Effective management of type 2 diabetes depends on nutrition knowledge and diet quality (1), but validated data among Vietnamese outpatients remain scarce. This cross-sectional study aimed to assess nutrition knowledge and diet quality, and to identify associated factors, among n = 195 outpatients with type 2 diabetes at a university hospital in Vietnam in 2026. Knowledge was measured using the Diabetes-Related Nutrition Knowledge (DRNK) questionnaire (2). Diet quality was evaluated with the Diet Quality Questionnaire (3). This generated scores for intake of food groups that protect against non-communicable diseases (NCD-Protect) and food groups that pose a risk for non-communicable diseases (NCD-Risk), which were combined into an overall Global Dietary Recommendations (GDR) score. Multivariable linear regression with robust standard errors was used to examine associated factors. The mean DRNK score was low, at 24.5 ± 11.5%. Median domain scores ranged from 0% for food label reading and 16.7% for food choices, to 25% for portion size and food amount, and 37.5% for nutrient content. Higher knowledge was associated with higher education, family history of diabetes and having received dietary counselling (all p < 0.05), while older age was associated with lower knowledge (p = 0.009). The mean GDR score was 13.0 ± 2.3, with a median NCD-Protect score of 5 (IQR 3–7) and a median NCD-Risk score of 1 (IQR 0–1), indicating low intake of risk-related food groups. Higher GDR scores were associated with proactive nutrition information-seeking, having received dietary counselling on a single occasion, and older age (all p < 0.05), whereas diabetes complications were linked to lower GDR (p = 0.007). These associations were mainly driven by the NCD-Protect component. In conclusion, outpatients with type 2 diabetes had low nutrition knowledge and moderate diet quality. Education, counselling and proactive information-seeking appear important for improving both knowledge and diet quality.