Concentrations of the Stress Hormone Copeptin Increase upon Hypoglycaemia in Patients with Type 1 Diabetes Dependent of Hypoglycaemia Awareness

Objective: Copeptin, a marker for stress mirroring vasopressin concentrations, has been shown to increase upon insulin-induced hypoglycaemia in patients after transsphenoidal surgery of pituitary adenomas. Patients with type 1 diabetes mellitus are prone to hypoglycaemia, but no data about copeptin levels upon hypoglycaemia are available. Furthermore, the perception of hypoglycaemia can vary from total unawareness to disabling episodes. The aim of this study was to investigate whether copeptin increases upon hypoglycaemia in patients with type 1 diabetes mellitus and is associated with the degree of hypoglycaemia awareness. Materials and Methods: In this prospective observational study, 17 patients with type 1 diabetes underwent a standardized insulin infusion test. Blood sampling for glucose and copeptin was performed at baseline and after 60 minutes (min). To assess hypoglycaemia associated symptoms the Mood and Symptom Questionnaire (MSQ) was conducted at baseline and after 60 min. Results: During insulin infusion, blood glucose decreased from 5.1 (SD +/- 0.2) to 3.0 (+/- 0.5) mmol/L at 60 min (p<0.001). Copeptin concentrations increased from 3.2 (+/- 1.7) to 3.8 (+/- 1.9) pmol/L (p = 0.03). Mood and Symptoms Questionnaire scores increased from 14 (+/- 3.0) to 18 (+/- 5.8), (p = 0.006). Patients with good hypoglycaemia awareness had an increase in copeptin from 3.0 (+/- 1.8) to 4.2 (+/- 2.4) pmol/L (p = 0.03) in contrast to patients more unaware of hypoglycaemia who only showed an increase in copeptin from 3.3 (+/- 1.6) to 3.6 (+/- 1.4) pmol/L (p = 0.4). There was a trend to a larger copeptin increase in patients aware of hypoglycemia compared to patients unaware of hypoglycemia (p = 0.074). Conclusion: Copeptin increases in patients with type 1 diabetes upon insulin induced hypoglycaemia. Interestingly, the copeptin increase seems associated with the degree of hypoglycaemia awareness. This hypothesis warrants further verification.