This study examines if **metformin**, a medication, can lower the risk of death, heart attacks, or strokes in Veterans with pre-diabetes and heart or blood vessel problems. **Pre-diabetes** means having blood sugar levels that are higher than normal but not high enough to be diabetes. **Atherosclerotic cardiovascular disease** is when blood vessels are narrowed or blocked by plaques, which are fatty deposits that can lead to heart attacks or strokes. This trial will compare metformin with a **placebo**, a dummy treatment, to see if metformin helps reduce these risks. Participants will be randomly chosen to receive metformin or placebo and will also get advice on healthy living choices. The trial aims for a full-scale launch in October 2022, following a successful pilot trial.

• Study involves taking metformin or a placebo and receiving lifestyle advice.
• Participants must have pre-diabetes and signs of cardiovascular disease.
• Excludes those using metformin or other diabetes medications recently.