Metformin, an anti-diabetic drug, can protect the heart in pre-diabetic patients.
Even without a frank diagnosis of type 2 diabetes, normotensive or hypertensive patients with insulin resistance can develop left ventricular hypertrophy (LVH) and coronary artery disease (CAD). Insulin resistance (IR) is implicated in the development of LVH. Dysglycaemia is very common in patients with CAD and is linked to IR. Left ventricular hypertrophy is regarded as one of the strongest independent predictors of CV outcome, and LVH regression reduces future CV events irrespective of BP changes.
Metformin is an anti-diabetic drug and has been shown to safely improve insulin sensitivity and reduce IR. A recently published randomized clinical trial involving 68 patients who did not have diabetes, but had insulin resistance, received a 2000-mg daily dose of metformin or a placebo. In this 12-month trial, metformin reduced left ventricular mass. Metformin also reduced body weight, systolic blood pressure, and biomarkers for oxidative stress. The results suggest that metformin acts to reverse insulin resistance and is cardioprotective.
This study should be taken in the context that macrovascular damage to vessel walls accumulates in the pre-diabetic stage,so it is untenable to ignore patients with insulin resistance with the HgBa1C range of 5.6 to 6.5. Future evaluation with ultrasound carotid intimal wall thickness measurement and coronary calcium score would be fascinating.
We should strive to reverse diabetes before it becomes established, and certainly before patients develop LVH and progression of coronary calcification.