Illness and Diabetes: How to Recognize and Respond to Blood Sugar Changes

When you’re living with diabetes, managing your blood sugar levels becomes a daily priority. But what happens when illness strikes? Whether it’s a common cold, the flu, or another infection, being sick can dramatically affect your blood sugar control in ways that might surprise you. Understanding how illness impacts diabetes and knowing how to respond appropriately can mean the difference between a manageable sick day and a medical emergency.

Illness and stress from being sick cause your body to release hormones that raise blood glucose levels, making it harder to keep your blood glucose in your target range, and while having diabetes does not make you more likely to get a cold or flu, it does raise your chances of getting seriously sick. This comprehensive guide will help you recognize blood sugar changes during illness, understand why they occur, and respond effectively to protect your health.

The Complex Relationship Between Illness and Blood Sugar

The connection between illness and blood sugar fluctuations is more complex than many people realize. Your body’s response to infection or illness triggers a cascade of physiological changes designed to help you fight off the threat, but these same protective mechanisms can wreak havoc on blood sugar control.

Why Illness Affects Blood Sugar Levels

When you’re sick with the flu or another illness, your body releases hormones to fight infection, these hormones raise blood sugar levels, and they also make it hard for insulin or other medicines to lower your blood sugar. This physiological response is part of your body’s natural defense system, but for people with diabetes, it creates a significant management challenge.

When you’re feeling stressed, your body releases stress hormones like cortisol and adrenaline, but the hormones actually make it harder for insulin to work properly, known as insulin resistance, and as energy can’t get into your cells, your blood sugar levels rise. This phenomenon occurs whether the stress is physical (from illness) or emotional.

The Role of Stress Hormones

Cortisol is released by the adrenal glands in response to stress and helps mobilize energy by increasing blood glucose levels, doing this by stimulating the liver to release stored glucose into the bloodstream and by promoting gluconeogenesis, the process by which the liver creates glucose from non-carbohydrate sources such as proteins. Understanding this mechanism helps explain why blood sugar can rise even when you’re not eating much during illness.

Both adrenaline and noradrenaline trigger an increase in heart rate, blood pressure, and blood flow to muscles, while also raising blood glucose levels, with adrenaline raising blood sugar by stimulating the liver to release more glucose, and additionally, adrenaline inhibits the action of insulin, making it more difficult for cells to absorb glucose. This dual effect makes managing diabetes during illness particularly challenging.

The Unpredictability Factor

Illness causes the body to release stress hormones to fight the infection, these hormones can cause blood sugar levels to rise, which makes it difficult for those with diabetes to keep their blood sugar within target range, and at the same time, blood sugar levels can drop too low if symptoms like nausea, vomiting or loss of appetite disrupt normal eating routines. This bidirectional risk makes illness management particularly complex for people with diabetes.

Recognizing Blood Sugar Changes During Illness

Early recognition of blood sugar changes is crucial for preventing serious complications. During illness, your body may send different signals than usual, and symptoms can overlap between the illness itself and blood sugar problems.

Signs of High Blood Sugar (Hyperglycemia)

Hyperglycemia during illness can develop quickly and become severe. Common signs include:

Increased thirst and dry mouth: Your body tries to dilute excess glucose in your bloodstream by pulling water from tissues, leading to dehydration
Frequent urination: Your kidneys work overtime to filter excess glucose, resulting in more frequent trips to the bathroom
Fatigue and weakness: When glucose can’t enter cells properly, your body lacks the energy it needs
Blurred vision: High blood sugar can cause the lens of your eye to swell, affecting your ability to focus
Headaches: Dehydration and high glucose levels can trigger persistent headaches
Difficulty concentrating: Your brain needs steady glucose levels to function optimally

Signs of Low Blood Sugar (Hypoglycemia)

Low blood sugar can be equally dangerous during illness, especially if you’re not eating normally but continuing to take your diabetes medications. Watch for:

