Urinary excretion of acetylcarnitine during human diabetic and fasting ketosis

The urinary excretionof acetylcarnitinewas studied in patients with diabetic ketosisbefore and during insulin therapy and in normal-weight and obese subjects during fasting. In the diabetic ketotic patients, acetylcarnitinerepresented 61% of the total acylcarnitine excretion. During the first 24 h of insulin treatment, acetylcarnitine excretiondecreased and on the 5th day of treatment was 18% of the acylcarnitines excreted. The urinary excretionof the other acylcarnitines fell slowly. In normal-weight subjects fasted for 3 days, the urinary excretionof acetylcarnitineincreased on the 2nd day of fasting, and on the 3rd day acetylcarnitineaccounted for 78% of the excretedacylcarnitine. In obese subjects there was a progressive increase in urinary acetylcarnitine excretion, but on day 6 it represented only 55% of the total acylcarnitine excreted. The urinary excretionof acetylcarnitinecorrelated with blood beta-hydroxybutyrateconcentration in the normal-weight subjects during fasting and in the diabetic ketotic patients. Acetylcarnitineaccounts for a major fraction of the acylcarnitines excretedin the three ketotic conditions studied. The contribution of acetylcarnitineto the change in acylcarnitines as ketosisappears or disappears is significantly less in the obese subjects than in the normal-weight subjects or in the diabetic patients. This difference may reflect an alteration in the production or disposition of acetyl-CoAand acetylcarnitinein obesity.