Carotid Atherosclerosis: MEtformin for Insulin ResistAnce Study

A Randomised Placebo-controlled Trial of Metformin on Progression of Carotid Atherosclerosis in Non-diabetic Patients With Cardiovascular Disease Treated With Conventional Risk Reducing Agents

Hypothesis: Treatment with metformin in overweight non-diabetic individuals with coronary heart disease and on standard cardiovascular risk reducing agents including statins will have a beneficial impact on carotid artery atherosclerosis compared to placebo.

Rationale: Once subjects have a heart attack, they remain at much higher than average risk of another heart attack and stroke, despite the best current therapies to lower their cholesterol and blood pressure and thin their blood. Many subjects with heart disease also have problems metabolising (i.e. processing) sugar even if they do not have diabetes. There is some evidence that metformin, a drug which improves sugar metabolism, decreases the risk of future heart attacks in diabetic patients. However, whether metformin further reduces the risk of heart disease beyond established treatments in people without diabetes is unknown.

Method: The investigators will test the ability metformin, a drug with proven safety, to slow the progression of furring up (known as atherosclerosis) of blood vessels in non-diabetic subjects with heart disease. This will be achieved by treating 2 groups of subjects with metformin and placebo pills respectively. To measure atherosclerosis, the investigators will carry out ultrasound scans of the big blood vessels in the neck at the start of the study, after 1 year and after 1.5 years of therapy.The investigators will then be able to assess whether metformin has had a beneficial impact.

Inclusion Criteria:

• Proven coronary heart disease (prior acute coronary syndrome, prior CABG or angiographically proven CHD)
• Aged 35-75 years
• Elevated waist circumference as per the International Diabetes Foundation criteria (94 cm in men and 80 cm in women)
• All patients will be on statin

Exclusion Criteria:

• Pregnancy and/or lactation at screening
• Premenopausal woman not on contraception
• Known or newly diagnosed diabetes mellitus on oral glucose tolerance testing (OGTT will be performed on subjects with HbA1C 6.0-6.9% and fasting plasma glucose [FPG] < 7.0 mmol/L at screening18)
• Screening results: HbA1C ≥ 7.0% and/or fasting plasma glucose ≥ 7.0 mmol/L
• Patients with Acute Coronary Syndrome within the last 3 months
• Clinically unstable heart failure
• Uncontrolled angina
• Contraindications to metformin