Berberine has been shown to regulate glucose and lipid metabolism in vitro and in vivo. This pilot study was to determine the efficacy and safety of berberine in the treatment of type 2 diabetic patients. In study A, 36 adults with newly diagnosed type 2 diabetes were randomly assigned to treatment with berberine or metformin (0.5 g t.i.d.) in a 3-month trial. The hypoglycemic effect of berberine was similar to that of metformin. Significant decreases in hemoglobin A1c. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2410097/
Here in this study, the patients were taking .5g 3x per day (500mgs per meal, 3 meals per day) for 3 mos.