HbA1c, diabetes and cognitive decline: the English Longitudinal Study of Ageing

Abstract

Aims/hypothesis The aim of the study was to evaluate longitudinal associations between HbA 1c levels, diabetes status and subsequent cognitive decline over a 10 year follow-up period. Methods Data from wave 2 (2004)(2005) to wave 7 (2014-2015) of the English Longitudinal Study of Ageing (ELSA) were analysed. Cognitive function was assessed at baseline (wave 2) and reassessed every 2 years at waves 3-7. Linear mixed models were used to evaluate longitudinal associations. Results The study comprised 5189 participants (55.1% women, mean age 65.6 ± 9.4 years) with baseline HbA 1c levels ranging from 15.9 to 126.3 mmol/mol (3.6-13.7%). The mean follow-up duration was 8.1 ± 2.8 years and the mean number of cognitive assessments was 4.9 ± 1.5. A 1 mmol/mol increment in HbA 1c was significantly associated with an increased rate of decline in global cognitive z scores (−0.0009 SD/year, 95% CI −0.0014, −0.0003), memory z scores (−0.0005 SD/year, 95% CI −0.0009, −0.0001) and executive function z scores (−0.0008 SD/year, 95% CI −0.0013, −0.0004) after adjustment for baseline age, sex, total cholesterol, HDL-cholesterol, triacylglycerol, high-sensitivity C-reactive protein, BMI, education, marital status, depressive symptoms, current smoking, alcohol consumption, hypertension, CHD, stroke, chronic lung disease and cancer. Compared with participants with normoglycaemia, the multivariable-adjusted rate of global cognitive decline associated with prediabetes and diabetes was increased by −0.012 SD/year (95% CI −0.022, −0.002) and −0.031 SD/year (95% CI −0.046, −0.015), respectively (p for trend <0.001). Similarly, memory, executive function and orientation z scores showed an increased rate of cognitive decline with diabetes. Conclusions/interpretation Significant longitudinal associations between HbA 1c levels, diabetes status and long-term cognitive decline were observed in this study. Future studies are required to determine the effects of maintaining optimal glucose control on the rate of cognitive decline in people with diabetes.

Association between diabetes and cognitive function at baseline in the Brazilian Longitudinal Study of Adult Health (ELSA- Brasil)

“…Although Brazil has a distinct epidemiological profile, the observed associations between diabetes, cognitive performance and metabolic risk factors are similar to those observed in cohorts in developed countries 48,49 . Preventive strategies may be more effective to avoid the worsening of cognition functions in these high-risk individuals 50 .…”

Associations of hemoglobin A1c with cognition reduced for long diabetes duration

“…For both interactions, relatively good cognition was associated with the combination of longer T2D duration and higher mean HbA1c-as hypothesized. This supplements studies where higher HbA1c alone [16][17][18], or longer T2DM duration alone [4,5], was found to be associated with greater cognitive impairment. The seemingly paradoxical finding that having both risk factors mitigated rather than exacerbated their separate deleterious effects on cognition is hypothesized by the Protected Survivor Model.…”

Prefrontal cortex brain damage and glycemic control in patients with type 2 diabetes

“…Alternatives ways to preserve brain tissue integrity in T2DM may need to be considered as well as continuing with current evidence-based recommendations such as exercise, nutrition (eg, thiamine supplement), excellent control of blood glucose and cardiovascular disease risk factors (eg, hyperglycemia, hypertension). 40,[46][47][48][49] The present study has some limitations. The small sample size limited our ability to consider important variables in our analyses (such as duration of T2DM, mood, medications, and comorbidities).…”