Alpha-glucosidase inhibitors for type 2 diabetes


Generic Name Brand Name
acarbose Precose
miglitol Glyset

How It Works

Acarbose and miglitol help keep blood sugar levels within a safe range by slowing the rate at which the intestines absorb sugar (glucose) from food. These medications do not cause the pancreas to produce more insulin. They will not cause low blood sugar (hypoglycemia) unless they are used in combination with other oral medications for diabetes or with insulin.

Why It Is Used

Alpha-glucosidase inhibitors have proven helpful for people with type 2 diabetes who have not been able to keep their blood sugar levels within a safe range by eating a balanced diet, losing weight, and exercising. They are very helpful in controlling the blood sugar levels of people who have high blood sugar levels right after they eat.

These medications are most useful for people who have just been diagnosed with type 2 diabetes and who have blood sugar levels only slightly above the level for diabetes. They may also be used to treat people who are taking other medicine for diabetes, such as metformin.1

Both medications may be used alone, with another medication for diabetes, or with insulin.

How Well It Works

These medications have been found to be especially helpful for people who tend to have high blood sugar levels right after they eat (postprandial hyperglycemia).

People taking insulin who start using acarbose usually are able to decrease the amount of insulin they take.

People taking acarbose alone tend not to gain weight or may lose a small amount of weight.

Side Effects

The most common side effects are temporary digestive symptoms: typically abdominal discomfort, excessive gas (flatulence), and diarrhea. You may be able to lessen this side effect by decreasing the amount of high-carbohydrate foods you eat, such as pasta, breads, and rice. Adolescents may be reluctant to continue taking these medications if they have this side effect.

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

What To Think About

These medications do not cause low blood sugar or weight gain, which are common side effects of the sulfonylurea medications and insulin.

Acarbose and miglitol may need to be taken 3 times per day, with each meal.

If you take one of these medications along with another medicine that lowers blood sugar (such as insulin or a sulfonylurea medication), your blood sugar level can drop very low. If your blood sugar level does drop too low, use glucose tablets—rather than other simple sugars such as fructose, lactose, or sucrose—to raise your blood sugar level. If you do not treat low blood sugar with glucose tablets, it may require more food to raise your blood sugar level than it would for a person who is not taking one of these medications.


Few studies have been done on the use of oral medications for type 2 diabetes in children, and these medications have not been approved by the U.S. Food and Drug Administration (FDA) for use in children. But because these oral medications are safe for adults, most health professionals use them to treat children with type 2 diabetes. Also, these medications are not absorbed into the bloodstream and therefore do not have systemic side effects.

However, the increase in abdominal gas associated with their use makes them less desirable than other oral medications for diabetes.

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



  1. Lebowitz HE (2005). Management of hyperglycemia with oral antihyperglycemic agents in type 2 diabetes. In CR Kahn et al., eds., Joslin's Diabetes Mellitus, 14th ed., pp. 687–710. Philadelphia: Lippincott Williams and Wilkins.

Last Updated: June 16, 2008

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