ABSTRACT
This chapter reviews the pathophysiology of hypoglycaemia, and describes the physiological mechanisms that virtually prevent hypoglycaemia in the non-diabetic and explaining how these defences are compromised in diabetes. Glucose reaches the neurons and glial cells of the nervous system by a process of facilitated diffusion involving specialized carrier proteins, the glucose transporters. The physiological mechanisms that prevent hypoglycaemia are so effective that, even under extreme physiological conditions, circulating glucose concentrations are prevented from falling to levels in which brain function is compromised. Early human studies used boluses of intravenous insulin to induce hypoglycaemia. Hypoglycaemia has the potential to impair a range of cognitive functions. Activation of the autonomic nervous system in response to impending hypoglycaemia leads to the release of counter-regulatory hormones which, by inhibiting peripheral glucose uptake and increasing hepatic glucose output, resist the glucose-lowering effects of insulin.
