Welcome to HCM! Milk Thistle is known to be possibly effective for lowering blood sugar at dosage ranges of 200 mg three times daily for 4 months. I do want to caution you that we do not have a cure for diabetes and by using this treatment you may not be helping yourself at all in answer to your question. I can offer a possible explanation, however, as to why your son may have improved. One, he could have had a viral infection that temporarily affected his pancreas and thus his blood sugar. When the infection cleared, so did his blood sugar. Or, as you say, he still has it, but his blood sugar is much lower because he quit drinking all that soda and the doctor is just saying he can keep it under control by avoiding these bad habits and eating healthier. I could possibly provide you more effective additions to your Metformin treatment if I knew more about your condition. Personally, if you were my patient and you were looking for an herbal treatment I would use Berberine at 500 mg two times per day. Studies have shown it to be as effective as Metformin in lowering blood sugars. A side-effect of Berberine might possibly be weight loss. And, I would also recommend a healthy diet and exercise program to accompany the treatment. However, you are already on Metformin with heart problems with both conditions being interrelated. Interfering with your current medical treatment by adding an herb that works in a similar manner as your medication may negatively affect your health profile as a whole. I do advise, however, that if you have been on Metformin for 3 years or more to have your B12 level checked since deficiency of this nutrient becomes more common the longer this medication is used. Always talk to your doctor before self-treating. My sincerest regards, Kathy J. Shattler, MS, RDN