Impacting Millions: Human Insulin’s Surprising Resilience to Temperature Variations

A recent evaluation conducted by Cochrane has uncovered a remarkable revelation concerning the stability of insulin, a critical medication for individuals with diabetes. Contrary to previous assumptions, certain varieties of insulin demonstrate resilience when stored at room temperature for extended durations. This development holds profound implications for diabetes care, particularly in regions lacking reliable refrigeration facilities.

The study in question, undertaken by Bernd Richter and his team from the Institute of General Practice, Medical Faculty of the Heinrich-Heine-University in Düsseldorf, Germany, delves into the resilience of insulin under diverse storage conditions. This comprehensive review scrutinized seventeen separate studies, encompassing laboratory examinations of insulin vials, cartridges/pens, and prefilled syringes. Astonishingly, these investigations consistently affirmed the potency of insulin across a spectrum of temperatures, ranging from 4°C to 37°C, with no clinically significant decline in insulin activity.

For individuals afflicted with diabetes, insulin is an indispensable lifeline. Those with type 1 diabetes, in particular, rely on frequent insulin injections to manage their condition. It is a well-established protocol that insulin must be refrigerated to maintain its efficacy before use. However, millions of people residing in low- and middle-income countries face the stark reality of limited access to electricity and refrigeration. Furthermore, populations enduring conflict zones, natural disasters, or the brunt of climate crises often lack the luxury of powered refrigeration.

The groundbreaking Cochrane review offers a glimmer of hope to these underserved communities. It consolidates the findings of various studies, including hitherto unpublished data from insulin manufacturers. Notably, it suggests that specific types of human insulin can be safely stored at temperatures of up to 25°C for a maximum of six months and up to 37°C for up to two months, all without experiencing any clinically significant degradation in insulin activity. Remarkably, one study demonstrated the absence of insulin activity loss even when subjected to fluctuating ambient temperatures between 25°C and 37°C for up to three months, resembling the diurnal temperature fluctuations in tropical regions.

This revelation underscores the pressing need for clear guidance to be disseminated to individuals facing critical life situations and hailing from regions that lack official sources of information. For people with type 1 diabetes, insulin is not merely a medical treatment; it is a lifeline, their very survival depends on it.

The implications extend beyond mere theoretical knowledge. They pave the way for innovative solutions in insulin storage for challenging environments. If reliable refrigeration is unattainable, the study proposes the utilization of simple cooling devices such as clay pots for insulin preservation. Moreover, these findings spotlight areas of future research, including mixed insulin’s stability, the influence of motion on insulin effectiveness (as observed in insulin pumps), contamination in opened vials and cartridges, and investigations into cold environmental conditions.

In conclusion, the Cochrane review, funded by the World Health Organization, has illuminated a new path for individuals in resource-constrained settings. It offers the reassurance that alternatives to powered refrigeration for insulin storage are not only possible but also safe. As we delve deeper into the intricacies of insulin stability, we take significant strides toward enhancing the lives of those who depend on this vital medication for their well-being.

Reference: “Thermal stability and storage of human insulin” by Bernd Richter, Brenda Bongaerts, and Maria-Inti Metzendorf, November 6, 2023, Cochrane Database of Systematic Reviews.
DOI: 10.1002/14651858.CD015385.pub2

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More about Insulin Stability

• Cochrane Database of Systematic Reviews: Thermal stability and storage of human insulin
• World Health Organization
• Diabetes Care
• Insulin Management
• Healthcare Access in Low-Income Countries