Usefulness of a new indicator test for the diagnosis of peripheral and autonomic neuropathy in patients with diabetes mellitus.

AIMS: The aim of the present study was to assess the performance of a new indicator test (NIT), based on the measurement of sweat production after exposure to dermal foot perspiration, in the diagnosis of both peripheral sensorimotor polyneuropathy (PSN) and autonomic neuropathy in patients with diabetes. METHODS: One hundred and seventeen diabetic patients were examined. PSN was assessed using the neuropathy symptoms score, the neuropathy disability score and the vibration perception threshold. Cardiac autonomic neuropathy (CAN) was assessed using the battery of the four classical standardized tests proposed by Ewing et al., Diabetes Care 1985; 8: 491-498. Sudomotor dysfunction was assessed using the NIT. RESULTS: Fifty patients (42.7%) had PSN and 44 patients (37.6%) had CAN. Of the 50 patients with PSN, 43 had a positive NIT (sensitivity 86%) and, out of the 67 patients without PSN, a negative NIT was obtained in 45 patients (specificity 67%). The positive and the negative predictive value of the NIT in detecting PSN were 66.2 and 86.5%, respectively. The sensitivity and specificity of NIT in detecting CAN was 59.1 and 46.5%, respectively. In the case of severe CAN, the sensitivity was increased to 80.9% and the specificity to 50%. CONCLUSIONS: The NIT has good sensitivity and negative predictive value for diagnosis of PSN and can be used as a screening method for detection of this complication in patients with diabetes. In addition, the test has a low sensitivity for detection of autonomic neuropathy in patients with milder forms of CAN.

Peripheral neuropathy does not invariably coexist with autonomic neuropathy in diabetes mellitus.

Background: Peripheral somatic and autonomic neuropathies are the most common types of diabetic polyneuropathy. Although duration and degree of hyperglycemia are considered to be risk factors for both autonomic and peripheral neuropathy, recent studies have raised the question of a different development and natural history of these neuropathies in diabetes. In addition, a few studies have investigated the relationship between chronic painful and autonomic neuropathy. The aim of this study was to investigate to what extent autonomic and peripheral neuropathy coexist, as well as whether painful neuropathy is more common in diabetic patients with autonomic neuropathy. Methods: Subjects with type 1 (n=52; mean age 31.7 years) and type 2 diabetes (n=53; mean age 54.5 years) were studied. Evaluation of peripheral neuropathy was based on clinical symptoms (neuropathic symptom score), signs (neuropathy disability score), and quantitative sensory testing (vibration perception threshold). Assessment of autonomic neuropathy was based on the battery of standardized cardiovascular autonomic function tests. Results: Prevalence rates of pure autonomic and of pure peripheral neuropathy in patients with type 1diabetes were 28.8 and 13.5%, respectively. The respective rates in patients with type 2 diabetes were 20.7% (P=0.33 vs. type 1 diabetes) and 20.7% (P=0.32). Peripheral and autonomic neuropathy coexisted in 28.8% of type 1 and in 45.3% of type 2 diabetic subjects (P=0.08). Prevalence rates of chronic painful neuropathy in subjects with type 1 diabetes, with and without autonomic neuropathy, were 16.6 and 22.7%, respectively (P=0.85) and in type 2 diabetic subjects 20 and 22.2%, respectively (P=0.58). Multivariate analysis after adjustment for age, sex, blood pressure, duration of diabetes, HBA(1c), and presence of retinopathy or microalbuminuria showed that neither the indices of peripheral nerve function (neuropathic symptom score, neuropathy disability score, vibration perception threshold) nor the presence of peripheral neuropathy or chronic painful neuropathy are associated with the presence of autonomic neuropathy in individuals with either type 1 or type 2 diabetes. Conclusions: Peripheral and autonomic neuropathies do not invariably coexist in diabetes. In addition, chronic painful neuropathy may be present irrespective of the presence of autonomic neuropathy.