[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Biochemistry](https://durgical.com/en/biochemistry/) › Gluconeogenesis [Biochemistry](https://durgical.com/en/biochemistry/) · Metabolic pathway # Gluconeogenesis Gluconeogenesis makes new glucose from lactate, alanine or glycerol during a long fast; it happens mainly in the liver. Updated 2026-11-01 ## Interactive map **Balance:** ATP -4 GTP -2 NADH -2 ## Key facts - It is not glycolysis run backwards: it shares 7 reversible steps but goes around the 3 irreversible ones with 4 enzymes of its own (pyruvate carboxylase, PEPCK, fructose-1,6-bisphosphatase and glucose-6-phosphatase). - Cost per glucose: 4 ATP, 2 GTP and 2 NADH (6 high-energy bonds), against the 2 ATP that glycolysis yields. - Site: liver (90 %) and renal cortex; in prolonged fasting the kidney supplies up to 40 %. The first step is mitochondrial and the last takes place in the endoplasmic reticulum. - Substrates: lactate (Cori cycle), alanine and other glucogenic amino acids (glucose–alanine cycle), glycerol from triglycerides (enters as DHAP) and propionate. Even-chain fatty acids and acetyl-CoA give no net glucose. - It takes over after about 12–18 h of fasting, once liver glycogen runs out. **Also called** Glucose synthesis from non-carbohydrate precursors ## Regulation - Glucagon and cortisol switch it on; insulin switches it off (represses PEPCK and glucose-6-phosphatase). - Acetyl-CoA from beta-oxidation activates pyruvate carboxylase: fatty acids pay the energy bill and push pyruvate toward glucose. - Fructose-2,6-bisphosphate inhibits fructose-1,6-bisphosphatase and activates PFK-1; glucagon lowers it, so the cell does not run both pathways at once (futile cycle). - AMP inhibits fructose-1,6-bisphosphatase: with little energy, no glucose is made. ## The steps, one by one - **Step 1 · [Pyruvate carboxylase](https://durgical.com/en/biochemistry/enzymes/pyruvate-carboxylase/)** irreversible [Pyruvate](https://durgical.com/en/biochemistry/molecules/pyruvate/) + CO₂ + [ATP](https://durgical.com/en/biochemistry/molecules/atp/) → oxaloacetate + ADP + phosphate (Pi) In the mitochondrion it adds CO₂ to pyruvate to form oxaloacetate: the first detour around the pyruvate kinase step. **If it fails:** Pyruvate carboxylase deficiency causes lactic acidosis, hypoglycaemia and neurological damage from birth. [Lactic acidosis →](https://durgical.com/en/conditions/lactic-acidosis/) - **Step 2 · [Phosphoenolpyruvate carboxykinase (PEPCK)](https://durgical.com/en/biochemistry/enzymes/phosphoenolpyruvate-carboxykinase/)** irreversible oxaloacetate + GTP → phosphoenolpyruvate + gdp + CO₂ It removes the CO₂ and adds a phosphate from GTP: oxaloacetate becomes phosphoenolpyruvate. **If it fails:** Cytosolic PEPCK deficiency is very rare: fasting hypoglycaemia and liver damage. - **Step 3 · Enolase (in reverse)** phosphoenolpyruvate + H₂O ⇌ 2-phosphoglycerate It adds water to phosphoenolpyruvate to form 2-phosphoglycerate; from here on the glycolytic enzymes are used. - **Step 4 · Phosphoglycerate mutase (in reverse)** 2-phosphoglycerate ⇌ 3-phosphoglycerate It moves the phosphate from carbon 2 to carbon 3. - **Step 5 · Phosphoglycerate kinase (in reverse)** 3-phosphoglycerate + [ATP](https://durgical.com/en/biochemistry/molecules/atp/) ⇌ 1,3-bisphosphoglycerate + ADP It spends one ATP to form 1,3-bisphosphoglycerate. - **Step 6 · [Glyceraldehyde-3-phosphate dehydrogenase (in reverse)](https://durgical.com/en/biochemistry/enzymes/glyceraldehyde-3-phosphate-dehydrogenase/)** 1,3-bisphosphoglycerate + NADH ⇌ glyceraldehyde 3-phosphate + [NAD⁺](https://durgical.com/en/biochemistry/molecules/nad/) + phosphate (Pi) It uses NADH to reduce 1,3-bisphosphoglycerate to glyceraldehyde 3-phosphate. Part of it becomes DHAP (triose phosphate isomerase), where glycerol also enters. - **Step 7 · Aldolase (in reverse)** glyceraldehyde 3-phosphate + dihydroxyacetone phosphate ⇌ [Fructose 1,6-bisphosphate](https://durgical.com/en/biochemistry/molecules/fructose-1-6-bisphosphate/) It joins the two triose phosphates into fructose 1,6-bisphosphate. - **Step 8 · [Fructose-1,6-bisphosphatase (FBPase-1)](https://durgical.com/en/biochemistry/enzymes/fructose-1-6-bisphosphatase/)** irreversible [Fructose 1,6-bisphosphate](https://durgical.com/en/biochemistry/molecules/fructose-1-6-bisphosphate/) + H₂O → fructose 6-phosphate + phosphate (Pi) It removes the phosphate on carbon 1: it bypasses the PFK-1 step and is the pathway's main control point. **If it fails:** FBPase-1 deficiency causes hypoglycaemia with lactic acidosis during fasting or fever, and worsens with fructose. - **Step 9 · Phosphoglucose isomerase (in reverse)** fructose 6-phosphate ⇌ [Glucose 6-phosphate](https://durgical.com/en/biochemistry/molecules/glucose-6-phosphate/) It turns fructose 6-phosphate into glucose 6-phosphate. - **Step 10 · [Glucose-6-phosphatase](https://durgical.com/en/biochemistry/enzymes/glucose-6-phosphatase/)** irreversible [Glucose 6-phosphate](https://durgical.com/en/biochemistry/molecules/glucose-6-phosphate/) + H₂O → [Glucose](https://durgical.com/en/biochemistry/molecules/glucose/) + phosphate (Pi) In the endoplasmic reticulum of liver and kidney it frees glucose, which goes out into the blood; muscle lacks this enzyme. **If it fails:** Its deficiency is glycogen storage disease type I (von Gierke): severe hypoglycaemia with high lactate, uric acid and triglycerides. [Von Gierke disease (glycogen storage disease type I) →](https://durgical.com/en/conditions/von-gierke-disease/) ## Clinical notes - Alcohol uses up liver NAD⁺: excess NADH diverts pyruvate to lactate and oxaloacetate to malate, and stalls gluconeogenesis. Hence hypoglycaemia in the fasting drinker. - Metformin lowers hepatic glucose output; in kidney or liver failure lactate can build up. - Glucose-6-phosphatase deficiency (von Gierke) blocks the last step shared by gluconeogenesis and glycogenolysis: severe fasting hypoglycaemia. - In type 2 diabetes hepatic gluconeogenesis stays high despite insulin and accounts for much of the fasting glucose. ## Related conditions - [Von Gierke disease (glycogen storage disease type I)](https://durgical.com/en/conditions/von-gierke-disease/) - [Lactic acidosis](https://durgical.com/en/conditions/lactic-acidosis/) - [Type 2 diabetes mellitus](https://durgical.com/en/conditions/type-2-diabetes-mellitus/) - [Hereditary fructose intolerance](https://durgical.com/en/conditions/hereditary-fructose-intolerance/) ## Related - [Glycolysis](https://durgical.com/en/biochemistry/pathways/glycolysis/) - [Pyruvate](https://durgical.com/en/biochemistry/molecules/pyruvate/) - [Lactate](https://durgical.com/en/biochemistry/molecules/lactate/) - [Glucose](https://durgical.com/en/biochemistry/molecules/glucose/) - [Glucose 6-phosphate](https://durgical.com/en/biochemistry/molecules/glucose-6-phosphate/) - [Fructose 1,6-bisphosphate](https://durgical.com/en/biochemistry/molecules/fructose-1-6-bisphosphate/) - [ATP (adenosine triphosphate)](https://durgical.com/en/biochemistry/molecules/atp/) - [NAD⁺ (nicotinamide adenine dinucleotide)](https://durgical.com/en/biochemistry/molecules/nad/) - [Pyruvate carboxylase](https://durgical.com/en/biochemistry/enzymes/pyruvate-carboxylase/) - [Phosphoenolpyruvate carboxykinase (PEPCK)](https://durgical.com/en/biochemistry/enzymes/phosphoenolpyruvate-carboxykinase/) - [Fructose-1,6-bisphosphatase (FBPase-1)](https://durgical.com/en/biochemistry/enzymes/fructose-1-6-bisphosphatase/) - [Glucose-6-phosphatase](https://durgical.com/en/biochemistry/enzymes/glucose-6-phosphatase/) - [Glyceraldehyde-3-phosphate dehydrogenase (GAPDH)](https://durgical.com/en/biochemistry/enzymes/glyceraldehyde-3-phosphate-dehydrogenase/) - [Cori cycle](https://durgical.com/en/biochemistry/topics/cori-cycle/) - [Glucose–alanine cycle](https://durgical.com/en/biochemistry/topics/glucose-alanine-cycle/) - [Acetyl-CoA](https://durgical.com/en/biochemistry/molecules/acetyl-coa/) - [Glycogen metabolism](https://durgical.com/en/biochemistry/pathways/glycogen-metabolism/) ## Test yourself Think of the answer, then tap the question to see it. ## Which four enzymes are unique to gluconeogenesis? Pyruvate carboxylase, PEPCK, fructose-1,6-bisphosphatase and glucose-6-phosphatase: they go around the three irreversible steps of glycolysis. ## Why do even-chain fatty acids give no net glucose? They yield acetyl-CoA and PDH is irreversible; the two carbons of acetyl-CoA leave as CO₂ in the Krebs cycle. ## Why can muscle not release glucose into the blood? It lacks glucose-6-phosphatase; its glucose 6-phosphate stays inside the fibre. ## Which molecule activates pyruvate carboxylase? Acetyl-CoA: it signals plenty of fatty acids and diverts pyruvate toward glucose. ## Why does alcohol during fasting cause hypoglycaemia? Its oxidation floods the liver with NADH; pyruvate goes to lactate and oxaloacetate to malate, leaving gluconeogenesis without substrate. [Add to my cards (5)](https://durgical.app/estudiar/?add=/en/biochemistry/pathways/gluconeogenesis/) Educational information, not medical advice. For any symptom, see a health professional. Sources: [Gluconeogenesis](https://reactome.org/PathwayBrowser/#/R-HSA-70263) (Reactome, 2026); [PC: Pyruvate carboxylase, mitochondrial (human)](https://www.uniprot.org/uniprotkb/P11498/entry) (UniProt, 2026); [G6PC1: Glucose-6-phosphatase catalytic subunit 1 (human)](https://www.uniprot.org/uniprotkb/P35575/entry) (UniProt, 2026); Textbook of Biochemistry for Medical Students, 6th ed. (Jaypee Brothers Medical Publishers (Vasudevan DM, Sreekumari S, Vaidyanathan K), 2011). [← All of biochemistry](https://durgical.com/en/biochemistry/) ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/biochemistry/pathways/gluconeogenesis/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/biochemistry/pathways/gluconeogenesis/