HbA1C levels are associated with long-term cognitive decline regardless of patient diabetes status, according to an article published in Diabetologia.

Fanfan Zheng, PhD, from the Brainnetome Center of the Institute of Automation at the Chinese Academy of Sciences in Beijing and the Institute of Cognitive Neuroscience at University College London, and colleagues, conducted a study using the English Longitudinal Study of Ageing (ELSA) to assess the affiliation between HbA1C level, diabetes prominence, and successive decline of cognition during a 10-year span.

The researchers used data from wave 2 (2004-2005) to wave 7 (2014-2015) to compare cognition every 2 years in eligible patients with diabetes. Candidates included 5189 volunteers (55.1% women) with starting HbA1C levels varying from 15.9 (3.6%) to 126.3 (13.7%) mmol/mol.

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During an average follow-up of approximately 8 years and an average of nearly 5 cognitive evaluations, the investigators reported that an increased HbA1C level by 1 mmol/mol significantly affected z scores for diminishing global cognition, memory, and executive function (-0.0009, -0.0005, and -0.0008 SD/year, respectively) after certain adjustments.

A multivariable-adjusted degree of decline comparing volunteers with prediabetes and diabetes to those without resulted in reduced cognition. Cognitive declines for prediabetes and diabetes were -0.012 SD/year and -0.031 SD/year, respectively. Memory, executive function, and orientation also resulted in similar reductions among patients with diabetes.

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“Our findings show a linear correlation between circulating HbA1C levels and cognitive decline, regardless of diabetic status,” wrote the authors.

“Future studies are required to determine the long-term effects of maintaining optimal glucose control on cognitive decline in people with diabetes.”


  1. Zheng F, Yan L, Lang Z, et al. HbA1C, diabetes and cognitive decline: the English longitudinal study of ageing. Diabetologia. 2018 Jan 25. doi: 10.1007/s0012 [EPub ahead of print]