Insulin is primarily destroyed in two main organs: the liver and the kidneys.
Insulin Breakdown Process
The breakdown of insulin involves the enzyme protein-disulfide reductase (glutathione). This enzyme breaks the disulphide bonds that link the A and B chains of the insulin molecule.
Primary Sites of Insulin Clearance
| Organ | Role in Insulin Clearance |
|---|---|
| Liver | Clears the majority of insulin during its first passage through the bloodstream after secretion by the pancreas. |
| Kidney | Clears the majority of insulin that circulates within the systemic bloodstream. |
How the Liver and Kidneys Handle Insulin
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Liver: After the pancreas secretes insulin, it first travels to the liver through the portal vein. A significant portion of the insulin is removed from the circulation by liver cells during this first-pass transit. This process helps regulate the amount of insulin that reaches the systemic circulation.
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Kidneys: Any insulin that escapes the liver and enters the general blood flow is then primarily cleared by the kidneys. This process occurs during systemic circulation and helps maintain appropriate insulin levels.
Additional Points
- While the liver and kidneys are the major sites of insulin clearance, other tissues can also break down small amounts of insulin.
- The exact proportions of insulin clearance may vary depending on physiological conditions and individual differences.
- Understanding the mechanisms of insulin clearance is crucial in the treatment of diabetes, particularly in the management of insulin dosing.
