Gluconeogenesis is the process by which glucose is created from non-carbohydrate carbon substrates such as pyruvate, lactate, glycerol, and glucogenic amino acids.
The vast majority of gluconeogenesis takes place in the liver and, to a smaller extent, in the cortex of kidneys. This process occurs during periods of fasting, starvation, or intense exercise and is highly endergonic (energy absorbing). Gluconeogenesis is often associated with ketosis.
Gluconeogenesis is also a target of therapy for type II diabetes, such as metformin, which inhibit glucose formation and stimulate glucose uptake by cells.