Navigating the Overlap: The Connection Between Diabetes and IBS and How to Manage Both

Do you have Irritable Bowel Syndrome (IBS)? Have you also been diagnosed with type 2 diabetes or prediabetes? Furthermore, you might be thinking that these conditions are completely unrelated. In this article, you’ll learn more about the connection between the two conditions and how dietary changes can help you to manage both.

Firstly, both are highly prevalent in the population, for instance, diabetes affects around 4% of Australians and IBS affects around 15%. Managing two chronic diseases at the same time can be overwhelming! If you need help with meal planning, reducing symptoms and improving your blood sugars, consider working with a specialized dietitian. Registered Dietitians are regulated health professionals and are the experts in nutrition care and medical nutrition therapy.

Understanding IBS and Diabetes

What is IBS?

IBS is a chronic, functional gut disorder characterized by abdominal pain or discomfort along with a range of other symptoms, including bloating, diarrhea, constipation, or alternating episodes of both. IBS is one of the most commonly diagnosed diseases that affect the digestive tract. It is also known as IBC colitis, spastic colon, nervous colon, and spastic bowel.

IBS is defined by a group of symptoms that can occur together but don’t cause any visible signs of damage or disease to the gastrointestinal system.

Common symptoms of IBS include:

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• Diarrhea
• Constipation
• Pain in the stomach
• Changes in bowel movements
• Bloating
• Whitish mucus in your stool
• Feeling like you haven’t finished a bowel movement

If you’re experiencing symptoms of IBS, it’s important to reach out to your healthcare provider. The diagnosis can sometimes involve several steps, including a review of your symptoms, health and family histories, a physical exam, and certain lab tests.

What is Diabetes?

Diabetes is a chronic disease that occurs when an individual’s blood glucose, aka blood sugars, are too high. Glucose is a source of energy for our bodies, which we get both from the food we eat, as well as through some production by our bodies. Diabetes occurs due to an issue with the hormone insulin, which acts like a gatekeeper for blood sugar into our cells. In diabetes, the pancreas either does not produce enough insulin, or our cells become ‘resistant’ to insulin and stop letting sugar in. Hence, the sugar builds up in our blood.

• Type 1 Diabetes: In Type 1 diabetes, the pancreas makes little or no insulin. It is an autoimmune condition where the body attacks its own pancreas cells. People with type 1 diabetes must take insulin daily to stay alive.
• Type 2 Diabetes: In type 2 diabetes, the most common form, the pancreas may still make insulin, however the cells have become resistant to insulin. Type 2 diabetes is considered a ‘lifestyle disease’, meaning it can be prevented through diet and lifestyle.
• Prediabetes: In prediabetes, an individual’s blood sugar averages are higher than normal, however not yet high enough to be considered diabetes.
• Gestational diabetes: Gestational diabetes occurs during pregnancy, and often goes away after delivery.

The Connection Between IBS and Diabetes

At first glance, it might not seem that IBS, a condition that affects the digestive system, and diabetes, a metabolic disease, have anything in common. But both connections can affect the GI tract and cause similar symptoms. Though one condition does not cause the other, some people can be affected by both IBS and diabetes at the same time. If you have diabetes, IBS symptoms like diarrhea, constipation, and bloating could mean that blood sugars are not under control. Long-term, this can lead to nerve damage in the GI tract. However, these symptoms could also be tied to eating certain foods, consuming sugar alcohols, or taking certain diabetes medications, such as metformin.

Over time, diabetes can affect the structure and function of the colon, which can cause GI symptoms, including constipation, diarrhea, and stomach pain. According to one article published in American Family Physician, GI complications of diabetes have become more common as the rate of diabetes has increased in recent years.

