Metformin is very narrowly approved by the FDA to lower the blood sugar in patients who have the risk factor type 2 diabetes. The metformin story is one of the greatest disconnects between the old medical science and the new. In the old paradigm metformin is a medication that lower the glucose level by reducing insulin resistance in the liver. That understanding of the potential of metformin is itself a barrier to best practice treatment of cardiovascular disease.
Metformin is not just a drug that is effective in diabetes. It protects patients from a heart attack as well as statin treatment. In high-risk patients who already have known artery disease, statin treatment lowers the risk of heart attack, stroke, and sudden death by 25% for every 40 point reduction in LDL (bad) cholesterol level. Metformin is more beneficial or at least as beneficial as statins in preventing cardiovascular events. Patients on metformin who lower the glucose to the same level as achieved by other diabetic treatments have 40% fewer heart attacks and a 32% reduction in other diabetic complications. Metformin is a cardiovascular drug, but most health professionals think of it as a medication to lower the risk factor of high glucose. That is a huge barrier to better chronic disease management. Metformin and statins provide a modest risk reduction for cardiovascular events.
That brings up a side observation. If metformin lowers the risk of heart attack and stroke by 40%, that means there is a residual or remaining heart attack risk of 60%. Even if patients have the protection of taking metformin, 60% will still have a cardiovascular event. How can we further reduce that risk? The question is not “which is the most effective drug to prevent cardiovascular events?” The real question is “what combination of medications and lifestyle measures provide the most protection from cardiovascular events.” That is the definition of optimal medical therapy (OMT). We have 21 years of follow-up in a study of very high-risk patients with type 2 diabetes and chronic kidney disease who received OMT. Statins lower cardiovascular events by 25%. OMT lowers cardiovascular events three-fold after 13 years of follow-up. As the table shows, patients in usual care had 158 cardiovascular events after 13 years and patients on OMT had 51 events. Patients receiving usual care had four times as many heart attacks and five times as many strokes.
OMT that achieves aggressive risk factor control with a protocol using medications like lisinopril, losartan, spironolactone or eplerenone for hypertension, statins for cholesterol, and metformin for diabetes are much more effective than the old risk factor science.
Wow!