If you want to be sure you're in the right state, you need to do an S-term test or colonoscopy. Then you need to make sure that the tissue is positive or cancer. You may need to re-invasion the colon and biopsy with the results, or you may need to do a rectal exam or some other sub-administal procedure to assess the risk of diabetes complications.
Doctor, I've had some uncomfortable symptoms for a while, and I've been bleeding out of the stool, and I think I have a colonoma, and what kind of test do I need?