You might be misremembering the doctor, or he was being general, because the issue we found with adolescent females (and some males, though I saw less of them) was that they were hiding their shots (not taking them), so that they would by hyperglycemic. Your body is constantly using fat as an energy source simply due to metabolic pathways, but the one that really kicks into overdrive is the ketone production when there is not a good source of carbohydrates, because certain areas of the body (the brain is the big one) do not use protein catabolism for energy production and rely on either glucose or ketones to feed into the kreb cycle.

Smart kids either made the connection in their high school bio classes or heard the information passed along at the doctor’s office, and there was a large wave of DKA hospitalizations that happened due to avoiding the shots of insulin.