The blood glucose and plasma immunoreactive insulin(IRI) levels were measured glucose tolerance test in 7 healthy subjects and 6 patients with chronic liver diseases. The glucose tolerance was impaired in 5 of the 6 patients and normal in 1. Plasma IRI responses were markedly increased and delayed in all patients, suggesting insulin resistance. Patients with more glucose intolerance showed less increase in plasma IRI than the group with less intolerance. It is suggested that some insulin antagonists may decrease the peripheral insulin sensitivity and stimulate compensatory hyperactivity of pancreatic islets. If the compensatory hyperactivity is inadequate due to genetic predisposition to diabetes mellitus or exhaustion of ${eta}$-cells of pancreatic islsts, the glucose intolerance and overt diabetes mellitus may ensue.