Standing to Lying Heart Rate Variation. A New Simple Test in the Diagnosis of Diabetic Autonomic Neuropathy

We have examined the immediate heart‐rate response to standing to lying (S‐L) in 83 male insulin‐dependent diabetic subjects aged 40 ± 11 years (mean ± S.D.) who underwent five other cardiovascular autonomic tests. Using a specially devised scoring system, the patients were divided into 3 groups: (1) 54 subjects without autonomic neuropathy; (2) 17 ‘borderlines’; (3) 12 with autonomic neuropathy. The results were compared with those of 50 sex and age matched controls. We evaluated: S‐L 1 = ratio between R‐R mean before lying and R‐R minimum over the first 5 beats after lying; S‐L 2 = ratio between R‐R maximum between the 20th to 25th beat and R‐R minimum over the first 5 beats after lying. In controls S‐L 1 was 1.23 ± 0.098 (mean ± S.D.), S‐L 2 1.56 ± 0.2. In diabetic subjects without autonomic neuropathy S‐L 1 was 1.18 ± 0.096 ( p <0.01), S‐L 2 1.50 ± 0.23. In the autonomic group S‐L 1 was 1.03 ± 0.01 ( p <0.001), S‐L 2 1.16 ± 0.086 ( p <0.001). We propose that the lowest normal and highest abnormal limits of S‐L 1 are 1.10 and 1.07, respectively, and that normal and highest abnormal limits of S‐L 2 are 1.23 and 1.14, respectively. We suggest the use of S‐L 1 as a pure parasympathetic test and S‐L 2 as a mixed but predominantly sympathetic test in the diagnosis of autonomic neuropathy.