Association between HbA1c variation and cognitive decline in older people

Yu ZB, Zhu Y, Li D et al (2020) Association between visit-to-visit variability of HbA_1c and cognitive decline: a pooled analysis of two prospective population-based cohorts. Diabetologia 63: 85–94

• Cognitive decline occurs before dementia. Identifying risk factors for cognitive deterioration would enable at-risk individuals to be screened and aid early intervention.
• Longitudinal studies have indicated that variability in HbA_1c is associated with adverse outcomes in people with diabetes and researchers wanted to determine whether there was an association between variation in HbA_1c and decline in cognitive function in older adults.
• They performed a pooled analysis of data from 6,237 individuals who participated in the English Longitudinal Study of Ageing and US Health Retirement Study for which there were baseline and two or more repeated measurements of cognitive function.
• Participants were followed up for 10.5 years, during which their memory and executive function were assessed every 2 years and their HbA_1c every 4 years.
• The rate of cognitive decline was significantly greater in participants with the highest variability in HbA_1c versus the lowest variability in HbA_1c, regardless of mean HbA_1c values during the follow-up period. In the adjusted model, this effect was found to be greatest in participants who did not have diabetes.
• It was concluded that, in people without diabetes, long-term variability in HbA_1c was significantly associated with cognitive decline and researchers suggested further studies be carried out to determine the effect of glucose control on the rate of cognitive decline.

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