It is the process by which glucose is synthesised from non-carbohydrate sources. The process begins with pyruvic acid. However, oxaloacetic acid and dihydroxyacetone phosphate may also form entry point. Lactic acid, certain amino acid obtained after protein degradation and glycerol obtained from fat can be converted into glucose by the process of gluconeogenesis. It can be considered as reverse process of glycolysis, though certain steps differ. First step of gluconeogenesis is the conversion of pyruvic acid to oxaloacetic acid. It is the compound that also reacts with acetyl CoA in the citric acid cycle.Net concentration of acetyl CoA and energy level in cells (ATP) determines the pathway in which oxaloacetic acid will be used. Low concentration of acetyl CoA and high ATP concentration in cells will trigger the gluconeogenesis pathway.The main site of gluconeogenesis is liver and cortex of the kidney. Brain, skeletal muscles, heart muscles or other body tissues are the sites where very low rate of gluconeogenesis is known to occur. This is because these organs have a very high demand of glucose. So, it this metabolic pathway is constantly occurring in the liver to maintain blood glucose level to meet energy demands.