Overlapping Symptoms

Overlapping symptoms of IBS and diabetes can include:

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• Constipation
• Diarrhea
• Stomach pain
• Bloating

How Diabetes Affects the Bowels

Diabetes can affect the structure and function of the bowels and research shows that people with diabetes are at a higher risk of certain bowel disorders, including:

• Chronic constipation
• Enteropathic diarrhea
• Colorectal cancer
• Inflammatory bowel disease (IBD)
• Microscopic colitis
• Clostridium difficile colitis

The Role of Nerve Damage

Over time, high blood sugar from diabetes can cause damage to the nerves, called neuropathy, in the gastrointestinal tract. This can impair your brain’s ability to communicate with your gut. The damage can cause a slowing down or speeding up of intestinal function, leading to either constipation or diarrhea - common symptoms of IBS.

There are other ways that high blood sugar can lead to gastrointestinal symptoms:

• High blood sugar may slow down the emptying of the stomach, leading to fullness, nausea, and bloating.
• People with diabetes are at a higher risk of developing yeast infections in the GI tract or bacterial overgrowth.
• Diabetes makes it harder to properly break down sugars in the small intestine.
• A serious complication of diabetes known as ketoacidosis can cause stomach pain.
• Nerve damage in the esophagus may cause heartburn and make it difficult for you to swallow.
• People with type 1 diabetes have a higher risk of a condition called celiac disease. People with this condition can’t tolerate gluten, a protein found in wheat, rye, and barley. Eating gluten can cause GI symptoms, such as diarrhea.

The Gut Microbiome Connection

Much research has been done on the connection between the gut microbes and insulin resistance, although not as much has been done on IBS and diabetes specifically. Development of diabetes and IBS are both categorized with low grade inflammation. Inflammation is our bodies natural response to a foreign invader or pathogen. However, chronic inflammation can occur when the immune system is overstimulated all the time.

It turns out that certain types of microbes in your gut can impact insulin sensitivity, and therefore may impact risk of type 2 diabetes and/or management. The gut microbiome is gaining recognition as a potential contributor to metabolic diseases, including obesity and type 2 diabetes. Obesity has been linked to an increase in Firmicutes and Actinobacteria, and a decrease in Bacteroidetes in the host’s microbiome.

Read also: The Ultimate Guide to Heart and Diabetes Diet

As we’ve discussed, the health of your microbiome may impact your body’s ability to metabolize sugar (aka insulin sensitivity).

Gastroparesis

Gastroparesis is a digestive condition characterized by delayed gastric emptying. This means that food stays in the stomach for too long rather than moving into the small intestine to be digested further. Diabetes is the leading cause of gastroparesis. High blood sugar from diabetes can damage the vagus nerve - the nerve that connects the brain to the gastrointestinal tract.

When this happens, the vagus nerve can no longer send messages that tell the stomach muscles to empty the stomach.

Symptoms of gastroparesis include:

• Nausea
• Reduced appetite
• Feeling full after eating small amounts of food
• Vomiting
• Stomach pain
• Heartburn

Metformin and GI Issues

Metformin is the most widely used oral type 2 diabetes medication. People newly diagnosed with type 2 diabetes are often prescribed metformin to manage their blood sugar.

Some people who start taking metformin experience side effects in the digestive tract like diarrhea, nausea, and abdominal pain. These symptoms typically go away over time as the body adjusts to the medication. You can reduce these effects by taking metformin with a meal.

Managing IBS with Diabetes

If you’ve been diagnosed with IBS, there are several treatment suggestions your healthcare provider can make that won’t affect your diabetes treatment.

Common treatment strategies for IBS include:

• Dietary changes
• Lifestyle changes (including increasing physical activity and reducing stress)
• Medicines
• Probiotics
• Mental health therapy

Dietary Changes

More research is needed to determine which dietary modifications are most effective at treating or relieving IBS. However, recommendations from the ACG may also support dietary changes recommended for the management of diabetes.

• Increase in soluble fiber intake: The ACG recommends increasing your intake of soluble fiber to treat IBS symptoms. Soluble fiber helps to draw water to the digestive tract and slow digestion. Foods that are high in soluble fiber include oat bran, barley, nuts, seeds, beans, lentils, peas, and some fruits (including apples, strawberries, and citrus) and many vegetables.
• Try a low FODMAP diet: You may consider working with a healthcare provider or registered dietitian to try a limited FODMAP diet to see whether or not it helps to alleviate your symptoms. There are many foods that are low in FODMAPs, including bell peppers, bok choy, blueberries, kiwi, meat, poultry, almond milk, eggs, peanuts, and flours made from corn, potato, rice, oats, quinoa, or spelt.

