Anti-HIV drug therapy using protease inhibitors has become very common treatment for HIV-positive patients. Recently, however, serious side effects involving how the body uses fat have been reported in people taking protease inhibitors. Examples of these side effects are redistribution of body fat and development of diabetes. People taking protease inhibitors have been found to have higher levels of fat in their blood than is normal, which can cause heart problems. It is hoped that giving lipid-lowering drugs can help prevent serious heart problems. First, however, it is important to see what happens when protease inhibitors and lipid-lowering drugs are given together.