Alpha-glucosidase inhibitors (AGIs) are antidiabetic agents used to lower glucose (blood sugar) in patients with type 2 diabetes. These drugs block enzymes in the digestive tract from breaking down complex carbohydrates from food into glucose. This slows the absorption of sugars into the small intestine and bloodstream, keeping glucose levels lower throughout the day.  

These medications can be prescribed when meal planning, weight loss and exercise alone are not effective in controlling type 2 diabetes. AGIs are especially helpful for patients whose blood glucose levels are slightly above normal. They may not be as helpful for those whose diabetes is more severe, unless they are used in combination with another antidiabetic agent or insulin.

Alpha-glucosidase inhibitors can also benefit those who have high blood glucose right after they eat, a condition known as postprandial hyperglycemia. By slowing the rate at which complex carbohydrates are broken down into sugars in the digestive tract, these drugs lengthen the digestive process. This prevents these sugars from rushing into the bloodstream and causing an unhealthy rise in blood glucose levels.

Other antidiabetic agents, including sulfonylureas and biguanides, and insulin sometimes are prescribed in combination with AGIs to help increase the effectiveness of this therapy. After adding an AGI to their treatment regimen, people who take insulin are usually able to lower their insulin dosage, as advised by their physician. The primary side effects of AGIS are gastrointestinal, such as gas and diarrhea, and they may not be advised for some patients, such as those with digestive disorders.

AGIs are also being studied as a possible treatment for heart disease, a common complication in diabetic individuals.