Since 1960, studies in this laboratory have focused on the interactions between ethanol and carbohydrate metabolism. It has been demonstrated that alcohol has hypoglycemic properties when administered after appropriate periods of dietary deprivation. The blood-sugar-lowering action is independent of changes in insulin secretion or alterations in the peripheral utilization of glucose. It results from direct inhibition of gluconeogenesis. Ketogenesis may be interrupted at the same time coincident with hepatic “over-production” of lactic acid. Mediation has been ascribed to the “extra-reducing equivalents” which are generated in the liver during alcohol oxidation. The diverse potentialities in vivo depend upon the metabolic mixture which is being utilized at the time of exposure to alcohol and upon the ongoing turnover of pyruvate and glycogen within the liver. These considerations have prompted efforts to employ the blood sugar response to standard infusion of alcohol as a new clinical tool for characterizing metabolic disorders.