Diabetes is the most common known cause of gastroparesis, a digestive disorder that may lead to poor nutrition, problems managing blood glucose, and a reduced quality of life. Here, Dr. Adil E. Bharucha—one of the authors of the chapter, “Gastrointestinal Manifestations of Diabetes,” in the NIDDK publication Diabetes in America, 3rd Edition—discusses how health care professionals can diagnose and treat gastroparesis in patients with diabetes.

Q: What is gastroparesis? How common is gastroparesis in people who have type 1 or type 2 diabetes?

A: Gastroparesis is a condition in which the muscles in the wall of the stomach work poorly or don’t work at all, slowing or delaying the rate at which food empties from the stomach to the intestine. This is called delayed gastric emptying. In gastroparesis, gastric emptying is delayed because the muscles don't work effectively, not because a blockage prevents food from moving from the stomach to the intestine.

While delayed gastric emptying is relatively common in people with type 1 or type 2 diabetes—affecting up to half of this population in some studies—a diagnosis of gastroparesis requires both delayed gastric emptying and moderate to severe digestive symptoms, such as feeling full shortly after starting a meal, nausea or vomiting, abdominal pain, or bloating. Based on this definition, gastroparesis is uncommon.

In one study, over a period of 10 years, about 5% of people with type 1 diabetes and about 1% of people with type 2 diabetes developed gastroparesis. Less than 1% of people without diabetes developed gastroparesis during the study.

Q: In people with diabetes, what is the relationship between gastroparesis and blood glucose levels?

A: There is a two-way relationship between blood glucose and stomach emptying—that is, blood glucose levels affect stomach functions, and vice versa. Some studies suggest that high blood glucose levels increase the risk for gastroparesis. Conversely, gastroparesis may make it difficult for some people with diabetes to manage their blood glucose levels.

That said, there are several unanswered questions about the relationship between blood glucose and stomach emptying, and research is ongoing in this area.

Q: When should health care professionals suspect that a patient with diabetes has gastroparesis?

A: It is important for health care professionals to ask people with diabetes whether they have some of the digestive symptoms of gastroparesis, such as

• the feeling of fullness shortly after starting to eat a meal

• the inability to complete a regular meal

• a sense of fullness that persists long after completing a meal

• other symptoms such as abdominal pain, nausea, bloating, vomiting, heartburn, and a lack of appetite

In some studies, up to 50% of people with diabetes have delayed gastric emptying, but most of these people have no digestive symptoms or have only mild symptoms. In some patients, problems managing blood glucose levels may be a sign of delayed gastric emptying. Health care professionals might consider assessing stomach emptying in patients who have problems managing their diabetes.

People who have diabetes and diabetes-related complications—such as a peripheral or autonomic neuropathy, retinopathy, or nephropathy—have a greater likelihood of having stomach complications. However, people without other diabetes-related complications may also develop delayed gastric emptying. So, health care professionals can’t rely on the presence or absence of these complications to effectively determine whether patients have delayed gastric emptying.

Q: How is gastroparesis diagnosed?

A: Health care professionals can’t diagnose gastroparesis based on symptoms alone. A gastric emptying study—using gastric emptying scintigraphy, a gastric emptying breath test, or a wireless motility capsule—is necessary to determine whether the stomach empties normally, slowly, or rapidly. If a gastric emptying study shows that the stomach empties slowly, health care professionals may need to order an upper gastrointestinal (GI) endoscopy to make sure nothing is physically blocking the movement of food from the stomach to the small intestine.

Q: How does gastroparesis affect health and quality of life?

A: Many people with gastroparesis feel uncomfortable, have severe nausea, or vomit after eating. These symptoms can be devastating to some patients. Most people with gastroparesis tend to consume less nutrients than they need. So, gastroparesis can markedly impair a person’s quality of life.

Q: What are the treatment options for gastroparesis?

A: Treatment typically starts with making changes to a patient's diet, which is often effective. Changes include

• limiting fat intake to 25% to 30% of total calories

• limiting fiber intake to 15 grams for every 1,000 calories consumed

• eating foods like mashed potatoes that are easy to mash with a fork into small particles

If changing a patient’s diet doesn’t work, health care professionals can recommend medicines to reduce nausea or improve gastric emptying. Health care professionals should also review the list of medicines a patient is taking and, if possible, discontinue medicines that might delay stomach emptying, especially opioids.

To help prevent high or low blood glucose levels in patients with diabetes and gastroparesis, health care professionals may recommend changes in how patients manage their diabetes, including changes in how they take insulin or other diabetes medicines. Typically, people take a dose of regular insulin 15 to 20 minutes before a meal. With that timing, the insulin should be effective when food empties from the stomach, nutrients are absorbed, and glucose enters the blood stream. However, if the stomach empties slowly and the nutrients take longer to be absorbed, the insulin may begin to exert its effect before glucose enters the bloodstream.

Q: What research is being conducted on gastroparesis in people who have diabetes?

A: Exciting, ongoing research studies are investigating why people with diabetes develop gastroparesis. For example, some studies are investigating whether immune cells called macrophages might injure the stomach muscles and delay stomach emptying in people with diabetes. Understanding the process by which macrophages injure stomach muscles could lead to new treatments that address that process.

My research group is evaluating whether epigenetic changes—that is, changes that affect the expression of genes, not the genes themselves—might affect stomach emptying in people with diabetes. Several drugs that are safe and approved for use in humans may affect these epigenetic changes, and these drugs are undergoing clinical trials.

How do you check for and manage gastroparesis in patients who have diabetes? Tell us below in the comments.