Background: Hyperinsulemia and glycemic control may play a role as prostate cancer prognostic factors, while use of certain antidiabetic drugs, i.e metformin, could improve the prognosis. We examined the link between anti-diabetic medication use and prostate cancer survival taking into account simultaneous use of multiple drugs. Methods: The study cohort composed of 6,537 men in The Finnish Randomized Study of Screening for Prostate Cancer with prostate cancer diagnosed 1996-2009. Use of Medication was attained from the nationwide prescription database of the Social Insurance Institution of Finland. Median follow-up was 9.2 years post-diagnosis. 1,603 (24,5 men had used antidiabetic medication. 771 men died of prostate cancer during the follow-up. We used multivariable-adjusted Cox regression to evaluate the risk of prostate cancer death and onset of androgen deprivation therapy (ADT) with adjustment for prostate cancer clinical characteristics, co-morbidities and use of other drugs. Separate analyses were further adjusted for blood glucose. Results: Risk of prostate cancer death was higher among antidiabetic drug users overall (HR1.42, 95.18-1.70) compared to non-users, separately among insulin and metformin users. Adjustment for blood glucose level abolished the risk increase. Risk of ADT initiation was increased among the medication users; HR1.26 (95.05-1.49). Conclusions: Men with prostate cancer using antidiabetic medication are generally at increased risk of dying from prostate cancer compared to non-users. The risk association is driven by underlying diabetes, as adjustment for blood glucose level ameliorates the risk increase. Impact: Type2 diabetes should be considered as a risk factor when considering prostate cancer prognosis.