How Illness Affects Blood Sugar and What to Do

Why Illness Causes Blood Sugar to Rise

When you're feeling under the weather, the last thing you want to worry about is your blood sugar. But for people with diabetes, illness can trigger significant and sometimes dangerous changes in glucose levels. Understanding why this happens — and what to do about it — can help you stay safe during sick days.

When your body fights an infection, stress hormones like cortisol and adrenaline are released. These hormones are part of your immune response, but they also signal your liver to release extra glucose into the bloodstream. At the same time, they can make your cells more resistant to insulin. The result? Blood sugar levels can climb rapidly, even if you're barely eating.

This phenomenon is sometimes called the "sick day effect," and it affects both Type 1 and Type 2 diabetes. Even a mild cold or flu can cause blood sugar to spike well above your normal target range.

Monitoring Blood Sugar More Frequently When Sick

One of the most important things you can do during illness is check your blood sugar more often. Healthcare providers typically recommend checking every two to four hours rather than your usual schedule. This is where a reliable blood glucose meter becomes absolutely essential.

Having an accurate, easy-to-use meter on hand allows you to track trends in real time and make informed decisions about food, fluids, and medication. Resources like mdsdiabetes.com offer helpful guidance on choosing the right monitoring tools and understanding your readings during high-stress health situations.

Keep a log of your readings, symptoms, and any medications you take. This information will be invaluable if you need to contact your doctor or visit an emergency room.

Sick Day Rules Every Diabetic Should Know

Most diabetes care teams provide what are called "sick day rules" — a set of guidelines to follow when you're ill. Here are the key principles:

• Never stop taking your diabetes medication without consulting your doctor, even if you're not eating much.
• Stay hydrated. Drink plenty of sugar-free fluids like water, broth, or herbal tea to prevent dehydration, which can worsen high blood sugar.
• Eat small amounts regularly if possible. Try to consume around 15 grams of carbohydrates every hour if you can't eat full meals.
• Test for ketones if you have Type 1 diabetes and your blood sugar is above 240 mg/dL. High ketones combined with high blood sugar can signal diabetic ketoacidosis (DKA), a medical emergency.
• Avoid certain over-the-counter medications that contain sugar or may raise blood pressure, such as some cough syrups and decongestants. Always read labels carefully.

When to Call Your Doctor

Not every illness requires an emergency room visit, but some situations demand immediate medical attention. Call your doctor or seek emergency care if:

• Blood sugar remains above 300 mg/dL despite taking medication
• You detect moderate to large ketones in your urine
• You've been vomiting or have diarrhea for more than six hours
• You show signs of severe dehydration such as dry mouth, dizziness, or rapid heartbeat
• You feel confused or have difficulty breathing

Preparing a Sick Day Kit in Advance

The best time to prepare for sick days is when you're feeling well. Consider putting together a sick day kit that includes your blood glucose meter and extra test strips, ketone testing supplies, a thermometer, a list of your medications and dosages, sugar-free fluids and easy-to-digest foods, and your doctor's contact information.

Being proactive means you won't be scrambling when you're already feeling terrible. Planning ahead gives you peace of mind and keeps you safer during illness.

The Bottom Line

Illness and diabetes are a challenging combination, but with frequent monitoring, proper hydration, and adherence to your sick day plan, you can get through it safely. Always keep your healthcare team informed, trust your blood glucose meter, and never hesitate to seek medical help when something feels seriously wrong.