Metformin is the most popular Type 2 Diabetes drug. There are many others, however this one is prescribed the most often, because, aside from its proven track record, it is considered "weight-neutral" and will not by itself cause an increase in the person's weight as others are known to do.
Non-insulin dependent diabetes medications are Oral Hyperglycemic Agents. Common are Glibenclamide, Metformin and maybe Gliclizide.