An Insulin FAQ

by Beth Howard Patient Expert

Insulin can be a powerful treatment to control blood glucose for people living with type 2 diabetes. While many people start their treatment with pills, eventually, insulin may be needed to control blood glucose.

How is insulin administered?

Insulin can be administered by injection or a pump that dispenses it under the skin. Insulin cannot be taken by mouth because digestive enzymes break it down before it reaches the bloodstream.

What kinds of insulin are there?

There are four different types of insulin: rapid-acting insulin, regular or short-acting insulin, intermediate-acting insulin, and long-acting insulin. There is also a new type of insulin on the market now – inhaled insulin.

What is rapid-acting insulin?

Rapid-acting insulin starts working about 15 minutes after injection and peaks in about an hour with the effects lasting about two to four hours.

What is regular or short-acting insulin?

Regular or short-acting insulin hits the bloodstream within 30 minutes of being injected and peaks two to three hours later with the effects lasting for three to six hours.

What is intermediate-acting insulin?

Intermediate-acting insulin reaches the bloodstream about two to four hours after injection and peaks four to 12 hours afterwards. It’s effective for about 12 to 18 hours.

What is long-acting insulin?

Long-acting insulin starts to work several hours after injection and lowers glucose levels evenly over a 24-hour period.

What is inhaled insulin?

Inhaled insulin starts to work within 12 to 15 minutes, peaks by 30 minutes, and is effective for around three hours.

What kind do I need?

Your doctor may prescribe more than one type of insulin – a “background” (intermediate to long-acting) insulin and a “mealtime” (rapid to short-acting) insulin. The types of insulin you get will depend on the type of diabetes you have, your blood sugar levels and how much your levels fluctuate throughout the day.

What are the characteristics of insulin?

There are three characteristics of insulin: onset, peaktime, and duration. Onset is the length of time before insulin reaches the bloodstream. Peaktime is the time during which insulin is at maximum strength at lowering blood glucose. Duration is how long the insulin administered continues to lower blood glucose.

How strong is insulin?

The most commonly used strength in the U.S. today is U-100, meaning there are 100 units of insulin per milliliter of fluid. Higher dosage (U-500) is available for those who are particularly insulin-resistant.

Beth Howard
Meet Our Writer
Beth Howard

Beth Howard is a health writer based in Charlotte, NC. She writes about health, medicine, and health care for publications including U.S. News & World Report, The Wall Street Journal, and Prevention Magazine.