What Should a Diabetic Eat When They Have Diarrhea?

When diarrhea hits and you have diabetes, the priority shifts to two things at once: replacing lost fluids and electrolytes while keeping blood sugar from swinging wildly in either direction. Standard oral rehydration solutions, including those containing glucose, are safe for people with diabetes experiencing acute diarrhea and do not cause dangerous blood sugar spikes. But beyond rehydration, the food choices that settle your gut and stabilize glucose require more thought than the generic “BRAT diet” advice most people encounter.

Hydration Comes First

Diarrhea drains water and electrolytes fast. For someone with diabetes, dehydration is especially dangerous because it can concentrate blood sugar, making hyperglycemia worse and potentially triggering a medical emergency. Replacing fluids is the single most important step before worrying about solid food.

A study of diabetic patients with acute diarrhea and some dehydration found no significant differences in blood glucose concentrations, stool output, or recovery time among groups given oral rehydration solutions containing glucose, rice powder, or glycine. All three formulations were safely administered without destabilizing blood sugar.¹ That means standard pharmacy-bought oral rehydration solutions are a solid first choice. You don’t need to hunt for a special sugar-free version, though if you prefer one with lower glucose, that’s fine too.

Beyond prepared rehydration solutions, clear broths, diluted electrolyte drinks, and water with a pinch of salt work well in milder cases. Avoid sugary sodas and full-strength fruit juices, which can worsen diarrhea through osmotic pull and spike your glucose at the same time. Sipping small amounts frequently tends to stay down better than gulping large volumes.

Foods That Help Without Spiking Blood Sugar

Once you can tolerate something beyond fluids, the goal is bland, low-fiber foods that are easy on the gut while not sending glucose through the roof. The classic approach of bananas, rice, applesauce, and toast gets mentioned constantly, but for someone with diabetes, that lineup is almost entirely fast-acting carbohydrate. You can adapt it.

White rice and plain toast are reasonable in small portions because they’re low in fiber and gentle on an irritated gut. Pair them with a modest source of protein to slow glucose absorption. Plain scrambled eggs, skinless poached chicken, or a small serving of low-fat cottage cheese can fill that role. Bananas are helpful because they’re high in potassium, which diarrhea depletes, but a whole banana is roughly 25 grams of carbohydrate, so half a banana at a time is a practical compromise.

Applesauce is trickier. Unsweetened applesauce contains pectin, a soluble fiber that can help firm up stools, but sweetened varieties add unnecessary sugar. Check the label and choose versions with no added sugar. Plain oatmeal cooked with water, allowed to cool slightly so it thickens, is another source of soluble fiber that tends to be well tolerated and produces a slower glucose rise than white bread.

Foods to avoid until your gut settles include anything greasy or fried, high-fiber raw vegetables, whole grains with lots of insoluble fiber, dairy (which many people tolerate poorly during GI illness), spicy dishes, and caffeine. These can all accelerate motility or irritate an already inflamed intestinal lining.

Sugar Alcohols Can Make Things Worse

Many “sugar-free” or “diabetic-friendly” products contain sugar alcohols like sorbitol, xylitol, mannitol, or maltitol. These sweeteners are popular in sugar-free candies, protein bars, and some diabetic snack foods. Here’s the problem: sugar alcohols are poorly absorbed in the small intestine, and when they reach the colon, they draw water in by osmosis. In unaccustomed individuals especially, this causes bloating, gas, and diarrhea.²

If you already have diarrhea and reach for a sugar-free snack thinking it’s safer for your blood sugar, you could be adding fuel to the fire. Check ingredient labels for anything ending in “-ol” (sorbitol, xylitol, erythritol, maltitol, mannitol) and avoid those products until you’re fully recovered. Erythritol tends to be better tolerated than the others because more of it gets absorbed before reaching the colon, but during an active bout of diarrhea, even that mild osmotic effect isn’t worth the risk.

