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How Much Do You Know About Ketones?
Most people with diabetes — and anyone who has read about low-carbohydrate diets — has probably heard of ketones, but how many people really know what they are? Messages about ketones can be confusing: Some sources say they are toxic and dangerous, while others suggest that ketones are a positive sign of weight loss through fat burning.
When you have diabetes, it’s important to know the facts about ketones, as well as when to check for them, how to check for them, and what to do if you detect them. Take this quiz to see how much you know about ketones. (You’ll find answers later in this article.)
1. What are ketones?
2. Which of the following statements about ketones is not true?
3. All persons with diabetes should check for ketones when their blood glucose level is over 240 mg/dl.
4. Ketones can only be measured in the urine.
5. What is the role of ketones in the development of diabetic ketoacidosis (DKA), the acute diabetes complication characterized by high levels of ketones, high blood glucose, and dehydration? (More than one answer may be correct.)
6. People with Type 2 diabetes cannot develop diabetic ketoacidosis.
7. What steps are necessary to reduce ketones in the body? (More than one answer may be correct.)
1. A. Properly called ketone bodies, ketones are acids that come in three varieties: acetone, acetoacetic acid, and beta-hydroxybutyric acid. Ketones are released by the liver when insulin levels are insufficient for glucose metabolism and the liver switches to hepatic lipid metabolism — burning of fat to fuel the body. Low to moderate levels of ketones in the blood cause no symptoms, but higher blood levels, especially of beta-hydroxybutyric acid, may cause nausea and vomiting.
2. D. Ketones are formed when the body burns fat for energy. When the body simultaneously burns glucose for energy, few ketones are formed. But if there is no (or very little) glucose available for fuel, or if there is no (or very little) insulin available to metabolize glucose, larger and potentially dangerous amounts of ketones are formed. The low levels of ketones created when following a low-carbohydrate diet are generally regarded as harmless. Ketones rarely build up to a dangerous level unless the level of insulin is very low.
While ketones are by-products of fat burning, which can lead to weight loss, ketones themselves play no active role in weight loss.
3. FALSE. People with Type 1 diabetes are advised to check for ketones when their blood glucose level is high, but medical experts differ over the level at which to check, with most recommending a level between 240 mg/dl and 300 mg/dl. In addition, some care guidelines advocate testing for ketones on the first occurrence of an elevated blood glucose number, and others only if two readings in a row are elevated. People with Type 1 diabetes are also advised to check for ketones every 4–6 hours when ill. Persons with Type 2 diabetes generally do not need to check for ketones unless their high blood glucose is accompanied by nausea or vomiting. Women with gestational diabetes have still different recommendations for checking for ketones.
4. FALSE. Ketones can be measured either by using a urine dipstick (such as Ketostix or Acetest) or by testing a drop of blood using a handheld meter. Both the Abbott Precision Xtra and the Nova Biomedical Nova Max Plus blood glucose meters are also capable of testing blood ketones using special strips. Urine dipsticks change color in the presence of acetoacetic acid and, to a lesser degree, acetone; the level of ketones is then assessed by comparing the color of the stick to a color chart that comes with the stick. The blood test measures the level of beta-hydroxybutyric acid. Since beta-hydroxybutyric acid is the type of ketone that contributes the most to acidity in the blood, blood testing is preferred, especially for people with Type 1 diabetes. Blood testing also gives a more accurate depiction of the metabolic state of the body in real time; urine testing indicates the blood ketone levels approximately three hours previously.
5. A and C. In diabetic ketoacidosis, a lack of insulin leads to high levels of ketones and glucose in the bloodstream. Ketones make the blood more acid, and high blood glucose (not ketones) leads to excessive urination and dehydration. Excessive urination also causes depletion of electrolytes such as sodium, potassium, calcium, magnesium, and phosphorous. Excretion of ketones in the urine leads to further losses of electrolytes.
DKA is a life-threatening medical emergency that must be treated in the hospital.
6. FALSE. Although rare, people with Type 2 diabetes whose blood glucose levels are very high for a significant period can enter a state called glucose toxicity, which causes beta-cell function in the pancreas to cease temporarily. With no beta-cell function, no insulin is produced, creating a temporary state physiologically similar to Type 1 diabetes, and DKA can occur. In many instances, these people are misdiagnosed as having Type 1 diabetes when they arrive in the emergency room in DKA. Hispanic and African-American people with Type 2 diabetes are more prone to developing DKA than other racial and ethnic groups.
7. A, B, and D. Increasing the level of insulin in the body allows it to switch back from burning fat to burning primarily glucose. This halts the production of ketone bodies. As the body’s cells start using glucose for fuel again, the excess ketones are flushed into the urine. Increasing fluid intake accelerates their elimination from the body by increasing urination. High levels of ketones usually result from insufficient insulin, which is commonly caused by increased insulin requirements (because of illness, for example) or therapy errors (missing doses or insulin pump malfunctions).
Glucagon is used to treat low blood glucose (hypoglycemia) by causing the liver to release stored glucose. It does not lower ketones.
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