What to Do If Your Blood Sugar Is Over 400 (Severe Hyperglycemia Emergency Guide)
A blood sugar reading above 400 mg/dL is considered severe hyperglycemia and signals a critical imbalance in how your body is handling glucose. At this level, your cells are unable to absorb sugar efficiently, often due to insufficient insulin or insulin resistance. When left untreated, this condition can quickly escalate into life-threatening complications such as diabetic ketoacidosis (DKA) or hyperosmolar hyperglycemic state (HHS). For most people: Normal fasting blood sugar: 70–99 mg/dL Prediabetes: 100–125 mg/dL Diabetes (fasting): 126 mg/dL or higher Dangerous level: 300–400+ mg/dL A reading of 400 or above is not just high — it is dangerous and requires immediate medical attention. Is Blood Sugar Over 400 a Medical Emergency? Yes. Blood glucose at this level may indicate your body is entering a crisis state. Without proper insulin, your body begins breaking down fat for energy, producing acids called ketones. High ketone levels lead to DKA, which can cause: Dehydration Organ failure Diabetic coma Death This makes a blood sugar level over 400 an urgent situation that should never be ignored. Immediate Steps to Take If Your Blood Sugar Is Over 400 1. Stay Calm but Act Quickly Panic can worsen blood sugar through stress hormones. Stay composed, sit down, and prepare to take action. 2. Recheck Your Blood Sugar Wash your hands with warm water and soap, dry thoroughly, and retest. False readings can happen due to: Dirty fingers Expired test strips Incorrect meter calibration Improper storage of supplies If the second result still shows above 400 mg/dL, treat it as real and dangerous. 3. Contact Your Doctor or Diabetes Care Team Immediately Call your healthcare provider and report: Your current blood sugar reading Any symptoms you feel Medications taken recently Follow their instructions carefully. They may advise: Additional insulin (correction dose) Increased hydration Urgent ER visit Check for Ketones Immediately If your blood sugar exceeds 240 mg/dL, you should test your urine or blood for ketones using home testing strips or a ketone meter. Why Ketones Matter High ketones mean your body is breaking down fat due to lack of insulin, indicating possible DKA. If Ketones Are Present: Do NOT exercise Drink water Go to the emergency room as instructed Presence of moderate to large ketones combined with high glucose is a medical emergency. When to Call 911 or Go to the Emergency Room Seek emergency care immediately if you have high blood sugar along with: Rapid or deep breathing Fruity-smelling breath Severe nausea or vomiting Confusion or inability to focus Chest pain Extreme fatigue Severe abdominal pain Dry mouth and skin These are classic symptoms of diabetic ketoacidosis and require urgent treatment. What Happens If Blood Sugar Over 400 Is Left Untreated? Long-term or repeated episodes can lead to: Diabetic neuropathy (nerve damage) Kidney disease or failure Vision loss (diabetic retinopathy) Heart attack and stroke Weakened immune system Diabetic coma Prolonged severe hyperglycemia damages blood vessels and organs, reducing life expectancy significantly. Common Causes of Blood Sugar Spikes Above 400 Medication-Related Missed insulin doses Incorrect insulin dosage Expired insulin Steroids (prednisone) Certain antibiotics Lifestyle Causes Overeating carbohydrates Sugary drinks Lack of physical activity Dehydration Emotional or physical stress Poor sleep Medical Conditions Infections Illness or fever Hormonal disorders Pancreatic problems How to Lower Blood Sugar Safely After a Spike ✅ Follow Doctor Instructions Only take correction insulin as prescribed. ✅ Hydrate Aggressively Drink water every 15–30 minutes unless restricted. ✅ Rest Avoid strenuous activity if ketones are present. ✅ Monitor Every 1–2 Hours Track readings to ensure levels are decreasing. Natural Ways to Prevent Blood Sugar Over 400 1. Eat Low-Glycemic Foods Choose: Leafy greens Whole grains Lentils and beans Nuts and seeds Lean proteins Avoid: Sodas Candy White bread Pastries 2. Follow the Plate Method 50% vegetables 25% protein 25% complex carbs 3. Exercise Regularly Aim for 150 minutes of moderate activity per week. Walking after meals helps significantly. 4. Prioritize Sleep Poor sleep increases insulin resistance and glucose levels. 5. Manage Stress Use meditation, breathing exercises, or yoga to reduce cortisol spikes. Best Supplements That May Help Control Blood Sugar (Always consult your doctor first) Chromium Magnesium Alpha-lipoic acid Berberine Cinnamon extract Vitamin D Monitoring Tips for Better Control Check fasting glucose daily Monitor post-meal levels Use continuous glucose monitors if available Keep a blood sugar log Frequently Asked Questions At what blood sugar level does a diabetic coma occur? Typically above 600 mg/dL combined with dehydration and ketones. Should I take insulin if my blood sugar is over 400? Only if prescribed and instructed by your doctor. How long does it take for blood sugar to drop? With treatment, levels may drop within 2–6 hours, depending on severity. Can stress alone cause blood sugar over 400? Stress can contribute but rarely causes levels this high alone. Difference Between DKA and HHS Condition Common In Blood Sugar Level Ketones DKA Type 1 Diabetes 300–600 High HHS Type 2 Diabetes 600+ Low/None Both are medical emergencies. Emergency Checklist for Blood Sugar Over 400 ✅ Recheck glucose ✅ Drink water ✅ Test for ketones ✅ Call doctor ✅ Monitor symptoms ✅ Seek ER care if symptoms worsen Long-Term Strategy for Preventing Severe Hyperglycemia Regular A1C testing Medication adherence Diabetes education Diet planning Routine physical activity Continuous monitoring The Takeaway A blood sugar level over 400 mg/dL is a serious medical condition that should never be ignored. Immediate action, medical intervention, and careful monitoring are essential to prevent life-threatening complications such as diabetic ketoacidosis or diabetic coma. With early response and proper lifestyle management, severe hyperglycemia can be controlled and prevented in the future.