Ethnolinguistic differences in diabetic retinopathy within a shared geographic setting in South India: The Gudalur diabetic retinopathy study

PURPOSE: To compare diabetic retinopathy (DR) prevalence and severity between Tamil- and Malayalam-speaking adults with type 2 diabetes mellitus (T2DM) living within a shared geographic setting and to examine differences in clinical, behavioral, and dietary characteristics. DESIGN: Community-based cross-sectional screening study. METHODS: Adults aged ≥40 years with self-reported T2DM, ≥10 years' residence in Gudalur taluk (Nilgiris, Tamil Nadu), and mother tongue Tamil or Malayalam were recruited through 12 outreach eye camps conducted between January and December 2024. Participants underwent dilated fundus examinations by indirect ophthalmoscopy. Sociodemographic and socioeconomic characteristics, anthropometry, diabetes duration, physical activity, knowledge and screening practices, and dietary intake were assessed using standardized instruments. Between-group comparisons were performed using appropriate tests, and logistic regression was used to evaluate the association between mother tongue and any DR. RESULTS: Among 295 participants (Malayalam n = 171; Tamil n = 124), Malayalam speakers were older ( P = 0.008) and had longer diabetes duration ( P < 0.001), while HbA1c was comparable. DR was more prevalent among Malayalam speakers (49.7% vs 30.6%; P = 0.002). Malayalam mother tongue remained associated with any DR after adjustment (adjusted OR 1.88; 95% CI 1.10-3.22; P = 0.021). Awareness and annual eye examination uptake were higher among Malayalam speakers, who also had higher total energy intake and a greater contribution of saturated fat in the dietary subset ( P < 0.001). CONCLUSIONS: Within a shared geographic setting, Malayalam-speaking adults with T2DM had higher DR prevalence and severity than Tamil-speaking adults, after adjustment for age and diabetes duration, alongside differences in awareness and dietary fat patterns.