The knowledge about population’s awareness of diabetes mellitus (DM) complication can be used to arrange preventive measures. This study was aimed to assess the population’s awareness about diabetic retinopathy (RDM) as a DM complication and the source from whom/which they heard about RDM. This cross-sectional study was done in 2016 in Waingapu, the capital city of East Sumba in East Nusa Tenggara province. The subjects were adult outpatients of Waingapu city primary healthcare center. One hundred and eleven consecutive patients responded to questionnaire-based interview. A “yes” answer to the question of whether DM can cause visual disturbance was defined as being aware of RDM. Descriptive analysis was done using SPSS 16.0 software. Seventy-nine subjects (71.2%) were female. Most of the subjects were under 50 years old (74.8%). The majority was native of East Sumba (58.6%). Many subjects had graduated from junior high school or higher (55.9%), yet illiteracy rate was still high (10.8%). The predominant occupations were housewives (41.5%), fishermen, and construction workers. Thirty eight (34.2%) subjects were aware of RDM as the complication of DM. The predominant source of information was relative that suffered from DM and its complications, followed by healthcare providers, electronic media, and unaffected relative. Population in this study reflected lower and middle classes in economy and education. Their awareness of RDM was still low. However, the finding that most of the subjects who were aware of DR got the information from their affected relatives could be a clue for future health promotion strategy.