How does Metformin work? Metformin works by supressing glucose production in the liver, and also increasing the bodies sensitivity to insulin both of which help bring blood sugar levels down. How do I take Metformin? The amount of Metformin people need to take varies depending on their medical history and blood sugar levels. Your doctor or diabetes team will tell you what dose you should be taking. A typical starting dose is one 500mg or 850mg tablet, twice or three times per day. This IQ Doctor online clinic for Metformin is only suitable for you if you are currently being prescribed this medication by your GP. This service allows you to purchase a further supply of your tablets without going to your GP.