Sweating and shakiness: Your body releases adrenaline in response to low blood sugar
Rapid heartbeat: Your heart works harder to deliver what little glucose is available
Confusion or difficulty thinking clearly: Your brain is particularly sensitive to low glucose levels
Irritability or mood changes: Low blood sugar affects neurotransmitter function
Dizziness or lightheadedness: Insufficient glucose delivery to the brain causes these symptoms
Hunger: Your body signals its need for glucose
Pale skin: Blood flow patterns change in response to hypoglycemia

Warning Signs of Diabetic Ketoacidosis (DKA)

When your body doesn’t make enough insulin, cells can’t turn glucose into energy, and in response, your body will start to break down fat as fuel, a process that can cause a harmful buildup of acids (ketones) in the blood, creating a life-threatening medical emergency known as diabetic ketoacidosis.

DKA most commonly affects people with type 1 diabetes, but the condition can occur in people with type 2 diabetes who have a severe illness or infection. Warning signs include:

Fruity-smelling breath: Ketones produce a distinctive odor
Nausea and vomiting: The buildup of acids affects your digestive system
Abdominal pain: Often severe and persistent
Rapid, deep breathing: Your body tries to eliminate excess acid through respiration
Extreme fatigue: Your cells are starving for energy despite high blood sugar
Confusion or difficulty staying awake: Severe cases can lead to altered consciousness

Creating Your Sick Day Action Plan

Having a plan for sick days ahead of time will help you manage your diabetes and will make additional complications less likely. Don’t wait until you’re sick to figure out what to do—prepare now while you’re feeling well.

Essential Components of a Sick Day Plan

Before you get sick, decide on an action plan with your health care team that should include when to call your doctor, how often to check your blood glucose, what foods and fluids to take during your illness, how to adjust your insulin or oral medication if you need to, and if and when you need to check for ketones.

Work with your healthcare provider to establish specific guidelines for:

Blood sugar target ranges during illness: These may differ from your usual targets
Medication adjustments: Know whether to continue, adjust, or temporarily stop certain medications
Ketone testing protocols: Understand when and how to test for ketones
Emergency contact information: Have phone numbers readily accessible
Specific symptoms that require immediate medical attention: Know your personal red flags

Assembling Your Sick Day Kit

Keep a dedicated sick day kit stocked and easily accessible. Your kit should include:

Blood glucose meter and extra test strips: You’ll be testing more frequently
Ketone testing supplies: Either urine strips or a blood ketone meter
Thermometer: For monitoring fever
Fast-acting glucose sources: Glucose tablets, juice, regular soda, or honey
Sugar-free fluids: Water, sugar-free gelatin, diet soda, broth
Easy-to-digest foods: Crackers, applesauce, toast, soup
Medications: Extra diabetes medications and any over-the-counter remedies approved by your doctor
Written sick day plan: A clear, step-by-step guide you created with your healthcare team
Emergency contact list: Healthcare provider numbers, pharmacy, emergency services

Blood Sugar Monitoring During Illness

Frequent monitoring becomes even more critical when you’re sick. Your usual testing schedule won’t be sufficient during illness.

How Often to Check Blood Sugar

Test your blood sugar every 4 hours and keep track of the results. However, your healthcare provider may recommend even more frequent testing depending on your situation. Check your blood sugar more often than usual (every 2 to 4 hours), and there may be times when you need to check your blood sugar every hour.

More frequent testing is especially important if:

Your blood sugar is above 240 mg/dL
You’re experiencing vomiting or diarrhea
You’re unable to eat or drink normally
You have ketones in your urine or blood
You’re adjusting medication doses

Ketone Testing Guidelines

Do ketone testing if needed, and if you take insulin, do a test for ketones, especially when you have high blood sugar. People with Type 1 diabetes should monitor their blood sugar and ketones every four hours, while people with Type 2 diabetes should check their blood sugar every two to four hours and check for ketones if the blood sugar is over 240mg/dl.

Ketone testing is crucial because it helps identify whether your body is breaking down fat for energy due to insufficient insulin. This can lead to the dangerous condition of diabetic ketoacidosis if left unchecked.

