Large blood sugar reduction, a risk factor for dementia in elderly with diabetes

China: A large reduction in blood sugar depicted by glycemic index and HbA1c levels in older adults with type 2 diabetes (T2D) could be a potential predictor and possibly a risk factor for dementia, according to a recent study published in the journal Age and Ageing. The finding suggests that blood sugar levels should be optimized with caution in such patients.

Dementia is a global health problem and its prevention is particularly important to people with T2D as their number is growing. Although T2D patients are twice as likely to develop dementia than those without, whether optimizing glycemic level in late life can reduce the risk of dementia remains uncertain. Linda C W Lam, The Chinese University of Hong Kong, Hong Kong SAR, China, and colleagues examined if achieving the glycemic goal recommended by the American Diabetes Association (ADA) within a year was associated with a lower risk of dementia in 6 years, in this population-based observational study. ADA recommendation defines the glycemic goal as HbA1c < 7.5%.

For the purpose, the researchers examined 2246 community-living dementia-free Chinese older adults with type 2 diabetes who attended the Elderly Health Centres in Hong Kong at baseline and followed their HbA1c level and cognitive status for 6 years

The study outcome was incident dementia in 6 years, diagnosed according to the 10^th revision of the International Statistical Classification of Diseases and Related Health Problems (ICD-10) or Clinical Dementia Rating of 1–3.

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Key findings of the study include:

• Those with HbA1c ≥ 7.5% at baseline and HbA1c < 7.5% in 1 year were associated with higher rather than lower incidence of dementia, independent of severe hypoglycemia, glycemic variability, and other health factors.


• Sensitivity analyses showed that a relative reduction of ≥10%, but not 5–10%, in HbA1c within a year was associated with a higher incidence of dementia in those with high (≥8%) and moderate (6.5–7.9%) HbA1c at baseline.

"With a large decrease in glycemic level being a potential predictor and possibly a risk factor for dementia in older adults with diabetes, our findings suggest the need for being attentive to both increasing and decreasing HbA1c levels, with an emphasis on not only achieving a particular glycemic target but also promoting moderation of glycemic level," concluded the authors.

The study, "Higher dementia incidence in older adults with type 2 diabetes and large reduction in HbA1c," is published in the journal Age and Ageing.

DOI: https://doi.org/10.1093/ageing/afz108