Insulin is a pancreatic hormone that plays a vital role in carbohydrate and lipid metabolism. Insulin regulates glucose concentrations by:
- Promoting glycolysis - directly leads to the uptake of glucose by cells for energy
- Stimulating glycogenesis - the conversion of excess blood glucose to glycogen storage in the liver
- Inhibiting glycogenolysis - the conversion of glycogen back to glucose
- Inhibiting gluconeogenesis - the formation of glucose from noncarbohydrates
Insulin increases lipid synthesis in the liver and fat cells and inhibits lipolysis (the release of non-esterified fatty acids (NEFAs) from triglycerides in fat and muscle cells). Insulin also promotes protein synthesis.
If insulin resistance occurs, carbohydrate and lipid metabolism are impaired; the impaired insulin action results in elevated plasma glucose levels. The increase in lipolysis increases blood concentrations of NEFAs and causes abnormal blood lipid levels.
