THE PREVALENCE OF AUTONOMIC AND PERIPHERAL NEUROPATHY IN INSULIN-TREATED DIABETIC SUBJECTS

The prevalence of autonomic and peripheral neuropathy was examined in 506 diabetic subjects treated with insulin, mean age 43 years, diabetes duration 15 (range 1-54) years. Autonomic neuropathy was present if two or more (of four) cardiovascular autonomic function tests were abnormal using age-related ranges derived from 310 normal control subjects. Peripheral neuropathy was defined as a vibration threshold >95th centile for age combined with absent/impaired ankle reflexes. Eighty-four (16.6%) of diabetic subjects had abnormal autonomic function and 119 (23.5%) peripheral neuropathy, concordant in 44/506 (8.7%). Of the diabetic subjects with autonomic neuropathy 40/84 (47.6%) did not have peripheral neuropathy and only 44/119 (37.0%) with peripheral neuropathy had abnormal autonomic function (p<0.001). The prevalence of both neuropathies increased in relation to diabetes duration (both p<0.001). Autonomic neuropathy was more common in subjects diagnosed <20 years of age (18.2%) vs age >40 years (11.1%) (p<0.05). In contrast peripheral neuropathy was more common with older age at diagnosis (<20 years 13.5% vs 36.8% >40 years, p<0.001). The age-related prevalence of autonomic neuropathy peaked at age 40-49 years while peripheral neuropathy increased progressively with age (p<0.001). The prevalence of peripheral exceeded autonomic neuropathy 20 years after diagnosis (40.2% vs 30.7%, p<0.001).