Overview

Hypoglycaemia is defined as a blood glucose concentration <3.5 mmol/L and most commonly occurs due to excess insulin or oral hypoglycaemic agents combined with reduced glucose intake or increased activity. It can be diagnosed through the use of Whipple’s triad:

  • Plasma hypoglycaemia
  • Symptoms that correlate with hypoglycaemia
  • Resolution of symptoms after correcting hypoglycaemia

Epidemiology

  • More common in people with diabetes mellitus

Risk Factors

  • Alcohol consumption
  • Insulinoma
  • Excess insulin or hypoglycaemic agent (e.g. sulfonylurea) use
  • Starvation
  • Self-induced hypoglycaemia (factitious hypoglycaemia)
  • Adrenal insufficiency

Presentation

Blood glucose levels and symptoms severity are not always correlated, especially in patients with diabetes mellitus. This is because patients with diabetes mellitus may have hypoglycaemia unawareness due to diabetic neuropathy. Features can be divided into their underlying mechanisms:

  • Sympathoadrenal (responses to hypoglycaemia from the sympathetic nervous system and adrenal glands, usually seen at glucose concentrations <3.3 mmol/L):
  • Neuroglycopenic (brain malfunction secondary to hypoglycaemia, usually seen at glucose concentrations <2.8 mmol/L):
    • Confusion
    • Drowsiness
    • Irritability
    • Vision blurring

Diagnosis

Whipple’s triad

Hypoglycaemia can be diagnosed through the use of Whipple’s triad:

  • Plasma hypoglycaemia
  • Symptoms that correlate with hypoglycaemia
  • Resolution of symptoms after correcting hypoglycaemia

Management

Any patient that has hypoglycaemia secondary to an oral antidiabetic drug must be admitted to the hospital, as their hypoglycaemic effects can linger for 12-24 hours.

  • 1st-line: oral glucose via liquid, gel, or tablet form
  • If the patient is unconscious or unable to swallow, consider SC or IM glucagon
  • If there is IV access through a large vein, consider IV 20% glucose solution
  • Treat underlying cause

Patient Advice

  • Patients should be educated on the signs and symptoms of hypoglycaemia and should seek medical help should they arise.
  • Glucose tablets or gel may be recommended to patients and should be taken if signs and symptoms of hypoglycaemia arise.

Complications

  • Seizure
  • Coma
  • Permanent neurological complications

Insulinoma

Overview

Insulinomas are the most common pancreatic endocrine tumours that arise from beta cells in the Islets of Langerhans and are associated with multiple endocrine neoplasia 1 (MEN-1). They can release excess amounts of insulin in response to glucose, leading to hypoglycaemia.

Presentation

  • Features of hypoglycaemia
  • Unexplained weight gain, particularly rapid weight gain

Investigations

  • Insulin:
    • Elevated
  • Proinsulin:insulin ratio:
    • Elevated
  • C-peptide:
    • Elevated
  • Supervised 72-hour fast:
    • Hypoglycaemia should suppress insulin release. Insulin is not properly suppressed
  • CT pancreas:
    • May show insulinoma

Management

  • 1st-line: surgical removal
  • If unsuitable for surgery: diazoxide + somatostatin

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