Inclusion Criteria:  All participants who are capable of giving informed consent. All participants aged 16 years or over. All participants must have no known contraindications to rectal biopsy procedures.  All participants must be resident in the United Kingdom. All participants must have no known contraindications to aspirin and metformin.  Exclusion Criteria:  Unable to give informed consent. Under the age of 16 years. Individuals who are taking anti-coagulation medication. Individuals with platelet disease or other bleeding issues. Individuals with a history of a significant rectal bleed. History of diabetes mellitus or impaired glucose tolerance. Any contraindication to either aspirin or metformin. Female subjects of child bearing age who are not taking effective contraception during the period of the trial