Side Effects. Thiazolidinediones can have serious side effects. They can increase fluid build-up, which can cause or worsen heart failure in some patients. Combinations with insulin increase the risk. Patients with heart failure should not use them. People with risk factors for heart failure should use these drugs with caution.
In particular, rosiglitazone has been associated with increased risks for heart attack and heart failure. Because of these safety concerns, some doctors are urging that rosiglitazone be pulled from the market. The FDA is currently reviewing heart safety data on rosiglitazone and is scheduled to make a recommendation in July 2010. In the mean time, patients who take rosiglitazone, especially those who have heart failure, heart disease, or who are at high risk for heart attack, should talk to their doctor about their treatment options.
Thiazolidinediones may cause more weight gain than other diabetes medications or insulin. Any patient who has sudden weight gain, water retention, or shortness of breath should immediately call their doctor. These drugs have also been linked to increased risks for bone fracture.
There have been rare reports of rosiglitazone causing or worsening diabetic macular edema. This is an eye condition associated with diabetic retinopathy that causes swelling in the macular area of the retina. Symptoms include blurred vision and decreased color sensitivity. Most patients who had this side effect also had swelling in the feet and legs (peripheral edema). The condition resolved or improved when patients stopped taking the drug.
Thiazolidinediones can also cause liver damage. Patients who take these drugs should have their liver enzymes checked regularly.
Alpha-glucosidase inhibitors, including acarbose (Precose, Glucobay) and miglitol (Glyset), reduce glucose levels by interfering with the absorption of starch in the small intestine. Acarbose tends to lower insulin levels after meals, a particular advantage, since higher levels of insulin after meals are associated with an increased risk for heart disease. Alpha-glucosidase inhibitors are not as effective alone as other single oral drugs, but combinations, such as with metformin, insulin, or a sulfonylurea, increase their effectiveness.
Side Effects. These medications need to be taken with meals. Unfortunately, about a third of patients stop taking the drug because of flatulence and diarrhea, particularly after high-carbohydrate meals. The drug may also interfere with iron absorption.
Alpha-glucosidase inhibitors do not cause hypoglycemia when used alone, but combinations with other drugs do. In such cases, it is important that the patient receive a solution that contains glucose or lactose, not table sugar. This is because acarbose inhibits the breakdown of complex sugar and starches, which includes table sugar.
GLP-1 Inhibitors (Exenatide and Liraglutide)
Incretin mimetics belong to a new class of drugs that help improve blood sugar control. Incretins include glucagon-like peptide-1 (GLP-1) inhibitors and DDP-4 inhibitors. GLP-1 inhibitors are given by injection and are prescribed for patients with type 2 diabetes who have not been able to control their glucose with metformin or a sulfonylurea drug. They can be taken in combination with these drugs or alone.
Review Date: 04/01/2010
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.