How Do Antidiabetic Biguanides Work?


Antidiabetic biguanides are a class of drugs used with a proper diet and exercise to control high blood sugar in people with type 2 diabetes mellitus (T2DM). T2DM is a long-term medical condition in which the body does not use insulin normally and, therefore, cannot control the amount of sugar in the blood. Controlling high blood sugar helps in preventing kidney damage, blindness, nerve problems, loss of limbs, and sexual function problems and may also reduce the risk of a heart attack or stroke. Biguanides are a group of oral antihyperglycemic drugs that work by preventing the production of glucose in the liver, improving the body’s sensitivity to insulin, and reducing the amount of sugar absorbed by the intestines. The only available biguanide medication is “metformin,” which is commonly used as a first-line treatment for T2DM.

Biguanides are not used to treat insulin-dependent or type 1 diabetes (a condition in which the body does not produce insulin and therefore cannot control the amount of sugar in the blood) and diabetic ketoacidosis (increased ketones in the blood or urine).

Biguanides are available as liquid, tablets, and extended-release (long-acting) tablets. The liquid is taken with meals one or two times a day. The regular tablet is taken with meals two or three times a day, and the extended-release tablet is taken once daily with the evening meal. 

Biguanides work in the following ways:

  • They reduce the production of glucose during digestion by decreasing the amount of glucose absorbed from the food.
  • They prevent the liver from converting fats and amino acids into glucose.
  • They increase the excretion of sugar by the kidneys.
  • They decrease the amount of sugar that the body absorbs through the stomach and intestines.
  • In addition, they activate an enzyme (AMPK) that increases the sensitivity to insulin (a natural substance that controls the amount of glucose in the blood produced by the pancreas), helping cells to respond more effectively to insulin and use more glucose as energy, and thus reducing the concentration of glucose in the bloodstream.


Antidiabetic biguanides are used as an adjunct to diet and exercise to improve glycemic control in adults with T2DM.


Some of the common side effects include:

  • Diarrhea
  • Nausea
  • Vomiting
  • Stomach upset
  • Bloating
  • Frequent urination
  • Dry mouth
  • Weakness
  • Asthenia (abnormal physical weakness or lack of energy)
  • Flatulence (gas)
  • Myalgia (muscle pain)
  • Heartburn (burning pain in the chest)
  • Dyspepsia (feeling of burning, pain, or discomfort in the digestive tract)
  • Unpleasant metallic taste in the mouth

Other rare side effects include:

  • Hypoglycemia (low blood sugar level)
    • Sudden sweating
    • Fast heartbeat
    • Blurred vision
    • Tingling in hands/feet
  • Low serum vitamin B 12
  • Lactic acidosis (increased lactic acid in the bloodstream which is produced when oxygen levels become low in cells within the areas of the body where metabolism occurs)
  • Upper respiratory tract infection
  • Dizziness (feeling faint, weak, or unsteady)
  • Abdominal distention
  • Hyperkalemia (high blood potassium level)
  • Chest pain
  • Necrotizing fasciitis of the perineum (Fournier gangrene is an infection in the scrotum which includes the testicles, penis, or perineum)
  • Female genital mycotic infections (vulvovaginal candidiasis)
  • Dyslipidemia (blood lipid levels that are too high or low)
  • Signs of kidney problems 
  • Change in the amount of urine
  • Swelling in legs/feet
  • Signs of urinary tract infection
  • Burning/painful/frequent/urgent urination
  • Pink/bloody urine

Information contained herein is not intended to cover all possible side effects, precautions, warnings, drug interactions, allergic reactions, or adverse effects. Check with your doctor or pharmacist to make sure these drugs do not cause any harm when you take them along with other medicines. Never stop taking your medication and never change your dose or frequency without consulting your doctor.


Generic and brand names of antidiabetic biguanides include:


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