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Dawn phenomenon in type 1 diabetes — SCE Endocrinology MCQ

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ModerateDiabetesDawn phenomenon in type 1 diabetesSCE Endocrinology

A 41-year-old man with type 1 diabetes reports glucose rising from 5 mmol/L at 03:00 to 13 mmol/L at 07:00 without nocturnal hypoglycaemia. He uses basal-bolus injections and has no intercurrent illness. Continuous glucose monitoring confirms a steady early-morning rise. What is the most likely diagnosis?

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Correct answer: B — Dawn phenomenon

The CGM trace shows early-morning hyperglycaemia without preceding hypoglycaemia, consistent with dawn phenomenon from nocturnal counter-regulatory hormone secretion. Somogyi effect requires rebound after overnight hypoglycaemia. The pearl is that CGM timing distinguishes basal insufficiency from rebound physiology.

Reference: https://www.nice.org.uk/guidance/conditions-and-diseases/diabetes-and-other-endocrinal-nutritional-and-metabolic-conditions