Tests for autonomic neuropathy in diabetic children

Five simple tests of autonomic nerve function were studied in 38 children (12.0 years, s.d. = 3.3) with insulin-dependent diabetes mellitus and a further 38 age and sex matched controls in order to validate the use of these tests in children. The five tests included one test (immediate heart rate response to standing) previously reported. Compared to controls, diabetics showed a significantly faster heart rate at rest (P = 0.022), a reduced heart rate variation during quite respiration (P = 0.003), a smaller change in heart rate following a single deep breath (P = 0.006), a lower Valsalva ratio (P = 0.084) and a lower maximum R-R/minimum R-R ratio in response to standing (P = 0.033). The heart rate response to the Valsalva manoeuvre is less suitable for use in children than adults as it requires considerable co-ordination and co-operation and it did not correlate with the other tests of autonomic nerve function. The other tests significantly correlated with each other and were quick and easy to perform. They required no special co-operation and required no special equipment other than a standard ECG machine. Three diabetics had abnormalities in four of the tests (mean heart rate, heart rate variations during quiet respirations, change in heart rate produced by a single deep breath and the previously reported immediate heart rate response to standing). None of the controls had abnormalities in more than two of the tests.