5 Types of Insulin and How They Work

Rapid-acting Insulin

What it's called:

Humalog (lispro), NovoLog (aspart), Apidra (glulisine)

A rapid-acting insulin is taken just before or after meals, to control spikes in blood sugar. This type is typically used in addition to longer-acting insulin.

It often works in 15 minutes, peaks between 30 and 90 minutes, and lasts 3 to 5 hours.

"You can take it a few minutes before eating or as you sit down to eat, and it starts to work very quickly," says Manisha Chandalia, MD, director of the Stark Diabetes Center at the University of Texas Medical Branch, in Galveston.

Short-acting Insulin

What it's called:

Humulin R, Novolin R

Short-acting insulin covers your insulin needs during meals. It is taken about 30 minutes to an hour before a meal to help control blood sugar levels.

This type of insulin takes effect in about 30 minutes to one hour, and peaks after two to four hours. Its effects tend to last about five to eight hours.

"The biggest advantage of short-acting insulin is that you don't have to take it at each meal. You can take it at breakfast and supper and still have good control because it lasts a little longer," Dr. Chandalia says.

Intermediate-acting Insulin

What it's called:

Humulin N (NPH), Novolin N (NPH)

Intermediate-acting insulin can control blood sugar levels for about 12 hours or longer, so it can be used overnight.

It begins to work within one to four hours, and peaks between four and 12 hours, depending on the brand.

"Intermediate-acting insulin offer baseline insulin coverage and can be used with short-acting insulin or rapid-acting insulin," says Dr. Chandalia.

Long-acting Insulin

What it's called:

Lantus (glargine), Levemir (detemir)

Long-acting insulin has an onset of one hour and lasts for 20 to 26 hours with no peak.

This insulin type tends to cover your insulin needs for a full day. It is often taken at bedtime.

"These long-acting insulin provide 24-hour coverage, and have been helpful at achieving good blood sugar control in type 2 diabetes with just one shot," Dr. Chandalia says.

Pre-mixed Insulin

What it's called:

Humulin 70/30, Novolin 70/30, NovoLog 70/30, Humulin 50/50, Humalog mix 75/25, Humalog mix 50/50

This type of insulin combines intermediate- and short-acting insulin. It is often taken twice a day before meals. It should be taken 10 minutes to 30 minutes before eating.

Pre-mixed insulin takes effect in 5 to 60 minutes, and its peak times vary. Its effects last from 10 to 16 hours.

Pre-mixed insulin was designed to be more convenient. However, not everybody has the same insulin requirements, so the pre-mixed categories don't apply to everyone.

Insulin Delivery

Not only are there a variety of insulin types, but there are also many more ways to deliver the medication than ever before. Insulin can be taken via an injector pen, a tiny needle, or even an insulin pump.

In whichever way you take it, insulin can be a lifesaver. It lowers toxic blood sugar, preventing blindness, nerve damage, kidney damage, and other diabetes-related complications.

And the more careful you are about taking insulin correctly (don't skip doses), the less likely you are to have health problems down the road.