with unexplained worsened clinical status and without diabetes in OGTT.

RESULTS

Forty-two patients aged from 8.5 to 19 years were screened using OGTT for CFRD. According to ADA criteria, 23 patients (54.8%) displayed normal glucose tolerance, 14 (33.3%) impaired glucose tolerance, and 5 diabetes (11.9%). Out of 37 nondiabetic, the CGMS was used in 20 patients with unexplained altered general status. The CGMS revealed peaks of glucose values greater than 2 g/L in 16 patients, 9 patients with normal glucose tolerance, and 7 patients with impaired glucose tolerance. The mean CGMS glucose and time of glycemic monitoring above 1.4 g/L increased in patients with peaks greater than 2 g/L compared to patients without peaks (p=0.0016 and p=0.0069 respectively). After analysis of the CGMS, the prevalence of diabetes increased from 11.9 to 50%. Three patients aged less than 10 years with a normal OGTT profile presented glycemic peaks greater than 2 g/L during CGMS.

CONCLUSION

CGMS revealed more glucose metabolism abnormalities than OGTT in patients with unexplained altered general status.