This table from the Northern endoscopy guidelines is a useful guide for answering this question:
Colonoscopy urgency categories

The following website simplifies the current guidelines for polyp surveillance based on results of the most recent colonoscopy: https://www.polyp.guide/

See Bowel preparation page on our website.

FOBT is recommended every 2 years from age 50.

However, if the patient has had a colonoscopy, the decision regarding the next colonoscopy is based upon the findings of that colonoscopy. Otherwise, FOBT is indicated 4 years post colonoscopy.

The following link is part of the Northern endoscopy guidelines and is an excellent guide to the management of diabetic patients peri-operatively:
Diabetes management for Endoscpic procedures

The following link is part of the Northern endoscopy guidelines and provides an excellent summary of the principles of managing anticoagulants around gastrointestinal endoscopy:
Anticoagulation guidelines for Endoscopy