Recording Your Results

Write down or record all your blood sugar levels, the time of each test, and the medicines you have taken. Keep a detailed sick day log that includes:

Date and time of each blood sugar reading
Blood sugar values
Ketone test results (if applicable)
Temperature readings
Food and fluid intake
Medications taken (including doses and times)
Symptoms experienced
Any medication adjustments made

This information will be invaluable if you need to contact your healthcare provider or seek emergency care.

Managing Medications During Illness

One of the most common mistakes people with diabetes make when sick is stopping their diabetes medications. This can be dangerous.

Continue Your Diabetes Medications

Continue taking your insulin and diabetes pills as usual. Keep taking your diabetes medicine, even if you vomit and have trouble eating or drinking, but if you are vomiting and can’t take your medicine, call your doctor. This is critical because your body may actually need more insulin during illness, not less, due to the stress hormones being released.

When you are sick you still need to take your medicine, and even if you are throwing up, do not stop your medicine unless your provider tells you not to take it, and if you cannot take your pills, you may need insulin.

When Medication Adjustments May Be Needed

If you cannot eat your normal amount of carbohydrates, use your sick day plan or contact your provider, as you may need to make a change in your insulin dose or in the dose of your diabetes pills or other injections, and you may also need to do this if your illness is making your blood sugar higher than normal.

Never adjust medications on your own without guidance from your healthcare provider. Your sick day plan should include specific instructions for medication adjustments based on your blood sugar readings.

Over-the-Counter Medications

Be careful with over-the-counter medicines, don’t take any nonprescription medicines unless you talk to your doctor first, as many nonprescription medicines can affect your blood sugar level. Decongestants and products to treat colds can increase your blood sugar level and blood pressure.

Before you get sick, discuss with your healthcare provider which over-the-counter medications are safe for you to use. Keep a list of approved medications in your sick day kit. Always check labels for sugar content, and ask your pharmacist for sugar-free alternatives when available.

Nutrition and Hydration During Illness

Maintaining adequate nutrition and hydration during illness can be challenging, but it’s essential for managing blood sugar levels and supporting recovery.

The Critical Importance of Hydration

Drink plenty of water to prevent dehydration. Drink plenty of sugar-free fluids to keep your body from getting dried out (dehydrated), drinking at least twelve 8-ounce cups (3 liters) of fluid a day. Dehydration can worsen high blood sugar and make you feel even worse.

Be sure you’re getting enough water—so drink plenty of it, and if you’re having trouble keeping water down, have small sips every 15 minutes or so throughout the day.

Good sugar-free fluid choices include:

Water
Sugar-free gelatin
Diet soda or sugar-free beverages
Unsweetened tea
Clear broth
Sugar-free popsicles

Eating When You’re Sick

Try to eat as you normally would. Try to eat your normal types and amounts of food, drink extra fluids to prevent dehydration, and ask your doctor about how much and how often you should eat and drink when you’re sick.

A general guideline is to try to eat or drink 50 grams of carbohydrate every 3 to 4 hours. If you can’t eat solid foods, focus on liquids that contain carbohydrates to maintain blood sugar levels and prevent hypoglycemia.

Easy-to-digest foods during illness include:

Crackers or toast
Applesauce
Bananas
Rice
Soup or broth
Yogurt
Oatmeal
Scrambled eggs

Managing Low Blood Sugar During Illness

If your blood sugar is less than 100 mg/dL (5.5 mmol/L) or falling quickly, it is OK to drink fluids that have sugar in them. Having simple carbs handy like regular soda, Jell-O, or popsicles will help keep your blood glucose up if you are at risk for lows.

The American Diabetes Association recommends following the 15-15 rule while sick, an approach that suggests you eat 15 grams of carbs, then check your blood sugar 15 minutes afterward. If your blood sugar is still low, repeat the process.

