AimsAn increasing number of oncologists will be confronted with individuals having diabetes and cancer. We assessed changes in patient-, tumour- and treatment-related variables in patients with colorectal cancer with and without diabetes. MethodsAll 17170 cases of primary colorectal cancer between 1995 and 2010 in the South-Eastern Netherlands were included. The Cochrane-Armitage test and logistic regression analysis were used to analyse trends. ResultsIn total, 11893 patients were diagnosed with colon cancer and 5277 with rectal cancer, of whom 1711 (14%) and 609 (12%), respectively, had diabetes at the time of cancer diagnosis. Patients with colorectal cancer with diabetes compared with those without were approximately 5years older and more often diagnosed with proximal colon tumours (60 vs. 54%; P<0.0001). Chemotherapy administration significantly increased in patients with stageIII colon cancer with and without diabetes (from 17% in ConclusionsAlthough the administration of chemotherapy and radiotherapy increased between 1995 and 2010 in patients with colorectal cancer with and without diabetes, patients with colorectal cancer with diabetes continue to receive chemotherapy less frequently than those without diabetes.