Hypoglycaemia

Causes

• insulinoma - increased ratio of proinsulin to insulin
• self-administration of insulin/sulphonylureas
• liver failure
• Addison's disease
• alcohol
  • causes exaggerated insulin secretion
  • mechanism is thought to be due to the effect of alcohol on the pancreatic microcirculation → redistribution of pancreatic blood flow from the exocrine into the endocrine parts → increased insulin secretion
• nesidioblastosis - beta cell hyperplasia

Physiological response to hypoglycaemia

• hormonal response: the first response of the body is decreased insulin secretion. This is followed by increased glucagon secretion. Growth hormone and cortisol are also released but later
• sympathoadrenal response: increased catecholamine-mediated (adrenergic) and acetylcholine-mediated (cholinergic) neurotransmission in the peripheral autonomic nervous system and in the central nervous system

Features

• blood glucose levels and the severity of symptoms are not always correlated, especially in patients with diabetes.
• blood glucose concentrations <3.3 mmol/L cause autonomic symptoms due to the release of glucagon and adrenaline (average frequency in brackets):
  • Sweating
  • Shaking
  • Hunger
  • Anxiety
  • Nausea
• blood glucose concentrations below <2.8 mmol/L cause neuroglycopenic symptoms due to inadequate glucose supply to the brain:
  • Weakness
  • Vision changes
  • Confusion
  • Dizziness
• Severe and uncommon features of hypoglycaemia include:
  • Convulsion
  • Coma

Investigation of hypoglycaemia

• if the cause of hypoglycaemia is not clear then a combination of serum insulin and c-peptide levels can be measured