A 48-year-old man with type 2 diabetes mellitus (HbA1c 9.2%) and chronic kidney disease stage 3b (eGFR 38 mL/min/1.73m²) is admitted with a 2-week history of poor oral intake due to uremia. His fasting blood glucose is 68 mg/dL (normal fasting 70–100 mg/dL), and he is asymptomatic. Serum electrolytes show potassium 6.8 mEq/L, phosphate 5.2 mg/dL, and bicarbonate 18 mEq/L. Urine output is 800 mL/24h. Which of the following best explains the paradoxically low fasting glucose despite diabetes?