The Effect of Undiagnosed Diabetes on the Association between Self-Reported Diabetes and Cognitive Impairment among Older Mexican Adults

Purpose: To study the effect of undiagnosed diabetes on the relationship between self-reported diabetes and cognitive impairment. Methods: Data were from 1033 participants aged ≥60 from Wave III (2012) of the Mexican Health and Aging Study. Participants were classified as nondiabetic (n = 589), undiagnosed diabetic (n = 201), and self-reported diabetic (n = 243). Multivariate logistic regression models were used to estimate the relationship between self-reported diabetes and severity of cognitive impairment (nonimpaired, moderate impaired, severe impaired). Results: Self-reported diabetes was associated with significantly higher odds for severe, but not moderate, cognitive impairment (odds ratio [OR] = 2.70, 95% confidence interval [CI] = 1.39-5.32). The association between self-reported diabetes and severe cognitive impairment decreased by 6.3% when undiagnosed diabetics were included in the nondiabetic category and by 30.4% when undiagnosed diabetics were included in the self-reported diabetes category. Discussion: The association between self-reported diabetes and severe cognitive impairment is underestimated when undiagnosed diabetics are not differentiated from self-reported diabetics and nondiabetics.