Lipid Biochemistry USMLE Step 1 Practice Question
A 45-year-old man with a 20-year history of type 2 diabetes mellitus presents with fatigue and dyspnea on exertion. Vital signs: BP 152/88 mmHg, HR 92 bpm, RR 18/min, SpO2 98% on room air. Laboratory studies reveal fasting glucose 285 mg/dL, triglycerides 520 mg/dL, HDL cholesterol 26 mg/dL, and LDL cholesterol 145 mg/dL. He denies chest pain. Currently taking metformin monotherapy with poor glycemic control. Which biochemical mechanism best explains his lipid abnormality?
Answer choices
- AIncreased hepatic VLDL production from excess acetyl-CoA derived from hyperglycemiaCorrect answer
- BReduced CETP activity leading to HDL accumulation
- CDecreased lipoprotein lipase activity due to insulin deficiency
- DIncreased apolipoprotein B-48 synthesis in the intestine
- EImpaired cholesterol esterification by LCAT
- FIncreased LDL receptor expression on hepatocytes due to enhanced SREBP-2 signaling
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