Insulin is an important part in the treatment of people with diabetes. This medication is used in people with type 1 diabetes and in some people with type 2 diabetes. Insulin helps keep the blood glucose levels within the normal target range. The different types of insulin vary by time of onset, or how fast the insulin starts working; by peak time, which is when the insulin is working the hardest to lower blood glucose levels; and by time of duration, which is how long the insulin lasts in the bloodstream. These factors help the doctor decide which insulin to use, how much to use and the timing of the doses.
Rapid-Acting Insulins
One type of insulin is rapid-acting insulin. These insulins begin to lower blood glucose about 15 minutes after injection. The peak effect of this group of insulins is between 30 to 90 minutes after injection and the duration of effect ranges from three to five hours. According to the Group Health website, these insulins work quickly to manage the sugars being eaten at meals and can also be called mealtime insulins. Examples of rapid-acting insulins include insulin aspart, insulin lispro and insulin glulisine.
Short-Acting Insulins
Short-acting insulins can be used as mealtime insulins as well. The onset of action of these insulins---at 30 to 60 minutes---is not as fast as the rapid-acting insulins. The peak action of short-acting insulins is two to four hours and the duration of action is between five and eight hours, according to the National Diabetes Information Clearinghouse website. Regular insulin is the main kind of short-acting insulin, and there are several different pharmaceutical companies that sell a type of regular insulin.
Intermediate-Acting Insulins
The pattern of action of intermediate- and long-acting insulins more closely resembles that of the human pancreas, according to the Group Health website. Insulins that work continuously are called basal insulins, and intermediate-acting insulins can work for up to 16 hours. The time of onset of these insulins is between one and three hours, and the peak action is eight hours after injection. NPH is the main type of intermediate-acting insulin, but there are different brands of NPH sold by different pharmaceutical companies.
Long-Acting Insulin
Another type of basal insulin is the long-acting insulins. These and the intermediate-acting insulins can be used in combination with the shorter-acting insulins to manage blood glucose levels. The onset of action of long-acting insulin is one hour as well, and the duration of action is 20 to 26 hours, according to the National Diabetes Information Clearinghouse website. There is no well-defined peak of action for this type of insulin. Examples of long-acting insulins are insulin detemir and insulin glargine.
Pre-Mixed Insulins
Combinations of short-acting and intermediate-acting insulins are available for patients with diabetes as well. These combinations are pre-mixed and can be useful for people who have problems drawing up the different kinds of insulins into syringes, according to the American Diabetes Association. For some patients, having the pre-mixed insulin may be simply more convenient. Examples of combination insulins include a mixture of 70 percent NPH and 30 percent regular and 50 percent insulin lispro protamine and 50 percent insulin lispro. The time of onset of the 70/30 mixture is 30 to 60 minutes and the duration is 10 to 16 hours, according to the National Diabetes Information Clearinghouse website. The time of onset of the 50/50 combination is 10 to 15 minutes; the duration is also 10 to 16 hours.
