Glycated Haemoglobin (HbA ), Diabetes and Neuropsychological Performance in Community-dwelling Older Adults

Aims: Given that diabetes is associated with cognitive impairment and dementia in later life, we aimed to investigate the relationship between glycated haemoglobin (HbA ), diabetes and domain-specific neuropsychological performance in older adults.

Methods: Cross-sectional cohort study using data from the Trinity-Ulster-Department of Agriculture (TUDA) study. Participants underwent detailed cognitive and neuropsychological assessment using the Mini-Mental State Examination (MMSE), Frontal Assessment Battery (FAB) and Repeatable Assessment for Neuropsychological Status (RBANS). Linear regression was used to assess associations between HbA , diabetes status and neuropsychological performance, with adjustment for important clinical covariates.

Results: Of 4938 older adults (74.1 ± 8.3 years; 66.9% female), 16.3% (n = 803) had diabetes (HbA  ≥ 6.5%; 48 mmol/mol), with prediabetes (HbA  ≥ 5.7%-6.4%; 39-47 mmol/mol) present in 28.3% (n = 1395). Increasing HbA concentration was associated with poorer overall performance on the FAB [β: -0.01 (-0.02, -0.00); p = 0.04 per % increase] and RBANS [β = -0.66 (-1.19, -0.13); p = 0.02 per % increase]. Increasing HbA was also associated with poorer performance on immediate memory, visuo-spatial, language and attention RBANS domains. Diabetes was associated poorer performance on neuropsychological tests of immediate memory, language, visual-spatial and attention.

Conclusions: Both increasing HbA and the presence of diabetes were associated with poorer cognitive and domain-specific performance in older adults. HbA , and not just diabetes status per se, may represent an important target in the promotion of optimal brain health in older adults.