Sulfonylureas for Type 2 Diabetes

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Sulfonylureas for Type 2 Diabetes


Generic NameBrand Name
gliclazide Diamicron

Most sulfonylurea medicines for type 2 diabetes can be taken once a day. Some need to be taken twice a day.

These medicines work for a long time and can cause low blood sugar. It is very important not to skip or delay meals when taking these medicines.

How It Works

Sulfonylurea medicines increase the amount of insulin produced by the pancreas. This is the primary action of these medicines.

Why It Is Used

Sulfonylurea medicines are prescribed when changes in diet, weight loss, and exercise do not keep the blood sugar level within a target range. When taking one of these medicines, it is still important to eat a balanced diet, exercise, and lose weight if needed.

These medicines can help control blood sugar levels in children and young adults who have type 2 diabetes and are overweight.

Sulfonylurea medicines are not safe if you:

  • Are pregnant or trying to become pregnant. They may harm the fetus.
  • Have liver or kidney problems. Sulfonylurea medicines are broken down by the liver and pass out of the body through urine produced in the kidneys.

Tell your doctor if you have had a serious allergic reaction to a sulfa antibiotic, such as Bactrim or Septra. You may not be able to use a sulfonylurea.

How Well It Works

Sulfonylurea medicines work rapidly to control elevated blood sugar levels. They often are the first medicine selected to treat people newly diagnosed with type 2 diabetes. Metformin is preferred for initial treatment because it doesn't cause low blood sugar or weight gain. The great majority of people have better control of their blood sugar by using a sulfonylurea medicine along with diet and exercise than by using diet and exercise alone.

But the medicine may become less effective after several years of use. Some people who no longer respond to one sulfonylurea may respond to a different one.

Sulfonylurea medicines decreased the risk for complications of the eyes (retinopathy), kidneys (nephropathy), and nerves (neuropathy).1 Sulfonylurea do not decrease fat (triglycerides) in the blood as does metformin.

Side Effects

Side effects are uncommon when sulfonylureas are taken as prescribed. Low blood sugar is the most common side effect. The risk of very low blood sugar is greater with medicines that work longer in the body.

Drinking alcohol increases the risk of a low blood sugar level if you take a sulfonylurea medicine. If you drink alcohol, limit yourself to only 1 to 2 drinks a day and eat something before you drink alcohol.

Sulfonylurea medicines can cause weight gain. They also tend to keep insulin levels in the body high for long periods of time. Over time, high levels of insulin (hyperinsulinemia) may increase your chances of getting heart disease.

Blood levels of vitamin B12 can decrease in some people who take metformin.

See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)

What To Think About

Sulfonylurea medicines are an effective treatment for many people with type 2 diabetes. If one of these medicines keeps your blood sugar within a target range, your risks of long-term complications of diabetes can be reduced. Other important factors that contribute to complications include high blood pressure, being overweight, high cholesterol levels, and smoking.

Few studies have been done on the use of oral medicines for type 2 diabetes in children, and they have not been approved by the Therapeutic Products Directorate (TPD) for use in children. But because these oral medicines are safe for adults, some doctors use them to treat children with type 2 diabetes.

Complete the new medication information form (PDF) (What is a PDF document?) to help you understand this medication.



  1. Inzucchi SE, Sherwin RS (2008). Type 2 diabetes mellitus. In L Goldman, D Ausiello, eds., Cecil Medicine, 23rd ed, pp. 1748–1760. Philadelphia: Saunders Elsevier.


By Healthwise Staff
Primary Medical Reviewer E. Gregory Thompson, MD - Internal Medicine
Primary Medical Reviewer Brian D. O'Brien, MD - Internal Medicine
Specialist Medical Reviewer Matthew I. Kim, MD - Endocrinology
Last Revised August 4, 2010

This information does not replace the advice of a doctor. Healthwise, Incorporated disclaims any warranty or liability for your use of this information.