The prevalence of diabetes has increased worldwide. We have undertaken an epidemiological analysis of drug-treated diabetes in a well defined community. We present estimates of prevalence, incidence, and mortality of patients with such diabetes during 1993-, based on data for all 470000 people living in the county of Fyn, Denmark. Although prevalence increased (odds ratio: female, 1.026 [95% CI 1.020-1.032]; male, 1.041 [1.036-1.047]), mortality in those treated declined (rate ratio: female, 0.976 [95%CI 0.952-1.001]; male, 0.966 [0.943-0.990]). We did not identify a clear trend for incidence. Future research into the causes of rising diabetes prevalence should take this fall in mortality into account to avoid incorrect conclusions about the relation between western lifestyle and the growing number of diabetics.