Digital health literacy, proactive health behaviours, the digital healthcare environment and health-related quality of life among older adults with type 2 diabetes in Chinese primary care: a cross-sectional study

Background Digital health literacy (DHL) may be associated with health-related quality of life (HRQoL) in older adults with type 2 diabetes, but the behavioural and contextual correlates of this association remain unclear. This study examined that association, the indirect association through proactive health behaviours (PHB), and potential effect modification by the digital healthcare environment. Methods A cross-sectional survey was conducted from July to August 2025 among older adults with type 2 diabetes recruited by convenience sampling from primary healthcare chronic disease management registries in Huai’an, China. DHL, PHB and four single-item digital healthcare environment indicators were assessed using structured instruments, and HRQoL using the EuroQol five-dimensional three-level questionnaire (EQ-5D-3L) and EuroQol Visual Analogue Scale (EQ-VAS). Adjusted indirect-association (5000 bias-corrected bootstrap resamples) and effect-modification analyses used heteroscedasticity-consistent type 3 (HC3) standard errors. Results Among 1053 participants, the mean DHL score was 21.24±10.43, the mean PHB score 76.75±9.88 and the mean EQ-5D-3L utility score 0.968±0.069. The adjusted total association between DHL and utility was significant (B=0.000569, 95% CI 0.000228 to 0.000910), whereas the direct association was not (B=0.000152; p=0.338). The indirect association through PHB was significant (B=0.000418, bias-corrected 95% CI 0.000260 to 0.000619) and accounted for 73.5% of the total. There was no robust evidence of effect modification for EQ-5D-3L utility: interactions with remote service use and online health management use reached significance only under HC3 inference and were not reproduced in sensitivity analyses. An exploratory positive PHB-by-remote-service-use interaction was observed for the supplementary EQ-VAS outcome. Conclusions Higher digital health literacy was associated with better HRQoL among older adults with type 2 diabetes, with a significant cross-sectional indirect association observed through proactive health behaviours. No robust effect modification was identified for the primary EQ-5D-3L outcome. These findings support further longitudinal and intervention research on digital health capabilities and proactive health behaviours in this population.