OBJECTIVE To measure both peripheral and central autonomic function in patients newly diagnosed with type II diabetes. METHODS Measurements were made on 49 diabetic patients (8 with long-standing diabetes and neuropathic complications, 41 with newly diagnosed type II diabetes) and on 49 healthy, age- and sex-matched, control subjects. Five of the 41 newly diagnosed type II diabetic patients had retinopathy, and 4 had clinical evidence of neuropathy. No patient or control subject had significant vascular disease. Cardiac autonomic function was investigated by using standard cardiovascular reflex tests. The digital vasoconstrictor responses to deep breathing and body cooling were measured using venous occlusion plethysmography. RESULTS The vasoconstrictor responses to a deep breath and body cooling were significantly reduced (P < 0.001) in the fingers and toes of the neuropathic patients compared with their matched control subjects, as were the heart rate responses (P < 0.02). The vasoconstrictor responses were significantly reduced in the toes (P < 0.001) and fingers (P < 0.05, P < 0.01) of the newly diagnosed patients compared with the corresponding responses in the control subjects. There was no significant difference in the heart rate or blood pressure responses of these patients and control subjects during standard tests of cardiac autonomic function. CONCLUSIONS Patients with type II diabetes may have impaired peripheral autonomic function at diagnosis.