Diabetic ketoacidosis is a potentially fatal complication of diabetes mellitus. Why does diabetic ketoacidosis occur and what effects would it have on the body?

The suffix -osis refers to a condition or syndrome, so person with diabetic ketoacidosis has excessive amounts of ketones in their blood, and the high ketone concentration is an effect of the diabetes mellitus. The ketones are acids, so the blood pH is lowered (this is an acidosis or acidaemia).

Insulin deficiency and an increase in the counter-regulatory hormones (which work against the action of insulin, raising blood glucose levels in response to hypoglycemia) increases gluconeogenesis and accelerates glycogenolysis. Insulin deficiency and increased counterregulatory hormones also lead to the release of free fatty acids into circulation from adipose tissue (lipolysis) The free fatty acids converted to ketone bodies in the liver.

There are many effects of diabetic ketoacidosis. Patients will of course have impaired glucose utilisation because of the deficiency of insulin that triggered the diabetic ketoacidosis. The acidosis changes the pH of the blood and that affects the function of enzymes. The high levels of ketones in the urine have an osmotic effect that causes increased urine production and dehydration. Insulin promotes potassium entry into cells. In diabetic ketoacidosis potassium moves out of cells, thus raising plasma potassium levels. The ongoing potassium movement out of the cell is keeps potassium levels high, but the potassium is excreted through the kidneys, so whole-body potassium depletion develops. This changes the balance of sodium and potassium ions across the cell membrane, affects the cell membrane potential and therefore the electrical activity in cells. The electrical changes can be very significant in the heart where they can cause fatal electrical abnormalities (arrhythmias).