Older adults who have had diabetes for at least 5 years and have HbA1c levels of more than 7% are more likely to develop mild cognitive impairment and dementia than those with shorter diabetes duration and lower HbA1c measures, according to findings published in Diabetes Care.
“We have previously shown that diabetes in mid-life is an important risk factor for cognitive decline and dementia in later life,” Elizabeth Selvin, PhD, MPH, professor of epidemiology and medicine at the Johns Hopkins Bloomberg School of Public Health in Baltimore, told Endocrine Today. “The present study highlights the importance of diabetes prevention and control even in older adults to prevent cognitive decline.”
Using data from the Atherosclerosis Risk in Communities (ARIC) study, Selvin and colleagues evaluated the association between cognitive health and diabetes, diabetes duration, HbA1c and other glycemic biomarkers, such as fructosamine, glycated albumin and 1,5-anhydroglucitol, among 5,099 participants (mean age, 75.8 years; 59.2% women). Participants were recruited from sites in North Carolina, Mississippi, Minnesota and Maryland and had six visits from 1987 to 2017. A visit from 2011 to 2013 was used as baseline with a follow-up visit and self-reports from 2016 to 2017 used to identify changes in cognitive function.
At baseline, 1,781 participants had diabetes, including 1,276 with HbA1c below 7% (mean age, 76 years; 58.3% women) and 459 with HbA1c of 7% or more (mean age, 75.1 years; 55.3% women). In the entire cohort, the risk for having any form of cognitive impairment during follow-up was higher for those with diabetes (HR = 1.14; 95% CI, 1-1.31) and an HbA1c level of 7% or more (HR = 1.38; 95% CI, 1.12-1.69) compared with those without diabetes. The risk was also higher for those with diabetes for at least 5 years (HR = 1.59; 95% CI, 1.23-2.07) compared with those with diabetes for less than 5 years. For those who presented with mild cognitive impairment at baseline, similar risk factors were observed for dementia development, but these did not reach significance.
The researchers also wrote that developing mild cognitive impairment during follow-up after being deemed “cognitively normal” at baseline was more likely for those who had diabetes (HR = 1.23; 95% CI, 1-1.51) and those who had HbA1c of 7% or more (HR = 1.73; 95% CI, 1.26-2.38) compared with those without diabetes and for those who had diabetes for 5 years or more (HR = 1.58; 95% CI, 1.04-2.41) compared with those with diabetes for a shorter period of time. Having diabetes for at least 5 years also increased the risk for dementia (HR = 1.91; 95% CI, 1.09-3.35) for those considered cognitively normal, but HbA1c levels did not significantly affect dementia risk for this population. However, the researchers noted that dementia risk was higher when measures of fructosamine and glycated albumin were elevated.
“The link between diabetes and dementia is well-documented, but progression from normal cognitive function to mild cognitive impairment and then on to dementia is less well-studied,” Selvin said. “Our results suggest that improving diabetes control in late life may help stave off cognitive impairment.” – by Phil Neuffer
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Elizabeth Selvin, PhD, MPH, can be reached at firstname.lastname@example.org.
Disclosures: Selvin reports no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.