Hypoglycaemia occurs when glucose concentration falls below 3.3 mmol/L. The threshold for the onset of hypoglycemic symptoms varies with patients. Severe symptomatic hypoglycemia occurs in most adults at blood glucose levels ≤ 2.2-2.8 mmol/L.
Hypoglycemia in patients with diabetes is defined as a blood glucose level ≤ 3.9 mmol/L.
Whipple triad – Helps to confirm the diagnosis of hypoglycemia
- Low blood glucose levels (patients with diabetes have symptoms of hypoglycemia at higher thresholds than healthy individuals)
- Signs or symptoms consistent with hypoglycemia
- Relief of symptoms when blood glucose increases after treatment
- Precipitating factors
- Insulin related
- Glucose related
- Irregular ingestion of food
- Alcohol ingestion
- Extreme activity – increased utilization of glucose
- Prior episodes of hypoglycemia leading to impaired awareness of hypoglycemia
- Hypopituitarism and adrenal insufficiency
- Acute illness
- Sepsis
- Trauma
- Burns
- Organ failure
- Pathophysiology
- Hypoglycaemia → activation of the sympathetic nervous system → autonomic symptoms
- Hypoglycaemia → brain dysfunction → neuroglycopaenic symptoms
- Recurrent episodes of hypoglycaemia → reduced epinephrine release, which lowers the threshold needed to trigger symptoms → Hypoglycemia-associated autonomic failure (HAAF) → asymptomatic hypoglycaemia
- Beta-blockers can mask signs of hypoglycemia by antagonizing the effects of epinephrine
- Signs and symptoms
- Autonomic symptoms
- Tremor
- Pallor
- Anxiety
- Tachycardia
- Sweating
- Palpitations
- Hunger
- Paresthesia
- Nausea
- Vomiting
- Neuroglycopenic symptoms
- Agitation
- Confusion
- Behavioral changes
- Fatigue
- Seizure
- Focal Neurologic signs
- Somnolence → Obtundation → Stupor → Coma → Death
- Autonomic symptoms
- Differentials
- Stroke or transient ischaemic attack
- Myocardial infarction
- Sepsis
- Epilepsy
- Idiopathic postprandial syndrome (pseudohypoglycaemia)
- Investigations
- Random blood glucose
- < 3.3 mmol/L
- Serum insulin
- Elevated in insulinoma
- Serum C-peptide
- Elevated in insulinoma and sulfonylurea use
- Serum cortisol
- Reduced in adrenal insufficiency or hypopituitarism
- Toxicology screen for illicit drug use
- TSH for hypothyroidism
- LFTs for chronic liver disease or liver failure
- Blood alcohol for alcohol-induced hypoglycemia
- U&E for chronic kidney disease
- Random blood glucose
- Treatment
- Reverse hypoglycemia and expect prompt recovery
- 15-20g of quick-acting carbohydrate snack (200ml orange juice or sweets) for patients who can swallow
- GlucoGel or Dextrogel between the teeth and gums in uncooperative patients
- IV Dextrose 10% at 200mL/h or IV Dextrose 10% 200mL/15min if unconscious or not responding to treatment
- Fast-acting carbohydrates cannot be used to treat hypoglycemia caused by alpha-glucosidase inhibitors
- Glucagon will not work in malnourished patients since glycogen reserves have been depleted
- Repeat snacks up to 3 times
- Recheck Blood glucose q10-15min
- Once blood glucose is >4.0 mmol/L, give long-acting carbohydrates such as bread
- Diazoxide can be used in some patients with chronic hypoglycaemia from excess endogenous insulin secretion
- Treat the underlying cause
- Reverse hypoglycemia and expect prompt recovery
- Complications
- Coma
- Seizures
- Permanent neurologic deficits
- Hemiparesis
- Memory impairment
- Diminished language skills
- Decreased abstract thinking capabilities
- Ataxia
- Arrhythmia
- Death
- Hypoglycaemia unawareness is more common in type 2 diabetes. This increases the risk of neuroglycopenic complications of hypoglycemia.
Hyperinsulinism due to Exogenous insulin vs Sulfonylureas
| Exogenous insulin | Sulfonylurea | |
|---|---|---|
| Plasma insulin | Very high | High |
| C-peptide | Normal or low | High |
| Pro-insulin | Normal or low | Normal |
| Urine sulfonylurea | None | Present |