Ketones aren't always a problem, even for people with diabetes. If you're trying to lose weight and your blood sugar levels remain in the normal range, the presence of ketones might be OK. Trouble arises when ketone levels get too high, because your blood becomes too acidic. That can lead to so-called diabetic ketoacidosis (DKA), which is a medical emergency. You might feel nauseous, vomit, have trouble breathing, become confused, or pass out. Your breath might also smell fruity; that's a direct result of the ketones.
The best way to prevent this from happening is to keep a close eye on your blood sugar, and, if you take insulin, to use it exactly as instructed by your doctor. Ketones do not usually develop instantly or after missing one injection of insulin, but rather occur over a period of neglect, says Mildred Bentler, CDE, RDN, a diabetes educator, insulin pump trainer, and registered dietitian.
This is your body on sugar: