QS Study

Role of Insulin in the regulation of Blood Sugar Level

Insulin is a hormone that is significant for metabolism and deployment of energy from the ingested nutrients – especially glucose. It is a protein chain or peptide hormone. It helps keeps your blood sugar level from getting too high or too low. In a normal person, the blood glucose concentration is narrowly controlled, usually between 80 mg/d1 and 90 mg/dl.

Insulin lowers the blood glucose level by the following steps:

(A) Promotion of liver uptake, storage, and use of glucose.

  • Inhibition of liver phosphorylase prevents break down of the glycogen.
  • Enhanced uptake of glucose from the blood by liver cells.
  • Increases the activity of glucokinase and causes the phosphorylation of glucose and trapped glucose into cells.
  • Insulin increases the activity of glycogen syntheses.

(B) Inhibition of liver gluconeogenesis:

  • Insulin promotes the conversion of excess liver glucose into fatty acids.
  • These fatty acids are transported to the adipose tissue and deposited as fat.
  • Insulin decreases quantity and activity of liver enzymes required for gluconeogenesis.
  • Insulin decreases the release of amino acids from muscle or other tissue to prevent gluconeogenesis.

(C) Storage of glucose in muscle cells.

Insulin causes the muscle membrane permeable to glucose, and help to form glycogen in the muscles.

(D) Increase the utilization by most other cells.

Principal actions of insulin

(A) Rapid (seconds) – Increases transport of insulin, amino acids, and K+ into insulin-sensitive cells

(B) Intermediate

  1. Stimulation of protein synthesis,
  2. Inhibition of protein degradation,
  3. Activation of glycolytic enzymes and glycogen synthase,
  4. Inhibition of phosphorylase and gluconeogenic enzymes.

(C) Delayed – Increase in mRNAs for lipogenic and other enzymes.