Correlation of cardiovascular and neuroendocrine tests of autonomic function in diabetes

Six normal subjects and 16 insulin-dependent diabetics with varying degrees of autonomic damage each had blood sampled for norepinephrine and pancreatic polypeptide for fifteen minutes after a mixed meal and intravenous (IV) edrophonium (Tensilon). The normal subjects showed a brisk but short-lived rise in norepinephrine after edrophonium (average maximum increase 70% between 2 and 6 minutes), as did most diabetics. However, diabetics with cardiovascular reflex evidence of sympathetic damage showed no rise in norepinephrine. Pancreatic polypeptide concentrations increased up to 400% above baseline after a mixed meal in both the normal and the diabetic group with normal cardiovascular reflexes. There was no significant rise in pancreatic polypeptide either in the diabetics with parasympathetic damage alone or in those with additional sympathetic damage. These results provide further evidence for the diffuse nature of the damage in diabetic autonomic neuropathy.