The association between C-reactive protein-albumin-lymphocyte index and depression in adults with type 2 diabetes mellitus: A cross-sectional study from NHANES.

Objective: Inflammation and nutrition are interrelated, and both are related to depression. This study explored the association between the C-reactive protein (CRP)-albumin-lymphocyte (CALLY) index, a novel immunonutrition scoring system, and depression in patients with type 2 diabetes mellitus (T2DM).

Methods: We included 3517 patients with T2DM from the National Health and Nutrition Examination Survey 2005-2010 and 2015-2018. The Patient Health Questionnaire-9 was used to evaluate depression. The CALLY index was based on a comprehensive assessment of serum CRP, serum albumin, and the lymphocyte counts from whole blood. Weighted multivariate logistic regression models were used to examine the relationship between the CALLY index and depression. The restricted cubic spline was applied to explore the nonlinear relationship.

Results: Compared with the non-depressed group, CALLY index and albumin in the depressed group were significantly reduced, while CRP and lymphocytes were significantly increased (P < 0.05). After adjusting for covariates, only the CALLY index significantly decreased (the highest quartile vs the lowest quartile, odds ratio = 0.58, 95 % confidence interval: 0.38-0.89, P = 0.014). The non-linear association between the CALLY index and depression was not significant (P for nonlinear=0.69). The results of subgroup analysis were basically consistent (P for interaction > 0.05).

Conclusion: The CALLY index was significantly negatively correlated with depression in American patients with diabetes and served as a potential marker for early identification.