Diabetic nephropathy constitutes one of the foremost causes of end-stage renal disease. Health literacy plays a fundamental role in enabling effective self-care.To analyze the impact of a diabetic nephropathy educational video among individuals with diabetes and limited health literacy.The study was conducted at a university-based diabetes outpatient clinic. Individuals with diabetes aged 18 years or older who attended the clinic during a two-week period in 2025 were invited to participate. A sociodemographic questionnaire was administered, followed by the application of the Health Literacy Assessment Test (HLAT). Participants then viewed a validated diabetic nephropathy educational video, after which the HLAT was reapplied without administrator interference. Questions 17 and 18 were excluded from scoring. Participants were classified as Level 1 (functionally illiterate) or Level 2 (functionally literate) according to their pre-test responses. Level 1 corresponded to questions 1, 3, 5, 7, 15 and 16 of the HLAT, while Level 2 corresponded to questions 2, 8, 10, 12, 13 and 14. Sociodemographic variables and tests scores were analyzed.Among the 21 individuals evaluated, 52% were women, with ages ranging from 27 to 79 years; among men, ages ranged from 42 to 77 years. Regarding years of study, 13 participants (62%) had incomplete primary schooling, 8 of whom were women. Additionally, 33% of the total sample had completed secondary schooling. Within the group with incomplete primary schooling, 31% (n = 4) were classified as Level 1, and 69% (n = 9) as Level 2. Those at level 1 had 1 to 3 correct answers and those at level 2 had 2 to 6 additional correct answers in the post-test.In country XXX (2024), among individuals with incomplete primary schooling, 51% achieved Level 1 and 19% reached Level 2 literacy. Level 1 participants were of particular interest for evaluating post-test changes, as HLAT performance at this level more effectively identifies limited health literacy.Functional literacy classification positively influenced post-test performance among individuals with incomplete primary schooling. Identifying limited health literacy and implementing strategies such as educational videos enhanced participants’ understanding of disease processes, thereby supporting improvements in care provided to patients under follow-up.