What to Do if Your Blood Sugar Is Over 400

If you have diabetes, it's very important to keep your blood sugar, or glucose, levels within a healthy range to avoid certain health complications.

In general, the American Diabetes Association (ADA) says the target blood sugar level range for people with diabetes is between 80 and 130 mg/dL before a meal and lower than 180 mg/dL after a meal.

Still, because people's target blood glucose levels can vary, it's best to work with your doctor or health care provider to determine the right numbers for you.

A blood sugar over 400 milligrams per deciliter (mg/dL) is considered hyperglycemia, though, and may be a medical emergency, according to the Mayo Clinic.

Here's what to do if your blood sugar is over 400:

If your blood sugar reading is over 400 mg/dL, there is a chance you have a false reading — particularly if you don't have other symptoms such as frequent urination or increased thirst.

For example, if there were food particles on your fingers or you used outdated or improperly stored test strips, you might have gotten an inaccurate reading.

If you re-test your levels and your blood sugar is indeed above 400 mg/dL, follow the advice your doctor has given you — whether that includes taking extra insulin or drinking more water — and contact them for further treatment advice.

Your doctor may ask you to test your urine for ketones (there are home testing strips designed for this purpose available at most pharmacies). High levels of these chemicals are a potential sign of diabetic ketoacidosis (DKA), a complication of hyperglycemia when your body is no longer able to use insulin to break down glucose for energy, per the ADA. This can be fatal.

Your doctor will tell you when you should perform the test, but the ADA says that, in general, you may want to check your urine for ketones when your blood sugar levels hit more than 240 mg/dL.

"In our clinic, if a person has blood sugar levels of over 300 mg/dL, we will check for urine ketones," says Susan Spratt, MD, an endocrinologist and associate professor of medicine at Duke University School of Medicine. "If their blood sugar levels are over 300 mg/dL — and certainly over 400 mg/dL — we're concerned that they may be going into diabetic ketoacidosis."

If your urine test reveals that ketones are present, call your doctor, who can give you further instructions. You may need to go to the emergency room to seek treatment right away.

The ADA says that if you have ketones present in the body, you shouldn't exercise. In this case, exercise can cause your blood sugar levels to spike even higher.

As we noted above, untreated hyperglycemia can lead to diabetic ketoacidosis.

Beyond ketones in your urine, DKA symptoms include the following, per the Centers for Disease Control and Prevention (CDC):

• Fast, deep breathing
• Dry skin and mouth
• Flushed face
• Fruity-smelling breath
• Headache
• Muscle stiffness or aches
• Fatigue
• Nausea and vomiting
• Stomach pain

Even if you are not having severe symptoms, keep in mind that you could progress rapidly to DKA and that this could become a medical emergency at any time.

Additionally, even if you don't have symptoms, untreated hyperglycemia may lead to long-term health complications like nerve damage (diabetic neuropathy), damage to the blood vessels of the eye (diabetic retinopathy), kidney problems and heart problems, per the Mayo Clinic.

According to the Cleveland Clinic, your blood sugar can spike (or swing) when you have diabetes for the following reasons:

• You're not taking the right dose of insulin or diabetes medication
• The amount of carbohydrates you're eating isn't balanced with your insulin medication dosage
• You're less physically active
• You're physically or emotionally stressed
• You're taking steroids, beta blockers, birth control pills or certain types of mental health medications
• You're experiencing the dawn phenomenon, which is when your body produces a surge of hormones early in the morning

Other than seeing your doctor regularly and taking your medication as directed, there are a few things you can do at home to help prevent blood sugar spikes or hyperglycemia. These can include the following, per the Cleveland Clinic:

• ‌Avoid sugary beverages:‌ Drinks like juice, soda, sweet tea and sports and energy drinks have excess sugar and can increase your blood sugar quickly. Limiting them can help regulate your blood sugar levels. Try to limit other sugary foods that raise blood sugar, too, like candy.
• ‌Choose complex carbohydrates:‌ Eating too many carbs (especially simple, processed carbs) can contribute to high blood sugar. Try to choose nutrient-dense, high-fiber carbs like beans, berries, sweet potatoes and whole-grain bread.
• ‌Eat balanced meals:‌ Make sure you pair complex carbs with a lean source of protein and non-starchy vegetables, like broccoli or green beans. A well-balanced meal will help keep your blood sugar stable.
• ‌Exercise reguarly:‌ The ADA recommends starting with 30 minutes of cardio exercise three times per week. Then, work your way up to five times per week. You can try walking or strength training.
• ‌Manage stress:‌ Stress can negatively affect your blood sugar levels and can lead you to cope with unhealthy habits like drinking excessively or emotional eating. Managing your stress can help you take better care of yourself.
• ‌Use your blood glucose monitor:‌ If you've already been diagnosed with prediabetes or type 1 or type 2 diabetes, you're familiar with checking your blood glucose using a monitor. Make sure you're checking your levels before and after meals, or whenever you're feeling symptoms, to help you keep things in check.
• ‌Quit smoking:‌ Nicotine raises your blood sugar because it affects how your body responds to insulin. Quitting smoking can not only help you lower your blood sugar, but it can positively affect your overall health.