American research shows glucose levels affect accuracy and reaction time
By Dr Uffe Søholm [1]
Hypoglycaemia, or low blood glucose, is common among adults with insulin-treated diabetes. When glucose levels fall, the person with diabetes can experience a range of symptoms.
In the past, researchers have looked at the effects of hypos on everyday brain functions, such as thinking, learning, attention, memory, and reaction time. But they have done this in in the safety of hospital-based experiments. Here, researchers lower blood glucose in a controlled way, and conduct various tests to examine the impact of the lower glucose levels. Some argue that lowering glucose in the hospital setting does not reflect real-life experiences. For example, in everyday life, hypos interact with physical activity, delayed intake of glucose, or being busy with work or something else. Therefore, there is increasing interest in understanding the effects of low blood glucose in everyday life. Smartphones have made it possible to assess this.
In a recent US study, researchers explored the link between glucose levels and cognitive functioning in adults with type 1 diabetes in their everyday lives. Using their smartphones, participants did several tests multiple times daily. They also wore a glucose sensor. Tests included attention, accuracy, and reaction time tasks as described below:
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- Attention: look at a series of city and mountain scenes and tap the screen only when you see a city scene, but not the mountain scene.
- Accuracy: track a dot as it moves among other dots on the screen.
- Reaction time: match a set of symbols to a set of numbers. The time to complete is recorded.
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The researchers explored if having more low or high blood glucose than usual affected test results. They found that:
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- hypos during the day were linked with less optimal accuracy
- night-time hypos were linked with slower reaction times the next day
- hypos (during the day or at night) did not seem to affect attention
- hyperglycaemia (high blood glucose) had no effect on any test.
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All studies have limitations. The researchers note that their study may be limited by:
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- using test score averages within each day. More research is needed to understand whether more acute effects could be seen within a single day.
- a small sample. Only 20 people took part in the study, so larger studies are needed to confirm these findings.
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Despite these limitations, the study offers useful insights into how hypos can affect cognitive function in everyday settings. It shows that reducing hypos may help adults with type 1 diabetes with tasks where reaction times and accuracy are important.
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Reference:
Miranda Zuniga-Kennedy, Olivia H. Wang, Luciana M. Fonseca, Michael J. Cleveland, Jane D. Bulger, Elizabeth Grinspoon, Devon Hansen, Zoë W. Hawks, Laneé Jung, Shifali Singh, Martin Sliwinski, Alandra Verdejo, Kellee M. Miller, Ruth S. Weinstock, Laura Germine & Naomi Chaytor (2024) Nocturnal hypoglycemia is associated with next day cognitive performance in adults with type 1 diabetes: Pilot data from the GluCog study [2], The Clinical Neuropsychologist, DOI: 10.1080/13854046.2024.2315749 [3]