If your sugars are at 300 mg/dl then, yes, if you are dumping ketones that would be a nearly sure sign of diabetic ketoacidosis and reason to get treatment immediately, even ER-type immediately. Fortunately, this is unlikely and it is not something that would be caused by LC eating. Eating LC and having sugars that high will just result in you not being able to start burning ketones until your sugars come down.