Higher Blood Glucose Linked To Lower Cognitive Function

Featured Article
Main Category: Diabetes
Also Included In: Alzheimer's / Dementia;  Mental Health;  Seniors / Aging
Article Date: 29 Jan 2009 - 1:00 PST

email to a friend   printer friendly   opinions  

A sub-study of a trial looking at the effect of diabetes on heart disease risk found that higher levels of hemoglobin A1C levels (a measure of a person's average blood glucose over a 2 to 3 month period) were linked to lower cognitive function.

The research was published online in the peer-reviewed journal of the American Diabetes Association, Diabetes Care on 26 January, and is part of the ongoing Memory in Diabetes (MIND) study, a sub-study of the Action to Control Cardiovascular Risk in Diabetes (ACCORD) trial.

Previous studies have suggested that people with diabetes have a 1.5 times higher chance of experiencing cognitive declien and dementia than people that don't have diabetes: the results from this MIND research suggests diabetes may be linked with mild cognitive impairment.

Lead investigator Dr Tali Cukierman-Yaffe, who is from the Gertner Institute for Epidemiology and Health Policy Research, Endocrinology Institute at Sheba Medical Center and Sackler School of Medicine at Tel-Aviv University in Israel, said:

"Even a mild impairment in cognitive function is of concern for people with type 2 diabetes."

The overall ACCORD-MIND study is looking at whether the rate of structural brain change and cognitive decline in 2,800 people with diabetes differes according to whether they get standard care or intensive care.

We should note that the results that are published in this paper are from a cross-sectional view of the data: that is the links they found don't tell you if the higher blood glucose is responsible for the lower cognitive function or whether somehow, cognitive impairment decreases the body's ability to control blood sugar, or it may even be a third, yet undiscovered factor that links the two.

Such a causal link can only be established by following study patients over a period of time and testing them at intervals during the trial. That is the plan with the ongoing ACCORD-MIND study, where one of the ideas being tested is whether lowering A1C improves cognitive function.

Meanwhile, in these interim results, the researchers found that poorer performance in three cognitive tasks that tested memory, speed and multi-tasking skills, and a lower score on an overall test of cognitive function, were all linked to higher levels of A1C hemoglobin.

The tests they used were: the Digit Symbol Substitution Test (DSST), Mini Mental Status Examination (MMSE), Rey Auditory Verbal Learning Test, and the Stroop Test.

The results showed:

• A statistically significant link between A1C and all 4 tests, even after adjusting for age.


• Specifically, the results were: 1 per cent higher A1C linked to significant 1.75 decrease in DSST score; 0.20 lower MMSE score; 0.11 lower memory score; and 0.75 s or more (ie worse) score on the Stroop Test.


• The link between the DSST score and A1C persisted through all the statistical models they ran.


• The researchers also measured fasting plasma glucose, but this did not show any links with test results.

The researchers concluded that:

"Higher A1C levels are associated with lower cognitive function in individuals with diabetes."

"The effect of glucose lowering on cognitive function will be determined by the ongoing ACCORD-MIND trial," they added.

"Relationship Between Baseline Glycemic Control and Cognitive Function in Individuals With Type 2 Diabetes and Other Cardiovascular Risk Factors: The Action to Control Cardiovascular Risk in Diabetes-Memory in Diabetes (ACCORD-MIND) trial."
Tali Cukierman-Yaffe, Hertzel C. Gerstein, Jeff D. Williamson, Ronald M. Lazar, Laura Lovato, Michael E. Miller, Laura H. Coker, Anne Murray, Mark D. Sullivan, Santica M. Marcovina, Lenore J. Launer for the Action to Control Cardiovascular Risk in Diabetes-Memory in Diabetes (ACCORD-MIND) Investigators.
Diabetes Care 32: 221-226, 2009
DOI: 10.2337/dc08-1153

Click here for Abstract.

Sources: Journal Abstract, American Diabetes Association press release.

Written by: Catharine Paddock, PhD
Copyright: Medical News Today
Not to be reproduced without permission of Medical News Today

• Additional
• References
• Citations