Sulfonylureas are the oldest class of oral diabetes medication, and were first introduced in the 1950s. Brand names of these drugs include Amaryl (glimepiride), DiaBeta (glyburide), Diabinese (chlorpropamide), Dymelor (acetohexamide), Glucotrol (glipizide), Glucotrol XL (glipizide), Glynase PresTab (glyburide), and Micronase (glyburide). The generic sulfonylureas tolbutamide and tolazamide are also available, but are prescribed infrequently.

The oldest sulfonylurea drugs — Diabinese, tolbutamide, and tolazamide — require the largest dosage sizes (with daily doses ranging from 100 to 3,000 milligrams). The newer, or second-generation, sulfonylureas are much more potent. These second-generation drugs are usually taken once daily; your doctor will tell you when and how often to take your medication. Whatever the schedule, you should always try to take it consistently at the same time from day to day.

How They Work

Called hypoglycemic agents, sulfonylurea drugs work by causing the pancreas to release more insulin, which in turn lowers blood glucose levels. For this reason, sulfonylureas may not be effective in people with long-standing diabetes who have lost most pancreatic beta cell function.

Amaryl (glimepiride), the newest of the sulfonylurea drugs, also works to decrease insulin resistance by binding with insulin receptors. So in addition to increasing insulin output, this drug allows the body to more effectively use the insulin it produces.

Possible Side Effects

The most serious potential side effect of the sulfonylurea drugs is a hypoglycemic reaction, or low blood sugar episode. The older sulfonylureas, in particular, are more likely to cause this reaction if taken in conjunction with other medications.

Patients taking some of these first-generation drugs may run an increased chance of cardiovascular problems, so anyone with a history of heart problems should speak with his or her doctor about the potential risks.

Other possible side effects include, but are not limited to, the following:

• Nausea

• Rash and/or itching

• Photosensitivity (skin sensitivity to sunlight)

• Dizziness

• Drowsiness

• Headache

• Weight gain

The potential for weight gain can be a problem for overweight patients, as weight gain will work against the benefits of the drug by increasing insulin resistance. Your physician may prefer to use a different class of drugs, such as biguanides, for your treatment if you are significantly overweight.

Sulfonylureas (particularly chlorpropamide) also have the potential to react with alcohol, causing nausea, vomiting, and facial flushing. If you drink, talk to your doctor about this side effect before starting your prescription.