Diabetes can affect any part of the digestive system. Over time, persistently high blood sugar levels can lead to damage that results in a range of symptoms, including diarrhea in some cases.

It’s unclear why this happens. Nerve damage, medication, and other factors may play a role.

About 20% of people with diabetes experience diarrhea. Those with diabetes are more likely to have diarrhea than those without diabetes.

Diabetes occurs when your body can’t produce or use the hormone insulin effectively. Your pancreas releases insulin when you eat. It allows your cells to absorb sugar from food to make energy. If your body can’t use or absorb this sugar, it builds up in your blood, leading to high blood sugar levels.

Diarrhea may be persistent, or it may alternate with periods of regular bowel movements. It may also alternate with constipation.

Diabetes and constipation: What’s the connection?

The connection between diabetes and diarrhea isn’t clear. Research suggests the following factors may play a role:

  • Celiac disease and microscopic colitis: People with diabetes appear to have a higher risk of these conditions. The only symptom may be diarrhea.
  • Sugar-free sweeteners and other ingredients: Consuming these products may increase the risk of diarrhea. Sorbitol, mannitol, and xylitol, for example, can have a laxative effect.
  • Neuropathy: High blood sugar levels can lead to nerve damage. If this affects the nerves of the small intestine, it can lead to diarrhea, especially at night. Neuropathy can also affect anorectal function, making fecal incontinence more likely.
  • Pancreatic function: Diabetes affects how the pancreas works. This can lead to gastrointestinal disturbances. People with diabetes are two to four times more likely to experience pancreatitis, for instance, than those without diabetes. Diarrhea is a symptom of pancreatitis.
  • Diabetic enteropathy: This is a condition that affects the large intestine. It can cause diarrhea, constipation, and fecal incontinence. It’s more likely to occur in people with diabetes than those without.
  • Diabetes medication: Metformin, statins, and other drugs you might be taking for diabetes and related conditions can affect how your intestines work. Research suggests 15% to 24% of people who take metformin may have diarrhea.
  • Bacterial overgrowth: This happens when certain types of bacteria become too plentiful in the gut. It can occur with diabetic enteropathy.

People with diabetes can also have the same causes of diarrhea as people without diabetes, such as:

  • allergies and food intolerances, such as to dairy and fructose
  • long-term use of antibiotics, which can affect the makeup of the gut microbiota
  • medications, such as antacids containing magnesium and some cancer therapies

Diarrhea is more likely to affect people with type 1 diabetes than type 2. This may be due to longer-term exposure to high blood sugar levels.

Diabetes that’s difficult to manage may also have a higher risk of diarrhea. Persistently high glucose levels increase the risk of nerve damage and other complications of diabetes.

People with diabetes who have complications and related disorders — such as neuropathy, obesity, and pancreatic problems — have a higher risk of experiencing diarrhea.

Older adults with diabetes may experience frequent diarrhea more often. This is because the likelihood of diarrhea increases for people with a long history of diabetes.

Contact a doctor if you’re experiencing frequent diarrhea. They’ll look at your health profile and assess your blood sugar levels. They may also perform a brief physical exam to help rule out any other medical conditions.

Before you start a new medication or another treatment regimen, your doctor will want to be sure you’re not experiencing any other gastrointestinal issues.

Treatment can vary. The most important factor is to manage blood sugar levels. Medications and other approaches can help reduce symptoms and the likelihood of diarrhea from other factors.

To manage diarrhea, your doctor may recommend:

  • consuming less of the sweetener sorbitol
  • taking loperamide (Imodium) before meals to manage symptoms
  • taking clonidine (Kapvay) to regulate bowel movements and reduce spasms
  • taking amitriptyline to reduce cramping and slow digestion
  • practicing pelvic floor training, and possibly getting a colostomy, for people with fecal incontinence

Depending on their assessment, your doctor may refer you to a gut specialist called a gastroenterologist for further investigation.

How do you fix diabetic diarrhea?

It may not be possible to prevent diarrhea with diabetes, but managing blood sugar levels can help reduce the risk in the long term.

Limiting or avoiding artificial sweeteners, such as sorbitol, may help. A doctor can also prescribe medications, such as loperamide (Imodium), to help manage symptoms.

How long does diabetic diarrhea last?

People with diabetes have a higher risk of chronic or persistent diarrhea. It may last from several weeks to several months, but treatment can help manage it.

What should you eat if you have diarrhea with diabetes?

If you have diarrhea with diabetes, avoid artificial sweeteners, such as sorbitol, to see whether it helps. Drinking plenty of fluids, particularly water, can prevent dehydration from diarrhea.

Some research suggests the probiotics Lactobacillus and Bifidobacterium may help, too, but more studies are needed to confirm this.

Ask a doctor before making any major dietary changes. They can make sure doing so won’t interfere with other treatments or worsen other symptoms.

Gastrointestinal problems, including persistent diarrhea, are fairly common with diabetes.

Experts don’t know exactly why this happens, but it may be due to damage caused by high blood sugar levels. The use of some medications, such as metformin, may also contribute.

Talk with a doctor if you have diarrhea with diabetes. They can help you find ways to manage the symptoms. They may suggest avoiding artificial sweeteners and using loperamide to make the passage of food more regular.