Hi @Jaxx01 , What the LCHFers are talking about is Nutritional Ketosis. This is different from Diabetic Ketoacidosis.
When eating in a low carb, higher fat way, your body moves over from using a glucose based energy system to a fat based energy system. This process generates ketones and detecting these in the blood and urine is a way to determine whether your body has fully moved over to a fat based energy system. Typical levels of blood ketones in this state are 3-5 mmol/l and it occurs at normal blood glucose levels. It is perfectly healthy.
DIabetic Ketoacidosis (DKA) is the side effect of not enough insulin. It is typically accompanied by high blood glucose levels and is extremely dangerous. The amount of ketones in the blood causes it to become acidic and you rapidly lose consciousness. typically, DKA is considered to be occurring at blood ketone levels of >10 mmol/l.
Nutritional Ketosis is also a great way to lose weight via fat loss as your body is using your fat stores rather than glucose to create energy for your muscles.