Insulin is a natural hormone in the body, produced in the pancreas, that makes it possible for the body to use food as energy. In type 1 diabetes, the pancreas no longer creates insulin, while in type 2 diabetes, the insulin is made, but the body does not use it properly, or does not make enough of it. Because insulin needs are as individual as the patients who need it, there are several different types of insulin. According to the American Diabetes Association, each type of insulin has a different "onset" time, which is the amount of time it takes for the insulin to begin working in the body. Each type also has a different "peak," which is the length of time it takes to reach its top performance of lowering blood sugar before it starts to wear off. Each type also has a different "duration," which is the length of time in which it remains in the body before a new dose is needed.
Rapid-Acting Insulin
Rapid-acting insulin works just as its name says. The National Institutes of Health report that insulin gets into the bloodstream within 15 to 30 minutes after it has been injected. Its peak is 2 to 3 hours after injection, and the duration is 3 to 6 hours. According to the ADA, the higher the dose, the longer the duration will be. Some names of rapid-acting insulin are insulin aspart (NovoLog), insulin glulisine (Apidra) and insulin lispro (Humalog). This insulin is specifically designed to use before meals, as when the food is eaten and begins to enter the bloodstream, the rapid-acting insulin is there to transport the sugar to the cells.
Short-Acting Insulin
Another type of insulin that is used before meals is short-acting insulin. The onset time is slightly longer, taking 30 to 60 minutes to enter the bloodstream, but the peak lasts 2 to 4 hours, and the duration can be from 5 to 8 hours. Some names of short-acting insulin are "regular," (R), insulin, or Humulin R, and Novolin R.
Intermediate-Acting Insulin
The ADA reports that intermediate-acting insulin is mixed with another substance that makes it absorb more slowly. This is what gives it a longer onset time of 1 to 3 hours. It also takes longer to peak--8 hours--but has a much longer duration of 12 to 16 hours. Some names of intermediate-acting insulin are NPH (N), Novolin N and Humulin N. Intermediate-action insulin is often injected in the morning and in the evening.
Long-Acting Insulin
Long-acting insulin is also referred to as a "background" insulin, as it has continuous action within the body. It is taken either before bed or in the morning, and has an onset of 1 hour. It does not peak, but remains steady, and has a duration of 20 to 26 hours. Some names of long-acting insulin are insulin detemir, Levemir, insulin glargine and Lantus.
Pre-mixed Insulin
Some insulin comes pre-mixed, and is especially helpful for those who are older and have shaky hands or poor eyesight. They are also often available in an insulin pen, making injections easier. These mixtures can include a combination of rapid-acting, short-acting or intermediate-acting insulin, and can therefore have an onset of anywhere from 15 minutes to 1 hour, and a peak of 10 to 16 hours. The NIH lists some names of pre-mixed insulin as Humolog Mix, NovoLog Mix, (intermediate-acting insulin mixed with rapid-acting insulin), Humolin 70/30, Novolin 70/30 and Humolin 50/50 (intermediate-acting insulin mixed with short-acting insulin).
