Insulin Injection Sites

If you inject insulin three or more times a day then it’s a good idea to rotate your injection sites. Injecting in the same place much of the time can cause hard lumps or extra fat deposits to develop. These lumps are not only unsightly; they can also change the way insulin is absorbed, making it more difficult to keep your blood glucose on target.
Follow these two rules for proper site rotation:

• Same general location at the same time each day.
   
• Rotate within each injection site.

Injection site rotation is important for both insulin syringe and pen users.

Same Time, Same General Location

Insulin is absorbed at different speeds depending on where you inject, so it's best to consistently use the same part of the body for each of your daily injections. For example, do not inject your lunch bolus dose in the abdomen on Monday and in the thigh on Tuesday. If you have picked the thigh for your evening injection, then continue to use the thigh for all of your evening injections.

According to Eli Lilly, the leading manufacturer of insulin, most insulin enters the blood:

• Fastest from the abdomen (stomach)
• A little slower from the arms
• Even slower from the legs
• Slowest from the buttocks

Unless your doctor has told you otherwise, it is a good idea to inject your breakfast and lunch bolus doses into the abdomen. Insulin is absorbed fastest when injected into this area. Fast absorption is needed at mealtimes to cover the carbohydrates you are about to eat.
On the other hand, your supper or bedtime dose of long-acting insulin could be injected into the thigh, buttocks, or upper arm. That's because you want the long-acting insulin to take effect gradually and cover your needs throughout the night.
If you mix two types of insulin in one shot, you can inject into the abdomen, arm, thigh, or buttocks.

Rotate Within an Injection Site

To avoid developing hard lumps and fat deposits, it is important to inject in different spots within a general part of the body.

• Change sides within an area. For example, if you inject your evening insulin in the thigh, try using the right thigh one evening, and the left thigh the next evening.
   
• You might find it useful to picture the face of a clock on your abdomen. That helps you to keep each of your injections at least one finger’s width from the last injection.
  
  Let’s say that you inject four times a day, and all of the injections are in your abdomen. Look down at your abdomen and picture “Noon” below your belly button. Place your first injection at Noon, your second injection at 1 o’clock, the third injection at 2 o’clock, and the fourth injection at 3 o’clock. You will not come back to the “Noon” spot again until day 4, which gives that spot a chance to rest. 

The most common insulin injection site is the abdomen (or stomach). The back of the upper arms, the upper buttocks or hips, and the outer side of the thighs are also used. These sites are the best to inject into for two reasons:

• They have a layer of fat just below the skin to absorb the insulin, but not many nerves - which means that injecting there will be more comfortable than injecting in other parts of your body.
   
• They make it easier to inject into the subcutaneous tissue, where insulin injection is recommended.

Depending on your body type, you'll find that certain insulin injection site work better than others.

• Some people, for example, prefer injecting in the abdomen because the insulin absorbs well there.
   
• But injecting in the abdomen isn't right for everyone, especially young children or people who are so thin and/or heavily muscled that they can't pinch up a half-inch of fat.