Autonomic function in children with Type 1 diabetes mellitus

Abstract

We investigated autonomic function in 58 children and young adults with Type 1 diabetes mellitus (aged 7-22 years, duration from 3 to 18, 8.6 +/- 3.4 years) and in 74 healthy controls (6-21 years) using power spectral analysis of blood pressure and heart rate in addition to conventional standard autonomic function tests: deep breathing, the Valsalva manoeuvre, and a standing test. None of the diabetic patients were symptomatic. Reproducibility of the tests was assessed by determining the coefficient of variation in 9 controls (7.8-37.7%). Thirteen per cent of the subjects had difficulty in adequately performing the Valsalva manoeuvre. After adjustment for age, sex, body mass index, and respiratory frequency, results of the Valsalva manoeuvre and deep breathing were not different between patients and controls and there was no significant postural reduction in systolic blood pressure (> or = 20 mmHg) in the patients. Heart rate variation in the supine position during natural breathing was low in patients, although power spectral analysis of heart rate variation did not show a significant decrease in the power density in the high and the low frequency in patients compared to healthy controls. Beat-to-beat blood pressure fluctuation was significantly lower in patients and correlated with metabolic control (mean annual haemoglobin A1c), but not with disease duration and was abnormal in 7 diabetic children (12%). In contrast, tests of vagal activity were not impaired in the patients in this age range. We concluded that vagal involvement in Type 1 diabetic patients determined by spectral analysis of R-R intervals in addition to conventional tests is uncommon, but that beat-to-beat blood pressure variation was more likely to be affected.

Autonomic blood pressure control in children and adolescents with type 1 diabetes mellitus

“…The larger one of these studies also demonstrated a negative correlation between baroreflex sensitivity and diabetes duration. Two previous studies report normal baroreflex sensitivity in patients with type 1 diabetes at the age of 10–17 yr and 7–22 yr, respectively, compared with healthy controls (26, 27).…”

Impaired microvascular function related to poor metabolic control in young patients with diabetes

“…Measurements of nerve conduction examine the function of large myelinated nerve fibres whereas the venoarterial response most likely is mediated through sympathetic C-fibres (Henriksen, 1976). However, in young patients with diabetes autonomic dysfunction is rare (Vinik et al, 1992) and the reproducibility and sensitivity of autonomic tests is poor (Tanaka et al, 1998;Bornemyr et al, 1999) and therefore such tests were not performed. From the present study it is concluded that nerve conduction defects are much more common than microvascular abnormalities measured by LDPI in a group of children and adolescents with type 1 diabetes mellitus.…”

Evidence of decreased sympathetic function in children with psychosomatic symptoms

“…As reported by Borres et al [3], an equal number [5] of boys and girls reported psychosomatic or psychosocial symptoms.Age was not a factor influencing the reporting of numbers of psychosomatic or psychosocial symptoms; children in lower grades reported similar numbers compared to children in middle and higher grades. Similar to our previous study reported by Borres et al [3], we divided subjects into three groups according to the number of symptoms: group A (n = 43, aged 11.0 ± 2.7 years) had no symptoms; group B (n = 53, 10.8 ± 2.4 years) had one or two symptoms; group C (n = 17, 11.2 ± 2.6 years) had three or more symptoms.…”

“…Subjects practised rising twice before the tests. Active standing was usually completed within 3-4 seconds.As previously reported [5], it is easier for young children to perform uncontrolled breathing without psychological strain. No intravascular instrumentation was used.…”