Impact of diabetes on cognitive function in middle-aged and older adults: A longitudinal study

This study investigated diabetes' impact on cognitive dysfunction in middle-aged/older adults (≥45 years) and explored underlying mechanisms, including the mediating role of Activities of Daily Living (ADL) and moderating effects of sleep, depression, and exercise.

Using unbalanced panel data from the China Health and Retirement Longitudinal Study (CHARLS, Waves 1-5; N = 16,856), linear mixed-effects models and Cox regression assessed diabetes-related cognitive decline. Mediation/moderation analyses tested mechanisms, and subgroup analyses examined heterogeneity by age, diabetes status, obesity, and residence.

Diabetes demonstrated a significant negative association with cognitive function (β = -0.140, p < 0.01). ADL mediated 10.87 % of this adverse effect. Moderator analyses revealed excessive sleep (>9 h) exacerbated diabetes-related cognitive decline more substantially than insufficient sleep (<6 h) (β = -0.517 vs. -0.242, p < 0.01), and depressive symptoms amplified cognitive detriment (β = -0.020, p < 0.01). Conversely, regular physical exercise (β = 0.171, p < 0.1) and intergenerational co-residence (β = 0.207, p < 0.1) significantly attenuated diabetes-induced cognitive impairment. Subgroup analyses identified heightened vulnerability among individuals with diabetes (β = -0.222, p < 0.05), younger seniors (60-79 years), non-abdominally obese participants, and those living in spacious accommodations (per capita >40 m²).

Diabetes adversely impacts cognitive function partially through ADL impairment. However, maintaining regular sleep patterns, emotional well-being, and consistent physical exercise may mitigate this association. Intergenerational co-residence also showed protective potential. Implementing targeted lifestyle interventions addressing these modifiable factors-particularly in identified high-risk subgroups like diabetics and younger seniors-could help ameliorate cognitive decline in middle-aged and older adults with diabetes.