The flu presents a significant challenge to anyone with diabetes, transforming a common illness into a high-risk situation. When the body fights an infection, it releases stress hormones like cortisol and adrenaline, which are counter-regulatory to insulin. These hormones increase the liver’s glucose production and cause cells to become resistant to insulin, leading to a rapid rise in blood sugar levels. This metabolic disruption can quickly lead to life-threatening complications like Diabetic Ketoacidosis (DKA) or Hyperosmolar Hyperglycemic State (HHS). This information is for educational purposes only and is not a substitute for medical advice.
Immediate Steps for Monitoring
Illness requires a dramatic increase in the frequency of blood sugar monitoring. Blood glucose levels should be checked every two to four hours, even throughout the night, to provide actionable data for medication adjustments. This frequent monitoring is necessary because the body’s insulin needs can fluctuate wildly in a short period, potentially causing dangerous highs or lows.
Testing for ketones is mandatory, especially for individuals with Type 1 diabetes or anyone whose blood sugar is consistently elevated. Ketone testing should be performed if blood glucose levels remain above 250 mg/dL (or 14 mmol/L). The presence of ketones indicates the body is breaking down fat for energy due to a lack of usable insulin, which can quickly lead to DKA.
Ketones can be measured using urine strips or a dedicated blood ketone meter. Blood ketone meters are preferred because they measure beta-hydroxybutyrate, the primary ketone body in DKA, and provide a more current measure of the body’s status. The priority during illness is to prevent extreme hyperglycemia and the accumulation of ketones.
Managing Insulin and Oral Medications
Stopping insulin during illness due to decreased appetite is dangerous. The body’s need for insulin often increases when sick due to the surge in stress hormones and resulting insulin resistance. Individuals using insulin must continue their basal (long-acting) dose and will likely need a “sick day regimen” involving more rapid-acting or correctional insulin to counteract high blood sugars.
Adjustments to oral diabetes medications must be discussed with a healthcare team, as some drugs may need to be temporarily stopped. Medications like Metformin and SGLT2 inhibitors (e.g., canagliflozin, dapagliflozin) may be discontinued if the individual is struggling with hydration, vomiting, or diarrhea. Continuing these medications in a dehydrated state increases the risk of serious complications like lactic acidosis or euglycemic DKA.
When using over-the-counter (OTC) cold and flu remedies, check ingredient labels carefully. Many syrups and lozenges contain hidden sugars that can significantly spike blood glucose. Decongestants and other cold-relief ingredients can also interfere with blood sugar control, making it advisable to choose sugar-free formulations.
Maintaining Hydration and Nutrition
Hydration
Preventing dehydration is a primary focus during illness, as high blood sugar increases fluid loss through frequent urination. Individuals should aim to drink at least eight ounces of fluid every hour while awake. If blood sugar is high, the best choices are water, sugar-free drinks, or broth.
Nutrition
If the individual cannot eat solid food or is experiencing nausea, they must still consume carbohydrates to prevent hypoglycemia, especially if taking insulin or certain oral medications. A practical approach is to consume about 15 grams of carbohydrates every hour. This can be achieved with small amounts of carbohydrate-containing fluids like juice, regular soda, or sports drinks if blood sugar is trending low. These small, frequent servings help stabilize blood glucose and prevent starvation ketosis. If an individual is vomiting or has diarrhea, small sips of sugary fluids or oral rehydration solutions are important to maintain blood sugar and electrolyte balance. The inability to keep any fluids down for several hours requires immediate medical attention.
Recognizing Emergency Warning Signs
Several symptoms indicate a medical emergency requiring immediate intervention, such as calling 911 or going to the emergency room.
Diabetic Ketoacidosis (DKA)
For those with Type 1 diabetes, the main concern is DKA, signaled by persistent vomiting, severe abdominal pain, and deep, rapid breathing known as Kussmaul respiration. A distinct fruity odor on the breath, caused by the exhalation of ketones, is a hallmark DKA symptom.
Hyperosmolar Hyperglycemic State (HHS)
Individuals with Type 2 diabetes, particularly older adults, are more susceptible to HHS. Symptoms include extreme thirst, significant confusion or disorientation, and a fever above 101°F. These conditions require professional medical treatment involving intravenous fluids and insulin.
General signs of severe illness that warrant urgent care include:
- Chest pain.
- Severe shortness of breath.
- A high fever that does not improve with medication.
- An inability to wake up.
Contact a healthcare provider or emergency services immediately if blood sugar remains above 300 mg/dL despite extra insulin, or if moderate to large levels of ketones are present.