Bile Acid Sequestrants (BASs)

Reviewed by: HU Medical Review Board | Last reviewed: August 2023

Bile acid sequestrants (BASs) are drugs used to help lower cholesterol. But they can also lower blood sugar for people with type 2 diabetes (T2D).

BASs are not usually the first treatment used for T2D. Your doctor may suggest them if your blood sugar is not controlled by other treatments or lifestyle changes. BASs are most useful for people with T2D who also have high cholesterol. Talk to your doctor about the benefits of BASs.

How do bile acid sequestrants work?

Bile acids are a major part of bile. The liver makes bile acids from cholesterol. The acids are then stored in the gallbladder. Bile acids make fats (lipids) soluble in the small intestine so that we can digest them. Most bile acids are recycled back into the liver to be used again. Only about 5 percent are excreted in stool.1

BASs are most often used to treat high cholesterol. They work by soaking up (sequestering) bile acids in the intestines. This increases the excretion of bile acids in stool. To make up for this, the body then makes more bile acids using cholesterol. This lowers the amount of cholesterol in the blood.1,2

We do not yet understand exactly how BASs also lower blood sugar. Some possible explanations include that BASs:1,3

  • Reduce glucose absorption in the intestines
  • Reduce the amount of glucose made by the liver
  • Activate proteins called “bile acid receptors,” which increases the secretion of insulin


In 2008, the US Food and Drug Administration (FDA) approved a BAS called colesevelam (WelChol®) to treat people with T2D. Colesevelam is the only FDA-approved BAS for treating people with T2D.4,5

Other BASs are used to lower cholesterol, but are not yet approved for T2D. These include:5

  • Cholestyramine (Prevalite®)
  • Colestipol (Colestid®)

What are the possible side effects?

Side effects can vary depending on the specific BAS you are taking. BASs are usually safe. Common side effects include:4

  • Constipation
  • Nausea
  • Indigestion (dyspepsia)
  • Increased fat (triglycerides) in the blood

These are not all the possible side effects of BASs. Talk to your doctor about what to expect when taking BASs. You also should call your doctor if you have any changes that concern you when taking BASs.

Other things to know

Use BASs exactly as your doctor prescribes. BASs are usually taken by mouth as a tablet or a powder for oral suspension. They should be taken with meals. Your doctor may start you at a lowest dose and slowly increase the dose. This can lower your risk of side effects.4

BASs should be used with lifestyle changes such as regular exercise and a healthy diet. BASs may also be combined with other T2D drugs. Do not stop taking any medicines without talking to your doctor first.4

Before beginning treatment for T2D, tell your doctor about all your health conditions and any other drugs, vitamins, or supplements you take. This includes over-the-counter drugs.

Before taking BASs, tell your doctor your full medical history. BASs can change how your body absorbs other drugs. Your doctor can suggest how to take other medicines safely. Talk to your doctor about:4

  • Other drugs you take, including over-the-counter drugs and supplements
  • Other medical conditions you have, especially gastroparesis or pancreatitis
  • Any allergies
  • Pregnancy or planned pregnancy

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