regular insulin, a short-acting insulin prescribed in the treatment of diabetes mellitus when the desired action is relatively prompt, intense, and short-acting. The onset of action is between 30 and 60 minutes. The peak is in 2 to 3 hours, and the duration of action is approximately 8 to 10 hours. Regular insulin can be mixed with long-acting forms of insulin. Compare intermediate-acting insulin, long-acting insulin, rapid-acting insulin.
