INSULIN BASICS: THE REASONS BEHIND THE RECOMMENDATIONS

by Ann S. Williams, MSN, RN, CDE

This column focuses on providing information to help people make their diabetes care fit their needs and their lives.

This month's column contains general information about insulin. I have received quite a few questions lately about why people are supposed to do particular things when drawing insulin and giving injections. So here are answers to those questions, organized into three general topics: storing, drawing, and injecting insulin.

This is definitely not everything there is to know; these are just the questions I have been asked most often.

Storing Insulin

Q: Why am I supposed to store insulin in a refrigerator?

A: Insulin is a protein dissolved in water. (You can think of it as something like a soup broth.) Like any other protein, it can spoil. Keeping it cold helps to keep it from spoiling.

Q: What will happen if the insulin starts to spoil?

A: Bacteria growing in it will break down the protein. The insulin will not poison you or make you sick. It just won't work very well. If this happens to you, your blood sugar would be higher than you expect, even though you have given your injection in the right amount at the right time.

Q: How cold does it need to be?

A: Insulin you are not using should be kept between 36 degrees and 46 degrees Fahrenheit. If it gets colder than that it can freeze. If it gets warmer than that, it will be good for a while, but eventually it will start to break down.

Q: I have been told it's OK to keep a bottle of insulin I'm using at room temperature. Is this really OK? If so, why?

A: Yes, the standard recommendation from all the insulin manufacturers is that a vial of insulin you are using can be kept at room temperature for up to 28 days. Room temperature is defined as between 59 degrees and 86 degrees Fahrenheit. This works because all the standard insulin preparations have preservatives in them -- which will keep the insulin good for a while, but eventually stop working. Bacteria begin to grow in the insulin, and start breaking down the protein.

Many people say injections of insulin are more comfortable when the insulin is not cold. Also, many people find it easier to get rid of air bubbles when the insulin is room temperature. If these factors don't matter to you, and you prefer to keep your insulin in the refrigerator, that is fine.

Q: I live in a hot climate, and I don't have air conditioning. Can I still keep my insulin at room temperature?

A: If your room temperature goes above about 80 degrees Fahrenheit, you would be safer to keep your insulin in the refrigerator.

Q: I use an insulin pen. I have heard I should keep my pen at room temperature for only two weeks. But insulin in vials can be kept at room temperature up to 28 days. Why?

A: The insulin manufacturers did experiments with insulin pen cartridges, and found some kinds of insulin began to spoil sooner in pen cartridges than in vials. So, insulin in pens and cartridges now have different recommended storage times. To find out the recommended storage time for the pen or cartridge you use, ask your pharmacist, check the package insert, or check the manufacturer's web site. (See below for the Web sites and contact phones for all three insulin manufacturers.)

Q: I'm storing my insulin at room temperature. I don't use up the whole vial in 28 days. What should I do with the extra insulin, and why?

A: All the insulin manufacturers recommend throwing out the rest of the insulin in the vial, because they cannot guarantee the insulin is still good.

Q: What would happen if I kept using insulin past 28 days at room temperature, or past the expiration date on the box?

A: Your insulin might still be good after the expiration date on the box, or after 28 days at room temperature, but it's not guaranteed to be good. I know some people who don't have health insurance and have to pay out-of-pocket for all of their insulin do continue to use insulin past the recommended times. Generally, for the first few days, nothing much happens. Then, a time comes when the insulin does not control their blood sugar very well, and it's hard to find a dose that works. This happens because the insulin is spoiling. When they measure a certain number of units of insulin, there is actually less active insulin in the syringe, and no one can be sure exactly how much active insulin is left.

I do NOT recommend using insulin past the recommended times. If you feel you need to do that, you will have the best chance of keeping your insulin good if you have kept it refrigerated. You should also know that Lantus insulin and the rapid insulins (Humalog and Novolog) spoil faster than Regular and NPH insulin.

Q: I can't afford to throw out insulin, and I don't want to have unpredictable insulin action. What can I do?

A: All the insulin manufacturers have patient assistance programs to help people who need insulin and cannot afford it. You can find out more information about exactly how each company's program works by checking their Web sites, or going to www.helpingpatients.org, the Web site of the drug industry association PhRMA; telephone: (202) 835-3400. You will need to ask the doctor who prescribes your insulin to help you get signed up for one of these programs.

Drawing Insulin

Q: When I was first taught how to use NPH insulin, I was told to roll the vial between my hands ten times before drawing the insulin. Why?

