Study Shows Insulin Can Be Maintained in Hot Climates Without Refrigeration

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You’ve probably, at some point, worried that high temperatures have ruined your insulin. Maybe you forgot your insulin inside a hot car (mistakes happen), or feared that the insulin in your pump was cooking during a summer outing.

And if you struggled to afford your insulin, a vial or pen rendered ineffective from high heat could represent a true crisis.

Now imagine living in a climate with extreme heat—say, arid sub-saharan Africa—and being too poor to own a refrigerator at home. What would you do then?


That’s the reality for many people with diabetes, and the consequences can be debilitating. Imagine if your home daily reached temperatures nearing 100°F, and you were told that at home your insulin would degrade within a day. Imagine if you had to travel to a hospital or doctor’s office, every day, in order to get your life-saving shot. Imagine how profoundly limiting your condition would be—and how profoundly limited your ability to properly treat it would be.

With help from the celebrated non-profit Doctors Without Borders, a team of Swiss researchers decided to test how much insulin degrades in exactly these sorts of conditions. Their findings are a cause for celebration: insulin can withstand higher daily temperature fluctuations better than anyone expected.

The study, which was published in PLOS ONE, began with an analysis of the conditions in Kenya’s Dagahaley refugee camp, where Doctors Without Borders runs a diabetes program. The camp has over 200,000 refugees and asylum seekers, most of whom have fled famine and civil war in Somalia; some have lived there for decades. During the hottest and driest time of the year, temperatures ranged from highs near 99°F to overnight “lows” of 77°F. Those highs far exceed the upper limits for storage set by insulin manufacturers, suggesting that within a day the insulin would be rendered powerless and should be discarded.

If Doctors Without Borders could prove that insulin retained potency in these hot conditions, it would alleviate a lot of trouble for the patients of the Dagahaley diabetes program, and in many other similar places.

Back at the University of Geneva, scientists designed an experiment to mimic these real-life conditions. Insulin was stored at fluctuating temperatures tracking those in the refugee camp; twice daily, the insulin was lightly agitated and 10-12 units were removed, slightly agitating the insulin, penetrating the seal, and consistently adding air to the vial.

After 28 days, scientists measured the potency of the insulin in multiple ways, including liquid chromatography and residual bioactivity assessment. The results were definitive: despite the exposure to high regular temperatures, the insulin was just as effective as insulin that had been stored under optimal conditions.

Professor Leonardo Scapozza, speaking to Business Insider, said that the team also studied vials of insulin that came directly from the refugee camp and had actually been used by refugees. The result was the same: “the insulin was perfectly usable.”

The team went on to test insulin after 12 weeks of storage in the same conditions. Even this insulin showed essentially no loss of effectiveness. The PLOS ONE article puts it very, very mildly when it states that “the manufacturers’ recommendations for insulin storage during the period of use by the patient are quite conservative.”

In fact, there is plenty of other evidence that insulin is far more durable than the storage guidelines would have you believe. Earlier studies have found that insulin remains effective after 199 days of storage at room temperature, even though official recommendations advise you to throw unused insulin in the trash at day 29.

Despite the evidence, it’s rare to find authorities that will advise patients to use insulin outside of recommended parameters or after temperature deviations, perhaps for fear of liability. But some experts have suggested that careful patients can trust themselves to assess the potency of expired or overheated insulin. If a particular batch of insulin were to go bad, it should be easy to see on a blood sugar meter.

Now, Doctors Without Borders is hoping that the World Health Organization and insulin manufacturers will update their storage recommendations. New guidelines, with proper training, could help alleviate what is now an immense burden for people with diabetes in low-resource settings. Proper storage, of course, is only one of many issues facing patients in places like the Dagahaley refugee camp, but it’s something.

And for those of us lucky enough to live in more secure circumstances, it’s good to know that our life-saving medicine is more durable than previously suspected.

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SCC
SCC
3 months ago

Good to know as I live in the Phoenix area and wear my pump outside for many hours a day in 110+ degree temps. I’ve never noticed degradation of my insulin

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