What are sulfonylurea drugs for treating diabetes?

Sulfonylureas are a class of oral medicine for type 2 diabetes. They lower blood glucose by helping the pancreas make more insulin and by helping the body better use the insulin it makes. Sulfonylurea drugs have been in use since the 1950s. Chlorpropamide (Diabinese) is the only first-generation sulfonylurea still in use today. The second-generation sulfonylureas are used in smaller doses than the first-generation drugs. There are three second-generation drugs: glipizide (Glucotrol and Glucotrol XL), glyburide (Micronase, Glynase and Diabeta) and glimepiride (Amaryl). These drugs are generally taken one to two times a day, before meals. All sulfonylurea drugs have similar effects on blood glucose levels, but they differ in side effects, how often they are taken and interactions with other drugs.

Sulfonylureas are an effective treatment for type 2 diabetes. However, like most medication, they have their fair share of side effects: 

  • Sulfonylureas can sometimes cause hypoglycemia (low blood glucose), especially when you exercise vigorously or don’t eat enough. Since low blood glucose can be dangerous, make sure that you and your family know the symptoms. These include shakiness, fast heartbeat, weakness, crankiness, hunger, headache, anxiety or dizziness. If you have these symptoms, take in some quick-acting sugar. Good sources are three to four glucose tablets, half a cup of fruit juice or regular soda.
  • Most people gain a few pounds while on sulfonyureas. If used positively, this should provide an incentive to stick to your exercise and meal plan.
  • Drinking even a little bit of alcohol can cause a red flush on your face, neck and arms. This isn’t harmful. But it is a good reminder that you need to be careful about how you include alcohol in your meal plan. Ask your doctor or diabetes educators about this.
  • Sulfonylureas can also cause an upset stomach. Less often, they cause a skin rash. Call your doctor if you have either of these side effects.
Dr. Jack Merendino, MD

Sulfonylureas are the oldest class of medications other than insulin used for diabetes treatment. Commonly used sulfonylureas include glipizide (brand name Glucotrol), glyburide (brand names Micronase or Glynase) and glimepiride (brand name Amaryl). These medicines work by helping the body make more of its own insulin, and, provided the pancreas is still functioning, the medications are often very effective. All of the drugs are available generically, and they are inexpensive. They are most effective in treating the rise in glucose that occurs after you've eaten (postprandial glucose, to use medical terminology). Knowing whether the medications are effective involves doing after-meal finger-stick testing, and if two hours after eating, the glucose level is higher than desired (under 140 is ideal; up to about 180 may be acceptable), the dose may need to be increased or there may need to be a change in medication.

Sulfonylurea medicines should be taken before eating. If you take the medicines once daily, about 30 minutes before breakfast is best. If you are on a twice-daily schedule, you should take the medicine 30 minutes before breakfast and 30 minutes before dinner. Sometimes confusion arises because the bottle may have a sticker that says, "Take with food." That's actually a bit misleading. The medicine is labeled this way to prevent a low-blood-sugar reaction if you take the medicine and then don't eat anything for several hours.

Some doctors have their patients use these medicines before bed in order to lower their fasting glucose values. This works for some people, but in others can lead to episodes of hypoglycemia while sleeping, which may be dangerous. These drugs have a moderate risk of weight gain, and that risk is partly related to the potential to cause a low-sugar reaction, which can lead to overeating.

It is important to note that alcohol intensifies the risk of hypoglycemia with the sulfonylureas. People with diabetes often ask whether they can drink. If you're taking one of these drugs, you'll need to be careful about alcohol consumption, especially if you haven't eaten. When there's alcohol in your bloodstream, the sulfonylureas trigger an even greater insulin release than they do under normal circumstances, so your blood sugar can go much too low.

The Best Life Guide to Managing Diabetes and Pre-Diabetes

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The Best Life Guide to Managing Diabetes and Pre-Diabetes

Bob Greene has helped millions of Americans become fit and healthy with his life-changing Best Life plan. Now, for the first time, Oprah's trusted expert on diet and fitness teams up with a leading...
Donna Hill Howes, RN
Family Practitioner

Sulfonylurea drugs are used to treat type 2 diabetes. Side effects may include nausea, vomiting, abdominal discomfort, heartburn, weight gain and low blood sodium (hyponatremia).

This answer was adapted from Sharecare's award-winning AskMD app. Start a consultation now to find out what's causing your symptoms, learn how to manage a condition, or find a doctor.

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