Pubertal stage and hypoglycaemia counterregulation in type 1 diabetes

Abstract

Aims: To compare physiological and autonomic responses to acute hypoglycaemia in diabetic children in pre-, mid-, and post-pubertal stages of development.

Methods: Twenty seven children (8 pre-pubertal, 7 mid-pubertal, 12 post-pubertal) with type 1 diabetes were studied. Hypoglycaemia was induced by insulin infusion until an autonomic reaction (R) was identified. Counterregulatory hormone levels were measured at baseline, R, R+15, and R+30 minutes. Haemodynamic changes and sweat production were measured.

Results: The mean blood glucose level at R was lower in pre-pubertal than mid-pubertal children (2.0 v 2.5 mmol/l), and was positively correlated with HbA1c. Glucagon and noradrenaline responses to hypoglycaemia were minimal in all children. A brisk increase in pancreatic polypeptide (PP) concentration only occurred in post-pubertal children. Only two children showed a sweating response to hypoglycaemia.

Conclusions: The blood glucose level at which sympatho-adrenal responses to hypoglycaemia were activated was associated with glycaemic control, and varied with pubertal stage. As in adults, the glucagon response to hypoglycaemia was deficient within a few years of developing diabetes. However, sweating and secretion of PP in response to hypoglycaemia did not occur until after puberty, indicating some qualitative differences from adults.

Figure 1

Changes in heart rate and blood pressure induced by hypoglycaemia.

Figure 2

Relation of HbA_1c to blood glucose concentration at the onset of the autonomic reaction (R).

Figure 3

Pancreatic polypeptide levels in each pubertal group at baseline and at the onset of the autonomic reaction (R). *p < 0.001 for comparisons with baseline level in post-pubertal group, and level at R in pre-pubertal group.