Hypoglycaemia

Pathophysiology

• During hypoglycaemia, the body activates glycogenolysis and gluconeogenesis via counter-regulatory hormones (glucagon, adrenaline, cortisol, growth hormone).

• Common precipitants:

  • Reduced dietary carbohydrate intake

  • Increased physical activity

  • Inappropriate timing/use of diabetes medication

  • Renal impairment (reduced clearance of insulin/oral hypoglycaemic agents)

____________________________________

Symptoms

Threshold for Symptoms:

• Initial symptoms arise at ~3.0 mmol/L.

• Hypoglycaemic unawareness can occur with repeated episodes (no symptoms until severe hypoglycaemia).

____________________________________

Aetiology

Iatrogenic:

• Insulin or sulfonylurea overdose (most common cause).

• Advanced diabetic nephropathy (reduced drug clearance).

Medications:

• Beta-blockers (masks hypoglycaemia symptoms).

Lifestyle Factors:

• Missed meals, alcohol intake, weight loss, increased physical activity.

____________________________________

Risk Factors

Common or important patient risk factors for hypoglycaemia:

• Previous severe hypoglycaemia

• Hypoglycaemia unawareness

• Long duration of diabetes

• Insulin therapy

• Increased age

• Cognitive impairment

• Kidney or liver impairment

• Primary GI disease with malabsorption (e.g., coeliac disease)

• Primary failure of hormones that raise blood glucose (e.g., adrenal cortical failure)

Acute Precipitants (especially in insulin users):

• Irregular carbohydrate intake

• Suppressed gluconeogenesis by alcohol

• Incorrect insulin administration

• Vigorous exercise

____________________________________

Diagnostics

• Patient History: Physical activity, diet, medication, alcohol use.

• Laboratory Tests:

  • Blood glucose (FBG <4 mmol/L).

  • C-peptide (helps differentiate causes):

    • High insulin + high C-peptide: likely insulinoma.

    • High insulin + low C-peptide: exogenous insulin.

____________________________________

Management

Mild Hypoglycaemia

• Treatment: 15, 15 rule:

  • 15g of fast-acting carbohydrate (i.e., 6-7 jelly beans or half a cup of apple juice)

  • Recheck blood glucose level after 15 minutes

  • Repeat treatment if blood glucose remains below 4 mmol/L

Severe Hypoglycaemia

• Glucagon: 1 mg IM or SC (may be given by another person)

• IV Glucose: 20 mL of 50% glucose (adults) or 2 mL/kg of 10% glucose (children)

• Recheck blood glucose level after 15 minutes

• Transfer to hospital if patient remains unconscious or requires more than two doses

Note: Avoid 50% glucose IV in children or adolescents, as it increases risks of hyperosmolarity and necrosis.

____________________________________

Monitoring After Hypoglycaemic Episode

• Monitor blood glucose every 1-2 hours for first 4 hours, then resume usual testing.

• Investigate and address underlying causes.

• Review medications and diet to prevent recurrence.

____________________________________

Hypoglycaemia Unawareness

• Often occurs in patients with diabetes for over 10 years.

• Repeated mild hypoglycaemic episodes impair adrenergic response, increasing the risk of severe hypoglycaemia.

• Management: Patients should avoid driving until awareness improves, which may take several weeks.

____________________________________

Special Considerations

Alcohol-Associated Hypoglycaemia

• Alcohol impairs liver glucose production, increasing hypoglycaemia risk.

• Guidelines for patients with type 1 diabetes:

  • Use a medical alert device

  • Avoid skipping meals or drinking on an empty stomach

  • Monitor blood glucose closely, especially at night

Sulfonylurea-Induced Hypoglycaemia

• Prolonged hypoglycaemia may occur, particularly in patients with kidney impairment.

• Management: Hospital admission and frequent glucose monitoring are often necessary.

____________________________________

Notes:

• Hypoglycaemia Awareness: Establish by maintaining stable glucose levels. Consider dietary adjustments or insulin modifications if recurrent episodes occur.

• Driving Advisory: Individuals should avoid driving if they are at risk of hypoglycaemia or until hypoglycaemia awareness is restored.

• Avoidance: Educate patients on the "Rule of 15" for mild hypoglycaemia management