Insulin (Endogenous Peptide)

Overview

Insulin is a 51-amino acid peptide hormone produced by pancreatic beta cells, consisting of an A-chain (21 AA) and B-chain (30 AA) connected by two disulfide bonds. It is the master regulator of glucose metabolism and protein synthesis, functioning through the insulin receptor tyrosine kinase (INSR) to stimulate glucose uptake, glycogen synthesis, lipogenesis, and protein anabolism while suppressing lipolysis, glycogenolysis, and gluconeogenesis. Synthetic insulin analogs (fast-acting: lispro, aspart, glulisine; long-acting: glargine, detemir, degludec) have revolutionized diabetes management.

Mechanism of Action

Insulin binds the insulin receptor (INSR), a transmembrane tyrosine kinase that undergoes autophosphorylation and phosphorylates IRS-1/2 adapter proteins. This activates PI3K → PDK1 → Akt signaling, causing GLUT4 vesicle translocation to the plasma membrane (enabling glucose uptake in muscle and fat), glycogen synthase kinase-3 inhibition (promoting glycogen synthesis), and mTORC1 activation (stimulating protein synthesis). Simultaneously, Ras/MAPK/ERK activation mediates mitogenic effects. In the liver, insulin suppresses PEPCK and glucose-6-phosphatase (gluconeogenic enzymes), reducing hepatic glucose output.

Potential Benefits

• Essential treatment for type 1 diabetes
• Adjunct therapy in type 2 diabetes
• Powerful anabolic agent for muscle protein synthesis
• Glycogen synthesis promotion in muscle and liver
• Life-saving in diabetic ketoacidosis

Research Dosage Notes

The following reflects doses used in published research studies. This is not medical advice.

Highly individualized. Type 1 diabetes: basal 0.2–0.4 units/kg/day + bolus calculated per carbohydrate intake. T2D adjunct: various protocols. Bodybuilding use: extremely dangerous, not recommended.

Amino Acid Sequence

Side Effects & Safety

• Hypoglycemia (most dangerous; can be fatal)
• Weight gain
• Injection site lipodystrophy
• Hypokalemia at high doses

Synergistic Compounds

The following compounds have been studied alongside Insulin (Endogenous Peptide) for potential complementary or synergistic effects:

Related Peptides

Learn More

References & Further Reading

• [object Object]
• [object Object]