Diabetes May Quicken Cognitive Decline

Individuals with prediabetes and diabetes have an increased risk for faster rate of cognitive decline, a new study showed.

For their study, the researchers assessed data on 5189 participants (mean age 65.6 years) from waves 1 (2004 to 2005) to 7 (2014 to 2015) of the English Longitudinal Study of Ageing. Baseline hemoglobin A_1c (HbA_1c) levels ranged from 15.9 to 126.3 mmol/mol, and mean follow-up lasted 8.1 years.
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The researchers evaluated cognitive function at baseline (wave 2) and every 2 years at waves 3 to 7. Longitudinal associations were determined via linear mixed models.

Following adjustment for various factors, findings showed that HbA_1c was tied to a faster rate of cognitive decline. Specifically, a 1 mmol/mol increase in HbA_1c was found to be significantly associated with higher rates of decline in global cognitive z scores (−0.0009 SD/year), memory z scores (−0.0005 SD/year), and executive function z scores.

Ultimately, the adjusted rate of global cognitive decline increased by −0.012 SD/year and −0.031 SD/year in patients with prediabetes and diabetes, respectively, compared with patients with normoglycemia. The researchers observed a similar rate of cognitive decline in memory, executive function, and orientation z scores in patients with diabetes.

“Significant longitudinal associations between HbA_1c levels, diabetes status and long-term cognitive decline were observed in this study,” the researchers concluded. “Future studies are required to determine the effects of maintaining optimal glucose control on the rate of cognitive decline in people with diabetes.”

—Christina Vogt

Reference:

Zheng F, Yan L, Yang Z, Zhong B, Xie W. HbA_1c, diabetes and cognitive decline: the English Longitudinal Study of Ageing [Published online January 25, 2018]. Diabetologia. https://doi.org/10.1007/s00125-017-4541-7.