A 28-year-old man with a known history of alcohol use disorder presents with a 2-day history of reduced oral intake and persistent vomiting. On examination, he is icteric and has hepatomegaly. Laboratory findings show: blood glucose 38 mg/dL, serum lactate 8.2 mmol/L (normal <2), serum bicarbonate 16 mEq/L, and markedly elevated liver enzymes. Arterial blood gas shows pH 7.28 with an anion gap of 16. Which of the following best explains the profound hypoglycemia and lactic acidosis in this patient?