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Diabetologia. 2018 Apr;61(4):839-848. doi: 10.1007/s00125-017-4541-7. Epub 2018 Jan 25.

HbA1c, diabetes and cognitive decline: the English Longitudinal Study of Ageing.

Author information

1
Brainnetome Center, Institute of Automation, Chinese Academy of Sciences, Beijing, People's Republic of China.
2
Institute of Cognitive Neuroscience, University College London, London, UK.
3
Department of Epidemiology and Biostatistics, School of Public Health, Imperial College London, London, UK.
4
Affiliated Wuhan Mental Health Center, Tongji Medical College of Huazhong University of Science and Technology, Wuhan, People's Republic of China.
5
Department of Epidemiology and Biostatistics, School of Public Health, Imperial College London, London, UK. xiewuxiang@hsc.pku.edu.cn.
6
Peking University Clinical Research Institute, Peking University Health Science Center, No. 38 Xueyuan Road, Haidian District, 100191, Beijing, People's Republic of China. xiewuxiang@hsc.pku.edu.cn.

Abstract

AIMS/HYPOTHESIS:

The aim of the study was to evaluate longitudinal associations between HbA1c levels, diabetes status and subsequent cognitive decline over a 10 year follow-up period.

METHODS:

Data from wave 2 (2004-2005) to wave 7 (2014-2015) of the English Longitudinal Study of Ageing (ELSA) were analysed. Cognitive function was assessed at baseline (wave 2) and reassessed every 2 years at waves 3-7. Linear mixed models were used to evaluate longitudinal associations.

RESULTS:

The study comprised 5189 participants (55.1% women, mean age 65.6 ± 9.4 years) with baseline HbA1c levels ranging from 15.9 to 126.3 mmol/mol (3.6-13.7%). The mean follow-up duration was 8.1 ± 2.8 years and the mean number of cognitive assessments was 4.9 ± 1.5. A 1 mmol/mol increment in HbA1c was significantly associated with an increased rate of decline in global cognitive z scores (-0.0009 SD/year, 95% CI -0.0014, -0.0003), memory z scores (-0.0005 SD/year, 95% CI -0.0009, -0.0001) and executive function z scores (-0.0008 SD/year, 95% CI -0.0013, -0.0004) after adjustment 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. Compared with participants with normoglycaemia, the multivariable-adjusted rate of global cognitive decline associated with prediabetes and diabetes was increased by -0.012 SD/year (95% CI -0.022, -0.002) and -0.031 SD/year (95% CI -0.046, -0.015), respectively (p for trend <0.001). Similarly, memory, executive function and orientation z scores showed an increased rate of cognitive decline with diabetes.

CONCLUSIONS/INTERPRETATION:

Significant longitudinal associations between HbA1c levels, diabetes status and long-term cognitive decline were observed in this study. Future studies are required to determine the effects of maintaining optimal glucose control on the rate of cognitive decline in people with diabetes.

KEYWORDS:

Cognitive decline; Diabetes; HbA1c; Trajectory

PMID:
29368156
DOI:
10.1007/s00125-017-4541-7
[Indexed for MEDLINE]
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