Final answer:
The key characteristic of Insulin, Regular (Humulin R) is that it has a rapid onset and short duration of action, designed to lower blood glucose levels effectively after meals. The correct answer is option C).
Step-by-step explanation:
The key characteristic of Insulin, Regular (Humulin R) is C) It has a rapid onset and short duration of action. Unlike ultra-long-acting insulin, regular insulin is designed to mimic the insulin release of a healthy pancreas in response to a meal.
The effectiveness of insulin in lowering blood glucose levels is crucial, particularly after consuming a large or high-glucose meal. This short-acting insulin starts to work within 30 minutes of injection, peaks in 2 to 3 hours, and has a duration of about 5 to 8 hours.
Its main role is to enable cells to utilize glucose effectively, thereby reducing blood glucose levels. Moreover, insulin is a protein hormone crucial for glucose metabolism, with human insulin comprised of two peptide chains, 'A' with 21 amino acids and 'B' with 30 amino acids, which is synthesized as proinsulin.