Sometimes two types of medicines are given together in one pill. Common combinations include glyburide combined with metformin (brand name: Glucovance), glipizide combined with metformin (Metaglip), and rosiglitazone combined with metformin (Avandamet). One benefit of taking a combination pill is there's one less pill to remember to take. A potential downside: There's no control over the dosage of the medications in a combination pill.

A doctor may first prescribe one type of pill. If it doesn't control blood sugar, the physician may recommend taking more of the same medication, adding another pill or insulin to the treatment plan, or changing to a different oral drug or insulin.