My five year old daughter, diagnosed with type 1 diabetes five months ago, is on a low carb diet and her blood glucose level is normally around 100 mg/dl [5.6 mmol/L], but recently she got sick and even though her blood glucose was about 150-250 mg/dl [8.3-13.9 mmol/L], we found small to moderate amount of ketones in her urine. As I understand ketones are the side product of fat breakdown when the body doesn’t have enough energy. Would it be normal for a person who is on a low carb diet or even not eating carbohydrates at all to have some ketones in his/her urine? What could be the side effects of that?

Ketones can be tested in the urine (as acetone and acetoacetate) or in the blood (as beta hydroxybutyric acid) and reflect fat breakdown. This can occur if one is not getting adequate calories (starvation), unable to absorb calories (malabsorption, diarrhea, vomiting problems) or when carbohydrates are not being used appropriately during insulin deficiency.

During most respiratory illnesses, insulin deficiency occurs, and unless adequate extra insulin is provided, the body switches from being able to utilize carbs for energy to using its reserve fuels — usually mostly fats. During intercurrent illnesses involving the GI system, you could have insulin deficiency as well as merely inadequate absorption so ketones could occur with high sugars as well as low sugars depending upon which is occurring to a greater or lesser degree.

The ketones themselves are not damaging except that they could represent dehydration states, starvation states, inadequate calories or inadequate insulin. DKA [diabetic ketoacidosis] occurs when there is a buildup of ketoacids and thus ketone testing reflects the degree of DKA occurring. So it is important to measure either urine or blood ketones when a person has diabetes to help decide how much extra fluids are needed, how much extra insulin is needed and when to contact the medical team for further advice.

SB