Getting enough fiber is essential for maintaining healthy blood sugar balance, as well as a healthy gut microbiome.

Navigating the Low FODMAP Diet

Many ‘sugar-free’ ‘keto’ and ‘low carb’ products (bars, chocolates, snacks) are often high FODMAP due to the use of sugar alcohols like xylitol, maltitol, isomalt, sorbitol, and mannitol. Furthermore, as per 2023 World Health Organization Guidelines use of Non-Nutritive Sweeteners (aka NNS, or calorie-free sweeteners such as acesulfame K, aspartame, cyclamates, neotame, saccharin, sucralose, stevia) may not actually help with weight control and could potentially increase the risk of type 2 diabetes and obesity longer term.

Look for products without added sweeteners and low in added sugars: For cereals and bars, aim for under 8 grams per serving. White sugar, maple syrup and cane sugar are low FODMAP, but use them sparingly.

Carbohydrate Choices

Let’s start with the carbohydrate foods (breads, cereals, fruit, vegetables, pulses and dairy). But all carbohydrate foods are not equal.

• Fruit: All low FODMAP fruits are healthy and fine for diabetes management. Include 2 serves of low FODMAP fruit each day (most Australians get in only half this amount). One serve is around 150g fruit (e.g. 1 medium orange or banana, ~10 strawberries, 1 cup of grapes or 2 small kiwifruit); Limit fruit juice and dried fruit, most of which are high FODMAP anyway.
• Vegetables: All low FODMAP vegies are fine for people with diabetes. They’re healthy and naturally low in kilojoules, high in fibre, and packed full of vitamins, minerals and antioxidants. Include 5 serves of low FODMAP vegies per day (most Australians get less than half this amount!). One serve is around 75g of cooked vegetables (e.g. ½ cup cooked carrot, corn or zucchini); 1 cup of salad vegetables (e.g. lettuce) or ½ a medium starchy vegetables (e.g.
• Breads and cereals: Some low FODMAP breads and cereals are better than others. Best choices are higher fibre, whole grain varieties. Include 4-6 serves of low FODMAP bread and cereal foods each day (have a look at our app to see what we mean by one serve) Look for the words whole grain or wholemeal on the packaging. Whole grain foods are healthier because they are higher in fibre, vitamins, minerals and antioxidants whereas much of this goodness is lost through processing in refined grains (e.g.
• Dairy or alternatives: Low fat varieties are best and if you are lactose intolerant, use lactose free varieties.
• Legumes: As healthy as legumes are (e.g. cannellini beans, lentils, split peas and borlotti beans), they are also high in FODMAPs. Fortunately, there are lower FODMAP varieties such as canned chickpeas (1/4 cup) and canned lentils (1/2 cup). Best tip is to include low FODMAP legumes, on most days, in small quantities.

