Half life of insulin is:
**Core Concept**
The half-life of insulin is a critical pharmacokinetic parameter that determines its duration of action and efficacy in managing diabetes mellitus. Insulin is a peptide hormone that regulates glucose metabolism, and its half-life is influenced by various factors, including its molecular structure, clearance mechanisms, and binding to insulin receptors.
**Why the Correct Answer is Right**
The half-life of insulin is approximately 4-6 minutes in the bloodstream, which is relatively short due to its rapid clearance by the liver and kidneys. This rapid clearance is mediated by the insulin-degrading enzyme (IDE), which breaks down insulin into smaller peptides and amino acids. The short half-life of insulin necessitates continuous administration or frequent injections to maintain therapeutic levels and prevent hypoglycemia.
**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect, as the half-life of insulin is not typically measured in hours.
**Option B:** Incorrect, as the half-life of insulin is not comparable to that of other peptide hormones like growth hormone or parathyroid hormone.
**Option C:** Incorrect, as this option is either too short or too long, and does not accurately reflect the pharmacokinetics of insulin.
**Clinical Pearl / High-Yield Fact**
Insulin's short half-life is a key factor in its dosing regimen, necessitating multiple daily injections or continuous subcutaneous infusion to maintain optimal glucose control. This highlights the importance of precise dosing and timing in insulin therapy to prevent hypoglycemia and ensure effective glycemic control.
**Correct Answer: C. 4-6 minutes.**