<a><b>Objective:</b></a> Type 2 diabetes is an established risk
factor for dementia. However, the roles of glycaemic control and diabetic
complications in the development of dementia have been less well substantiated.
This large-scale cohort study aims to examine associations of longitudinal
HbA1c levels and diabetic
complications with
the risk of dementia incidence among patients with
type 2 diabetes.
<p><b>Research
Design and Methods: </b>Data
of eligible diabetes patients, aged over 50 years in the UK
Clinical Practice Research Datalink from 1987 to 2018, were analysed. Time-varying Cox regressions were
used to estimate adjusted hazard ratios (HR) and 95% confidence
intervals (CI) for dementia risk.<b></b></p>
<p><b>Results: </b>Among
457,902 diabetes patients, 28,627 (6.3%) incident dementia cases were observed during
a median of six years follow-up. Patients with recorded hypoglycaemic events or
microvascular complications were at higher risk of dementia incidence compared
to those without such complications (HR [95% CI]=1.30 [1.22-1.39] and 1.10 [1.06-1.14],
respectively). The HbA1c level, modelled as a time-varying exposure, was
associated with increased dementia risk (HR=1.08, 95% CI: 1.07-1.09 per 1%
HbA1c increment) among 372,287 diabetes patients with post-diagnosis HbA1c
records. Similarly, higher coefficient of variation of HbA1c during the initial
three years of follow-up was associated with higher subsequent dementia risk
(HR=1.03, 95% CI: 1.01-1.04 per 1 SD increment).</p>
<p><b>Conclusions:
</b>Higher or
unstable HbA1c levels and the presence of diabetic complications in patients
with type 2 diabetes are associated with increased dementia risk. Effective
management of glycaemia might have significant role in maintaining cognitive
health among older adults with diabetes.</p>