Hypos linked to cognitive decline in people with diabetes

Severe hypoglycaemic episodes or ‘hypos’, where blood glucose levels drop dangerously low, may lead to poorer memory and diminished brain power in people with type 2 diabetes, according to new research announced at Diabetes UK’s Annual Professional Conference.

The study looked at 1,066 people with type 2 diabetes aged between 60 and 75 years. Participants completed seven tests looking at memory, logic and concentration to establish their level of brain function. The 113 people who had previously experienced severe hypos scored lower than the rest of the group.

There are at least 670,000 people in England aged between 60 and 75 years old who have type 2 diabetes and around a third of them could be at risk of a hypo.

"This study reinforces previous evidence which suggests that poorly controlled diabetes affects the functioning of the brain," said Dr Iain Frame, Director of Research at Diabetes UK.

"Cognitive decline is the decline of brain functions such as memory, attention, vocabulary and planning. It can be a predictor of dementia although this is only in some cases.

"We already know that type 2 diabetes increases the risk of developing Alzheimer’s disease, which is a type of dementia, and this research adds another piece to a very complex jigsaw puzzle.

"However, more research is needed before we can come to any firm conclusions. If anyone with diabetes is concerned about their treatment they should consult their GP or diabetes healthcare professional."

The study found that the group who experienced previous severe hypos scored lower on general cognitive ability and vocabulary than the group who had not, even after the results took into account the participants’ age, gender and ‘pre-morbid cognitive ability’ (the cognitive ability that does not naturally decline with age).

Dr Jackie Price from the University of Edinburgh, who led the research, said: "These findings suggest that exposure to severe hypoglycaemia is associated with cognitive decline in people with type 2 diabetes aged between 60 and 75 years old.

"This can mean either that hypos lead to cognitive decline, or that cognitive decline makes it more difficult for people to manage their diabetes, which in turn causes more hypos.

"A third explanation could be that a third unidentified factor is causing both the hypos and the cognitive decline. We are carrying out more research to establish which explanation is the most likely."

The seven neuropsychological tests assessed people’s memory for faces, recollection of linear stories, vocabulary, the ability to re-organise a sequence of letters as well as some other cognitive functions.

(Source: Diabetes UK: March 2009)