Evaluating the Longitudinal Effects of Diabetes on Cognition
A 1 mmol/mol increase in HbA1c levels was significantly associated with an increased rate of global cognitive z scores.
Significant longitudinal associations between diabetes and cognitive decline were reported in a study published in Diabetologia.
Researchers analyzed data from the English Longitudinal Study of Ageing (ELSA) to examine whether people with diabetes and optimal glycemic control have decreased rates of cognitive decline. The study included 5189 individuals with a mean baseline glycosylated hemoglobin (HbA1c) level of 37.7±7.9 mmol/mol, with a mean follow-up duration of 8.1±2.8 years.
After multivariable adjustment analyses, researchers observed that a 1 mmol/mol increase in HbA1c was significantly associated with an increased rate of cognitive z scores (–0.0009 standard deviation [SD]/year; 95% CI), memory z scores (0.0005 SD/year; 95% CI), and executive function z scores (–0.0008 SD/year; 95% CI).
There was no association found between increases in HbA1c levels and orientation z scores (–0.0004 SD/year; 95% CI). The rates of cognitive decline associated with prediabetes and diabetes increased by –0.012 SD/year and 0.031 SD/year, respectively (P for trend <.0001) compared with participants with normoglycemia.
Researchers observed a significant trend for cognitive decline in individuals with prediabetes and diabetes over a 10-year period. The findings are limited by possible confounding factors such as genetic susceptibility for cognitive decline, including the APOE genotype.
“Our findings suggest that interventions that delay diabetes onset, as well as management strategies for glucose control, might help to alleviate the progression of subsequent cognitive decline over the long term,” researchers concluded.
Zheng F, Yan L, Yang Z, Zhong B, Xie W. HbA1c, diabetes, and cognitive decline: the English Longitudinal Study of Ageing [published online January 25, 2018]. Diabetologia. doi:10.1007/s00125-017-4541-7