Plasma dihydroxyphenylglycol (DHPG) as an index of diabetic autonomic neuropathy.

Forearm venous plasma noradrenalin and dihydroxyphenylglycol (DHPG) concentrations were measured in eight diabetic patients with and eight diabetic patients without neuropathy. Plasma noradrenalin was on average the same in patients with and without neuropathy and correlated to serum creatinine. Plasma DHPG concentrations were significantly reduced in patients with autonomic neuropathy as compared to patients without neuropathy (P less than 0.05). A low plasma DHPG/noradrenalin ratio in forearm venous blood identified all patients with autonomic neuropathy except one (P less than 0.02). Measuring the plasma DHPG/noradrenalin ratio may circumvent the problem of unrepresentative noradrenalin release from the forearm.