Alpha-glucosidase inhibitor

What are alpha-glucosidase inhibitors and how do they work?

The active ingredients from the group of substances known as alpha-glucosidase inhibitors inhibit enzymes in the intestine that break down carbohydrates absorbed with food into glucose. As a result, blood sugar rises only slowly after eating. However, alpha-glucosidase inhibitors have no effect when consuming foods with a high sugar content (lemonade, cola, cake) or even pure glucose, and the blood sugar level rises immediately.

They have no effect on the insulin release of the pancreas. However, long-term studies have not been able to prove a long-term benefit in diabetes or effectiveness against diabetes-related diseases. Only the blood sugar peaks are balanced with both drugs, so that the remaining function of the pancreas still has a chance. More than 30% of the diabetes patients in a study discontinued the drugs due to undesirable and unpleasant effects in the gastrointestinal tract.


Alpha-glucosidase inhibitors, such as acarbose and miglitol, are drugs that deactivate enzyme alpha-glucosidase in the human gut. This enzyme breaks down the sugar that is absorbed with food. As a result, the sugar can no longer be broken down and absorbed as easily.

The rise in blood sugar after a meal is thus delayed or the peak is reduced. In the long term, this also leads to a reduction in fasting blood sugar. To a certain extent, this is a food supplement that should always be taken immediately before a meal.

The alpha-glucosidase inhibitors are mainly used in patients with type 2 diabetes who have developed resistance to the blood sugar-lowering hormone insulin. Alpha-glucosidase inhibitors can also be used to prevent the development of diabetes. Since alpha-glucosidase inhibitors are rather weakly effective drugs, they should always be combined with a diet appropriate to the diabetes. As a rule, they are used in addition to other drugs, e.g. sulfonylureas.


At the beginning of therapy with alpha-glucosidase inhibitors, one should start with a low dose, which can be increased according to need and tolerance. The two most common inhibitors, acarbose and miglitol, are available in the form of divisible tablets of 100mg each. One can start with 50mg three times a day.

After a few weeks the dose can be doubled if well tolerated. Sensitive patients should start with 50mg twice daily. The dose should be increased carefully. The tablets should be taken regularly before meals, as they only have an effect on the meal taken afterwards. Overdosage can lead to diarrhoea and severe flatulence.

Side effects

The alpha-glucosidase inhibitors slow down the intestinal enzyme that digests carbohydrates. Instead, the carbohydrates remaining in the intestine are split by bacteria in the colon. In the process, gases develop which inflate the intestine and lead to unwanted wind blowing out.

In addition, the enzyme inhibition leads to lively bowel sounds and diarrhoea. In more than 50% of those treated, such “side effects” occur and often lead to an arbitrary discontinuation of the medication. Alpha-glucosidase inhibitors are broken down by the liver and can impair liver function. Your doctor should therefore check your liver values in a blood test every 3 months. If you feel unwell after taking alpha-glucosidase inhibitors, or if you experience nausea, vomiting, or yellowing of the eyes or skin, you should see your doctor immediately to check your liver.