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• This is the first prospective study of functional decline across glycemic transitions. • A transition from normal to diabetes was associated with an accelerated concomitant decline in cognition and functioning. • Associations with prediabetes were not observed. Evidence about the decline of cognition and physical function across glycemic status (normoglycemia, prediabetes, and diabetes) is inconsistent. We evaluated longitudinal changes in cognition and physical function according to glycemic status and also different glycemic transitions. Population-based cohort study. 9307 participants (mean age 59.7 years, 53.7 % women) were included from the China Health and Retirement Longitudinal Study (2011–2018). Global cognition (assessed by orientation, memory, and executive function) and physical function (calculated as the sum of impaired basic and instrumental activities of daily living) were assessed in each wave. The glycemic status was assessed in waves 2011 and 2015. Diabetes was defined as fasting blood glucose ≥7.0 mmol/L, HbA1c ≥6.5 %, self-reported diabetes, or glucose-lowering medication use. Prediabetes was defined as fasting blood glucose 5.6–6.9 mmol/L or an HbA1c of 5.7–6.4 %. Compared with normoglycemia, baseline diabetes was associated with a faster decline in orientation (−0.018 SD/year, 95%CI -0.032, −0.004) and a faster increase in physical function score (0.082 /year, 95%CI 0.038, 0.126). We did not observe any effect of prediabetes on the changing rate of cognition and physical function. Progression from normoglycemia to diabetes between waves 2011 and 2015 was associated with a significantly faster decline in global cognition, memory, executive function, and physical function compared with stable normoglycemia. Baseline diabetes was associated with accelerated decline of cognition and physical function. Associations with prediabetes were not observed, suggesting an important short diagnostic window when diabetes presents de novo. [ABSTRACT FROM AUTHOR]

Background: This study aimed to examine the associations of plasma superoxide dismutase (SOD) activity, an indicator of oxidative stress, with disability in activities of daily living (ADL) and objective physical functioning among Chinese older adults.Methods: We used cross-sectional data of 2223 older adults (≥65 years, including 1505 adults≥80 years) from the 2011/2012 main survey of the Chinese Longitudinal Healthy Longevity Survey (CLHLS) and the 2012 biomarker sub-study. Plasma SOD activity was assessed by the T-SOD assay kit based on the hydroxylamine method. Outcomes included ADL disability and disability in three objective physical tasks (standing up from a chair, picking up a book from the floor, and turning around 360°). Logistic regression models were used to examine the associations of plasma SOD activity with outcomes.Results: After controlling for age and sex, compared with participants in the lowest quartile group of SOD activity, those in the highest quartile group had 31% lower odds of ADL disability (odds ratio [OR]: 0.69; 95%CI: 0.48, 0.98); 60% lower odds of disability in standing up from a chair (OR: 0.40; 95%CI: 0.25, 0.63); and 57% lower odds of disability in picking up a book from a floor (OR: 0.43; 95%CI: 0.28, 0.65). The results did not change substantially after controlling for additional covariates. We did not observe statistically significant age and sex differences.Conclusions: Overall, plasma SOD activity was associated with subjectively and objectively measured disability in Chinese older adults, highlighting the potential of SOD activity to serve as a biomarker of physical functioning. [ABSTRACT FROM AUTHOR]