OBJECTIVE To assess the effect of an intervention targeted at primary care physicians (PCPs) in order to improve their management of diabetic patients. METHODS Diabetic patients seen by PCPs in King Khalid University Hospital, Riyadh, Kingdom of Saudi Arabia from January 2008 to July 2009 were included in this prospective cohort study. The PCPs were divided into intervention and control groups. The intervention group with the help of an assistant, utilized a customized designed computer program generating a checklist for the PCPs. The list included clinical and biochemical screening tests needed for the patients current visit, according to evidence-based diabetes guidelines. For the control group, no assistant was used. At the end of one year, an independent reviewer evaluated the patients' files in both groups to assess the adherence to diabetes guidelines. RESULTS We enrolled 162 patients in the control group and 517 patients in the intervention group. The intervention significantly improved the percentage of patients being screened for diabetic complications; retinopathy from 24.7-98.5%, neuropathy from 25.9-92%, and nephropathy from 37.8-73.7%. There was no improvement in glycemic control in both groups and glycosylated hemoglobin level (HbA1c) values were still above the 7% target. CONCLUSION Management of diabetic patients in the primary care clinics is below standard. The intervention applied was effective in promoting better adherence to evidence-based diabetes guidelines.