TOPLINE:
Naturally occurring glucose fluctuations affect cognitive function in people with type 1 diabetes, according to a new study. It matters less whether glucose is considerably higher or lower than the patient’s usual glucose level. Rather,
METHODOLOGY:
- The investigators used continuous glucose monitoring (CGM) digital sensors and smartphone-based cognitive tests (cognitive ecological momentary assessment [EMA]) to collect repeated, high-frequency glucose and cognitive data. Glucose data were collected every 5 minutes; cognitive data were collected three times daily for 15 days as participants went about their daily lives.
- The study included 200 participants (mean [standard deviation] age, 47.5 [15.6] years; 53.5% female; 86% White; mean A1c, 7.5 mmol/mol [1.3]).
- Using CGM and EMA, the researchers obtained “intensive” longitudinal measurements of glucose as well as cognition (processing speed and sustained attention).
- Hierarchical Bayesian modeling estimated dynamic, within-person associations between glucose and cognition, and data-driven lasso regression identified identify clinical characteristics that predicted differences from person to person in cognitive vulnerability to glucose fluctuations.
TAKEAWAY:
- Cognitive performance was reduced both at low and high glucose levels, “reflecting vulnerability to glucose fluctuations.”
- Large glucose fluctuations were associated with slower as well as less accurate processing speed, although slight glucose elevations (relative to the individual’s own means) were associated with faster processing speed, regardless of the absolute level (eg, euglycemic vs hyperglycemic) of those means.
- By contrast, glucose fluctuations were unrelated to sustained attention.
- The researchers identified seven clinical characteristics that predicted individual differences in cognitive vulnerability to glucose fluctuations: Older age, time in hypoglycemia, lifetime severe hypoglycemic events, microvascular complications, glucose variability, fatigue, and larger neck circumference.
IN PRACTICE:
“Our results demonstrate that people can differ a lot from one another in how their brains are impacted by glucose,” co-senior author Laura Germine, PhD, director of the Laboratory for Brain and Cognitive Health Technology, McLean Hospital, Boston, said in a news release. “We found that minimizing glucose fluctuations in daily life is important for optimizing processing speed, and this is especially true for people who are older or have other diabetes-related health conditions.”
SOURCE:
Zoë Hawks, PhD, research investigator, McLean Hospital, Boston, was the lead and corresponding author on the study. It was published online on March 18 in Digital Medicine.
LIMITATIONS:
The researchers required 24-hour access to a smartphone with reliable Internet access, which might have biased sampling toward people of higher economic status. Moreover, the present sample was predominantly White and non-Hispanic, so findings may not be generalizable to other populations.
DISCLOSURES:
The research was supported by grants from the National Institutes of Health, the Brain and Behavior Research Foundation, and the Alzheimer’s Association. Dr. Hawks received consulting fees from Blueprint Health. The other authors’ disclosures were listed in the original paper.
A version of this article appeared on Medscape.com.