Pragmatic Trial of Metformin for Glucose Intolerance or Increased BMI in Prostate Cancer Patients

Inclusion Criteria:

In order to be eligible to participate in this study, an individual must meet all of the following criteria. The patients will be screening for eligibility and offered an electronic consent via the Epic medical record and the patient portal (My Health Connection - MHC) or otherwise through Epic:

1. Provision to sign and date the consent form in MHC or otherwise via Epic.
2. Subjects must have an MHC Account to participate in the study
3. Be a male aged ≥18 years of age on day of signing the informed consent.
4. Impaired glucose tolerance and/or overweight, and appropriate to receive metformin, meeting at least one of the following in the last year (timing relative to the consent presentation not start of therapy):

   * HbA1c of 5.7 - 6.4 %
   * BMI≥25 kg/m\^2
5. Have a prostate cancer diagnosis
6. Have a clinical relationship with a participating provider at a UCHealth facility.

Exclusion Criteria:

1. On therapy for diabetes including any of the following alone or in combination medications (diet controlled or managed diabetes is allowed - e.g.

   diagnosis of Diabetes, but without an active prescription for anti-glycemic medication):
   1. Metformin
   2. Insulin
   3. Glipizide
   4. Glyburide
   5. Glimepiride
   6. Pioglitazone
   7. Rosiglitazone
   8. Sitagliptin
   9. Saxagliptin
   10. Linagliptin
   11. Alogliptin
   12. Canagliflozin
   13. Dapagliflozin
   14. Empagliflozin
   15. Ertugliflozin
   16. Liraglutide
   17. Dulaglutide
   18. Semaglutide
   19. Exenatide
   20. Lixisenatide
   21. Nateglinide
   22. Repaglinide
   23. Tirzepatide
2. Contraindication for metformin use which include any of the following which are exclusionary (in Epic will use most recent lab values):

   1. Estimated glomerular filtration rate (eGFR) of \< 50 ml/minute (calculated according to the formula utilized within Epic).
   2. Known Total Bilirubin ≥3 mg/dL)
   3. Diagnosis of fibrosis or cirrhosis of the liver (ICD10: K74)
   4. Diagnosis of alcohol related disorders (ICD10: F10)
   5. Metformin allergy in Epic (ICD10: T50.995A)
3. Non-English-speaking patient until Spanish language consent form and relevant materials can be made available. Due to the novel aspect of this trial, we plan to get some experience in treating approximately the first 50 patients, make any changes needed in the study operations and then implement a Spanish consent, as feasible.
4. Taking any medication with a known class D or higher drug interaction with metformin, including:

   1. Cimetidine
   2. Dolutegravir
   3. Patiromer
   4. Ranolazine
   5. Tafenoquine
5. The use of any carbonic anhydrase inhibitors since they are a risk factor for lactic acidosis, including:

   1. Topiramate
   2. Dichlorphenamide
   3. Acetazolamide
   4. Methazolamide
   5. Dorzolamide
   6. Brinzolamide
   7. Dichlorphenamide
   8. Sultiame
   9. Zonisamide
   10. Indisulam
6. Any treating investigator concern, related to tolerance, safety, adherence or for any other reason