A 49-year-old man has had increasing knee and hip pain for the past 10 years. The pain is worse at the end of the day. During the past year, he has become increasingly drowsy at work. His wife complains that he is a "world class" snorer. During the past month, he has experienced bouts of sharp, colicky, right upper abdominal pain. On physical examination, his temperature is 37degC, pulse is 82/min, respirations are 10/ min, and blood pressure is 140/85 mm Hg. He is 175 cm (5 feet 8 inches) tall and weighs 156 kg (body mass index 51). Laboratory findings show glucose of 139 mg/dL, Hb A1c of 10, total cholesterol of 229 mg/dL, and HDL cholesterol of 33 mg/dL. An arterial blood gas measurement shows pH of 7.35; PCO2, 50 mm Hg; and PO2, 75 mm Hg. Which of the following additional conditions is most likely present in this man?