Background: Dietary inflammatory index (DII) was associated with Type 2 diabetes mellitus and cognitive function impairment (CFI).
Objective: The aim of this study was to explore whether the associations among DII, glycohemoglobin (HbA1c), and CFI were similar in the participants with or without diabetes.
Methods: A total of 1,198 participants aged 60 and over from the National Health and Nutrition Examination Survey (NHANES) in 2011-2014 were involved in this study, dividing into subgroups as diabetes and non-diabetes for further analysis.
Results: We found that participants with pro-inflammatory diet had higher proportion of CFI patients (p < 0.05). Pro-inflammatory diet and HbA1c were positively associated with the risk of CFI; participants with pro-inflammatory diet was 1.479 times on occurrence of CFI compared with anti-inflammatory diet group. The interaction between inflammatory diet and HbA1c was positive on the risk of CFI and was negative on the CERAD-immediate and CERAD-delayed, respectively. Among the participants without diabetes, the associations of Energy-adjusted DII (E-DII) with Animal Fluency test and Digit Symbol Substitution Test (DSST) were partially mediated by HbA1c, and the mediated proportion was 5.8% and 6.6%, respectively. However, there was no such mediation effect in the diabetes patients.
Conclusion: In elderly participants without diabetes, there was an interaction between inflammatory diet and HbA1c on the association with CFI, especially for the dimension of CERAD-immediate and CERAD-delayed. Besides, the associations of E-DII with Animal Fluency test and DSST were partially mediated by HbA1c. For diabetic patients, HbA1c, rather than the inflammatory diet has a positive effect on the CFI risk.
Keywords: Cognitive function; HbA1c; diabetes; energy-adjusted dietary inflammatory index; inflammatory diet.