Evaluation of glucose tolerance and insulin secretion in cystic fibrosis patients

Blood glucose profile and insulin levels during the oral glucose tolerance test were retrospectively analyzed in 52 cystic fibrosis (CF) patients aged 10-33 years (mean 18 years). Thirty-seven subjects (71.1%)had normal glucose tolerance; 6 patients (11.5%) had impaired glucose tolerance and 9 patients (17.3%), with fasting blood glucose levels below 7.2 mmol/l were classified as diabetic, according to WHO diagnostic criteria. No significant differences in the total amount of secreted insulin (expressed as area under the curve) were detected in CF patients with or without glucose intolerance, but a significant delay in the insulin peak time appeared to be related to a compromised nutritional status. Our data indicate a significantly increased risk of glucose metabolism impairment related to poor nutritional condition (RR 5.40; 95% CI: 1.5-19.7) and worse clinical status (RR 4.27; 95% CI: 1.05-17.2). In particular, glucose tolerance abnormalities were found in 50% of CF patients with an unsatisfactory nutritional condition versus 15.6% of CF patients with good nutritional status. Conclusions: Since CF-related diabetes is often underdiagnosed and associated with deterioration in patients' overall clinical status, it is very important to identify subjects at risk of developing diabetes by strict monitoring of glucose metabolism when deterioration in nutritional and clinical conditions is seen which cannot be otherwise explained.