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diabetes in the news

Cognitive Functions Can Be Affected by Glucose Extremes

by, IDS Intern, Krystal Bosenbark, MPH, MS

T1D and cognition

For those who have type 1 diabetes, it is well-known that how we think and how well we process new information is greatly affected by our blood glucose.

I personally have had the unfortunate experience of trying to finish an exam when my blood sugar was nearing 50 mg/dl. If you guessed that my test score suffered as a result, you’d be correct. This was enough to make me add “eat something” to my list of things to do before I sit for any exam.

Researchers examining the effect of glucose on brain function had their study published in npj Digital Medicine in March 2024.  Specifically, study investigators looked at the extent hypoglycemia, euglycemia, and hyperglycemia affected attention and cognitive processing speeds, or how quickly people process incoming information. Another study outcome was to determine whether individual differences like age, history of complications, or lifetime severe hypoglycemic events, when considered with glucose variations, would also impact cognition.


For their study, investigators collected information on blood glucose using continuous glucose monitors (CGM) and information on processing speed and attention using cognitive ecological momentary assessment (EMA) from 200 adults with type 1 diabetes.

During a 15-day period, the participant’s blood glucose was collected every five minutes, while cognitive tests were completed three times each day. Researchers ultimately theorized that quick, moment-to-moment changes in blood glucose levels will influence processing speeds, while longer-term hyperglycemia and hypoglycemia would affect attention.


Results suggested that, indeed, there was a reduction in cognitive skills when blood glucose fell to very low (below 54 mg/dl) or rose to very high (above 250 mg/dl) levels. However, this finding was only observed with cognitive processing speeds, not attention. Researchers also found that specific groups of type 1 diabetes participants (including those who were older, spent more time with hypoglycemia, had more complications, and reported tiredness or fatigue) had cognitive processing speeds that were greater influenced by swings in glucose levels when compared to younger, less hypoglycemic individuals with less complications and less reported tiredness. Furthermore, investigators were able to determine that study participants performed the best intellectually when their blood glucose was slightly higher than normal glucose ranges.

The authors speculate that our brains get used to operating at a specific blood glucose level, and that this optimal glucose level may change based on sustained changes in HbA1c.

These research findings are promising, because they imply that there are some factors we can control (e.g. blood glucose variability, time spent with hypoglycemia, complications, tiredness) to ensure that if our blood glucose does rise or fall too much, our cognition won’t be greatly impacted.

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