New research that set out to analyze the temperatures at which people living with diabetes store their insulin is now warning against the harmful effects of improper storage for the quality and effectiveness of the hormone. People with type 1 diabetes need to have insulin injections or have insulin delivered with a pump in order to survive. Insulin is absolutely vital for helping cells get access to glucose and use it for energy. Without it, the person's blood sugar levels skyrocket, leading to hyperglycemia.

A new study, however, suggests that many of these people might not get the full benefits from their insulin therapy; the hormone may be stored at incorrect temperatures in people's domestic fridges, which could make it less effective. The study was led by Dr. Katarina Braune from Charité – Universitaetsmedizin Berlin, Germany alongside Prof. Lutz Heinemann, from Sciences & Co, Paris, France, and the digital health company MedAngel BV. Dr. Braune and colleagues presented their findings at the European Association for the Study of Diabetes Annual Meeting, held in Berlin, Germany.

Insulin needs to be stored in a refrigerator at a temperature around 2–8°C (36–46°F) in order for it to be effective. If carried in a pen or vial, it must be stored at around 2–30°C (36–86°F). Dr. Braune and her colleagues examined the temperature at which insulin was stored in domestic fridges and carried around by 388 people with diabetes living in the U.S. and European Union. They installed temperature sensors next to the volunteers' home fridges or in their diabetes bags. These sensors took measurements automatically every 3 minutes, or 480 times per day, for a period of 49 days. The measurements were sent to a database though an app. Overall, the analysis comprised 400 temperature logs, 79 percent of which fell outside of the temperature guidelines.

The analysis found that 11 percent of the time — or 2 hours and 34 minutes each day — the insulin was stored in the fridge at improper temperatures. Carried insulin fell outside of recommendations only 8 minutes per day. Freezing was also a significant problem, with sensors detecting temperatures below 0°C around 17 percent of the time, or 3 hours per month. Dr. Braune comments on the findings, saying, "Many people with diabetes are unwittingly storing their insulin wrong because of fluctuating temperatures in domestic refrigerators."

"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."

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