A: Certain types of insulin: NPH, Lente, and Ultralente insulin, look cloudy in the vial. They look cloudy because particles of insulin are not fully dissolved. When the insulin bottle or pen sits still for a few minutes, the particles of insulin settle out, and fall to the bottom of the container. Before you draw the insulin, you need to gently mix it up so the whole bottle has the same concentration of insulin all the way through. If you carry prefilled syringes, and they have any of the above "suspension" insulins in them, you'll need to gently agitate them, too, for the same reason. Otherwise, you would get different concentrations of insulin when you draw the clear part than when you draw the part that contains the settled particles.

Rolling the insulin between your hands is a good way to mix insulin in a vial without making a lot of little bubbles in the insulin itself. If you shake the insulin and mix in a lot of bubbles, they will not hurt you. But you might end up with little bubbles of air in your syringe, and that would mean you would not get your full dose of insulin.

Q: When I started using an insulin pen with an NPH mixture, I was taught to mix the insulin by rolling the pen ten times, and then pointing the pen up and down ten times. Is this really necessary? Why?

A: Research has shown that insulin in pens is a little harder to mix than insulin in vials. There are no air pockets to help the mixing process. When people roll the pens in their hands, the insulin can still have layers that are not completely mixed. But there is a tiny glass ball that rolls back and forth when the pen is pointed up and down. By doing this ten times, you may be sure all the layers of insulin are thoroughly mixed.

Q: When I was taught how to draw insulin I was told to inject air into the vial before I drew insulin out. Why?

A: The rubber stopper on the top of the vial does not let air through. When you're taking insulin out of the bottle, you need to put air into the vial to replace the insulin. If you don't do this, each time you draw out some insulin, you are building up a little bit of vacuum in the vial. After a while, it actually gets hard to pull the insulin out. And if you let go of the plunger, the vacuum in the bottle pulls the plunger back in.

Q: Why don't I have to inject air into my insulin pen before I use it?

A: Pens work in an entirely different way than syringes. The insulin never gets drawn from one container into another. Instead, there is a little plunger inside the insulin chamber in your pen. When you set the dose on your pen, you are setting how far forward this plunger will move. When you deliver the dose of insulin and the plunger moves forward, the space that holds insulin gets smaller. There is no need for air to fill up any of the extra space.

Q: I used to mix NPH and Regular insulin. Now I am taking Lantus for basal insulin, and a rapid insulin with meals. I have been told I should not mix them in one syringe. Why?

A: The action time of Lantus insulin changes when it is mixed with any other insulin. You end up with some mixture of long-acting and short-acting insulin, but the mixture is unpredictable. So the manufacturer of Lantus recommends it should not be mixed with any other type of insulin in the same syringe.

One easy way of making sure you don't mix Lantus with any other insulin is to take the Lantus with a vial and syringe (no Lantus pen cartridge is yet available), and take the other insulin with a pen.

Q: I have been told not to mix Lantus with another insulin, but I have been also told I can give my Lantus injection at the same time as one of my rapid insulin injections. Won't they mix themselves in my body?

A: As long as the Lantus and other insulin are not mixed together in a syringe, or given in exactly the same spot on your body, they will not change each other's time of action. What this means is if you give these injections at the same time, you should give them in different syringes, and in different spots on your body.

Injecting Insulin

Q: I started using insulin recently, and was told to be careful to not inject into the same spot over and over again. Why?

A: If you use the same spot repeatedly, your body reacts by creating changes in the fatty tissue just under the skin. It can either cause the fat tissue to deteriorate, and create a pit under the skin; this is called lypodystrophy, or it can grow a little extra fat tissue there, and create a lump just under the skin; this is called lypohypertrophy. Either one of these will change the absorption time of insulin. Also, many people don't like the way these lumps and pitting just under the skin look.

Q: When I started taking insulin years ago, I was told to rotate the sites for injection between my stomach, my thighs, my buttocks, and my arms. Recently, a diabetes educator told me to inject into my abdomen only. Why have the recommendations changed?

A: There are two reasons the recommendations have changed. First, we now know a lot more about insulin absorption. We now know the absorption of insulin is fastest and most predictable, when injected into the abdomen. So, for example, insulin injected into the buttocks might be absorbed slower than you expect. On the other hand, insulin injected into the arms and thighs is injected near some large muscles. When you use those muscles, the blood flow increases there. If this happens while the insulin is being absorbed, it speeds up the absorption rate. You might then have an unpleasant surprise -- low blood sugar!

Secondly, modern insulin is more pure than older insulin. This means there are fewer problems from injecting in the same area repeatedly.

Q: I'm using my abdomen only for my injections, and I inject four times a day. Do I still need to rotate where I give the injections?

