As a manifestation of the epidemiologic transition being experienced throughout the developing world, the prevalence of diabetes mellitus (DM) is increasing. However, whether an individual's risk of cardiovascular diseases as a consequence of DM is also higher in these countries is unknown. We conducted a case-control study at the medical center in the state of Qatar comparing the prevalence of DM in 512 patients who were admitted with acute myocardial infarctions (MI) and 262 cases of cerebrovascular accidents (CVA) to 382 hospital and outpatient controls to calculate the odds ratios (OR) associated with DM for MI and CVA. The OR for MI was estimated to be 4.01 compared to 2.92 for other countries in the Middle East and 1.75 for North America. The OR was even higher for Qatari natives. Understanding the reasons for this increase, including genetic differences, lifestyle, and medical management issues, is critical for the design and prioritization of effective interventions.