What describes the Somogyi Phenomenon?

• A. Increase in insulin sensitivity overnight
• B. Morning hyperglycemia due to late-night hypoglycemia and rebound effect from glucagon.
• C. Hypoglycemia after meals due to insulin mismatch
• D. Persistent hyperglycemia throughout the day

Answer: (B)

Somogyi phenomenon is a pattern where nighttime hypoglycemia triggers a rebound rise in glucose by morning due to the release of counterregulatory hormones (primarily glucagon, with help from epinephrine, cortisol, and growth hormone). In people on insulin or medications that can cause low nighttime glucose, a too-high or late-evening insulin dose can push glucose down during sleep. The body responds to this low by releasing those hormones, rapidly raising glucose, so fasting morning glucose is high. That sequence—overnight hypoglycemia followed by morning hyperglycemia from a rebound effect of glucagon and other hormones—best matches the description. The other options describe different patterns (insulin sensitivity changes overnight, postprandial hypoglycemia, or persistent daytime hyperglycemia) that don’t capture the nocturnal hypoglycemia with a rebound in the morning.