Excess glucose doesn't cause diabetic ketoacidosis, but rather too little insulin. You can run high blood sugar for literally years without going into DKA (although it does damage your body). It's even possible in certain, rare circumstances to enter DKA with normal blood sugar.
You're right. DKA is the result of the body burning fat for fuel when insufficient insulin prevents it from burning glucose. I should have remembered that. My patients with DKA always had a BGL of 500 or more (5x normal), so that's why I mistakenly associated DKA with high sugar.
