The most likely condition to cause the breath to smell of alcohol is diabetic ketoacidosis. This condition is one of the first signs of type 1 diabetes.
Diabetic ketoacidosis is usually manifested by the person's breath bearing a fruity or alcoholic odor. This is because the person's cells are not able to use the glucose he consumes for energy due to the cells' low insulin levels, according to MedlinePlus.
In this instance the body resorts to burning fat in order to provide energy for the cells, and by-products known as ketones are produced. As ketones accumulate in the bloodstream, the person's breath starts to give off an odor of alcohol.
Diabetic ketoacidosis is potentially life-threatening. See a doctor immediately if it is suspected.