Reduction of hepatic glucose production as a therapeutic target in the treatment of diabetes.

There has been an alarming increase in the population diagnosed with diabetes worldwide. Although there is an ongoing debate as to the role of liver in the pathogenesis of diabetes, reduction of hepatic glucose production has been targeted as a strategy for diabetes treatment. Indeed, reduction of hepatic glucose production can be achieved through modulation of both hepatic and extra-hepatic targets. This review describes the role of the liver in the control of glucose homeostasis. Gluconeogenesis and glycogenolysis are pathways for glucose production, whereas glycolysis and glycogenesis are pathways for glucose utilization/storage. At the biochemical and molecular level, the metabolic and regulatory enzymes integrate hormonal and nutritional signals and regulate glucose flux in the liver. Modulating either activities of or gene expression of these metabolic enzymes can control hepatic glucose production. Dysfunction of one or several enzyme(s) due to insulin deficiency or resistance results in increases in fluxes of glycogenolysis and gluconeogenesis and/or decreases in fluxes of glycolysis and glycogenesis, which thereby lead to glucose generation exceeding glucose consumption/disposal, as well as dysregulation of lipid metabolism. Activation of enzymes that promote glucose utilization/storage and/or inhibition of enzymes that reduce glucose generation achieve reduction of hepatic glucose production, and hence lower levels of plasma glucose in diabetes. This is also beneficial for the correction of dyslipidemia. Therefore, many enzymes are viable therapeutic targets for diabetes.