Cognitive Decline Associated With HbA1C Levels in Diabetes


A recent study found a link between HbA1C levels, diabetes status, and long-term cognitive decline.

Results of the study were published in Diabetologia (online January 25, 2018; doi:10.1007/s00125-017-4541-7).

The association between diabetes and dementia is well documented in previous studies. However, evidence of the link between diabetes, the role of HbA1C, and cognitive decline occurring prior to dementia is limited.

Fanfan Zheng, PhD, Chinese Academy of Sciences (Beijing, China), and Institute of Cognitive Neuroscience, University College (London, UK), and colleagues conducted a study to evaluate longitudinal associations between HbA1C levels, diabetes status, and subsequent cognitive decline over a 10-year follow-up period. Researchers used data from wave 2 (2004-2005) to wave 7 (2014-2015) of the English Longitudinal Study of Ageing (ELSA). A total of 5189 with baseline HbA1C levels ranging from 15.9 to 126.3 mmol/mol were sampled.

Cognitive function was assessed at baseline (wave 2) and reassessed every 2 years at waves 3-7. Researchers utilized linear mixed models to evaluate longitudinal associations.

After a median follow-up of 8.1 years, the median number of cognitive assessments was 4.9. Researchers noted that a 1 mmol/mol increment in HbAC1 was significantly associated with an increased rate of decline in global cognitive z scores (-0.0009 SD/year), memory z scores (-0.0005 SD/year), and executive function z scores (-0.0008 SD/year). This finding remained consistent after adjusting for baseline age, sex, total cholesterol, HDL-cholesterol, triacylglycerol, high-sensitivity C-reactive protein, BMI, education, marital status, depressive symptoms, current smoking, alcohol consumption, hypertension, CHD, stroke, chronic lung disease, and cancer.


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Furthermore, Dr Zheng and colleagues noted that compared with participants with normogylcemia, the multivariable-adjusted rate of global cognitive decline associated with prediabetes and diabetes was increased by -0.012 SD/year and -0.031 SD/year, respectively (P < .001). Memory, executive function, and orientation z scores also showed an increased rate of cognitive decline with diabetes, they wrote.

Dr Zheng and colleagues concluded that there are significant longitudinal associations between HbA1C levels, diabetes, and long-term cognitive decline. “Future studies are required to determine the effects of maintaining optimal glucose control on the rate of cognitive decline in people with diabetes,” they wrote.—Zachary Bessette