OBJECTIVE: To study the trend in the prevalence of diabetes in the Netherlands during the period 1999-2014. DESIGN: Descriptive study of prevalence. METHODS: The prevalence of diabetes during the period 1999-2014 was calculated on the basis of datafrom the PHARMO Database Network, a network of electronic databases that includes data from public pharmacies for 3.8 million residents of the Netherlands. A person with diabetes was defined as someone with at least two dispensings for a glucose lowering-drug within six months. Prevalence was adjusted for variation in age demographics per sex to investigate the influence of these variations on population demographics. RESULTS: The prevalence of diabetes in the Netherlands increased from 1.8% in 1999 to4.9% in 2014. The increase was more pronounced among men as age increased. Only half of the increase was explained by changes in age demographics per sex. CONCLUSION: The study showed that the prevalence of diabetes more than doubled during the period 1999-2014. This trend can only be partly explained by changes in age demographics per sex.