To estimate the prevalence of Readiness for enhanced health literacy in patients with type 2 diabetes mellitus through the diagnostic accuracy of the defining characteristics. A diagnostic accuracy study on the diagnosis of Readiness for enhanced health literacy in patients with type 2 diabetes mellitus was conducted using the latent class analysis model. The sample comprised 180 individuals attending a referral outpatient clinic in Maranhão, Brazil. The data analysis was conducted in the R Core Team software. The prevalence of the nursing diagnosis was 55.23%. The main defining characteristics were expresses desire to enhance health communication with healthcare providers and expresses desire to enhance the understanding of health information to make healthcare choices. All defining characteristics showed significant specificity values. Accurate diagnoses contribute to individualized care plans for patients. The diagnosis Readiness for enhanced health literacy should be considered in implementing care plans, including interventions to reduce complications in the health status of patients with type 2 diabetes mellitus.