Starch Blocker

seasoned potatoes

Starch blockers delay starch and sucrose absorption.

This medicine primarily helps lower your after-meal blood sugars.

Starch blockers lowers your blood sugar by delaying how quickly starch and carbohydrate (CHO) are absorbed from your intestines.

Starch Blocker (Acarbose)

Starch blockers inhibit the intestinal digestive enzyme, alpha glucosidase, which slows CHO absorption giving your body more time to handle all the CHO in your meal. This medicine primarily helps lower your after-meal blood sugars. Because it doesn’t reduce the amount of CHO absorbed, the effect on lowering  the  A1c is quite mild. The medicine also is a blood sugar normalizing pill or euglycemic, (drugs that help return the blood sugar to the normal range.)

The main side effect is flatulence (gas). To reduce this effect, the dose of this medicine should be increased slowly, and you should eat a similar amount of CHO day to day at your different meals.

This medicine is rarely used because the reduction of A1c is modest, and most people dislike the side effect of gas. You shouldn’t take these medications if you have intestinal, liver or kidney disease.

In short, a starch blocker delays digestion and absorption of starch and sucrose.

The most common side effects are:

  • Flatulence (Gas)
  • Stomach cramping
  • Diarrhea
  • Low blood sugar, if taken with insulin releasing pills and insulin


If you get a low blood sugar while treated with a starch blocker drug, you have to treat the low with glucose/dextrose pills or milk. The drug blocks the breakdown of table sugar (which is two sugar units hooked together) into single sugar units – so you cannot absorb the glucose into your blood stream!

For more information about starch blocker pill strength (formulations), initial and final doses, side effects, and different starch blocker containing preparations on the market, see our Medications Table.

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