<P> Gluconeogenesis is one of several main mechanisms used by humans and many other animals to maintain blood glucose levels, avoiding low levels (hypoglycemia). Other means include the degradation of glycogen (glycogenolysis) and fatty acid catabolism . </P> <P> Gluconeogenesis is a ubiquitous process, present in plants, animals, fungi, bacteria, and other microorganisms . In vertebrates, gluconeogenesis takes place mainly in the liver and, to a lesser extent, in the cortex of the kidneys . In ruminants, this tends to be a continuous process . In many other animals, the process occurs during periods of fasting, starvation, low - carbohydrate diets, or intense exercise . The process is highly endergonic until it is coupled to the hydrolysis of ATP or GTP, effectively making the process exergonic . For example, the pathway leading from pyruvate to glucose - 6 - phosphate requires 4 molecules of ATP and 2 molecules of GTP to proceed spontaneously . Gluconeogenesis is often associated with ketosis . Gluconeogenesis is also a target of therapy for type 2 diabetes, such as the antidiabetic drug, metformin, which inhibits glucose formation and stimulates glucose uptake by cells . In ruminants, because dietary carbohydrates tend to be metabolized by rumen organisms, gluconeogenesis occurs regardless of fasting, low - carbohydrate diets, exercise, etc . </P> <Ul> <Li> Glucogenic amino acids have this ability </Li> <Li> Ketogenic amino acids do not . These products may still be used for ketogenesis or lipid synthesis . </Li> <Li> Some amino acids are catabolized into both glucogenic and ketogenic products . </Li> </Ul> <Li> Glucogenic amino acids have this ability </Li>

When does the rate of gluconeogenesis increase in the cells