Health literacy, cognitive ability and self-reported diabetes in the English Longitudinal Study of Ageing

Objective To examine the association of health literacy and cognitive ability with risk of diabetes. Research Design and Methods: Participants were 8,669 English Longitudinal Study of Ageing participants (mean age 66.7 years, SD 9.7) who completed health literacy and cognitive ability tests at wave 2 (2004-2005), and who answered a self-reported question on whether a doctor had ever diagnosed them with diabetes. Logistic regression was used to examine the cross-sectional associations of health literacy and cognitive ability with diabetes status. In those without diabetes at wave 2, Cox regression was used to test the associations of health literacy and cognitive ability with risk of diabetes over a median of 9.5 years follow-up (n=6,961). Results Adequate (compared to limited) health literacy (OR 0.72, 95% CI 0.61-0.84) and higher cognitive ability (OR per 1 SD 0.73, CI 0.67-0.80) were both associated with lower odds of self-reported diabetes. Adequate health literacy (HR 0.64; CI 0.53-0.77) and higher cognitive ability (HR 0.77, CI 0.69-0.85) were also associated with lower risk of self-reporting diabetes during follow-up. When both health literacy and cognitive ability were added to the same model, these associations were slightly attenuated. Additional adjustment for health behaviours, education and social class attenuated associations further, and neither health literacy nor cognitive ability were significantly associated with diabetes. Conclusions Adequate health literacy and better cognitive ability were associated with reduced risk of diabetes. These associations were independent of each other, but not of other health- and socioeconomic-related variables.