OBJECTIVES: This study aimed to compare the level of diabetes knowledge among the residents in Bangkok (the capital) and other provinces in Central Thailand and investigate factors affecting diabetes knowledge in both groups. METHODS: A cross-sectional survey was carried out in five major areas of Bangkok and four other Central provinces of Thailand in mid-2007. Five hundred Thai residents aged greater than or equal to 15 years in each group were recruited from various public thoroughfares to complete a structured questionnaire comprising seven sections. RESULTS: The overall diabetes knowledge scores of most respondents in Bangkok (70.8%) and other provinces (75.4%) were acceptable (defined as greater than or equal to 50% of the total score). More than half of the respondents had acceptable scores in every section, except for the section ‘diabetes in women’. The mean (±SD) overall score of the other provinces group was significantly higher than that of the Bangkok group (60.95 ± 18.95% vs. 58.21 ± 20.69%, p =0.029). There were also more respondents with acceptable scores in the other provinces group compared to the Bangkok group in almost every section. Education level, age, and having family member, relative or friend with diabetes were important predictors of knowledge score of respondents in both groups while working status was a significant predictor only in the other provinces group. Friends or relatives and various kinds of media were reported as major sources of diabetes information in both groups. CONCLUSIONS: The level of diabetes knowledge of respondents in both groups was satisfactory, except for a few areas. Characteristics such as education level, age, and having family member, relative or friend with diabetes were all important in determining level of diabetes knowledge of the residents in both groups and should be considered in future planning of public health education programmes.