Secondary Rise in Plasma Free Fatty Acids Following Glucose Load

Abstract

The plasma free fatty acids (FFA) respond to glucose adminstration by decreasing. Four to 6 hours after glucose there is a rise in the FFA to values significantly higher than the fasting levels. This secondary rise in the FFA was studied in 28 subjects to whom a glucose load of 50 g had been given intravenously. A correlation of 0.86 was noted between the minimal blood sugar occurring after the initial glucose peak and the magnitude of the secondary rise in the FFA. Catecholamine response was studied during the glucose tolerance test by measuring the output of 3-methoxy-4-hydroxy mandelic acid (VMA) at hourly intervals. A significant increase in the VMA excretion over the fasting level occurred in all but one of the cases. The magnitude of the VMA peak showed a correlation of 0.55 with the secondary rise in the FFA. Control patients receiving no glucose showed no significant variation in the hourly excretion of VMA. Thus, those cases showing the least tendency to have a drop in the blood sugar to levels below the fasting levels are most likely to show the greater degree of increase in the FFA in the later hours of the glucose tolerance test.