The 'dawn phenomenon' in insulin-treated Type 1 diabetes involves a pre-dawn rise in blood glucose due to:
- A Insufficient basal insulin coverage combined with nocturnal growth hormone and cortisol surges ✓
- B Hypoglycaemia-induced glucagon secretion at 2–3 AM causing rebound hyperglycaemia (Somogyi effect)
- C Early morning gastric emptying resumption causing post-prandial spike without corresponding meal bolus
- D Waning of evening insulin dose with inadequate basal cover but absent counter-regulatory surge
Correct answer: A. Insufficient basal insulin coverage combined with nocturnal growth hormone and cortisol surges
Explanation
The dawn phenomenon (not to be confused with the Somogyi effect) occurs due to a physiological surge of growth hormone and cortisol in the early morning hours (4–8 AM). These counter-regulatory hormones increase hepatic glucose production and reduce peripheral glucose utilisation. When basal insulin coverage does not match this increased insulin requirement, pre-breakfast hyperglycaemia results. Option B describes the Somogyi effect (nocturnal hypoglycaemia-rebound); option D describes simple insulin waning without the hormonal surge.
Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.
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Written and medically reviewed by the StethoPrep medical team.