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Gluconeogenesis
Synthesis of glucose from noncarbohydrate precursors (lactate, glycerol, glucogenic amino acids, propionate) primarily in liver and kidney during fasting.
Gluconeogenesis bypasses three irreversible glycolytic steps using pyruvate carboxylase, PEP carboxykinase, fructose-1,6-bisphosphatase, and glucose-6-phosphatase. It maintains blood glucose during fasting after hepatic glycogen is depleted (~24 hr). Glucagon, cortisol, and reduced insulin upregulate the pathway. Inhibition by metformin (mild AMPK activation and complex I effects) underlies its glucose-lowering action in type 2 diabetes.
How each textbook covers it
Advanced Nutrition and Human Metabolism, 8th ed. (Gropper) — Glossary
Hepatic and renal pathway producing glucose from lactate, glycerol, and glucogenic amino acids. Essential during fasting to supply glucose to brain and erythrocytes. Regulated by glucagon, cortisol, and insulin.
Modern Nutrition in Health and Disease, 12th ed. — Ch 1: Proteins and Amino Acids
Gluconeogenesis bypasses three irreversible glycolytic steps using pyruvate carboxylase, PEP carboxykinase, fructose-1,6-bisphosphatase, and glucose-6-phosphatase. It maintains blood glucose during fasting after hepatic glycogen is depleted (~24 hr). Glucagon, cortisol, and reduced insulin upregulate the pathway. Inhibition by metformin (mild AMPK activation and complex I effects) underlies its glucose-lowering action in type 2 diabetes.
Related terms
AMPK, Cori cycle, Glucagon, Glycogenolysis, Glycolysis