Types of Insulin

Before you developed diabetes, your pancreas made all your insulin. And it knew exactly when to release the insulin to the body. Like a smoke detector, your body sensed when there was more sugar in the bloodstream. It sent out the alarm: time for more insulin!

Manufactured insulin comes in several types. Each type works at a different pace, and most people have to use more than one kind to mimic what their bodies used to do all by themselves.

Different types of insulin are like different types of Olympic runners. Some types of insulin are like sprinters. They start quickly, get to their top speed, and finish fast. Other types of insulin are like marathon runners. They start slower, and they keep going slow and steady for a long time. Then there are the ones in between-not as fast as a sprint and not as slow as a marathon. No one type of insulin is better than another. All types are important to keep your diabetes in control.

Rapid-acting insulins, such as lispro (Humalog®) or aspart (NovoLog®), are the fastest of all insulins. Once you inject it, it starts to work in about 5 minutes. It works hardest (or “peaks”) about an hour after you inject it. It’s pretty much used up in 4-5 hours. This kind of insulin is designed so you can inject it right before meals. By the time your meal is digested and glucose is beginning to move into the bloodstream, rapidacting insulin is working the hardest at moving that glucose into the cells.

Short-acting, or “regular,” insulin is sometimes used around mealtimes. It takes longer to start to work than rapid-acting insulin. So you take short-acting insulin about 30 to 45 minutes before you plan to eat, and it peaks in about 2-3 hours. It can keep working for as long as 6 hours or more. Rapid-acting and short-acting insulin are both clear.

Intermediate-acting insulin such as NPH is insulin mixed with something that makes the body absorb the insulin more slowly. That’s why this type of insulin looks cloudy and has to be mixed before it’s injected. It takes longer to start to work, and it stays in your body for a longer time. Intermediate-acting insulin usually begins to work about 2-4 hours after you inject it. It peaks 4-10 hours after injection, and keeps working for 10-16 hours. Intermediate-acting insulin works all day if you take it in the morning.

Then there’s the marathon runner of the bunch, long-acting insulin, called glargine (Lantus®) or detemir (Levemir®). Long-acting insulin starts to work in 2-4 hours and can stay in the body for 24 hours with no peak. They are usually taken before bed. Glargine and detemir are both clear.