Higher blood glucose levels, even within the ‘normal’ range, may have a significant impact on total brain volume and grey matter atrophy in later life, according to a study by researchers from the Centre for Healthy Brain Ageing (CHeBA) at UNSW Sydney and the Centre for Research on Ageing, Health and Wellbeing (CRAHW) at ANU. The findings were published in the July edition of the journal, Diabetes & Metabolism.
Dr Erin Walsh, lead author and postdoctoral research fellow at CRAHW, said the findings provided valuable new insights into the role of blood glucose levels beyond the effects associated with type-2 diabetes.
“This study showed that the impact of blood glucose on the brain is not exclusive to type-2 diabetes and that blood glucose levels even in the normal range can have a significant impact on total brain and grey matter atrophy,” said Dr Walsh.
“In combination with typical age-associated changes in brain volume, additional atrophy of this magnitude may be associated with an increased risk of mild cognitive impairment and Alzheimer’s disease.”
The study confirmed previous research about the link between higher blood glucose levels in type-2 diabetes and lower total brain, grey matter and white matter volume. However, it found individuals without diabetes or impaired fasting glucose who had a subtly higher blood glucose level in the normal range (e.g. 5.5 mmol/L versus 5.0 mmol/L) also experienced brain atrophy, predicted at a rate of approximately 0.06% reduction in total brain volume each year.
The study examined 279 participants, aged 60-64 years at baseline, from the longitudinal PATH Through Life Study led by ANU. Participants underwent four MRI scans taken four years apart to examine total brain volume, grey matter volume and white matter volume. Fasting blood glucose tests were taken on three occasions. Participants were divided into three groups: normal fasting glucose, impaired fasting glucose (a pre-diabetic condition also referred to as metabolomic syndrome), and type 2 diabetes.
Co-author and CHeBA Co-Director, Professor Perminder Sachdev, said that if further research can replicate these findings, they could have important implications for clinical interventions.
“Blood glucose levels appear to be important even in non-diabetic individuals, and we need to consider the role of higher normal levels as a risk factor for brain health.”
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