Fact Sheet

Type 2 Diabetes and TZDs

  • Editors
  • Silvio Inzucchi, MD
    Lawrence A. Leiter, MD
    Julio Rosenstock, MD

What is type 2 diabetes?

When you have type 2 diabetes, your blood glucose (sugar) levels are higher than normal.  Blood glucose comes mainly from the food you eat, and some is produced by your liver.  Your body uses glucose for energy with the help of insulin, a hormone made by your pancreas.  You can develop type 2 diabetes when your body

Most people with type 2 diabetes have both problems.


High blood glucose levels over time can lead to serious health problems, such as blindness, nerve damage, kidney disease, heart attacks, and strokes.  But keeping blood glucose, blood pressure, and cholesterol levels on target with meal planning, exercise, and medicines (if needed) can prevent or delay these problems.  

What are TZDs?

TZDs, also called thiazolidinediones or “glitazones,” are a type of pill for type 2 diabetes.  The generic names are

Did you know?

Middle-aged and older people are more likely to develop type 2 diabetes.  So are people who are overweight (especially around the waist) and physically inactive.

TZDs help keep your blood glucose levels on target by decreasing insulin resistance and making body tissues more sensitive to insulin’s effects.  Then glucose can enter your cells where it is needed.  TZDs also cut down on the amount of glucose made by your liver, which can be far too much in people with type 2 diabetes. 

Several other types of diabetes pills are available.  Each type works in a different way.  Rarely you might take a TZD as your only diabetes medicine but most often you take it with another type of diabetes pill, such as metformin or a sulfonylurea.  Some people take combination pills that contain a TZD plus another type of diabetes medicine. 

What are the potential benefits of TZDs?

TZDs can

How TZDs Affect Your Risk for a Heart Attack or a Stroke

People with diabetes are at high risk for heart attacks and strokes.  Researchers have studied the effects of TZDs.  Some studies suggest that pioglitazone might lower your risk for a heart attack or a stroke.  A few controversial studies suggest that rosiglitazone increases the risk of heart attacks, but other studies have not proven this.  Still, rosiglitazone is no longer available in much of the world.  In the U.S., it can only be prescribed to people who cannot take other diabetes pills.

What are the potential risks of TZDs?

TZDs can

Some studies suggest that pioglitazone may increase the risk of bladder cancer, but this has not been proven.  Even if a risk exists, it is very small.  This is usually not an issue unless you have a personal or family history of bladder cancer.

If you have type 2 diabetes and want to find out if TZDs might be right for you, talk with your doctor.  

Questions to ask your doctor