Quick-acting carbohydrate sources (each containing approximately 15 grams of carbohydrates):

4 glucose tablets
4 ounces (1/2 cup) of fruit juice
4 ounces of regular soda
1 tablespoon of sugar or honey
8 ounces of low-fat milk
6 saltine crackers

When to Seek Medical Help

Waiting too long to get medical care when you are sick can lead to getting much sicker, and when you have diabetes, a delay in getting care can be life threatening. Knowing when to call your doctor or go to the emergency room is crucial.

Call Your Healthcare Provider If:

In most cases if you are vomiting or have diarrhea more than three times over 24 hours or have had a fever over 101° for 24 hours. Additional reasons to contact your healthcare provider include:

Blood sugar levels remain above 240 mg/dL for more than 24 hours
Blood sugar levels drop below 70 mg/dL repeatedly despite treatment
You have moderate to large ketones in your urine or blood
You’re unable to keep down food or fluids for more than 6 hours
You’re experiencing persistent abdominal pain
You’re feeling increasingly confused or disoriented
Your illness is lasting more than 2 days without improvement
You’re unsure about what to do

Go to the Emergency Room Immediately If:

Go to the emergency room right away if you’re having trouble breathing, you have ketones in your urine, you can’t keep any liquids down for more than 4 hours or can’t keep food down more than 24 hours, you lose 5 pounds or more during the illness, your blood sugar is lower than 60 mg/dl, or you have vomiting and/or severe diarrhea for more than 6 hours.

Other emergency situations include:

Chest pain or pressure
Severe abdominal pain
Signs of severe dehydration (very dry mouth, inability to urinate, extreme weakness)
Altered consciousness or inability to stay awake
Fruity-smelling breath with nausea and vomiting
Rapid, deep breathing
Blood sugar above 300 mg/dL that doesn’t respond to treatment

Information to Have Ready

When calling your healthcare provider or going to the emergency room, have the following information ready:

Your recent blood sugar readings
Ketone test results (if applicable)
Temperature readings
List of symptoms and when they started
Medications you’ve taken (including doses and times)
What you’ve been able to eat and drink
Any medication adjustments you’ve made

Special Considerations for Different Types of Diabetes

While the general principles of sick day management apply to all people with diabetes, there are some important differences based on diabetes type.

Type 1 Diabetes

Minor illnesses in people with diabetes (especially children with type 1 diabetes) can lead to very high blood sugar levels and possible emergencies. People with type 1 diabetes are at higher risk for diabetic ketoacidosis during illness because their bodies produce little to no insulin.

Key considerations for type 1 diabetes:

Never stop insulin: Even if you’re not eating, you need basal insulin to prevent ketoacidosis
Check ketones frequently: Test for ketones every time you urinate if blood sugar is above 240 mg/dL
May need extra insulin: Illness often increases insulin requirements
Monitor more closely: Check blood sugar every 2-4 hours, or even hourly if needed
Lower threshold for seeking help: Contact your healthcare provider sooner rather than later

Type 2 Diabetes

People with type 2 diabetes may have more flexibility in managing illness, but vigilance is still essential. High blood sugar can cause ketoacidosis in people with Type 1 diabetes and hyperosmolar hyperglycemic non-ketotic coma in people with Type 2 diabetes, and both of these conditions are very serious and can be life-threatening.

Key considerations for type 2 diabetes:

Continue oral medications: Unless specifically instructed otherwise by your healthcare provider
May need temporary insulin: Some people with type 2 diabetes may need insulin during severe illness
Check ketones if blood sugar is very high: Particularly if blood sugar exceeds 240 mg/dL
Watch for hyperosmolar hyperglycemic state: A serious condition involving extremely high blood sugar and severe dehydration
Monitor medication interactions: Some oral diabetes medications may need adjustment during illness

Gestational Diabetes

Pregnant women with gestational diabetes need to be especially cautious during illness, as both high and low blood sugar can affect the baby. Contact your healthcare provider at the first sign of illness to discuss management strategies. You may need more frequent monitoring and closer medical supervision.

