Diabetes Medicine: Sulfonylureas

If you have Type 1 diabetes, your pancreas no longer makes enough insulin. Insulin is a hormone that helps glucose move from the bloodstream into your cells where the glucose is used for energy. Everyone who has Type 1 diabetes must take insulin, whether by injection, inhalation (for rapid-acting insulin), or insulin pump, to survive. There is no “insulin pill,” at least at this time.

With Type 2 diabetes, the situation is a bit different. In the early stages of Type 2 diabetes, the body makes plenty of insulin, but has a hard time using it. This is called insulin resistance. Certain medicines, such as metformin, can help improve insulin resistance so that the body can use insulin better. But as Type 2 diabetes progresses, the pancreas can get tired and stop making enough insulin to keep up with the demand. If and when this happens, insulin injections are usually needed.


This week, we’ll look at another class of diabetes pills called sulfonylureas.

What are sulfonylureas?
One of the trickiest drug names to pronounce, sulfonylureas (SUL-fah-nil-YOO-ree-ahs) are the oldest type of diabetes pills available. They were developed in the 1940’s and were the first type of diabetes pill to enter the market.

These pills, which are sometimes called “oral hypoglycemic agents,” work very differently than metformin. They signal the pancreas to release insulin and they also help the body’s cells use insulin better. Sulfonylureas may be old, but they’re effective: They can lower A1C levels (a measure of blood sugar control over the previous 2–3 months) by 1% to 2%.

There are two generations of sulfonylureas: first and second. The first-generation drugs include tolbutamide (brand name Orinase), tolazamide (Tolinase), and chlorpropamide (Diabinese). The second-generation drugs, which are more commonly used these days, include glimepiride (Amaryl), glipizide (Glucotrol and Glucotrol XL), and glyburide (Diabeta, Micronase, and Glynase). Sulfonylureas are often taken with other types of diabetes medicines, such as metformin and insulin. They’re also available as combination pills; for example, combined with metformin (Metaglip).

How are sulfonylureas taken?
Sulfonylureas are tablets that are taken anywhere from once a day to twice a day. Each type of sulfonylurea is available in different dosages or strengths. In general, your doctor will start you off on the lowest dose and gradually increase the dose, as needed, until your blood sugars come into target range.

What are the side effects of sulfonylureas?
The most common and serious side effect of these drugs is low blood sugar (hypoglycemia). To avoid this, it’s important that you not skip meals when taking these medicines. Another possible side effect is weight gain, likely due to increased insulin secretion. Less common side effects include a skin rash and stomach upset.

Sulfonylureas may not be safe for people who have liver or kidney problems. One of the drugs in this class, glyburide, may be safe for pregnant women with diabetes who choose not to take insulin; however, sulfonylureas are not deemed safe for nursing women.

What else should you know about sulfonylureas?
Sulfonylureas are very effective, but as with all medicines, there are pros and cons to taking them.

Up to 20% of people who take these drugs won’t respond to them; in other words, they won’t help to significantly lower blood sugar levels. For some other people, these drugs may work initially, but over time, they’ll become less effective.

It’s important to check your blood sugar levels regularly when taking a sulfonylurea.

Make sure you know the signs and symptoms of low blood sugar (dizziness, lightheadedness, shakiness, sweating, headache, hunger) and how to treat it (take 15 grams of carbohydrate, such as 3–4 glucose tablets, a tube of glucose gel, or 4 ounces of juice; wait 15 minutes to recheck your blood sugar, and treat again if it is still low).

If you are having frequent low blood sugars, let your doctor know; you may need a lower dose.

Your skin may be more sensitive to sunlight while on these drugs. Be sure to use adequate sun protection.

What underappreciated hormone can save you from severe low blood sugar? Bookmark DiabetesSelfManagement.com and tune in tomorrow to find out!

  • Kimberfly

    No mention of the beta cell failure causing decreased insulin production/secretion. Safer and more
    effective oral medication is available (and cheaper) Most endocrinologists use it rarely, sparingly-believing there is no longer a need for sulfonylureas to remain a first-line addition to metformin for those patients whose clinical characteristics are appropriate and whose health insurance and/or financial resources make an alternative drug affordable. After 25 years as a CDE, I am surprised we even see people taking this class of drugs anymore.