What causes "acetone breath" in people with diabetes?

Ketones. Ketones are chemicals produced when diabetics have blood sugars that are running to high. This is an ominous sign that you need to be doing much more to control your sugar through diet and medications. Failure to do so could land you in the intensive care unit of the hospital fighting for your life. You need to see your doctor asap to get this taken care of.
Acetone is. A ketone produced when there is absence of insulin: it is volatile and one can smell it in the breath.