Artificial Sweeteners Deserve Caution Too

Beyond sugar alcohols, some zero-calorie artificial sweeteners may also contribute to gut trouble. Lab studies have found that sucralose, aspartame, and saccharin can disrupt the tight junctions between intestinal cells at the molecular level, increasing gut permeability and damaging the barrier that normally keeps intestinal contents where they belong.³ Research on the newer sweetener neotame found similar effects: intestinal cell death and barrier disruption operating through the same taste-receptor pathway.⁴

These are laboratory findings on intestinal cells, not clinical trials in people with active diarrhea, so the dose and real-world impact remain uncertain. Still, if your gut is already irritated and you’re dealing with loose stools, loading up on diet sodas or heavily sweetened sugar-free foods is not a neutral choice. Plain water, broth, and unsweetened tea are safer bets while you recover.

Why Diabetics Get Diarrhea More Often

Diarrhea isn’t just a random event for many people with diabetes. It’s a recurring problem with several diabetes-specific causes, and understanding which one is driving your symptoms changes what you should do about it.

Metformin, the most widely prescribed medication for type 2 diabetes, is a well-known cause of GI side effects including diarrhea. For some people, this starts when the medication is first introduced and fades over weeks. For others, diarrhea can develop years into treatment, which catches people off guard because they assume they’ve long since adjusted to the drug. A trial of probiotics in people experiencing metformin intolerance found that probiotic supplementation significantly reduced the incidence of diarrhea compared to placebo.⁵ If you suspect metformin is the culprit, this is worth discussing with your doctor. Extended-release metformin formulations also tend to cause fewer GI problems than immediate-release versions.

Diabetic autonomic neuropathy is the other major driver. Long-term poorly controlled blood sugar can damage the nerves that regulate the digestive system, leading to a range of complications including chronic diarrhea and even fecal incontinence.⁶ This type of diarrhea tends to be intermittent, sometimes alternating with constipation, and often worse at night. It requires medical management beyond dietary adjustments alone.

Then there are the same triggers that affect everyone: viral gastroenteritis, food poisoning, antibiotic use, and food intolerances. The difference for someone with diabetes is that any of these can spiral into a blood sugar crisis faster, which is why the eating and hydration strategy during an episode matters more.

Sick-Day Rules for Medications

What you eat is only half the equation when you have diabetes and diarrhea. How you manage your medications during illness is the other half, and it’s alarmingly under-addressed. A study using simulated patients who visited community pharmacies presenting as an elderly diabetic with diarrhea found that only about a quarter of pharmacies provided any sick-day guidance, whether through temporary medication adjustment or referral to a physician. Most simply dispensed an anti-diarrheal product without investigating the patient’s diabetes medications or health conditions.⁷

The general principle is that certain diabetes medications can become dangerous during dehydrating illness. Metformin, for instance, carries a rare but serious risk of lactic acidosis when you’re dehydrated, so many clinical guidelines recommend pausing it during persistent vomiting or diarrhea until you can keep fluids down consistently. SGLT2 inhibitors (the class ending in “-flozin”) can worsen dehydration and increase the risk of diabetic ketoacidosis during illness. ACE inhibitors and diuretics, while not diabetes-specific drugs, are commonly prescribed alongside diabetes medications and also pose risks during dehydration.

If you use insulin, diarrhea adds a tricky variable: you’re eating less and absorbing less, which would normally lower blood sugar, but the stress of illness and dehydration tend to push it higher. This push-and-pull means you need to monitor blood sugar more frequently, sometimes every two to three hours, and adjust doses cautiously. The safest move is to have a written sick-day plan from your endocrinologist or diabetes educator before you ever get sick, so you’re not scrambling for guidance while miserable.

Timing and Portion Size

Large meals are harder to tolerate during and immediately after a diarrheal episode. Eating small amounts every two to three hours tends to work better than three full-sized meals. This approach also helps with blood sugar management because smaller carbohydrate loads produce smaller glucose spikes, which are easier to handle when your normal routine is disrupted and you may not be taking your full medication regimen.

