Cognitive Decline Linked to Poor Glucose Control in Adults with Diabetes

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As older adults with diabetes age, keeping glucose levels under control may help reduce the risk of cognitive decline, findings from a 2019 study in Diabetes Care suggest.

Researchers analyzed data from the Atherosclerosis Risk in Communities Study, which began in 1987, to identify cases of mild cognitive impairment or dementia. Of 5,099 participants (average age, 76 years) who had follow-up assessments between 2011 and 2013, 1,781 had diabetes. Of that group, 459 had poorly controlled glucose levels (defined as an HbA1c level of 7 percent or higher).

The researchers found that individuals with diabetes who were cognitively normal at the 2011–2013 assessment were more likely than those without diabetes to have mild cognitive impairment by a follow-up assessment five years later. The risk was greatest in individuals with poorly controlled glucose levels. Having diabetes for at least five years was associated with an increased risk for dementia, but HbA1c levels did not significantly affect dementia risk.

One reassuring finding: People with diabetes who kept their HbA1c levels under 7 percent did not have a higher risk of cognitive impairment. Still, it’s important to note that this was an observational study. As such, it can only provide evidence of an association between glucose levels and cognitive decline. It does not show causation.

In addition, it’s important to individualize treatment goals. This means, for example, that although aggressive treatment to lower blood sugar levels might be appropriate for healthy younger individuals, for older people with long-standing disease or multiple coexisting conditions, target levels for lowering blood sugar may be less aggressive—and avoidance of potentially dangerous hypoglycemia should be a consideration.