Diabetes: Insulin can be stored out of refrigeration even in hot settings!

Diabetes requires an extremely precise form of daily treatment, whereby patients have to inject themselves with several doses of insulin every day, which are suited to their diet and physical activity. Patients must therefore keep a supply of insulin which, according to pharmaceutical protocol, must respect the cold chain from production to injection. However, in some regions of the world like sub- Saharan Africa, not every household has a refrigerator. This forces people living with diabetes to go to hospital on a daily basis.

Faced with this issue, Médecins Sans Frontières (MSF) teamed up with the University of Geneva (UNIGE), Switzerland, to test insulin storage in real conditions, that is at temperatures ranging from 25°C to 37°C for four weeks. This corresponds to the time it usually takes a diabetic person to finish one vial of insulin.

The findings published in the journal PLOS ONE, demonstrate that the stability of insulin stored under these conditions is the same as that of cold-stored insulin, with no impact on efficacy. This allows people with diabetes to manage their illness without having to visit a hospital multiple times daily.

The MSF team in the Dagahaley refugee camp in northern Kenya found that the temperature in a home fluctuates between 25°C at night and 37°C during the day. The researchers then meticulously reproduced these conditions in laboratory setting, where they tested insulin storage.

​ “As you can insulin vials can be used for four weeks after opening, we carried out our measurements over the same time-frame, first with vials kept at the temperatures found in Dagahaley, and then with ‘control’ vials that were refrigerated,” explains Leonar- do Scapozza, a Professor of the School of Pharmaceutical Sciences in UNIGE’s Faculty of Sciences. The UNIGE team used high-performance liquid chromatography to analyse the insulin. “The risk is that insulin, a protein, precipitates under the influence of heat. In other words, it would begin to form ‘flakes’. Since the insulin is no longer in solution, it can’t be injected.”