Pharmacology · Other glucose-lowering drugs
Acarbose !
An oral drug that slows carbohydrate digestion in the gut, so glucose rises less after meals. Flatulence is the usual complaint.
Updated 2026-11-01
The figure shows acarbose (an oligosaccharide) in the active site of the N-terminal half of human maltase-glucoamylase.
Mechanism of action
Acarbose is a pseudo-oligosaccharide that competitively inhibits the brush-border alpha-glucosidases and pancreatic alpha-amylase. Starch, maltose and sucrose are split into glucose more slowly, so absorption moves further down the small intestine and the glucose peak after meals is lower. Undigested carbohydrate reaches the colon and is fermented by bacteria.
- Blocks alpha-glucosidases on the intestinal brush border
- Starch and sucrose are split into glucose more slowly
- The glucose peak after meals is lower
- Leftover carbohydrate ferments in the colon: gas
Pharmacokinetics
- Absorption
- Very little absorbed as active drug; it acts in the gut lumen.
- Metabolism
- Broken down in the gut by bacteria and digestive enzymes.
Indications
- Type 2 diabetes, with diet and exercise, mainly to lower glucose after meals Type 2 diabetes mellitus →
Adverse effects
Common
- Flatulence, bloating, abdominal pain
- Diarrhea
Contraindications
- Diabetic ketoacidosis
- Cirrhosis
- Inflammatory bowel disease, colonic ulceration
- Partial intestinal obstruction or predisposition to it
- Hypersensitivity to acarbose
Key interactions
- Insulin or sulfonylureas
- Hypoglycemia possible; it is treated with glucose (dextrose), not sucrose.
- Intestinal adsorbents (charcoal) and digestive enzyme preparations
- Can reduce the effect of acarbose.
- Digoxin
- Its absorption may change; levels are checked.
What is monitored
- Glucose after meals and HbA1c
- Liver enzymes
Administration and safety
- Oral tablet with the first bite of each main meal.
- Glucose tablets or gel are kept at hand if the patient also uses insulin or a sulfonylurea.
Nursing care
- Before: history of bowel disease, cirrhosis, obstruction.
- During: gas and diarrhea, which usually lessen with time.
- Teach: treat lows with glucose, not table sugar or juice with sucrose.
Pregnancy and breastfeeding
Safety in pregnancy has not been established; insulin is the usual choice.
Test yourself
Think of the answer, then tap the question to see it.
Where does acarbose act?
In the lumen of the small intestine, on brush-border alpha-glucosidases; very little enters the blood.
Why does acarbose cause flatulence?
Carbohydrate that is not digested in time reaches the colon, where bacteria ferment it and produce gas.
Name one bowel condition in which acarbose is contraindicated?
Inflammatory bowel disease (also colonic ulceration or intestinal obstruction).
Related drugs
Related conditions
← Back to the class: Other glucose-lowering drugs
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: Acarbose: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2026); DailyMed - ACARBOSE tablet (DailyMed (U.S. National Library of Medicine), 2026); Crystral Structure of the N-terminal Subunit of Human Maltase-Glucoamylase in Complex with Acarbose (RCSB Protein Data Bank, 2008); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026).
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Representative model, for educational purposes only.