Drug Review: Alpha-Glucosidase Inhibitors (acarbose and miglitol)

acarbose and miglitol for type 2 diabetesAlpha-glucosidase inhibitors (AGIs) available in the U.S. are acarbose (Precose) and miglitol (Glyset).  Drug names vary by country and manufacturer. 

This is only a brief review: consult your physician or pharmacist for full details.

How do they work?

Many of the carbohydrates we eat are just basic sugar molecules joined to each other by chemical bonds, creating disaccherides, oligosaccharides, and polysaccharides.  This is as true for bread and potatoes as it is for table sugar.  To digest and absorb them, we have to break them down into the basic sugar molecules (monosaccharides).  AGIs inhibit this breakdown process inside our intestine, decreasing the rise in blood sugar after we eat complex carbohydrates.  They delay glucose absorption.  So AGIs mainly decrease after-meal glucose levels.     


They work alone or in combination with other diabetic medications, especially if the diet contains over 50% of energy in the form of complex carbohydrates.  They are FDA-approved only for use in type 2 diabetes, but they have also been used in type 1. 


The starting dose is the same for both:  25 mg by mouth three times daily with the first bite of each main meal.

Side effects

Belly pain, intestinal gas, diarrhea.  Slight risk of hypoglycemia when its used alone; higher risk when used with insulin shots or insulin secretagogues.  If hypoglycemia occurs, you have to eat glucose to counteract it, not your usual non-glucose items because you won’t absorb them properly.   

Don’t use if you have . . .

. . . Liver cirrhosis (refers to acarbose: miglitol can be used), kidney impairment, or intestinal problems.

Steve Parker, M.D.


Filed under Drugs for Diabetes

3 responses to “Drug Review: Alpha-Glucosidase Inhibitors (acarbose and miglitol)

  1. Are the alpha glucosidase inhibitors used much? I figured they were used infrequently at best.

  2. derringer

    i can not tolerate drugs. after taking lantase i can tolerate no drugs.
    my fasting is 350.
    what can i do.
    will Miglitol help. i can not tolerate acarbose