This study is to see if metformin, a medicine, helps reduce the risk of death, heart attacks, or strokes in Veterans with pre-diabetes and heart or blood vessel issues. Pre-diabetes is when blood sugar levels are higher than normal but not high enough to be diabetes. Atherosclerotic cardiovascular disease means there are blockages in the heart or blood vessels. The study compares metformin to a placebo, which is a "fake" pill with no medicine. This is a double-blind study, meaning neither the patients nor the researchers know who gets the real medicine. This helps ensure fair results. Participants are randomly chosen to get either the metformin or placebo. They will also receive advice on healthy lifestyle changes.

• Study Length: The study started in April 2023 and requires ongoing participation.
• Requirements: Participants must not be on certain medications or have certain health conditions.
• Eligibility: Veterans with pre-diabetes and heart/blood vessel problems can join.