Could poor glycaemic control be a predictor of walking speed decline in older adults? Evidence from the English Longitudinal Study of Ageing.

AIM: Although diabetes is a risk factor for walking speed decline in older adults, it remains unclear how glycaemic control [assessed by glycated haemoglobin (HbA1c)] might affect the long-term trajectories of walking speed. We investigated whether the glycaemic control status accelerates the walking speed decline and whether this decline differs depending on previous mobility conditions. MATERIALS AND METHODS: In total, 3202 individuals aged ≥60 years from the English Longitudinal Study of Ageing (ELSA) were classified at baseline and after 4 and 8 years of follow-up according to glycaemic control status as 'without diabetes' (no self-reported diabetes and HbA1c <6.5%), 'good glycaemic control' (self-reported diabetes and HbA1c ≥6.5% and <7.0%) and 'poor glycaemic control' (PGC) (self-reported diabetes and HbA1c ≥7.0%). The generalized linear mixed models verified the walking speed trajectories in m/s. A second analysis was performed, including only participants without slowness at baseline (>0.8 m/s). RESULTS: Compared with the status 'without diabetes', the annual walking speed decline was -0.015 m/s for PGC and -0.011 m/s for good glycaemic control, totalling -0.160 and -0.130 m/s, respectively, over 8 years. Among those without slowness at baseline, only PGC had a significant walking speed decline, corresponding to -0.014 m/s per year and -0.222 m/s over 8 years. CONCLUSIONS: Poor glycaemic control is a discriminator of walking speed decline in older adults, regardless of previous mobility conditions. It may serve as an early screening tool for those at risk of decreased functional performance later in life.

Sex Differences in the Trajectories of Cognitive Decline and Affected Cognitive Domains Among Older Adults With Controlled and Uncontrolled Glycemia.

BACKGROUND: We aimed to analyze the trajectories of cognitive decline as a function of the presence of type 2 diabetes and glycemic control in analyzes stratified by sex in an 8-year follow-up period. METHODS: A total of 1 752 men and 2 232 women aged ≥50 years who participated in the English Longitudinal Study of Ageing (ELSA), conducted from 2004 to 2012, were analyzed. The outcomes of interest were performance on the cognitive domains of memory, executive function, and temporal orientation as well as the global cognition score. Cognitive performance was standardized in z-scores in strata based on schooling and age. The participants were classified as without diabetes, with controlled glycemia, and with uncontrolled glycemia, according to medical diagnosis, glucose-lowering medications use and HbA1c levels. Generalized linear mixed models controlled by sociodemographic, behavioral, and health-related characteristics were used for the trajectory analyses. RESULTS: No differences in z-scores were found for global cognition or cognitive domains based on diabetes classification in men and women at baseline. More than 8 years of follow up, women with uncontrolled glycemia had a greater decline in z-scores for global cognition (-0.037 SD/year [95% CI: -0.073; -0.001]) and executive function (-0.049 SD/year [95% CI: -0.092; -0.007]) compared with those without diabetes. No significant difference in trajectories of global cognition or any cognitive domain was found in men as a function of diabetes classification. CONCLUSIONS: Women with uncontrolled glycemia are at greater risk of a decline in global cognition and executive function than those without diabetes.

Does undiagnosed diabetes mitigate the association between diabetes and cognitive impairment? Findings from the ELSI-Brazil study.

BACKGROUND: Type 2 diabetes mellitus (T2DM) is associated with cognitive impairment. However, most of the evidence has been based on self-reported T2DM, and undiagnosed diabetes has not been considered as a separate category. We aimed to examine the extent to which undiagnosed diabetes modifies the association between diabetes and cognitive impairment in a representative sample of Brazilian adults aged 50 years and older. METHODS: We analyzed baseline data from 1944 participants of the Brazilian Longitudinal Study of Aging (ELSI-Brazil) conducted from 2015 to 2016. Diabetes was evaluated based on self-reported doctor diagnosis and glycosylated hemoglobin levels. Participants were classified as diabetics (D), undiagnosed diabetics (UDD), or nondiabetics (ND). Cognitive function was assessed by word list learning and verbal fluency tests. Three multiple logistic regression models were used to evaluate the changes in the strength of the associations. RESULTS: Participants with diabetes had 49% greater odds of exhibiting impaired memory than nondiabetics (odds ratio [OR] = 1.49; 95% CI: 1.01-2.20). By combining UDD and ND, the association between diabetes and impaired memory was attenuated by 2.0%, losing its statistical significance (OR = 1.46; 95% CI: 0.98-2.17). By combining UDD and D, the association was attenuated by 7.4% (OR = 1.38; 95% CI: 1.01-1.90). No significant association was found between T2DM and impaired verbal fluency. CONCLUSION: This study found an association between T2DM and impaired memory but not with impaired verbal fluency. When UDD individuals are considered diabetics, this association is attenuated; when UDD individuals are considered as ND, this association is attenuated to the extent that it loses its statistical significance, affecting thus the clinical interpretation.