Overview There is no universally accepted definition of hypoglycaemia (low blood glucose). Clinically significant hypoglycemia is confirmed by the presence of ‘Whipple’s triad’: the presence of symptoms consistent with hypoglycemia a low serum glucose level resolution of the symptoms and signs of hypoglycemia with the administration of glucose Clinical hypoglycaemia is defined as a blood glucose low enough to cause symptoms or signs (including brain impairment) or both. For most people this occurs at blood glucose levels less than 2.8- 3.3 mmol/L (50-60 mg/dL). Severe hypoglycaemia is defined as an event requiring the assistance of another person to actively administer carbohydrate, glucagon or provide other resuscitative measures. Relative hypoglycaemia occurs when a patient with diabetes reports hypoglycaemic symptoms, but the blood glucose remains above 3.8 mmol/L (70 mg/dL). This still requires treatment. Conversion of Blood Glucose: 1 mmol/L = 18 mg/dL, 1 mg/dL = 0.056 mmol/LCauses Known diabetics (most common) Hypoglycemic agents (suphonylureas, insulin) Decreased glucose delivery (missed meals or overnight fasting) Increased glucose utilisation (exercise) Reduced endogenous glucose production (alcohol ingestion) Increased insulin sensitivity (weight loss, increase in exercise) Reduced insulin clearance (renal failure) No history of diabetes (rare) – mnemonic ‘EXPLAINS H) Exogenous drugs (e.g insulin, oral hypoglycemics, ethanol intoxication, quinine, chloroquine, beta-blocker overdose, valproate overdose, salicylate overdose, pentamidine) Pituitary insufficiency Post-prandial hypoglycemia (e.g. ’late dumping’ after gastric surgery) Liver disease (e.g hepatocellular cancer, hepatitis and rare genetic defects) Addison’s disease Islet cell tumours (e.g. insulinomas) Immune hypoglycemia (e.g. anti-insulin receptor antibodies in Hodgkin’s disease or anti-insulin antibodies that release insulin when insulin levels are relatively low) Infection (e.g. severesepsis, malaria) Non-pancreatic neoplasms (e.g fibromas, sarcomas, mesotheliomas, and small cell carcinomas that produce IGF-2; extensive metastases that overwhelm the body’s ability to produce glucose) Nesidioblastosis or noninsulinoma pancreatogenous hypoglycemia (NIPH) syndrome (islet cell hyperplasia, which can be congenital or acquired, e.g. post-gastric surgery) Starvation and malnutrition Hypothyroidism (myxoedema coma) Pseudohypoglycemia (delayed measurement of a sample in the presence of leukocytosis, thrombocytosis or erythrocytosis)
