Around 25% of people with type 1 diabetes have reduced awareness of the symptoms of low blood sugars. New findings from our researchers at the University of Dundee are helping to shed light on why this might happen and how we could reverse it.
We know that if you have repeated hypos, you’re more likely to stop noticing when you go low. But we don’t yet fully understand why people lose their ability to sense hypos.
Habituating to hypos
One line of thinking points to habituation. Habituation is a form of adaptive memory that develops in response to repeated, often stressful, events. Some evidence suggests that hypo unawareness could be a habituated response – the body ‘gets used’ to low blood sugar levels and doesn’t respond in the same way after repeated hypos.
This has led researchers to ask, if habituation plays a role in causing hypo unawareness, then could dishabituation – introducing a new stress – act like a shock to the system and help to restore awareness?
Some research in rodents suggests that high intensity exercise could be used as a dishabituating stimulus. With our funding, Dr Catriona Farrell (pictured) wanted to know whether this could work in people with type 1 diabetes who had hypo unawareness.
The team at the University of Dundee asked 12 participants to either undertake a 20 minute single burst of high intensity exercise or rest. The following day, they were given infusions of insulin and glucose to gradually reduce their blood sugar levels to 2.5 mmol/l, before returning to a normal range.
The researchers measured the participants’ hormonal responses throughout the hypo experiment and asked participants to rate their awareness of low blood sugar symptoms and complete cognitive tests.
Two weeks later the participants carried out the intervention (high intensity exercise or rest) they had not yet completed. This was followed by another hypo experiment the next day.
Dr Farrell found, in comparison to rest, a single episode of high intensity exercise led to a 29% increase in adrenaline response, improved awareness of hypo symptoms and improved cognitive functioning when tested during hypoglycaemia.
This suggests that hypo unawareness develops in people with type 1 diabetes as a habituated response. And that introducing a new stressor - in this case exercise - could override how the brain adapts to hypos.
Would working out work?
To find out whether high intensity exercise could be an effective future treatment, we need to know if its benefits could be maintained over time. The research team are now exploring this in a longer-term clinical trial. If successful, exercise could offer us a new, simple way to help people with type 1 diabetes get their hypo awareness back.
New treatments would make a real difference for people with diabetes, removing anxiety, making living with the condition easier and, crucially, protecting people from the potentially serious consequences of low blood sugar levels.
This research has been published in Diabetologia.
