Background: diabetes is well studied in Saudi Arabia; however, there seems to be little research in the area of awareness, education and health care delivery. Objectives: to assess the awareness about diabetes mellitus among attendees of primary health care centers, Makkah, Saudi Arabia. Subjects and Methods: a cross-sectional study was conducted among a representative random sample of adult attendees of primary health care centers (diabetic and non-diabetics), Makkah Al-Mokkaramah, the kingdom of Saudi Arabia during the study period (1-31 November, 2016). An Arabic self-administered questionnaire was used for data collection. It includes 31 questions with sections of demographic data, community awareness regarding diabetes definition, risk factors, signs and symptoms, and complications community awareness regarding diabetes prevention. Results: the study included 662 adult patients. Approximately one-third of them (32.2%) aged 60 years or more. Females represent 51.1% of them. More than one-fifth of them (21%) were university graduated whereas 6.3% were illiterates. Prevalence of diabetes among the participants was 33.7% and majority of them (97.9%) had family history of diabetes. The most frequent sources were mass media (57.4%), health sector (29.9%) and educational sector (10.6%). Overall sufficient awareness regarding diabetes mellitus was reported among majority of the participants (91.2%). Among studied factors, only marital status and income were significantly associated with sufficient awareness. Conclusion: population in Makkah AL-Mokkaramah has enough knowledge of the general knowledge of diabetes regarding risk factors, symptoms, etc. However, they are not very well aware of the diabetes associated secondary complications.