Association of dietary phytochemical index with sleep quality, and inflammatory markers in adults with type 2 diabetes: a cross-sectional study

Background: Type 2 diabetes mellitus (T2DM) is associated with sleep disturbances, inflammation, and gut dysbiosis, potentially modifiable by diet. This study examined associations between the dietary phytochemical index (DPI), sleep quality, systemic inflammation, and oxidative stress markers in adults with T2DM. Methods: In this cross-sectional study, 675 adults with T2DM (aged 35-75 years) were recruited. DPI was calculated from a validated Food Frequency Questionnaire. Objective sleep was assessed via BodyMedia SenseWear armband (duration, efficiency, latency, WASO); subjective sleep via Pittsburgh Sleep Quality Index (PSQI). Inflammatory markers (CRP, IL-6, TNF-α), oxidative stress (MDA, TAC, SOD), and hormones (melatonin, cortisol) were measured. Linear regression and mediation analyses were performed. Results: < 0.001). Higher DPI was also associated with more favorable oxidative stress profiles and hormone concentrations. Conclusion: Higher DPI scores is associated with better sleep quality, and lower systemic inflammation in adults with T2DM. These findings highlight the potential role of phytochemical-rich diets in supporting sleep quality and metabolic health among adults with type 2 diabetes; however, prospective randomized controlled trials are required to confirm these associations and to establish causality.