Guidelines for Injecting Insulin Comfortably and Safely
Injecting insulin at room temperature is much more comfortable than injecting cold insulin straight from the refrigerator. Insulin should be kept in the fridge until you are ready to use it for the first time to guarantee full potency until the expiration date printed on the vial.
Once you put a syringe or pen-needle through the rubber stopper of the insulin vial or pen needle cartridge, the expiration changes and the countdown begins. It has nothing to do with whether or not you refrigerate the insulin. Each type of insulin has a different opened expiration date. Most insulins are good at room temperature for 28 days, with the exception of premixed insulins and insulin pen cartridges and prefilled insulin pens, which vary from 10 to 14 days. Check the package inserts for the insulins you use.
All insulin should be discarded at the end of one month. Your insulin will not work as well after a month’s time, and your blood glucose control will suffer.
If you use alcohol to clean the site before injecting insulin, it is important to let the alcohol dry first. Wet alcohol will sting. Hand-washing is important in protecting you from infection.
3. Injection site
Most insulins are absorbed at different rates from each injection site. This may not be true with some newer insulin analogs such as Lantus (insulin glargine). In general, the abdominal area has the quickest rate of absorption, followed by the arms, the thighs and the buttocks. Because the insulin is absorbed at different rates, changing the injection site when you take your insulin may cause your blood glucose to vary, resulting in poor control.
You might try to stay within the same general site and move around to a different area still within that site each time you inject to eliminate the variability. The abdomen is considered to have the least variability, since it is the least affected by exercise or other physical activity. If you decide to use only one site such as the abdomen, you should still rotate your injection sites even within that same site to prevent overusing an area, which may cause injection-site pitting or depressions (lipodystrophy) or excess quantities of fatty tissue to form (lipohypertrophy).
4. Needle length
You can choose between two different needle lengths for syringes and three for pen needles. In general, a short needle is 5/16 of an inch (8 mm) and a regular length is 1/2" (12.7 mm). Pen needles also come in mini (5-6 mm) lengths. The regular 12.7 mm needles are for very overweight people and the minis are for very young children and very thin people.
5. Rolling insulin and injecting air
All cloudy insulins such as NPH, lente, ultralente and premixed insulins, whether in a vial or in a pen or other injection device, need to be rolled gently in the palms of your hands (or shaken gently) to re-suspend the insulin. This is very important, and omitting this step can result in unpredictable insulin action.
To keep the pressure equal in the insulin vial, you should inject an amount of air into the bottle that will be equivalent to the amount of insulin you will be removing. When using an insulin pen, you should do a two-unit “air shot” first to make sure the pen is working properly. Dial up two units, hold the pen up in the air, and see if you can see a drop of insulin come out of the pen needle. If not, your pen may be clogged. You should change the pen needle and try again. Never keep an insulin pen needle attached to an insulin pen between injections, as this “open system” can result in insulin leakage or air entering the system, depending on the ambient temperature.
6. Pinching and injection angle
Insulin should be injected into the fatty tissue just beneath the skin. The best way to get there is to pinch the skin and inject at a 90° angle. The areas on the back of the upper arm, front and sides of the thigh, outer top of the buttocks and the abdomen (avoiding the navel area) are all acceptable sites. When using the abdomen, remember to draw an imaginary 2" circle around the navel. For ease and comfort, avoid injecting within that circle.
7. Allow enough time
When injecting the insulin using a syringe or an insulin pen, push the plunger all the way down slowly and then count to at least five. If you are taking more than 20 units at one time, you should count to 10. It takes time for all of the insulin to pass through the tiny opening in the needle. If you don’t do this, you may see insulin leaking out of the needle as you remove it from your skin.
8. Consider your blood glucose level and the injection site
Since the different sites absorb insulin differently, consider injecting your rapid-acting insulin into the abdomen if your blood glucose is high—over 200 mg/dl—or just before a meal. If your blood glucose is too low—less than 70 mg/dl, consider injecting into the thigh or buttock to take advantage of the slower absorption rates at those sites. If you want intermediate-acting insulin such as NPH to last longer, inject into the thigh or buttock. Since Lantus absorbs just as slowly no matter where you inject it subcutaneously, use a site you are not regularly using for your rapid-acting insulin, such as your thigh or buttock. Be sure you are not injecting insulin into muscle, which has increased blood supply and will absorb insulin too quickly. A very lean individual should be cautious with thigh injection sites unless using short needles or a shallow angle of injection with regular-length subcutaneous needles.
9. Be safe and responsible
Dispose of your used syringes, pen needles and lancets according to the regulations of your local health department.