Impaired Awareness of Hypoglycaemia

Impaired awareness of hypoglycaemia (IAH) is a reduced ability to perceive the onset of hypoglycaemia while cognition is still intact. It affects 20-25% of patients with type 1 diabetes and about 10% of those with insulin-treated type 2 diabetes.1

IAH arises when repeated episodes of hypoglycaemia raise the glycaemic threshold for symptom generation (i.e. symptoms are only triggered at a lower blood glucose level). Symptoms that would make people aware of impending hypoglycaemia, such as sweating or anxiety, no longer occur above the new threshold. A careful clinical history is often sufficient to identify IAH.2

In addition to significantly increasing the risk of severe hypoglycaemia,3 IAH increases people’s reliance on others to manage their diabetes and can even lead to loss of driving privileges and employment. Scrupulous avoidance of hypoglycaemia can reverse IAH, though this strategy runs the risk of compromising glycaemic control.2


  1. Hsu et al. Association of Clinical Symptomatic Hypoglycemia With Cardiovascular Events and Total Mortality in Type 2 Diabetes. Diabetes Care 2013; 36: 894.
  2. Cryer PE. Elimination of hypoglycemia from the lives of people affected by diabetes. Diabetes 2011;60:24.
  3. Gold AE et al. Frequency of severe hypoglycemia in patients with type 1 diabetes with impaired awareness of hypoglycemia. Diabetes Care 1994;7:697.