Type 2 diabetes has been catalogued as the epidemic of the 21st Century, both because of its increasing magnitude and its impact on cardiovascular disease, the leading cause of death in developed countries. This review analyses the evolution of the prevalence of diabetes in Spain over recent years, based on various cross-sectional studies. This study shows that previous estimates have been surpassed, with 10-15% of Spanish adults estimated to have diabetes. Factors influencing this phenomenon include the change in diagnostic criteria, population aging, a lower mortality among persons with diabetes or a true increase in the incidence.