Ketones are produced when glucose is not available to supply the body's cells with energy. This can occur when insulin levels are insufficient or lacking. To make energy, the body then begins breaking down fat into acetyl CoA.
The acetyl CoA produced is converted to acetone, acetoacetate, and beta-hydroxybutyrate. These are acids and when dissolved in body fluids in excess, they lower the blood pH. Increased ketones can result in a metabolic acidosis referred to as ketosis, ketoacidosis, or diabetic acidosis. Type 1 diabetic patients are especially at risk for ketoacidosis.
Urine and serum ketones are measured semi-quantitatively and a diabetic in ketosis is monitored for ketones and blood pH.