BACKGROUND AND OBJECTIVES:Quantifying the prevalence of diabetes mellitus is important to allow for rational planning and allocation of resources. Therefore, we designed this study to determine the prevalence of diabetes among Saudi nationals.DESIGN AND SETTING:A cross-sectional study among patients attending a primary care clinic in June 2009.PATIENTS AND METHODS:Patients were interviewed with structured questionnaires to determine the presence of diabetes by questioning for history of the disease, and charts were reviewed to document any diabetic therapies that the patients may have undergone in the past or were undergoing at that time.RESULTS:Of 6024 subjects, diabetes mellitus was present in 1792 (30%) patients. The mean (SD) age of the patients was 55.3 (13.2) years. The prevalence of diabetes was 34.1% in males and 27.6% in females (P<.0001). The mean (SD) age for onset of diabetes in males and females was 57.5 (13.1) and 53.4 (13.1) years, respectively (P<.0001). Females <50 years old had a higher prevalence than males in the corresponding age range—34.1% and 25.1%, respectively (P<.0001). The prevalence of diabetes decreased in patients older than 70 years. The prevalence of body mass index of ≥25 was 72.5%. Among patients with diabetes, the prevalence of body mass index of ≥25 was 85.7% (P<.0001). There was a higher prevalence of obesity (body mass index, ≥25) in females (87.7%) as compared to males (83.1%) (P=.008).CONCLUSION:The prevalence of diabetes is high among the Saudi population and represents a major clinical and public health problem. A national prevention program to prevent diabetes and address the modifiable risk factors at the community level, targeting high-risk groups, should be implemented soon.