This study was carried out on 100 saudi patients recording in the primary health centers (PHCs) at Riyadh city. The aim of this study was to assess diabetic patient's knowledge about Diabetes Mellitus (DM) in PHCs of Riyadh city. The data was collected using one tool; “Structured questionnaire sheet” which consists of 38 questions related to socio-demographic characteristics, patient's history and diabetes mellitus. The result of this study indicated that about more than half of both male and female patients had satisfactory knowledge regarding to DM. The most of male patients (90.9%), and 73.6% of female patients had satisfactory knowledge regarding the signs and symptoms. Meanwhile more than half of both male and female patients (54.5% and 52% respectively) had satisfactory knowledge regarding the Complications. There is significant relationship between gender and Patient's DM Type. Also, there was no significant relationship between gender and Frequency of follow up DM, and checking the blood glucose level.
