[The human kidney as an important producer of glucose]

According to current textbook knowledge the liver is the exclusive site of glucose production in postabsorptive humans. Although many animal and in-vitro data have documented that the kidney is capable of gluconeogenesis, production of glucose by the human kidney has been regarded as negligible to date. This traditional perception is based on methodologically inadequate net balance studies, which other than after a prolonged fast or during metabolic acidosis showed no significant net renal glucose release.

Recent tracer studies, however, showing a renal glucose production accounting for 25% of systemic glucose production, have refuted this view. glucose production by the human kidney is stimulated by epinephrine and inhibited by insulin. Glucagon stimulates hepatic but not renal glucose production. The most important renal gluconeogenic precursors are lactate, glutamine and glycerol. The implications of these recent findings on the understanding of the physiology and pathophysiology of human glucose metabolism are discussed.

Magnitude and regulation of renal glucose production have important consequences for the intermediary metabolism, counterregulation of hypoglycemia, glucose metabolism of uremia and the pathophysiology of type I and type II diabetes.