If a diabetes mellitus patient continually has high blood glucose, what is likel

With too much glucose present, the blood-brain barrier cells may remove glucose transporters from the patient's membranes. If blood glucose drops due to insulin therapy, the brain neurons may be unable to obtain sufficient glucose to function or remain alive. This can lead to a comatose state or even death.

One outcome if blood glucose remains high in diabetics is diabetic ketoacidosis (DKA). With diabetics, if there is no insulin or not enough insulin for glucose to be used appropriately by the body, the body thinks it needs to switch to fat stores as a source of energy. By metabolizing fat stores, ketone bodies accumulate in the blood. Ketone bodies are acidic and lower the pH of the blood.  The body tries to compensate by blowing off carbonic acid (CO2) with deep rapid breaths to try to raise the pH but will not be able to keep up. At the same time, high levels of blood glucose cause the body to excrete more water in urine causing dehydration. Because of the high levels of ketone bodies, the kidney begins excreting ketones which causes a depletion of cation electrolytes that are excreted with the ketones in the urine. So the result is a severely dehydrated, electrolyte depleted individual whose blood pH is falling. If untreated, the CNS will become depressed from the acidosis which causes the comatose or death.

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