Worldwide, tens of millions of people with diabetes (including all people with type 1 diabetes and about 15% of people with type 2 diabetes) require insulin therapy. For a long time, in our understanding, insulin is neither resistant to high temperature nor low temperature, and needs to be stored in refrigeration (4°C~6°C), and the longest storage period at standard room temperature (20°C~25°C) About 1 month, and it is necessary to avoid repeated shocks in different temperature environments.
In reality, it is difficult for quite a few patients to preserve insulin completely and correctly. A survey of nearly 4,000 Chinese patients showed that 23% of patients did not store their insulin in the refrigerator before opening the package. In situations where refrigeration is limited (such as when traveling, living in hot climates or low-resource areas, etc.), patients are more likely to face the problem of insulin preservation.
In recent years, some medical researchers have begun to challenge dogma and explore the shelf life of insulin at room temperature. Recently, The Lancet Diabetes & Endocrinology, an authoritative journal in the field of diabetes, published the results of an international collaborative team. The study suggests that insulin can likely be stored at room temperature for up to four months, much longer than so far predicted, which would help improve access to insulin therapy and reduce insulin waste for large numbers of diabetics around the world.
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Screenshot source: The Lancet Diabetes & Endocrinology
This study further explored the unopened storage of 6 insulins (including regular human insulin, protamine human insulin, insulin aspart, insulin glargine, etc.) under unrefrigerated conditions during the Indian summer for 1-4 months potency and concentration (compared to refrigerated samples of each insulin).
The study was conducted in 6 patient families. Insulin storage locations were designated into 2 categories, and the temperature of the storage environment was measured electronically every 15 minutes:
(1) In the box in the coolest room in the patient's home, the average temperature ranges from 29.4°C to 32.0°C, the average maximum temperature ranges from 30.4°C to 34.9°C, and the average minimum temperature ranges from 28.3°C to 29.8°C
(2) In a clay pot with a simple cooling function in a cool place (keep the contents of the pot cool by evaporating water), compared with the storage location (1), the average temperature is 2.6 °C lower.
The results of laboratory analysis showed that,
Maintain acceptable concentrations at room temperature for up to 2 months for all insulin formulations covered by the study, for all samples;
At 4 months, all samples of the 3 insulin analogues, and 75% of each human insulin, maintained ≥95% relative concentrations (within the USP potency range for safe use) at room temperature.
At 4 months, insulin preparations stored in clay jars had less relative potency loss than those stored in boxes.
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▲The relative potency (HPLC-UV spectrophotometry, dark blue) and total concentration (NMR analysis, light blue) of the six insulin preparations after storage for different periods of time. Different graphics represent different storage locations: square-refrigerator, round-clay pot, triangle-box. (Image source: Reference [1])
The findings are also similar to those found in another important study of insulin thermal stability in recent years. Previous research from a collaborative team at Doctors Without Borders (MSF) and the University of Geneva has shown that several insulins, including human insulin and insulin analogs, can be treated at higher and less stable ambient temperatures (25 Oscillation temperature range of °C-37 °C) for 4 weeks without significant deterioration in structure and biological activity.
Of course, the research team also pointed out the limitations of the above analysis. For example, the blood sugar control in humans after using these insulins was not directly detected. In addition, these insulins were not used during the study period, and in the real environment, unsealing may also affect the control of blood sugar levels. bacteria.
Dr Graham D Ogle, lead researcher at the University of Sydney, Australia, said, "If these results can be further validated in a larger study, it may change the conventional advice that 'insulin should only be stored at room temperature for 1 month'. The usable time will be extended by 4 times - 3-4 months, which will have a significant impact on resource-poor patients."
