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For millions of people with diabetes, technology has supplied us with wonderful, helpful aids to help control blood sugar. While some of these medications come in pill form and remain stable when stored out of light and at moderate temperatures, people with diabetes who use insulin need to depend on more than technology to make sure their insulin is in top form.
As associate dean and professor of pharmacy at Washington State University, a certified diabetes educator and a person with diabetes for more than 50 years, Keith Campbell knows the importance of keeping an eye on insulin. Campbell believes that establishing a routine surrounding insulin use helps ensure the product stays potent and stable.
Step One: Check the Label
Campbell advises that the first thing a person with diabetes should do is check the insulin's expiration date, even before leaving the pharmacy.
"Drug companies and the FDA are very conservative with the dates," says Campbell. This means they tend set expiration date at the earliest time the insulin could possibly go bad, and sometimes even earlier.
Sofia Iqbal, RPh, a drug information scientist with Novo Nordisk Pharmaceuticals, confirms this.
"Expiration dates and storage guidelines are based on stability data obtained for batches of each formulation of insulin," Iqbal says. She adds that the dates are valid as long as the insulin is kept stored under the correct conditions.
"Never use insulin after the expiration date printed on the label and carton," Iqbal warns.
If you get your insulin home and discover the expiration date has passed, what should you do? Campbell advises that you return it to the pharmacy immediately for replacement.
Step Two: Examine the Insulin
Eli Lilly and Company's Kara Appell, RPh, a medical information administrator, and Connie Shella, RN, CDE a clinical research team leader, both urge insulin users to visually examine each vial of insulin before injecting it. Iqbal agrees.
"Before each use of insulin, the vial or cartridge should be inspected for any changes," says Iqbal, noting that there should be no clumping, frosting, precipitation or changes in color or clarity in the vial. "Any such changes may signify a loss in potency of insulin."
Appell and Shella explain that Regular or Humalog insulin should appear clear and colorless.
Humalog Mix 75/25, Humulin N, Lente, 70/30, 50/50 or Ultralente should have an even, cloudy appearance after gentle mixing or rolling.
"This insulin should not be used if the liquid in the vial remains clear after the vial has been gently mixed," Iqbal warns, adding that rapid- or short-acting human insulin should never be used if it appears viscous or cloudy. All three professionals say insulin should not be used if particles appear on the vial bottom or wall or if the vial has a frosted appearance.
"If, after visual inspection, an uncertainty remains about the potency of the insulin, the vial should be replaced with another vial of insulin of the same type," Iqbal emphasizes.
Campbell gives insulin users the same advice, but ameliorates it with a simple observation. "I've been a diabetic for 51 years and I've never seen any problems with insulin myself."
Mary Hunt, a Michigan diabetic, begs to differ. She says she has experienceed insulin spoilage due to high temperature.
"I have had one bottle of Isophane spoil due to its reaching too high a temperature," she says. "Its appearance was still cloudy, but there were also clumps of the white material that could be seen upon close examination."
Hunt discarded her spoiled insulin.
Step 3: Store Insulin Properly
Iqbal, Campbell, Appell and Shella are clear in asserting that insulin will remain very stable and potent if the user carefully follows the manufacturers' storage directions. All agree, too, that the main enemies to potency and stability in insulin are extremes in temperature.
For long-term storage (longer than one month), unopened insulin vials should always be stored in the door of the refrigerator. Why? Because items stored in the main portion of a refrigerator may get pushed to the back, where there is a possibility of frost or even freezing. Storing the vials in the door will ensure that does not happen.
"Extreme temperatures and excess agitation should be avoided to prevent any loss of potency, clumping, frosting or precipitation," Iqbal explains carefully. She adds that insulin should not be left in sunlight either. "If refrigeration is not possible, the vial that is in use can be kept unrefrigerated as long as it is kept as cool as possible and away from heat and sunlight. Never use insulin that has been or is suspected of [having been] frozen, even after it has thawed."
Campbell suggests that the vial in use be stored at about 70 degrees for a very practical reason.
"It's less painful to inject yourself with insulin that is closer to body temperature [98.7 degrees]," he says.
