Nutritional ketosis is a normal, physiological response to carbohydrate and energy restriction. A ketogenic diet is an effective weight loss strategy for many. Ketoacidosis, on the other hand, is a pathological condition caused by insulin deficiency. The common theme is low insulin; however, in ketoacidosis, blood glucose levels are very high. Ketone levels are elevated in both states, although are 10-20x higher in ketoacidosis (~0.5-2 vs. > 20 mM). Nutritional ketosis and ketoacidosis should not be confused with one another, and a ketogenic diet doesn’t cause ketoacidosis.
In ketoacidosis, gluconeogenesis occurs at a very high rate and the lack of insulin prevents glucose disposal in peripheral tissues. Skeletal muscle protein breakdown contributes gluconeogenic substrates, exacerbating the problem. This can cause blood glucose to reach pathological levels, exceeding 250 mg/dL.