We have studied the correlation between NEFA and KB in 25 controls and in 24 diabetics, receiving or no insulin therapy. There is a correlation (r=0,64) between NEFA and KB in normal subjects and a more significant correlation (r=0,85) in diabetics. The "b" value of the two regression lines in the two groups is different, and this is dependent by variations in the hormonal (insulin and glucagon) and metabolic responses.