Diabetic autonomic neuropathy: the prevalence of impaired heart rate variability in a geographically defined population.

The prevalence of diabetic autonomic neuropathy and its relationship with other diabetic complications were studied in a geographically defined population. Heart rate variability was measured by a computerized technique at rest and in response to both a single deep breath and a Valsalva manoeuvre. Among 43 Type 1 (insulin-dependent) and 202 Type 2 (non-insulin-dependent) patients results below the 2.5 centile for age-related normal ranges occurred in 9 Type 1 and 32 Type 2 patients (16.7, 95% Cl 12.6 to 21.9, %). Symptomatic autonomic neuropathy was uncommon but was significantly more frequent in Type 1 than Type 2 patients (5 Type 1, 1 Type 2, p less than 0.001 Fisher's exact test). In Type 1 diabetes, cardiovascular autonomic dysfunction was significantly associated with impaired vibration perception and a higher logarithmic urinary albumin concentration and, in Type 2 diabetes, it was associated with a significantly higher body mass index, systolic blood pressure, and logarithm of the urinary albumin and fasting insulin concentrations. The aggregation of these factors with cardiovascular autonomic dysfunction suggests that mortality might be increased in Type 2 patients with asymptomatic autonomic neuropathy.