When functioning properly, the pancreas secretes the ideal amount of a hormone called insulin, which helps the body’s cells take in glucose (sugar) from the blood to use it for energy. In people with type 1 diabetes, the pancreas doesn’t produce insulin. People with type 2 diabetes produce insulin, but their bodies don’t use it properly. Over time, people with type 2 diabetes may also produce less insulin.
Various types of insulin may be prescribed for both types of diabetes to help regulate blood sugar. Each are injected into the fat under the skin to reach the bloodstream. Insulin injection sites include the stomach, the back of the arm, and the hip or thigh. It’s best to rotate sites to avoid bruising and scar tissue. (Insulin isn’t available in a pill because it would break down during the digestive process.) You can inject insulin with:
- A syringe: A needle connected to a hollow tube holds the insulin and a plunger pushes the insulin down into and through the needle.
- An insulin pen: A device that looks like a pen holds insulin with a needle tip.
- An insulin pump: A small machine worn on a belt or kept in a pocket holds insulin, pumps it through a small plastic tube and through a tiny needle inserted under the skin where it stays for several days.
The three things to consider when taking insulin are:
- Action:
- Onset: When it starts working
- Peak: When it’s at its most effective point
- Duration: How long it lasts in your body
- Dose Timing: The best time to take your insulin based on insulin action and mealtime.
- Purpose: The reason you are taking it and how it is meant to work in your body.
Rapid-Acting Insulin
Examples include: Humalog, Novolog, and Apidra
- Action:
- Onset: Begins to work about 15 minutes after injection
- Peak: About an hour after injection
- Duration: Continues to work for 2 to 4 hours
- Dose timing: It’s usually taken several times a day, 15 minutes before meals.
- Purpose: It is meant to start working as your food is digesting to avoid post-meal high blood sugar.
Regular- or Short-Acting Insulin
Examples include: Humulin R (Regular) or Novolin
- Action:
- Onset: Begins to work within 30 minutes of injection
- Peak: 2 to 3 hours after injection
- Duration: Continues to work for about 3 to 6 hours
- Dose timing: It is usually taken several times a day, 30 minutes before a meal.
- Purpose: It is meant to start working as your food is digesting to avoid post-meal high blood sugar.
Intermediate-Acting Insulin
Examples include: NPH
- Action:
- Onset: Begins to work 2 to 4 hours after injection
- Peak: 6 to 12 hours after injection
- Duration: Continues to work for about 12 to 18 hours
- Dose timing: This insulin is usually taken twice daily, in the morning before breakfast and in the afternoon before dinner. It is often used with a rapid-acting insulin.
- Purpose: NPH is also intended more to act as a baseline insulin when used once or twice per day in terms of its clinical use
Long-Acting Insulin
Examples include: Lantus, Levemir, Toujeo, and Basaglar
- Action:
- Onset: Begins to work about 2 hours after injection
- Peak: It has no peak
- Duration: It tends to lower blood sugar levels fairly evenly over 24 hours.
- Dose timing: It is usually taken once a day and is often used in addition to short- or rapid-acting insulin.
- Purpose: This acts as your body’s baseline insulin. It is meant to keep your blood sugar stable throughout the day. Your doctor may also prescribe short- or rapid-acting insulin to be taken before meals to lower your blood sugar after you eat.
Pre-Mixed Insulin
Examples include: Humalog 70/30, Novolog 70/30, Humulin 70/30, Humalog mix 75/25, and Humulin 50/50
These are a combination of a short or rapid-acting insulin and an intermediate-acting insulin.
- Action:
- Onset: Rapid-acting: 15 to 30 min; short-acting: 30-60 min. after injection. Intermediate acting: 2 to 4 hours after injection.
- Peak: Rapid-acting peaks in 1 to 3 hours; short-acting peaks in 2-5 hours. Intermediate peaks in 2 to 4 hours.
- Duration: Rapid-acting lasts 3 to 5 hours; short-acting lasts 5 to 8 hours. intermediate lasts 6 to 8 hours.
- Dose timing: This insulin is usually taken twice daily, once before breakfast and once before dinner.
- Purpose: The morning injection is meant to lower blood sugar after your meal and last until after lunch. The dinner injection is meant to lower your blood sugar after dinner and last until bedtime. Together these cover your insulin needs throughout the day and during meals.
- Example: Humalog 70/30 is 30% rapid-acting insulin and 70% intermediate-acting insulin.
Your doctor will work with you to determine the best insulin type, dosage, and routine to manage your diabetes and fit your lifestyle.