Understanding the Effect of Metformin on Corus CAD (or ASGES)

Inclusion Criteria: At least 21 years of age Any of the following: * Chest pain syndrome, stable angina, or anginal equivalent suggesting myocardial ischemia * Low-risk unstable angina, or * Asymptomatic individuals with a high probability of CAD Clinician diagnosis of pre-diabetes, per ADA guidelines, such that metformin therapy is prescribed: * HgA1C: \>5.7% - \<6.4%, * BMI\> 35 kg/m2 * Age\< 60 yrs * Prior Gestational Diabetes Mellitus * FPG: \>100mg/dl - \<126mg/dl * OGTT: \>140mg/dl - \<200mg/dl Willingness to comply with metformin therapy, for at least seven (7) days (P.O., per physician's dosage discretion) Willingness to maintain a drug diary for duration of study, for full follow-up period (7 + 7 days) Willingness and ability to provide two (2) samples for Corus (baseline, 7 (+ 7) days post- medication start) Provide written informed consent Exclusion Criteria: * History of or current level of HbA1C \>6.5 * History of or current prescription of metformin or any other diabetic medication * History of myocardial infarction (MI) or prior revascularization * Current MI or acute coronary syndrome (ACS) * Current New York Heart Association (NYHA) class III or IV congestive heart failure symptoms * Current systemic infectious or systemic inflammatory conditions * Subjects currently taking steroids, immunosuppressive agents or chemotherapeutic agents