A: Yes. As long as you give each injection about an inch away from the last injection, it's far enough away to prevent problems.

Q: I keep forgetting where I last injected. How can I keep track?

A: One system that is easy to remember is to draw an imaginary line vertically through your navel. Then draw another imaginary line horizontally across your stomach through the navel. Now you have four rectangles on your abdomen. Draw two more imaginary vertical lines to divide all the rectangles in half. Now you have eight areas that are approximately squares. Starting on one side, assign a square for each day of the week. Inside each square, use the top right hand area for the morning injection, the top left hand area for the noon injection, the bottom right for the evening injection, and the bottom left for the bedtime injection. Use the middle of each square, or the extra square, for any extra injections you might have to give.

Q: I have been told to pinch up some skin and fat, to be sure I don't inject insulin into a muscle. What would happen if I injected insulin into a muscle?

A: It would probably hurt. More seriously, the insulin would probably be absorbed very rapidly. You would have more chance of having a serious episode of hypoglycemia, or low blood sugar.

Q: Some people say you should inject insulin with the needle at a 45 degree angle, and others say you should just push the needle straight in at a 90 degree angle. Which is right?

A: Either one can be right. The idea is that you want to inject the insulin into the tissue just under the skin. Most people have enough fat in the areas used for injections that it's fine to inject straight in (90 degrees), and it's a little easier. Insulin needles are short enough that they don't reach in too far. But for small children, or thin adults, there might not be much space between the top of the skin and the muscle underneath. These people can be more certain of injecting into the right place by holding the needle at a 45-degree angle to the skin. Another choice would be to use shorter insulin needles, which would then allow them to use a 90-degree injection angle.

Q: Sometimes I can feel a bump right under my skin right after an injection. What is that?

A: It means you injected the insulin too close to the surface of the skin. The insulin is probably sitting in between the layers of the skin. This can happen if you're trying to do an injection at a 45-degree angle, but you actually use even less of an angle.

The insulin you just injected will be absorbed into your body, eventually. But there is not good blood circulation this close to the surface of your body, so it could take a long time to be absorbed. Meanwhile, you might have higher blood sugar for a while. To prevent a repeat of injecting the insulin between the layers of the skin, you should inject at a 90-degree angle, or use a shorter needle. This will allow you to use a 90-degree angle without any problems.

Q: When I was first taught how to give insulin injections, I was told to wipe my skin with alcohol before giving the injection. Now my diabetes educator has told me I don't need to do that. Why?

A: Wiping the skin with alcohol was a medical ritual everyone assumed we needed to do. But until a few years ago, it had really never been tested. When it was tested with careful research, we learned most people do not get higher rates of infection if they give insulin injections without wiping the skin with alcohol, as long as they bathe at least once a week, and the skin is basically clean. This works for several reasons:

1. Wiping with alcohol does not sterilize the skin. It only cleans the top layer of skin. You can get your skin just as clean by washing it with soap and water.

2. Insulin needles are small and slick. They are not good carriers for bacteria.

3. Most people keep the areas of the body they use for injections covered by clothing most of the time, so they are generally kept clean.

If the area you'd inject has been exposed, and has gotten dirty, say, for example, you have been wearing a bikini and rolling in the dirt, or if you have spilled something wet over an injection site and it has soaked through your clothes, you definitely should clean the site before giving an injection. You can either wash with soap and water, or wipe the area with an alcohol wipe. But if your skin is basically clean, you don't need to use alcohol routinely.

Q: How can I contact the insulin manufacturers?

A: Their web sites and customer service numbers are:

Aventis: Web site: www.lantus.com; Customer service number: 866-452-6887.

Eli Lilly: Web site: www.lillydiabetes.com; Customer service number: 800-545-5979.

Novo Nordisk: Web site: www.novonordisk-us.com; Customer service number: 800-727-6500.

Other Sources:

DIABETES ACTION NETWORK ARTICLES book: Contains useful articles like "Blind Diabetics Can Draw Insulin Without Difficulty," "Insulin Types: A Review," "Insulin Measurement Devices," and 20 more, available free in large print or 4-track audiocassette from the Materials Center, National Federation of the Blind, 1800 Johnson Street, Baltimore, MD 21230; telephone: (410) 659-9314; Web site: www.nfb.org

See also accompanying article in this issue: "Diabetes Self Care -- When You're Blind" -- more good information about drawing and injecting insulin.

Do you have questions about your diabetes care? If you would like your question answered in a future column, please contact me, Ann S. Williams, c/o the Voice editorial office.