What is the Dawn Phenomenon?

• A. Post-meal glucose spike due to high GI foods
• B. A nighttime release of growth hormone causing elevated blood glucose in the morning.
• C. Morning hypoglycemia due to insulin overuse
• D. Nighttime hypoglycemia due to excessive insulin

Answer: (B)

Dawn phenomenon is the early morning rise in fasting blood glucose caused by hormones that surge during the night, especially growth hormone, along with cortisol and other counterregulatory factors. This hormonal rise increases hepatic glucose production and lowers insulin sensitivity, so glucose climbs by dawn even if overnight levels were normal. It’s a pattern seen in diabetes and is distinct from a post-meal spike or from nocturnal hypoglycemia with rebound hyperglycemia (Somogyi effect). Management aims to blunt the morning rise by adjusting overnight basal insulin timing or dose, rather than focusing on morning meals.