Type of diabetic sensory neuropathy and autonomic involvement

Thirty controls and 39 diabetic patients were studied by means of nerve conduction and autonomic tests. Standing by lying (S/L) heart rate ratio was done to test cardiac vagal function. The fall of systolic blood pressure (BP) from lying to standing (greater than or equal to 30 mmHg) was done to test sympathetic function. In 30 controls the S/L ratio was 1.28 (SD 0.1), and none of them had BP fall. In 10 diabetic patients without clinical neuropathy, S/L ratio was 1.28 (SD 0.01) and BP fall was not present. In 8 diabetic patients (with predominantly large fibre type), S/L ratio was 1.0 (SD 0.0) and the BP fall was not present. In 7 diabetic patients (with predominantly small fibre type), S/L ratio was 1.07 (SD 0.05) and 2 patients had BP fall. In 14 diabetic patients with mixed large and small fibre type, S/L ratio was 1.02 (SD 0.04) and 8 patients had BP fall. Sympathetic dysfunction is related to the type of sensory neuropathy. Vagal function is not related to any specific type, but it is related to the presence of polyneuropathy.