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.

Association of Serum 25-Hydroxyvitamin D Deficiency with Risk of Incidence of Disability in Basic Activities of Daily Living in Adults >50 Years of Age

BACKGROUND

Vitamin D deficiency compromises muscle function and is related to the etiology of several clinical conditions that can contribute to the development of disability. However, there are few epidemiological studies investigating the association between vitamin D deficiency and the incidence of disability.

OBJECTIVES

We aimed to assess whether vitamin D deficiency is associated with the incidence of disability in basic activities of daily living (BADL) and to verify whether there are sex differences in this association.

METHODS

A 4-y follow-up study was conducted involving individuals aged 50 y or older who participated in ELSA (English Longitudinal Study of Ageing). The sample consisted of 4814 participants free of disability at baseline according to the modified Katz Index. Vitamin D was assessed by serum 25-hydroxyvitamin D [25(OH)D] concentrations and the participants were classified as sufficient (>50 nmol/L), insufficient (>30 to ≤50 nmol/L), or deficient (≤30 nmol/L). Sociodemographic, behavioral, and clinical characteristics were also investigated. BADL were re-evaluated after 2 and 4 y of follow-up. The report of any difficulty to perform ≥1 BADL was considered as an incident case of disability. Poisson models stratified by sex and controlled for sociodemographic, behavioral, and clinical characteristics were carried out.

RESULTS

After 4-y follow-up, deficient serum 25(OH)D was a risk factor for the incidence of BADL disability in both women (IRR: 1.53; 95% CI: 1.16, 2.03) and men (IRR: 1.44; 95% CI: 1.02, 2.02). However, insufficient serum 25(OH)D was not a risk factor for the incidence of BADL disability in either men or women.

CONCLUSIONS

Independently of sex, deficient serum 25(OH)D concentrations were associated with increased risk of incidence of BADL disability in adults >50 y old and should be an additional target of clinical strategies to prevent disability in these populations.