Most diabetics are storing potentially life-saving insulin at the wrong temperature, warns new research.
Up to four out of five people keep the hormone at either too cold or too warm a temperature in their fridge, potentially affecting the strength of their medication.
A study of 388 diabetes patients measured the temperature of their insulin when they kept it in the fridge or in a bag for carrying around.
And 79 per cent of temperature logs revealed the medicine was kept outside of the recommended range at some point – on average, insulin was stored at the wrong temperature for two hours and 42 minutes per day.
Researchers warn people may be ‘unwittingly’ making their insulin less effective and they should use thermometers to check it’s stored properly.
German scientists monitored the temperature of insulin formulations stored in fridges at home and carried as a spare.
Some 388 US and EU diabetes patients put temperature sensors next to their insulin in the fridge or their diabetes bag.
Automatic temperature measurements were taken every three minutes – up to 480 times a day – for an average of 49 days.
Of 400 temperature logs, 315 (79 per cent) had periods when the insulin fell outside the recommended temperature range.
On average, insulin stored in the fridge was out of the recommended temperature range 11 per cent of the time, approximately two hours and 34 minutes a day.
Whereas insulin carried by patients was only outside recommendations for around eight minutes a day.
Dr Katarina Braune, of Charité – Universitaetsmedizin Berlin said: ‘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.
‘For people living with insulin-dependent diabetes who take insulin several times a day via injections or continuously administer insulin with a pump, precise dosing is essential.’
Insulin is needed to control blood glucose levels in those with type 1 diabetes, a condition which affects over 400,000 Brits.
Healthy people make insulin – which allows the body to use sugar from food for muscle energy – in their pancreas.
However, type 1 diabetics cannot produce insulin themselves and have to inject the hormone as a medicine to stop their blood glucose getting dangerously high.
But how it is stored can have an impact on its blood-glucose lowering effect.
Like many injectable drugs and vaccines, insulin is highly sensitive to heat and cold and can be destroyed if temperatures shift a few degrees.
Insulin should be stored between between 2C (36F) and 8C (46F) in the refrigerator, or 2C (30F) to 30C (86F) when carried around in a pen or vial.
Freezing turned out to be a big issue in the study – 66 sensors, more than one in ten, recorded a temperature of below 0C.
Dr Braune added: ‘More research is needed to examine the extent to which temperature deviations during domestic storage affect insulin efficacy and patient outcomes.’
The findings were presented at the European Association for the Study of Diabetes (EASD) Annual Meeting in Berlin.