[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Biochemistry](https://durgical.com/en/biochemistry/) › Glucose

[Biochemistry](https://durgical.com/en/biochemistry/) · Molecule

# Glucose

Glucose is the sugar carried in the blood and the main fuel of the brain and the red blood cells.

Updated 2026-10-31

Loading the 3D model…

## Key facts

- A six-carbon aldohexose (C₆H₁₂O₆, 180 g/mol). In solution nearly all of it is a pyranose ring: about two thirds β, one third α.
- Normal fasting plasma glucose: 70–99 mg/dL (3.9–5.5 mmol/L); 126 mg/dL or more on two occasions defines diabetes.
- It enters cells through GLUT carriers (facilitated diffusion) or SGLT (with sodium, in gut and kidney).
- Once phosphorylated to glucose 6-phosphate it is trapped inside the cell.

**Also called**
Dextrose

**Formula**
C₆H₁₂O₆

**PubChem**
[CID 64689](https://pubchem.ncbi.nlm.nih.gov/compound/64689)

## Structure

- Carbon 1 (the anomeric carbon) decides whether the ring is α (OH down) or β (OH up); in β every large group is equatorial, the most stable form.
- Less than 1% is open-chain, the aldehyde form that reacts with proteins (glycation).

## Clinical notes

- GLUT4 (muscle and fat) moves to the membrane with insulin; its failure is central to insulin resistance.
- HbA1c measures glucose bound to hemoglobin and reflects roughly the past 3 months.
- SGLT2 inhibitors (gliflozins) make the kidney lose glucose in the urine.

## Pathways

- [Glycolysis](https://durgical.com/en/biochemistry/pathways/glycolysis/)
- [Gluconeogenesis](https://durgical.com/en/biochemistry/pathways/gluconeogenesis/)
- [Glycogen metabolism](https://durgical.com/en/biochemistry/pathways/glycogen-metabolism/)
- [Fructose metabolism](https://durgical.com/en/biochemistry/pathways/fructose-metabolism/)
- [Galactose metabolism](https://durgical.com/en/biochemistry/pathways/galactose-metabolism/)
- [Lysosomal ganglioside breakdown](https://durgical.com/en/biochemistry/pathways/lysosomal-ganglioside-breakdown/)

## Related conditions

- [Type 2 diabetes mellitus](https://durgical.com/en/conditions/type-2-diabetes-mellitus/)
- [Type 1 diabetes mellitus](https://durgical.com/en/conditions/type-1-diabetes-mellitus/)

## Related

- [Hexokinase](https://durgical.com/en/biochemistry/enzymes/hexokinase/)
- [Glucose 6-phosphate](https://durgical.com/en/biochemistry/molecules/glucose-6-phosphate/)
- [ATP (adenosine triphosphate)](https://durgical.com/en/biochemistry/molecules/atp/)

## Test yourself

Think of the answer, then tap the question to see it.

## Which glucose transporter depends on insulin?

GLUT4, in skeletal muscle, heart and fat.

## Why can't glucose 6-phosphate leave the cell?

The phosphate makes it negatively charged and there is no carrier to take it out.

## What fasting glucose defines diabetes?

126 mg/dL (7.0 mmol/L) or more, confirmed on a second test.

[Add to my cards (3)](https://durgical.app/estudiar/?add=/en/biochemistry/molecules/glucose/)

Molecules are shown in their neutral form, as the databases deposit them; in the cell the acids and phosphates are ionised.

Educational information, not medical advice. For any symptom, see a health professional.

Sources: [beta-D-Glucose (CID 64689)](https://pubchem.ncbi.nlm.nih.gov/compound/64689) (PubChem, NCBI, 2026) · Public domain; [Blood sugar test: MedlinePlus Medical Encyclopedia](https://medlineplus.gov/ency/article/003482.htm) (MedlinePlus, US National Library of Medicine, 2026); [Diabetes](https://www.who.int/news-room/fact-sheets/detail/diabetes) (World Health Organization, 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/molecules/glucose/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/biochemistry/molecules/glucose/