The combined effect of diabetes mellitus and sarcopenia on depression and cognitive function: insights from the CHARLS cohort, 2011–2020

Diabetes mellitus (DM) and sarcopenia are bidirectionally linked and commonly co-occur among middle-aged and elderly individuals. This study aims to examine the combined effect of DM and sarcopenia on depressive symptoms and cognitive function.

This was a nationwide cohort study using data from the China Health and Retirement Longitudinal Study. The definition of DM was self-reported and based on hemoglobin A1c (HbA1c) ≥ 6.5% or fasting blood glucose (FBG) ≥ 126 mg/dL. The diagnosis of sarcopenia was based on the Asian Working Group for Sarcopenia 2019 algorithm. The outcomes included depressive symptoms assessed using the 10-item Center for Epidemiologic Studies Depression Scale (CES-D-10) and cognitive function. Multi-adjusted linear and logistic regression models were conducted to evaluate the combined effect of DM and sarcopenia on depression and cognitive performance.

9148 participants were included in the longitudinal analysis, with 45.5% being men and an average age of 57.4 years. 6987 (76.4%) participants had neither DM nor sarcopenia, 1076 (11.8%) had DM only, 983 (10.8%) had sarcopenia only, and 102 (1.1%) had both DM and sarcopenia. In the cross-sectional analysis, the DM (+)/Sarcopenia (+) group exhibited the highest CES-D-10 score (β: 2.23, 95% confidence interval (CI): 1.26, 3.19) and the lowest cognitive score (β: − 1.02, 95% CI − 1.79, − 0.26) (P for trend < 0.05). In the longitudinal analysis, individuals in the DM (+)/Sarcopenia ( +) group had higher risks of moderate-to-severe depression (odds ratio (OR): 2.09, 95% CI 1.18, 3.71) and cognitive decline (OR: 1.87, 95% CI 1.19, 2.95) compared to the DM (−)/Sarcopenia (−) group. The population attributable fractions of DM and sarcopenia were 42.2% (95% CI 6.3, 90.4) for moderate-to-severe depression and 23.0% (95% CI 8.6, 39.3) for cognitive decline.

DM and sarcopenia additively increase the risk of moderate-to-severe depression and cognitive impairment, highlighting the importance of vigilant monitoring and management of these conditions to preserve mental health in middle-aged and elderly individuals.