Acetone

Acetone is a chemical produced by the body's normal metabolism which has the chemical formula (CH3)2CO. It is produced when the body digests fatty acids for energy instead of glucose. It is normal to find it in the blood and urine. Individuals who abstain from carbohydrates, are fasting, or have diabetes mellitus produce it in higher quantities. Once thought to be solely a waste product that is passed in urine, the body can use acetone in a complicated set of steps to produce additional energy. 
Commercially produced acetone is commonly used as a solvent, particularly in products such as nail polish remover. It is also used widely to clean laboratory equipment. 
In Diabetic ketoacidosis, acetone is one of the compounds that produces the characteristic fruity smell of the breath. 
Acetone at Wikipedia