Abstract

Background

Hypoglycaemia is one of the comorbidities that adversely affects the quality of life in patients with cystic fibrosis (CF).Isolated hypoglycaemia (IsoHypo) is poorly described in patients with CF and its aetiopathogenic significance is unclear.

Aim

To investigate the etiopathogenesis of IsoHypo and the role of pancreatic insufficiency (PI) in IsoHypo in children with CF.

Patients and Methods

The blood glucose, insulin, and glucagon responses of 44 patients with CF and 9 healthy controls were evaluated during a 3-hour oral glucose tolerance test. Based on the results, the patients were categorized into 5 groups: 1) normal glucose tolerance (NGT), 2) IsoHypo, 3) hypoglycaemia with abnormal glucose tolerance (Hypo+AGT), 4) AGT, and 5) CF-related diabetes. IsoHypo and NGT were sub-classified according to the presence of PI as PI(+) or PI(-). Hypoglycaemia was defined as <70 mg/dL.

Results

Hypoglycaemia was observed in 21 of 44 patients (47.7%), predominantly as IsoHypo (29.5%). Hypo+AGT was found in 8 patients (18.2%). The IsoHypo group showed undelayed and higher insulin secretion than the Hypo+AGT group, especially in IsoHypo PI(-) compared to IsoHypo PI(+). Both IsoHypo and Hypo+AGT groups exhibited an insufficient increase in glucagon at 180 minutes, with the deficiency being more pronounced in the Hypo+AGT group. Insulin and glucagon responses to oral glucose load in IsoHypo PI(+) were similar to Hypo+AGT, whereas they were less affected in IsoHypo PI(-) patients who had early and higher insulin secretion.

Conclusion

IsoHypo is common in CF children and might precede Hypo+AGT in those with pancreatic insufficiency. The abnormal insulin and glucagon responses to glucose are the most significant contributors to the development of IsoHypo in CF.