People with type 2 diabetes aged 50 to 80 performed worse on cognitive tests and experienced a faster rate of brain shrinkage than those without the conditionHealth 31 May 2022
By Clare Wilson
A stock image of a person testing their blood sugar level
People with type 2 diabetes may experience worse mental deterioration as they get older, perhaps because parts of their brain shrink faster than those without the condition.
The finding comes from a large UK study of people with and without diabetes, based on cognitive tests and brain scans.
Type 2 diabetes involves blood sugar rising too high after meals, often because the body’s cells don’t respond properly to the hormone insulin. Insulin should cause cells to take in sugar, helping to keep its level steady in the bloodstream.
Those affected are advised to try to regulate their blood sugar levels by avoiding sugary food. As the condition progresses, they may also need to start taking regular medication.
Lilianne Mujica-Parodi at Stony Brook University in New York and her colleagues took advantage of an ongoing health-tracking study called UK Biobank, where people have repeated medical tests and some have their brain scanned.
The team analysed the results of about 1000 people with type 2 diabetes and more than 19,000 similar people who didn’t have the condition, all of whom were aged between 50 and 80.
Those with diabetes generally did more poorly on cognitive tests. For instance, they performed about 13 per cent worse in tests that assessed their ability to plan complex tasks and nearly 7 per cent worse in tests of mental-processing speed.
Brain scans also showed some regions of their brain were shrinking faster, especially in people who had been diagnosed with diabetes the longest. For example, people who had been diagnosed at least 10 years ago had 26 per cent more shrinkage than those without diabetes.
This may happen because their brain cells don’t respond properly to insulin and therefore cannot take in all the glucose they need, says Mujica-Parodi. “We think neurons are being starved of energy and, as a result, are dying,” she says. The team didn’t study the effects of type 1 diabetes.
Peter Flatt at Ulster University, UK, says the results reinforce the importance of people with type 2 diabetes trying to keep their blood sugar levels balanced to avoid their condition progressing.
“Diabetes is associated with very many complications, including of the eyes, the kidneys and the circulation,” he says. “It’s no surprise that the brain is also affected.”
Journal reference: eLife, DOI: 10.7554/eLife.73138
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