Ketones are acid metabolic products, which are produced when the body burns fat. In large quantities, they may result in acidosis in insulin-dependent diabetes.
Ketones include beta-hydroxybutyrate, acetoacetate and acetone. Ketones are produced by the liver when the body breaks down fat to generate energy. More fat is burned due to fasting, a very low-carbohydrate diet or insulin deficiency.
In the treatment of diabetes, measuring ketones is recommended for people with insulin deficiency diabetes on sick days to administer sufficient insulin or if blood sugar is repeatedly significantly high.
The ketone level can be tested either from urine or blood. A urine strip provides an indication; it is not as accurate as a blood test.
Rapid measurement of ketones is possible with certain blood glucose meters using dedicated ketone test strips. There are also separate meters available for ketone measurement. When using a rapid meter with a fingertip sample, the amount of beta-hydroxybutyric acid is measured. A normal reference blood ketone level is below 0.6 mmol/l.
When you fast, some ketones appear in your blood when your body burns away your storage of fat. Ketones are also called hunger ketones. Fasting overnight alone may produce some ketones – even in a person with diabetes. The situation is corrected by absorbing carbohydrates from food.
When carbohydrate intake from food is low, glucose is released from the storage in liver in the same way as when fasting. Most of the glucose available through this process is used up by the neurones. Energy for muscle cells is produced by burning fatty acids. The blood ketone level depends on the intake of carbohydrates. In a mild ketosis, the ketone level is slightly high at 0.6–1.5 mmol/l. In a moderate ketosis resulting from, for example, a low-carbohydrate diet, the ketone level may be higher.
In the case of insulin deficiency, if the supply of insulin is interrupted or the need for insulin is drastically increased, the production of ketones is accelerated further and the blood sugar level increases. When the ketone level increases, there is a risk of acid build-up in the blood, resulting in acidosis or ketoacidosis. In diabetes, if the ketone level increases above 1.5 mmol/l, there is a higher risk of ketoacidosis and the insulin dose and liquid intake must be increased. If the ketone level is higher than 3 mmol/l, the risk of ketoacidosis is high. Read more about measuring ketones and insulin dosing:
Updated 30.9.2023
