Diabetes Mellitus USMLE Step 1 Practice Question
A 14-year-old boy presents with polyuria, polydipsia, weight loss, and fatigue for 2 weeks. Vital signs show BP 118/72 mmHg, HR 102 bpm, RR 20/min, temperature 37.2°C, and SpO2 98% on room air. Laboratory studies reveal glucose 410 mg/dL, positive anti-glutamic acid decarboxylase antibodies, C-peptide 0.8 ng/mL (low), and negative urine ketones. He denies recent infections or medication use. Which of the following best explains the underlying pathophysiology?
Answer choices
- AInsulin receptor downregulation from obesity
- BAutoimmune destruction of pancreatic beta cellsCorrect answer
- CPeripheral resistance to parathyroid hormone
- DSomatostatin excess from pancreatic delta cells
- EGlucagon secreting alpha cell tumor
- FType 2 diabetes mellitus from peripheral insulin resistance
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