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T1DM Osmotic Polyuria — RACP Adult Medicine MCQ

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EasyEndocrinologyT1DM Osmotic PolyuriaRACP Adult Medicine

A 25-year-old man presents with polyuria (10 L/day), polydipsia, and weight loss. His blood glucose is 28 mmol/L. HbA1c is 135 mmol/mol. Ketones are elevated. He has no prior diabetes history. Anti-GAD antibodies are positive. What is the most likely diagnosis?

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Correct answer: E — Diabetes mellitus

Polyuria with polydipsia, weight loss, marked hyperglycaemia, elevated HbA1c, ketonuria, and positive anti-GAD (confirming autoimmune destruction of beta cells) is new-onset type 1 diabetes presenting with osmotic diuresis. Glucose >10 mmol/L exceeds the renal threshold causing glycosuria and osmotic polyuria. Urgent insulin therapy is required. Check for DKA (pH, bicarbonate, ketones).

Reference: ADS – 2024 – Type 1 Diabetes; eTG Endocrine 2024