What Are Thiazolidinediones (TZDs) And When Are They Used?

Question:What are thiazolidinediones (TZDs) and when are they used?

Answer:The thiazolidinediones -- it's a tough one to pronounce so we call them the T-Z-Ds -- are a newer group of medications used to treat diabetes. Type 2 diabetes is caused by a combination of not making enough insulin and having something called insulin resistance, which means you need more insulin in order to keep your blood sugar levels in the normal range. What the TZDs do is they decrease your resistance to insulin. Or, another way of saying it is that they increase insulin sensitivity. By increasing insulin sensitivity -- if either you're making insulin yourself, as most people do with type 2 diabetes, or if you're taking insulin -- they make you more sensitive to the effect of the insulin.

These medications are taken as pills, usually once or twice a day. They are generally very well tolerated. There are relatively few side effects that one can develop with these medications. One of the ones that has been noted is -- especially if you have some risk for having heart failure -- you may develop some fluid retention or edema. This means that you have increased volume or fluid in your body and you can get swelling of your ankles or even may get a little bit short of breath. And if that's the case, usually the drug is stopped.

Another possible complication of the thiazolidinediones is that they may increase the risk for heart disease or heart attacks. And this has been suggested recently, especially for one of them, which is called rosiglitazone or Avandia.

The way that you know that these drugs are working the way they're supposed to is that your blood sugar levels will drop. So you're blood sugar levels will go from whatever elevated level they were at to a lower level and that's how you know that they're working.

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