Preventing Illness: Proactive Strategies

While you can’t prevent all illnesses, you can take steps to reduce your risk and minimize the impact when illness does occur.

Vaccinations

You’ll also want to be sure to get your annual flu shot to make getting the flu less likely. Recommended vaccinations for people with diabetes include:

Annual flu vaccine: Influenza can be particularly severe in people with diabetes
Pneumonia vaccines: Both PCV13 and PPSV23 as recommended by your healthcare provider
COVID-19 vaccines and boosters: Stay up to date with current recommendations
Hepatitis B vaccine: Recommended for adults with diabetes who haven’t been previously vaccinated
Tdap vaccine: Tetanus, diphtheria, and pertussis protection
Shingles vaccine: For adults 50 and older

General Health Practices

Maintaining good overall health can help prevent illness and improve your ability to fight infections when they do occur:

Maintain good blood sugar control: Better baseline control helps your immune system function optimally
Practice good hand hygiene: Wash hands frequently with soap and water for at least 20 seconds
Get adequate sleep: Aim for 7-9 hours per night to support immune function
Eat a balanced diet: Proper nutrition supports your immune system
Stay physically active: Regular exercise strengthens your immune response
Manage stress: Chronic stress weakens immune function and affects blood sugar control
Avoid close contact with sick people: When possible, maintain distance from those who are ill
Don’t share personal items: Avoid sharing cups, utensils, or towels

Recovery and Returning to Normal

As you recover from illness, you’ll need to gradually transition back to your normal diabetes management routine.

Gradual Transition

Don’t rush back to your normal routine too quickly. Continue monitoring your blood sugar more frequently until it stabilizes. Your body may take several days to fully recover, and blood sugar patterns may remain somewhat unpredictable during this time.

Steps for transitioning back to normal:

Gradually reduce blood sugar testing frequency as readings stabilize
Slowly return to your normal eating patterns
Resume your regular medication schedule (if adjustments were made)
Restart your exercise routine gradually, not at full intensity
Continue to stay well-hydrated
Get adequate rest to support full recovery

Follow-Up Care

Schedule a follow-up appointment with your healthcare provider after recovering from a significant illness. This visit allows you to:

Review how you managed the illness
Discuss any challenges you encountered
Update your sick day plan if needed
Address any lingering symptoms or concerns
Ensure your blood sugar control has returned to baseline
Check for any complications that may have developed

Learning from Experience

Each illness provides valuable information about how your body responds. Keep notes about what worked well and what didn’t during your illness. This information will help you manage future sick days more effectively.

Questions to reflect on:

How did your blood sugar respond to the illness?
Were your medication adjustments effective?
Did you have adequate supplies on hand?
Was your sick day plan easy to follow?
Did you contact your healthcare provider at the right time?
What would you do differently next time?

The Psychological Impact of Illness and Diabetes

Managing diabetes during illness isn’t just physically challenging—it can also take an emotional toll.

Stress and Anxiety

People with diabetes may be more sensitive to stress, as they worry about managing their condition and the potential complications that come with it, creating a vicious cycle, where stress leads to higher blood sugar, and high blood sugar, in turn, increases stress and anxiety.

It’s normal to feel anxious about managing diabetes during illness. The unpredictability of blood sugar levels, concerns about complications, and the added burden of feeling unwell can all contribute to stress. Recognize these feelings as valid and seek support when needed.

Seeking Support

Don’t hesitate to ask for help when you’re sick. Family members, friends, or caregivers can assist with:

Monitoring blood sugar levels
Preparing meals and fluids
Keeping track of medications
Recording test results
Communicating with healthcare providers
Providing emotional support
Recognizing warning signs you might miss

Being sick and/or having a low blood sugar level can cause fatigue or difficulty thinking clearly, and if needed, have someone else call your doctor or take you to the emergency room to avoid unsafe driving.

Advanced Topics in Sick Day Management

Using Continuous Glucose Monitors During Illness

If you use a continuous glucose monitor (CGM), it can be particularly valuable during illness. CGMs provide real-time glucose readings and trend arrows that show whether your blood sugar is rising, falling, or stable. This information helps you respond more quickly to changes.

