Administering Insulin - Insulin Therapy For Type 1 Diabetes: Diabetes

Content provided by the Faculty of the Harvard Medical School

Administering insulin

While most people are initially skittish about giving themselves one or more shots a day, injecting insulin quickly becomes routine, and the equipment available today makes injections virtually painless. Most people use syringes or insulin "pens," but other tools, such as jet injectors and insulin pumps, are also available.

Parents often help very young children, but otherwise most people give themselves injections. Whether you'll be injecting yourself or someone else, a diabetes educator will teach you how to measure, prepare, and administer the injections. The introduction of inhaled insulin may mean a decrease in the number of shots needed by some people with diabetes. (See "Inhaled insulin.")

Syringes

Almost all insulin in the United States has a concentration of U-100, meaning 100 units per cubic centimeter, and insulin syringes are designed for this concentration. Syringes can hold a total of 100, 50, or 30 units. Choose the size of your syringe based on the total dose of your injection. After the injection, cap the syringe and place it in a plastic or metal container for disposal. You can use your own syringes for more than one injection. Skin infections are rare. Never use a syringe that someone else has used, and never give anyone a syringe that you have used.

Pen injectors

Several aids are available to make insulin injections easier, the most common of which is the pen injector. Resembling a ballpoint pen, it uses disposable needles and insulin cartridges. Many people find it convenient because it's portable and discreet, and because it provides multiple accurate doses without measuring and filling syringes. The pens carry up to 150 units of insulin. You select the desired dose of insulin simply by turning a dial, and then deliver it by pressing a plunger on the end of the pen.

Jet injectors

Insulin jet injectors send a fine spray of insulin through the skin with a high-pressure air mechanism instead of a needle. Jet injectors, which are about the size of the small batons used in relay races, can be less painful than syringes when used correctly, and they may be a more efficient delivery system. Instead of pooling around an injection site, the mist of insulin disperses and reaches the blood faster. However, adjusting the intensity of the spray to provide adequate penetration has proved difficult in practice, and the units haven't gained popularity. They are bulky, somewhat unreliable, and require frequent cleaning. They're also expensive, about $300–$700, and some insurance companies don't cover them.

Insulin pumps

Resembling a pager, the insulin pump is lightweight (about 3 ounces) and small enough to be kept in a pocket, hooked to a belt, or worn around your neck. Pumps hold a supply of insulin that's delivered through plastic tubing (a catheter) attached to a very small needle or plastic tube that is inserted under the skin, usually in the abdomen, and secured by tape. The catheter is changed every one to three days, when the injection site is changed. The computerized pump continuously delivers insulin at a predetermined rate. You'll also be taught how to select an extra helping of insulin, known as a bolus, before each meal to prevent the increase in glucose that would otherwise occur. The bolus is based on the size of your meal, its content, and your blood sugar level before the meal. The pump doesn't get in the way of usual activities, such as exercise, showering, and sexual intercourse.

If you try the pump, your medical team will help you calculate how much insulin it will deliver to you throughout the day and how much more you'll need before meals or snacks. Sometimes problems can occur that affect absorption of insulin (such as an infection at the insertion site or a slowed flow), so regular blood glucose monitoring is crucial.

The biggest drawback is the price: An insulin pump costs roughly $2,000–$5,000, with maintenance and supplies (catheters, insulin, and blood testing strips) running about $100–$200 a month. However, many insurance companies provide coverage.

Where to inject insulin

Insulin can be injected into almost any fatty area under the skin: in your abdomen, thigh, hip, buttock, or the back of your upper arm. You'll want to find an area that's comfortable and easy to reach. To minimize discomfort, rotate injection sites and avoid injecting into the same site for every dose.

Your body absorbs insulin fastest when it's injected into your abdomen; it takes longer for the insulin to get into your bloodstream when it's injected into your arm, buttock, or thigh. However, other factors, especially exercise, can affect how quickly you absorb insulin. For example, if you inject insulin into your thigh and then run, the insulin will be absorbed more rapidly because of the increased blood flow to the legs.

To avoid developing certain skin problems, rotate injection sites. Deposits of fat that look like lumps can develop in areas that have been used for injections too often. Other very rare reactions to an insulin preparation include swelling, redness, or small dents in the skin at injection and other sites.

Last updated:	January 23, 2007