Iqbal agrees that keeping an open vial at room temperature for up to a month (Lilly advises 28 days; Novo Nordisk 30 days) will not hurt the insulin, as long as it is stored correctly.
The Lilly team provides detailed explanations of exactly how their insulin products should be stored.
Iqbal emphasizes the importance of following the specific directions that come with each type of insulin. There are two reasons for this:
Vials and pen cartridges have different storage requirements.
All four experts agree that insulin may lose some of its potency after 30 days in an opened vial or pen. They advise using the insulin before the 30-day period expires. Unrefrigerated insulin should definitely be discarded after the 30-day period, even if the vials or pens have never been opened.
In the past, there has been some controversy surrounding mail-order insulin products (see sidebar on p. 22). A study in St. Louis in the mid-90s revealed excessive mailbox temperatures could affect the potency and stability of medications sitting inside them longer than a few minutes. In addition, there has been some question about shipping insulin so that it is kept at the right temperature.
Lilly and Novo Nordisk and their distributors always store and transport insulin products under refrigeration and provide guidelines to wholesalers and retail distributors, as does the American Diabetes Association.
"In general, insulin may be shipped unrefrigerated in corrugated containers with precautions taken to avoid extremes of temperature and to assure delivery within two days," says Iqbal. She advises not shipping insulin on Thursdays or Fridays and prominently labeling it "Refrigerate Upon Arrival, Keep Cool, and Avoid Freezing."
"If you are uncomfortable with the appearance or condition of insulin shipped to you through a mail-order facility, our recommendation is not to use the product," Iqbal says.
Some people with diabetes have discovered their pharmacy is the reason their insulin has lost potency. Cindy Fry of Seattle, Washington, notes that she found that her pharmacist kept the insulin at room temperature for too long.
"Since reading my pharmacy the riot act, they refrigerate my prescription until I pick it up," says Fry.
Step 4: Use Common Sense Away From Home
Everyone travels now and again, and precautions should always be taken with regard to insulin care. Campbell says that even something as simple as parking in a shady spot can ensure that your insulin will remain viable. However, it is best to keep it refrigerated and out of heat and sunlight if at all possible.
Iqbal knows that circumstances do not always work out that way. She advises travelers to use an insulated container if refrigeration is not possible. "When adding a coolant [such as a gel pack or ice] to the container, take care not to store the insulin vial or cartridge in direct contact with the coolant," she warns. The glass may break or the insulin might freeze. Instead, wrap the insulin in a wet cloth before placing it in the container. As soon as you get to a place with a refrigerator, store the insulin there.
Mary Rose of Colorado does not want to be left out in the proverbial cold when she cross-country skis or snowshoes, so she takes common sense precautions outdoors. She keeps her insulin, as well as her Chemstrips, in her pants or shirt pocket. In the summer, she carries a small ice pack with her diabetes supplies.
David Adlerstein lives in South Florida, so he understands the importance of keeping insulin out of the sun and heat when out and about.
"Sometimes, I leave my frozen gel pack at home and have to remember to put my NPH insulin under the car seat for no more than an hour or carry it in my pocket," he says. But if I go to the beach, this is a problem since it's one more thing to carry. But I can always dip it in the ocean to keep it cool."
A Final Word to the Wise
Campbell says his years of expertise and experience have taught him that a reasoned approach to insulin storage will yield the best results.
"A lot of people worry about heat," he acknowledges. They buy devices to keep their insulin cool and worry excessively. But he believes that practicality is the way to go. "Insulin needs to be above 120 degrees before it's affected by heat. Keep it as close to 70 degrees as possible. Use common sense. Don't store your insulin in the car in the sun. Don't let your insulin freeze-keep it next to your body in the cold."
If you follow just a few simple steps, everything will go just fine.
Diabetes Health is the essential resource for people living with diabetes- both newly diagnosed and experienced as well as the professionals who care for them. We provide balanced expert news and information on living healthfully with diabetes. Each issue includes cutting-edge editorial coverage of new products, research, treatment options, and meaningful lifestyle issues.