However, remember that CGMs measure interstitial fluid glucose, which can lag behind blood glucose by 5-15 minutes. During rapid changes in blood sugar, confirm CGM readings with fingerstick tests before making treatment decisions.

Insulin Pump Management During Illness

If you use an insulin pump, illness management requires special considerations. You may need to increase your basal rates or use temporary basal rate adjustments. Some people find they need to change their infusion sites more frequently during illness. Always have backup supplies of insulin pens or syringes in case of pump failure.

Managing Diabetes During Surgery or Hospitalization

If your illness requires hospitalization or surgery, inform all healthcare providers that you have diabetes. Bring a list of your medications, your blood glucose meter, and enough supplies for your stay. Hospital staff will monitor your blood sugar, but you should continue to be involved in your care and advocate for appropriate diabetes management.

Resources and Support

Managing diabetes during illness doesn’t have to be a solitary endeavor. Numerous resources are available to support you.

Educational Resources

Several reputable organizations provide comprehensive information about diabetes sick day management:

American Diabetes Association: Offers detailed sick day guidelines and educational materials at diabetes.org
Centers for Disease Control and Prevention: Provides evidence-based information about diabetes management at cdc.gov/diabetes
JDRF (Juvenile Diabetes Research Foundation): Excellent resources for type 1 diabetes management
Diabetes Education Services: Professional diabetes education and training resources

Healthcare Team

Your diabetes healthcare team is your most valuable resource. This team may include:

Endocrinologist or primary care physician: Oversees your overall diabetes care
Certified diabetes care and education specialist: Provides education and support for daily management
Registered dietitian: Helps with meal planning and nutrition during illness
Pharmacist: Advises on medications and potential interactions
Mental health professional: Supports emotional well-being and stress management

Establish relationships with these professionals before you get sick, so you know who to contact and how to reach them when illness strikes.

Support Groups and Communities

Connecting with others who have diabetes can provide emotional support and practical advice. Consider joining:

Local diabetes support groups
Online diabetes communities and forums
Social media groups focused on diabetes management
Diabetes education classes or workshops

Hearing how others manage illness with diabetes can provide new strategies and reassurance that you’re not alone in facing these challenges.

Conclusion: Empowering Yourself for Sick Day Success

Managing diabetes during illness requires preparation, vigilance, and flexibility. While illness adds complexity to diabetes management, having a solid sick day plan and understanding how to respond to blood sugar changes can help you navigate these challenging times safely.

Remember these key principles:

Prepare in advance: Create your sick day plan and assemble your sick day kit before you get sick
Monitor frequently: Check blood sugar and ketones more often during illness
Stay hydrated: Drink plenty of fluids to prevent dehydration
Continue medications: Don’t stop your diabetes medications without medical guidance
Eat when possible: Try to maintain carbohydrate intake to prevent low blood sugar
Know when to seek help: Don’t hesitate to contact your healthcare provider or seek emergency care
Keep detailed records: Document blood sugar readings, symptoms, and treatments
Be patient with recovery: Allow time for your body to fully heal and blood sugar to stabilize

Illness is an inevitable part of life, but with proper preparation and knowledge, you can manage diabetes effectively even when you’re not feeling your best. By understanding how illness affects blood sugar, recognizing warning signs, and responding appropriately, you can minimize complications and support your body’s healing process.

Take time now, while you’re healthy, to review your sick day plan with your healthcare team. Make sure you have all necessary supplies on hand. Discuss any questions or concerns you have about managing diabetes during illness. This preparation will give you confidence and peace of mind, knowing you’re ready to handle whatever comes your way.

Your health and safety are paramount. When in doubt, always err on the side of caution and contact your healthcare provider. They would rather hear from you early when problems are manageable than deal with a crisis that could have been prevented. With the right knowledge, preparation, and support, you can successfully navigate the challenges of managing diabetes during illness and emerge healthy on the other side.

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