Researchers say temperature fluctuations in your refrigerator may put insulin in unsafe conditions at times.
For people with diabetes, there’s usually one place you store your lifesaving insulin: In the refrigerator.
In fact, that’s the recommendation of the three insulin manufacturers in the United States, according to the Institute for Safe Medication Practices, a nonprofit advocacy group.
Yet, that might not be the safest place to store it.
A new study, presented at the European Association for the Study of Diabetes (EASD) annual meeting in Berlin, is pointing out some of the potential dangers.
Researchers tracked diabetes patients living in the United States and Europe and outfitted them with refrigerator thermometers to see if their home refrigerators stayed within the recommended range for insulin storage — between 36°F and 46°F.
They also looked at insulin temperature variances for those who didn’t store their insulin in the fridge, putting temperature sensors in their diabetes bags.
The results raised some eyebrows.
Almost 80 percent of study participants saw their insulin fall out of the recommended range some of the time during the trial.
In addition, insulin stored in the refrigerator fell out of the recommended temperature range for the equivalent of 2 hours and 34 minutes daily, or 11 percent of the total observed storage time.
People who stored insulin outside of the fridge, by contrast, only saw the medication fall out of the “safe” range for roughly 8 minutes daily, the researchers found.
Why the difference? One reason may be that insulin that doesn’t require refrigeration is hardier.
“Insulin products contained in vials or cartridges supplied by the manufacturers (opened or unopened) may be left unrefrigerated, at a temperature between 59°F and 86°F, for up to 28 days and continue to work,” said a spokesperson for the U.S. Food and Drug Administration (FDA).
That means non-refrigerated insulin has more wiggle room before it falls out of the recommended range.
That might sound counterintuitive, since the refrigerator is a more tightly controlled temperature environment.
However, when you look at conflicting recommendations, it begins to make sense.
For example, the FDA recommends that refrigerators be set at 40°F or below for food safety.
In addition, refrigerator-maker Samsung states that a “slight temperature fluctuation” of plus or minus 5° is typical for a refrigerator.
And that’s before factoring in the temperature fluctuations that can come from opening and closing your refrigerator too often.
Here’s a scenario: Say you set your fridge at 37°F just to be on the safe side for food safety, and you’re storing your insulin in there. Per the manufacturer, your refrigerator’s internal temperature could dip as low as 32°F, or 4° lower than what insulin manufacturers recommend.
The researchers observed a variation of this exact circumstance, with 17 of the temperature sensors registering a temperature below the freezing point of 32°F.
That poses a risk.
“Insulin should be kept as cool as possible, but should not be frozen. Frozen insulin should not be used,” FDA representatives said.
People, however, don’t want to throw their insulin away, especially as the price of insulin has skyrocketed in recent years.
That puts more pressure on patients who need the hormone to make sure it’s stored safely and none of it is wasted.
There are some solutions in the works.
In the meantime, people who use liquid insulin that needs to be refrigerated, should keep a closer eye on their refrigerator temperature.
“Many people with diabetes are unwittingly storing their insulin wrong because of fluctuating temperatures in domestic refrigerators,” Dr. Katarina Braune, a research fellow at Charite Universitaetsmedizin Berlin in Germany, and the lead author of the recent study, said. “When storing your insulin in the fridge at home, always use a thermometer to check the temperature. Long-term storage conditions of insulin are known to have an impact on its blood-glucose lowering effect.”
Susan Weiner, a registered dietitian-nutritionist and certified diabetes educator, agrees.
“Getting a temperature sensor is a really fantastic idea,” she told Healthline.
It should be noted that refrigerator thermometers are relatively inexpensive, even more modern ones that contain features such as Wi-Fi connectivity. With these devices, you can even set an alarm to go off and notify your phone when your fridge falls out of the acceptable range.
And not everywhere in the refrigerator is created equal.
“Beware of cold and warm zones in the refrigerator,” Weiner said. “In the olden days, people used to talk about the butter compartment to store it, but if that’s on the door it might not be the best place.”
Instead, store your insulin on the center shelf or consider getting a small, dedicated refrigerator for your insulin that isn’t subject to the temperature fluctuations of your main unit, she recommended.
That said, even if your insulin does occasionally fall out of the manufacturer’s recommended range, that doesn’t mean you have to get rid of it immediately.
“More research is needed to examine the extent to which temperature deviations during domestic storage affect insulin efficacy and patient outcomes,” Braun said.
“However, an insulin product that has been altered for the purpose of dilution, or by removal from the manufacturer’s original vial, should be discarded within two weeks,” according to the FDA.