On this page, you can find general instructions on how to treat a stomach flu in type 1 diabetes or in other forms of insulin-dependence, such as type 2 diabetes, where the treatment is basal insulin or MDI therapy. However, please keep in mind that for a person with insulin-dependent diabetes, a stomach ache and vomiting may be signs of diabetic ketoacidosis (DKA), not a stomach flu.
Stomach flu and insulin-dependent diabetes
Even though, in an acute illness, the need for insulin is increased and blood sugar normally rises, with a stomach flu, the absorption of carbohydrates may be reduced and blood sugar tends to drop instead.
If you have type 1 diabetes or another form of insulin deficiency, never fail to administer your basal insulin, even if your blood sugar tends to fall during a stomach flu. If necessary, you can reduce the dose of basal insulin by 20-30%. If your blood sugar is prone to falling, consume small doses of carbohydrates in an easily absorbable form, such as sugared fruit soups, at frequent intervals without insulin. This can help you compensate for meals during a stomach flu. You may administer rapid-acting insulin only as corrective doses, if necessary, every 2-4 hours.
During an illness with vomiting and diarrhoea, ensure adequate intake of fluids and carbohydrates even if you don't have an appetite. The recommendation for an adult is at least 150 grams of carbohydrates in some form. Mineral water, diluted fruit juice, meat or vegetable broth, berry soups, etc., can help maintain the body's fluid balance. Consuming carbohydrates in small doses at frequent intervals can substitute for meals.
An adult should drink at least 2–3 litres of fluids during sick days to prevent dehydration. Pharmacies also offer powder preparations intended for the treatment of dehydration caused by diarrhoea, which can be used if necessary. Pharmacy staff can advise on their use.
Check your blood sugar every 2–4 hours. During nausea and vomiting, your ketone levels may be slightly elevated even if your blood sugar is normal or low. Usually, the level is however below 1 mmol/l. These are "starvation ketones" caused by not eating, which to correct themselves, require additional carbohydrates and rapid-acting insulin administered for them.
Fever increases the need for insulin. If you have fever in addition to vomiting or diarrhoea, there may be a sharp rise in your blood sugar level. In this case, you should make sure to increase the insulin doses on the basis of the results of blood sugar self-measurements.
If a person on insulin treatment gets such a severe stomach illness that food or drink cannot be retained due to vomiting, or if diarrhea is watery and profuse, it is essential to seek emergency medical care without delay.
If you have type 1 or another form of insulin-dependent diabetes, always keep in mind that abdominal pain and vomiting can be symptoms of ketoacidosis, not necessarily a gastrointestinal illness. Always check for ketones if you experience stomach symptoms.
Always take your basal insulin
If you have type 1 diabetes or another form of insulin deficiency, never fail to administer your basal insulin, even if your blood sugar tends to fall during a stomach flu. If necessary, you can reduce the dose of basal insulin by 20-30%. If your blood sugar is prone to falling, consume small doses of carbohydrates in an easily absorbable form, such as sugared fruit soups, at frequent intervals without insulin. This can help you compensate for meals during a stomach flu. You may administer rapid-acting insulin only as corrective doses, if necessary, every 2-4 hours.
Eating and drinking during stomach flu
During an illness with vomiting and diarrhoea, ensure adequate intake of fluids and carbohydrates even if you don't have an appetite. The recommendation for an adult is at least 150 grams of carbohydrates in some form. Mineral water, diluted fruit juice, meat or vegetable broth, berry soups, etc., can help maintain the body's fluid balance. Consuming carbohydrates in small doses at frequent intervals can substitute for meals.
An adult should drink at least 2–3 litres of fluids during sick days to prevent dehydration. Pharmacies also offer powder preparations intended for the treatment of dehydration caused by diarrhoea, which can be used if necessary. Pharmacy staff can advise on their use.
Blood sugar monitoring during stomach flu
Check your blood sugar every 2–4 hours. During nausea and vomiting, your ketone levels may be slightly elevated even if your blood sugar is normal or low. Usually, the level is however below 1 mmol/l. These are "starvation ketones" caused by not eating, which to correct themselves, require additional carbohydrates and rapid-acting insulin administered for them.
Fever increases the need for insulin. If you have fever in addition to vomiting or diarrhoea, there may be a sharp rise in your blood sugar level. In this case, you should make sure to increase the insulin doses on the basis of the results of blood sugar self-measurements.
When to go to the emergency?
If a person on insulin treatment gets such a severe stomach illness that food or drink cannot be retained due to vomiting, or if diarrhea is watery and profuse, it is essential to seek emergency medical care without delay.
If you have type 1 or another form of insulin-dependent diabetes, always keep in mind that abdominal pain and vomiting can be symptoms of ketoacidosis, not necessarily a gastrointestinal illness. Always check for ketones if you experience stomach symptoms.
Updated 7.3.2025