- There is no universally accepted definition of hypoglycaemia (low blood glucose).
- Clinically significant hypoglycemia is confirmed by the presence of ‘Whipple 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/L
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. severe sepsis, 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)