This information is for people who have type 2 diabetes. It tells you about taking two drugs together, a treatment used for type 2 diabetes. It is based on the best and most up-to-date research.
Does it work?
Yes. If you have type 2 diabetes, taking two drugs together can lower your blood glucose (sugar) better than taking one drug on its own.
But by combining treatments, you might get more bouts of low blood glucose ( hypoglycaemia).
What is it?
You can take two different drugs for type 2 diabetes. For example, you can take metformin along with a sulphonylurea,or a meglitinide,or an alpha-glucosidase inhibitor, or sitagliptin. Or you might take a sulphonylurea along with exenatide.
These are all drugs that lower the amount of glucose in your blood. You need a prescription from your doctor to get them.
The brand name for metformin is Glucophage.
Some sulphonylureas (and their brand names) are listed below.
There are two meglitinides.
Acarbose (Glucobay) is an alpha-glucosidase inhibitor and sitagliptin (Januvia) is a DPP-4 inhibitor..
Exenatide (Byetta, Bydureon) is an incretin mimetic.
Your doctor may also recommend adding other drugs, such as vildagliptinand saxagliptin. But we haven't looked in detail at these combinations. We also haven't looked at the research about taking three or more types of drugs together.
How can it help?
Taking a combination of two drugs for type 2 diabetes can help control your blood glucose better than taking just one. Overall, all the combinations seem to work about as well as each other.  
Studies show that your haemoglobin A1c level can drop between one-half point and two points more if you take the following combinations than if you take just one drug:                
metformin plus an older sulphonylurea (glibenclamide)
metformin plus a newer sulphonylurea (glimepiride)
metformin plus a meglitinide
metformin or a sulphonylurea plus an alpha-glucosidase inhibitor (acarbose)
metformin plus sitagliptin
sulphonylurea plus exenatide
Doctors use the haemoglobin A1c test to see how well you are controlling your diabetes.