What Are Sulfonylureas?

Sulfonylureas are oral medications that help lower blood sugar in patients with type 2 diabetes. Medications in this class include:

• Glucotrol and Glucotrol XL (glipizide)
• Diabeta, Glynase, PresTab, Micronase (glyburide)
• Amaryl (glimepiride)
• Chlorpropamide
• Tolbutamide
• Tolazamide

What Do They Do?

Insulin, a hormone produced by the pancreas, helps sugar move from the bloodstream into cells, where it acts as an energy source. When the body does not have enough insulin, or does not use the insulin it has effectively, blood sugar levels increase. Sulfonylureas stimulate beta cells in the pancreas to produce more insulin and also help the body use insulin, lowering blood sugar levels by up to 20%.

What They Do Not Do

Sulfonylureas do not directly replace insulin. Therefore, they are not appropriate for patients with type 1 diabetes.

History of Use

Sulfonylureas are the original oral medication for diabetes and have been used in the United States since 1955. Sulfonylureas are typically taken once or twice daily, before meals. Sulfonylureas can be used alone, or in combination with insulin or other oral medications for type 2 diabetes.

Who Should Not Use Sulfonylureas?

Patients with type 1 diabetes or with allergies to sulfonamides (sulfa drugs) should not use sulfonylureas. In addition, sulfonylureas may have to be discontinued in patients who are exposed to high levels of physical stress (infection, injury or surgery, for example), and may have to be stopped temporarily for patients who are not eating regularly. Glyburide should not be taken simultaneously with Tracleer (bosentan), which is used in the treatment of pulmonary artery hypertension.

What Are the Side Effects and Risks?

Sulfonylureas can cause hypoglycemia (low blood sugar), which usually occurs under the following circumstances:

• with the use of more than one diabetes medication
• after vigorous exercise
• after a missed meal
• with long-acting (once-daily) sulfonylureas
• in patients who also have kidney, heart or gastrointestinal disease

Other side effects of sulfonylureas include upset stomach, light sensitivity and liver abnormalities.

The medication chlorpropamide can cause skin flushing after drinking alcohol, and can cause hyponatremia (low blood salt).

What Are Other “Off-Label” Uses?

Glyburide may be used to treat gestational diabetes from the 11th to 33rd weeks of pregnancy.

What Else Should I Know?

Studies have suggested that the use of sulfonylureas results in poorer outcomes after a heart attack. However, a recent study published in the British Medical Journal looked at two trials with sulfonylureas: one found an association with worse outcomes, while the other did not. Questions about the use of sulfonylureas and outcomes with heart disease will require further study.

As with any plan for managing diabetes, it is important for anyone using sulfonylureas to follow a healthy lifestyle. This should include good blood pressure and cholesterol control to prevent heart disease.