Additional Dietary Tips

• Spacing out meals: Spacing out meals is helpful for both digestion and absorption, as well as supporting stable blood sugar levels. Aim to eat every 3-4 hours as hungry during the daytime. It is also helpful to eat during the daytime hours, rather than early morning or late evening for both digestive health as well as metabolic health.
• Fermented foods: Fermented foods are pretty amazing! We know you all are wondering about intermittent fasting (IF). We can’t talk about diabetes without some mention of this very trendy diet pattern! Here’s the honest scoop - the research on intermittent fasting for glycemic control in type 2 diabetes is controversial. It has been shown in recent systematic reviews to help with weight loss in those with type 2 diabetes when compared with a standard diet. When it comes to IBS, we know that larger portion sizes and frequent eating can be a trigger for digestive symptoms. When it comes to eating windows and meal timings, what we’ve seen is likely best is to try to eat your meals during the daylight hours when your digestive system is most metabolically active (as it works on a ‘diurnal pattern’). Aim to eat in a similar pattern each day, and try to avoid early morning or late night eating.
• If you have diarrhea: If you tend to have diarrhea as a result of IBS or diabetes, you may want to reduce the amount of soluble fiber in your diet. Soluble fiber is found in foods such as: oats, bananas, carrots, apples, barley.
• If you have constipation: If you tend to get constipated as a result of IBS or diabetes, you may want to increase your intake of insoluble fiber, which is found in foods like: whole grains, wheat bran, cereals, nuts, potatoes.
• Foods to avoid: Many people with IBS experience symptoms when they eat certain types of vegetables called cruciferous vegetables. Examples include: broccoli, Brussels sprouts, cabbage, cauliflower. Legumes, such as beans, may also trigger symptoms of IBS, though this isn’t true for everyone. You may need to keep a food diary to track which foods trigger your symptoms.
• Be careful with sugar substitutes: Many people with diabetes try to limit their sugar intake, so they instead opt for sugar substitutes. Unfortunately, many of these are linked to GI symptoms and may need to be avoided if you have both diabetes and IBS. Sorbitol and xylitol are two sugar substitutes that have been linked to GI symptoms. A good substitute for people with IBS and diabetes is a natural sweetener known as stevia.

Lifestyle Changes

You may be able to alleviate symptoms of both diabetes and IBS by making the following changes to your diet and lifestyle:

• Avoiding processed foods

• Avoiding foods high in sugar

• Increasing fiber intake

• Avoiding alcohol

• Adapting to a special eating plan known as a low FODMAP diet

• Increasing physical activity

• Reducing stress

• Walking: Walking after meals has been shown to improve glycemic control and boost insulin sensitivity.

• Sleep hygiene: Poor sleep has been linked with insulin resistance. We also know sleep is essential for digestive function and motility.

• Stress management: Stress causes a rise in our cortisol levels, a hormone which naturally increases blood sugars. High stress can also be a trigger for IBS flare-ups due to its effect on down regulating the ‘parasympathetic’ nervous system (aka deprioritizing our rest and digest response).

Medications

• Antimotility agents: These medicines help to slow down the digestive process and reduce the loss of fluid and electrolytes.
• Fiber supplements: If increasing your intake of soluble fiber from foods doesn’t help to increase the frequency and consistency of your bowel movements, you may consider adding a fiber supplement into your diet.
• Laxatives: Some laxatives may help to increase the frequency of your bowel movements, including products that contain polyethylene glycol (PEG), like Miralax. However, not all laxatives are safe for long-term use. Consult with your healthcare provider about which laxatives are safest to use for IBS and for how long they recommend using the product.
• Medications used to relieve constipation: These medications include lubiprostone (Amitiza), linaclotide (Linzess), and plecanatide (Trulance). All three are available by prescription only and will require a prior consultation with your healthcare provider or pharmacist.

Probiotics

Research on the effectiveness of probiotics when treating IBS-D is mixed, but data from one study following people with IBS for 4 weeks found that treatment with the probiotic Bifidobacterium infantis may help to alleviate diarrhea symptoms and improve overall bowel movements.

Additional Considerations

• IBS may make it difficult for your body to digest food at a normal rate. Because of this, blood sugar levels may be unpredictable after a meal. Checking your blood sugar levels before and after a meal can help you determine how your body responds.
• Both constipation, which is too few bowel movements, and diarrhea, which is frequent, loose bowel movements, are common in people with diabetes. It’s estimated that around 20 percent of people with diabetes experience frequent diarrhea, while up to 60 percent of people with diabetes experience constipation.
• Fecal incontinence, a loss of bowel control, may also occur in people with diabetes.

When to Seek Medical Advice

You should see your doctor if you’re experiencing frequent diarrhea or constipation or both, or you’re having trouble managing your blood sugar levels with diet, exercise, and medications. A medical professional will want to know about your symptoms and any medications that you’re taking.

tags: #diabetes #IBS #diet #connection