First, my limited understanding of ketosis - please correct any misconceptions I have.

If a person, diabetic or not, is metabolizing fat, they will produce ketone bodies that if above a certain level will (most likely) be detected by ketostix or other similar urinalysis reagent.

In Low Carbing, a person intentionally restricts their carbohydrate intake so as to force the body to switch to fat metabolization as a primary source of fuel placing them in a state of prolonged ketosis. If they consume carbohydrates in any quantity, their body will cease fat metabolism and switch to glucose metabolism - so it is one or the other at any given time. This poses little, if any, health risks (possibly a bit higher stress on the kidneys?).

In a diabetic following a non-LC diet, their goal (intentional or not) is to remain using glucose as their primary fuel source. If their body is unable to metabolize that glucose, either because they lack sufficient insulin or because they are so insulin-resistant that the glucose can't enter the cells properly, then even though they have sufficient glucose their body will still resort to metabolizing fat (and protein). This also places them in a state of ketosis, but for a very different reason. First and foremost, their body is metabolizing fat even though there is sufficient glucose still in the blood. The combination of both fuels being present while only one of them is being used (indirectly) results in a lowering of the blood pH levels to a dangerous level. This is the condition known as diabetic ketoacidosis.

So now we have the situation of a diabetic following an LC diet. Under normal conditions, if they are following plan, their blood sugar levels should remain reasonably low as long as they are ketosis. If, for whatever reason (too many carbs, missed medication, etc), their blood glucose level rises they will get knocked out of ketosis just like a non-diabetic. The problem is if they either experience increased blood glucose levels without getting knocked out or if they re-enter ketosis despite still having high blood glucose levels. Both conditions are indicative of diabetic ketoacidosis.

Any major misconceptions of fallacies so far?

So here is my question - does being firmly established in dietary ketosis increase the risk of incurring diabetic ketoacidosis if blood sugars get spiked? Perhaps what I am really asking is better understood by considering a hypothetical case.

Before I started low carbing it was not uncommon for my blood sugars to spike to 300 or higher. Now, let's assume that when that happened I was on the verge of developing diabetic ketoacidosis but didn't quite do it. Now shift to after I have been low carbing and maintaining myself in a firm state of dietary ketosis and I consume a bunch of bad carbs that cause my blood sugars to spike to the same level they did before. The question is whether I would now be more likely, less likely, or just as likely to develop diabetic ketoacidosis as a result?

A related question is how quickly can diabetic ketoacidosis develop? Minutes? Or does it require at least a somewhat prolonged period of time during which both high glucose and on-going fat metabolism are present?

Another related question. Before I was diagnosed with Type II, I had the classic symptoms of highly increased thirst, foggy mental processes, and also steady weight loss. My HbA1c levels were very high (12.8). Is it reasonably safe to assume that I was probably in a state of at least mild diabetic ketoacidosis during much of that time (several months)?

Thanks to anyone that can provide some insight.