If the acarbose isn't in your upper intestine when the food is coming in, then it won't slow the breakdown of the starches and sugars. Acarbose should be taken with the first bite of food. Most people take acarbose with each meal. If you often eat large carbohydrate snacks, you may want to check with your doctor to see if you should take acarbose before those snacks. When you start taking acarbose, some of the sugars and starches that aren't broken down make it all the way through the small intestine into the large intestine.
Bacteria feed on the sugars in the large intestine and produce gas.
This gas and sometimes diarrhea are the most common side effects. If you start at a low dose of acarbose, you may not get gas or diarrhea, or these symptoms may be mild. Even if you get symptoms, your gastrointestinal system adapts to acarbose, and symptoms usually improve within a few weeks. It certainly may. Insulin and some diabetes pills are often taken a half hour before a meal.