Diabetes and worse blood glucose control are associated with long-term cognitive decline, according to new study of some 5,000 older people in the UK.
It found rates of long-term cognitive decline were steeper in those who have diabetes compared with people with normal blood sugar control.
“Our study provides evidence to support the association of diabetes with subsequent cognitive decline”
As a result, the authors of the study suggested efforts to delay the onset of diabetes or control blood glucose levels might prevent subsequent progression of brain function decline.
The new research, based on data collected for the earlier English Longitudinal Study of Ageing, is published in Diabetologia, the journal of the European Association for the Study of Diabetes (EASD).
While previous research has linked cognitive decline with diabetes, the new study is one of the largest to establish the direct relationship between HbA1c and subsequent risk of cognitive decline.
The study involved 5,189 participants with a mean age of 66, of which 55% were women. Baseline HbA1c levels ranged from 15.9 to 126.3mmol/mol (3.6-13.7%).
Current cut-offs for defining diabetes using HbA1c are 6.5% and above, noted the researchers from Imperial College London and Peking University Clinical Research Institute in China.
Cognitive function was assessed at baseline and reassessed every two years. Computer modelling was then used to establish any possible associations. Mean follow-up lasted eight years and the mean number of cognitive assessments was five.
Analysis revealed that a 1 mmol/mol increase in HbA1c was significantly associated with an increased rate of decline in global cognitive z scores, memory z scores and executive function z scores – all signs of cognitive function decline.
“Interventions that delay diabetes onset might help alleviate the progression of subsequent cognitive decline over the long-term”
While cognitive function declined with age in participants, whether diabetic or not, the global cognitive decline associated with pre-diabetes and diabetes was significantly increased.
Similarly, memory, executive function and orientation z scores showed an increased rate of cognitive decline with diabetes.
Significantly, the rate of cognitive decline was directly linked to a person’s HbA1c status, whether or not they had diabetes already, the researchers found.
The authors, led by Dr Wuxiang Xie, said: “Our study provides evidence to support the association of diabetes with subsequent cognitive decline.
”Moreover, our findings show a linear correlation between circulating HbA1c levels and cognitive decline, regardless of diabetic status,” they said.
“Future studies are required to determine the long-term effects of maintaining optimal glucose control on cognitive decline in people with diabetes,” they noted.
They added: “Our findings suggest that interventions that delay diabetes onset, as well as management strategies for blood sugar control, might help alleviate the progression of subsequent cognitive decline over the long-term.”