Assessment of the relationship between hypoglycaemia awareness and autonomic function following islet cell/pancreas transplantation

BACKGROUND: This study assesses the autonomic function of patients who have regained awareness of hypoglycaemia following islet cell or whole pancreas transplant. METHODS: Five patients with type 1 diabetes and either islet cell (four patients) or whole pancreas (one patient) transplant were assessed. These patients were age-matched and gender-matched to five patients with type 1 diabetes without transplant and preserved hypoglycaemia awareness and five healthy control participants without diabetes. All participants underwent (i) a battery of five cardiovascular autonomic function tests, (ii) quantitative sudomotor axonal reflex testing, and (iii) sympathetic skin response testing. RESULTS: Total recorded hypoglycaemia episodes per month fell from 76 pre-transplant to 13 at 0- to 3-month post-transplant (83% reduction). The percentage of hypoglycaemia episodes that patients were unaware of decreased from 97 to 69% at 0-3 months (p < 0.001, Fisher's exact test) and to 20% after 12 months (p < 0.0001, Fisher's exact test). This amelioration was maintained at the time of testing (mean time: 4.1 years later, range: 2-6 years). Presence of significant autonomic neuropathy was seen in all five transplanted patients (at least 2/3 above modalities abnormal) but in only one of the patients with diabetes without transplantation. CONCLUSIONS: The long-term maintenance of hypoglycaemia awareness that returns after islet cell/pancreas transplantation in patients with diabetes is not prevented by significant autonomic neuropathy and is better accounted for by other factors such as reversal of hypoglycaemia-associated autonomic failure.