Why High Blood Sugar Levels Can Cause a Metallic Taste in Your Mouth

If you have type 1 diabetes, you may notice a funny, metallic taste in your mouth when your blood sugar levels swing too high. It isn't bad breath from poor oral hygiene — it could actually signal a serious, life-threatening condition called diabetic ketoacidosis (DKA).

DKA occurs when your body is no longer able to burn carbohydrates for energy and burns fat instead. Although this condition is mostly linked with type 1 diabetes, it can rarely occur with type 2 diabetes as well, according to the American Diabetes Association (ADA). (Diabetes statistics show the majority of people with diabetes have type 2.) Find out more about the causes of DKA, along with what to do if you suspect you are experiencing this condition.

When you eat carbs in foods like breads, pasta and fruits, your digestive system breaks them down into glucose, a type of sugar, according to the National Institute of Diabetes and Digestive and Kidney Diseases. Glucose then enters the bloodstream, where it raises your blood sugar levels. In response, your body releases more of the hormone insulin, which helps shuttle glucose out of your blood and throughout the cells in your body to be used as energy.

​Read more:​ Everything You Need to Know About Carbs

However, if you eat too many carbohydrates or don't give yourself enough insulin, the glucose in your bloodstream can build up. If this occurs, you can experience high blood sugar levels, or hyperglycemia, according to the ADA. Left untreated, hyperglycemia can lead to DKA.

Diabetic ketoacidosis is a serious condition that occurs when the body doesn't have enough insulin to use glucose for energy. When your cells can't use glucose for energy, they begin to burn fat instead, according to the ADA. If your body starts breaking down fats, it will also produce ketones, chemicals that can make your blood more acidic. Your body can't handle too many ketones, so it will try to flush them out through the urine; eventually, however, if they continue to build up in the blood, you'll develop diabetic ketoacidosis.

A byproduct of ketones is a chemical called acetone. Your body gets rid of the acetone by breathing it out, which is why you may have a strange taste in your mouth. Your breath may smell funny to others when you're experiencing ketosis as well. Some people describe the taste and smell as a "fruity" or "sweet" taste, while others say it tastes metallic. (Some people on the keto diet also report "ketosis breath," a metallic taste in the mouth due to the production of ketones from following this ultra-low-carb eating plan.)

Other symptoms of diabetic ketoacidosis include thirst, a dry mouth, frequent urination, nausea, trouble breathing, nausea, fatigue and confusion, according to the ADA.

​Read more:​ Why Too High or Too Low Blood Sugar Could Be Dangerous

Talk to your health care provider about when you should test your ketone levels, since this can vary from person to person. The ADA tells people to check for the presence of ketones when blood sugar levels rise above 240 mg/dL.

You can check your ketones with a simple blood or urine test (like your glucose tests, the urine test uses a test strip). If you do have higher-than-normal levels of ketones, you should call your doctor right away.

The ADA also warns people not to work out when they're experiencing high blood sugar and ketones since exercising during this time might cause blood sugar levels to rise even more.

Most people who go into diabetic ketoacidosis have type 1 diabetes, but occasionally, people with type 2 diabetes can develop it, too, says Susan Spratt, MD, an endocrinologist and associate professor of medicine at the Duke University School of Medicine. There is a higher risk of people with type 2 diabetes developing DKA if they take a diabetes medicine called an SGLT2 inhibitor. (People with type 1 diabetes don't produce insulin in the body and need to take insulin therapy in order to control their glucose levels. In some cases, diabetic ketoacidosis can develop in people who haven't been diagnosed with type 1 diabetes.)

For example, Dr. Spratt says, if a person who uses an insulin pump (a small device that delivers insulin to the body) overnight woke up to find that the device had somehow gotten dislodged, they can have high blood sugar levels of 400 mg/dL and be in diabetic ketoacidosis.

If you suspect that you have DKA, use your meter to check your blood sugar levels to see if they are high. An over-the-counter urine test or blood test can also reveal the presence of ketones. While there is a chance that you can bring your blood sugar levels back down on your own with more insulin, Dr. Spratt says, you should go to the emergency room if you're experiencing diabetic ketoacidosis symptoms including lightheadedness, confusion and chest pain.

At the emergency room, the doctors should treat you with intravenous fluids (an electrolyte solution) as well as check your potassium levels, says Dr. Spratt. "You can get very depleted in potassium when your body is acidotic," she says.

The goal of treating diabetic ketoacidosis is to reverse the high blood sugar levels with insulin, as well as to replace any fluids you might have lost if you've been vomiting, according to the U.S. National Library of Medicine. Doctors will also search for any underlying infections that might have caused the diabetic ketoacidosis in the first place. The good news: The organization notes that most people will respond to treatment within about a day.

Still, if you're experiencing symptoms of diabetic ketoacidosis, it's important to seek treatment right away. Possible complications, according to the U.S. National Library of Medicine, include cardiac arrest, kidney failure and a buildup of fluid in the brain. If left untreated for too long, diabetic ketoacidosis can lead to death.

​Read more:​ What Is a Healthy Blood Sugar Reading in the Morning?