Diabetes Sick Day Rules: Managing Blood Sugar When Ill

Why Illness Makes Diabetes Harder to Manage

When you're sick, your body releases stress hormones like cortisol and adrenaline to fight infection. Unfortunately, these hormones also raise blood sugar levels — even if you're not eating much. For people with diabetes, this can quickly lead to dangerous highs, dehydration, or even diabetic ketoacidosis (DKA). That's why having a solid sick day plan is essential for every person living with diabetes.

The Golden Rules for Sick Days

1. Never Stop Taking Your Diabetes Medication

This is perhaps the most important rule. Even if you can't eat, do not stop taking insulin or your prescribed diabetes medications without consulting your doctor first. Skipping doses during illness can cause blood sugar to skyrocket rapidly. If you use insulin, your doctor may actually need to increase your dose while you're sick.

2. Check Your Blood Sugar More Frequently

On sick days, aim to check your blood glucose every 2 to 4 hours rather than your usual schedule. Illness can cause blood sugar to fluctuate unpredictably, and frequent monitoring helps you catch dangerous highs or lows before they become emergencies. Keep a log of your readings so you can share them with your healthcare provider if needed.

3. Stay Hydrated

Vomiting, diarrhea, and fever all cause significant fluid loss. Dehydration worsens high blood sugar and increases your risk of DKA. Aim to drink at least 8 ounces of fluid every hour while awake. Choose water, broth, or sugar-free drinks when blood sugar is high. If it drops below your target range, small sips of juice or regular sports drinks can help.

4. Check for Ketones

If you have Type 1 diabetes — or Type 2 diabetes and use insulin — check your urine or blood for ketones whenever your blood sugar is above 240 mg/dL during illness. Moderate to high ketone levels combined with elevated blood sugar are a medical emergency requiring immediate attention. Many pharmacies carry affordable ketone testing strips.

5. Eat If You Can

Try to maintain your normal carbohydrate intake if possible. If solid foods are difficult, opt for easy-to-digest options like crackers, toast, applesauce, or broth. Aim for about 15 grams of carbohydrates every hour or two to keep your energy up and prevent blood sugar from dropping too low if you're on insulin or certain oral medications.

6. Know Which Medications to Avoid

Some over-the-counter cold and flu remedies contain sugar or ingredients that raise blood sugar. Decongestants like pseudoephedrine can also spike glucose levels. Always read labels carefully and choose sugar-free versions of cough syrups and liquid medications when possible. When in doubt, ask your pharmacist.

When to Call Your Doctor or Seek Emergency Care

Not every sick day requires an ER visit, but certain warning signs demand immediate medical attention. Call your doctor or go to the emergency room if you experience:

• Blood sugar above 300 mg/dL that won't come down
• Moderate or large ketones in your urine or blood
• Vomiting or diarrhea lasting more than 6 hours
• Difficulty breathing, chest pain, or confusion
• Signs of severe dehydration (extreme thirst, no urination, dry mouth)

Prepare Your Sick Day Kit in Advance

Emergency preparedness is a core part of diabetes management. Assemble a sick day kit that includes extra blood glucose test strips, ketone strips, a thermometer, sugar-free and regular fluids, easy carbohydrate snacks, and a written list of your medications and target blood sugar ranges. Resources like mdsdiabetes.com offer helpful guides and tools to help you build a personalized sick day action plan with your care team.

Final Thoughts

Illness and diabetes are a challenging combination, but preparation makes all the difference. By following these sick day rules — monitoring frequently, staying hydrated, continuing medications, and knowing when to seek help — you can navigate illness more safely and recover faster. Talk to your diabetes care team today about creating a written sick day plan tailored specifically to your needs.