Insulin ‘safe at room temperature for months’: Cochrane Review

Public health

By Geir O'Rourke

8 Nov 2023

Unopened vials of human insulin can be safely stored at room temperature for up to six months with no clinically relevant loss of insulin activity, a Cochrane Review has concluded.

The finding has important implications for patients in disaster zones and crisis-affected areas, but also those without constant access to refrigeration such as travellers, the investigators say.

Currently, Diabetes Australia advice states that “insulin can be kept at room temperature (less than 25 degrees Celsius) for up to 30 days, then it must be discarded.”

Data from 17 studies were included in the review, alongside information directly sourced from insulin manufacturers BIOTON, Eli Lilly and Novo Nordisk, although all but one of the studies were laboratory-based, according to the researchers.

The sole pilot clinical study investigated temperature conditions for insulin stored for six weeks in temperature between 25° and 27°C.

This found the mean fall in plasma glucose in eight healthy volunteers after insulin stored at room temperature in a clay plot was comparable to refrigerator‐stored insulin injection – albeit characterised as “very low‐certainty evidence” by the Cochrane team (link here).

In addition, the 16 in-vitro studies all showed no clinically relevant loss of insulin activity at temperatures up to 37°C for up to three months.

These included short‐acting insulin (SAI), intermediate‐acting insulin (IAI) and mixed insulin (MI) stored in a variety of vials, cartridges and pre-filled syringes, the researchers said.

Taken together with the supplied industry data, these suggested it was safe to store unopened vials and cartridges of specific types of human insulin at temperatures of up to 25°C for a maximum of six months, and up to 37°C for a maximum of two months, they reported.

They noted current recommendations were for unopened insulin vials to be stored in a refrigerator, but there was “no clear consensus” on how the product should be kept at home if reliable refrigeration could not be guaranteed.

Importantly, data from one study showed no loss of insulin activity for specific insulin types when stored in oscillating ambient temperatures of between 25°C and 37°C for up to three months, a fluctuation resembling the day-night temperature cycles experienced in tropical countries.

“Our study opens up new possibilities for individuals living in challenging environments, where access to refrigeration is limited,” said lead researcher Dr Bernd Richter from the Institute of General Practice at Heinrich-Heine-University in Düsseldorf.

“By understanding the thermal stability of insulin and exploring innovative storage solutions, we can make a significant impact on the lives of those who depend on insulin for their well-being.”

The authors also pointed to one study showing insulin had been safely stored in unglazed clay pots, which were “simple cooling devices if no reliable refrigeration is available”.

Nevertheless, there were uncertainties for future research to address, particularly around the need to better understand insulin effectiveness following storage under varying conditions, according to the authors.

Further research was also needed on mixed insulin, influence of motion for example when insulin pumps are used, contamination in opened vials and cartridges, and studies on cold environmental conditions, they said.

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