Metformin is one of the most commonly used and well-studied medicines for diabetes, and for most people it is considered safe and effective when taken as prescribed. It works by helping the body use insulin better and lowering blood sugar levels without usually causing low sugar episodes. Compared to many other diabetes medicines, it has a good safety profile and is often the first choice of treatment. In general, metformin does not harm the liver and is usually safe in people with normal liver function. For the kidneys, it is also safe in people with normal or mildly reduced kidney function, but it needs to be used carefully if kidney function is significantly reduced, as the drug is removed from the body through the kidneys. Doctors usually check kidney function before starting it and monitor it from time to time. Some people may experience mild side effects like stomach upset, which often improves over time or with dose adjustment. Overall, when used under medical guidance, metformin is a safe and reliable medicine for most patients.