Start with liquids only for the first several hours if solid food triggers nausea or cramping. As symptoms improve, move to soft, bland foods in very small portions. A practical sequence might look like this:

Hours 1–6: Oral rehydration solution, clear broth, small sips of water or unsweetened herbal tea. Monitor blood sugar frequently.
Hours 6–12: Add plain crackers, a few spoonfuls of white rice, or half a banana if tolerated. Keep portions tiny.
Day 2: Introduce soft proteins like scrambled eggs, plain yogurt (if you tolerate dairy), or a small portion of chicken breast. Gradually increase portion sizes as stools firm up.
Day 3 and beyond: Ease back toward your normal eating pattern. Reintroduce fiber slowly. Jumping straight back to a salad loaded with raw vegetables can trigger a relapse.

The timeline obviously depends on the severity of the illness. Mild cases might resolve in a day; something like viral gastroenteritis can take three to five days before your gut is back to normal.

Probiotics During and After Recovery

There’s reasonable evidence that probiotics can help during and after diarrheal episodes, though the benefit varies depending on the cause. For metformin-related diarrhea specifically, the clinical trial mentioned earlier showed that probiotics reduced diarrhea incidence in people who were intolerant to the drug.⁵ For acute infectious diarrhea, the evidence on probiotics is more mixed but generally leans positive for shortening the duration by roughly a day in many studies.

If you want to try probiotics, look for products containing well-studied strains like Lactobacillus rhamnosus GG or Saccharomyces boulardii. Plain yogurt with live cultures is a food-based option, though if you’re lactose intolerant or dairy worsens your symptoms, stick with a capsule supplement. Fermented foods like kefir, kimchi, or sauerkraut are helpful in general but may be too intense for a sensitive stomach during active illness. Introduce them during the recovery phase instead.

When Diarrhea Becomes a Medical Emergency

Most bouts of diarrhea resolve on their own within a few days with good hydration and careful eating. But for someone with diabetes, certain red flags mean you should contact your doctor or go to urgent care rather than riding it out at home:

Blood sugar above 250 mg/dL: that won’t come down with your usual corrections, especially in type 1 diabetes or if you’re checking for ketones and finding them elevated.
Inability to keep fluids down: for more than six to eight hours. Dehydration plus diabetes is a fast track to diabetic ketoacidosis or hyperosmolar hyperglycemic state.
Bloody stools or high fever: suggesting a bacterial infection that may need antibiotics.
Diarrhea lasting more than 48 hours: without improvement, or getting progressively worse.
Signs of severe dehydration: dizziness when standing, very dark urine, confusion, rapid heartbeat.

People with type 1 diabetes are at higher risk of rapid deterioration during GI illness because they depend entirely on exogenous insulin and are more vulnerable to ketoacidosis. But anyone with diabetes, type 1 or type 2, who cannot eat or drink normally for an extended period is in a precarious spot and should err on the side of seeking medical attention.

Foods That Help Replenish What Diarrhea Depletes

Beyond the immediate need for fluids and gentle foods, diarrhea strips your body of specific nutrients worth intentionally replacing as you recover. Potassium is the biggest loss. Low potassium can cause muscle weakness, cramps, and even heart rhythm disturbances. Bananas are the go-to source, but avocado, cooked spinach, and potatoes (without heavy toppings) are also potassium-rich and may sit easier in your stomach as you transition to more variety.

Sodium gets depleted too, which is why broth and oral rehydration solutions are emphasized early on. As you return to normal eating, don’t be afraid of lightly salting your food even if you normally watch sodium intake. Your body needs to replenish what it lost.

Zinc is another nutrient that plays a role in gut recovery. While zinc supplementation is most commonly recommended for children with diarrhea in developing countries, adults with diabetes who experience frequent bouts may benefit from ensuring their zinc intake is adequate through foods like eggs, chicken, and pumpkin seeds. A sustained pattern of diarrhea, whether from autonomic neuropathy, medication side effects, or another cause, can gradually erode micronutrient stores in ways that a single episode would not. If diarrhea is a recurring part of your life with diabetes, bringing this up with your healthcare team and possibly getting levels checked is a reasonable step.