Clinical correlates of painful diabetic neuropathy and relationship of neuropathic pain with sensorimotor and autonomic nerve function.

BACKGROUND: This study investigated the clinical correlates of painful diabetic polyneuropathy (PDPN) and the relationship of neuropathic pain with sensorimotor and autonomic nerve function. METHODS: Seventy-eight diabetic patients with PDPN (PDPN(+)), 57 with non-painful diabetic polyneuropathy (DPN(+)), and 56 without diabetic polyneuropathy (DPN(-)) were prospectively studied. Autonomic neuropathy, neuropathic symptoms and signs, vibration perception threshold, and neuropathic pain were assessed using 4 cardiovascular tests, scoring systems for symptoms and signs (Michigan Diabetic Neuropathy Score, MDNS), Biothesiometer, and a numerical rating scale. RESULTS: Compared to DPN(+), PDPN(+) patients displayed higher BMI (P=0.0043), waist circumference (P=0.0057), neuropathy symptom score (P<0.0001), MDNS (P<0.0001), and lower Valsalva ratio (P=0.037). In a multiple logistic regression analysis including PDPN as the dependent variable and age, sex, body mass index (BMI), abdominal obesity, diabetes type, diabetes duration, HbA1c, blood pressure, triglycerides, smoking, peripheral arterial disease, Valsalva ratio and MDNS as the independent variables, BMI (OR 1.22, P=0.0012) and MDNS (OR 1.27, P=0.0005) were significantly and independently associated with PDPN. In a multivariate regression analysis including as independent variables also sex, age, diabetes type, diabetes duration and Valsalva ratio, 24-h pain score was significantly related to neuropathy symptom score (P=0.0011), MDNS (P=0.0158), and 10g monofilament (P=0.018). DISCUSSION: BMI and sensorimotor deficits were the main determinants of PDPN and, as a novel finding, neuropathic pain intensity was related to the degree of neuropathy deficits. Thus, some peculiarity exists in metabolic correlates of diabetic neuropathic pain compared to insensate neuropathy but painfulness can still coexist with insensitivity.

Reappraisal of the diagnostic role of orthostatic hypotension in diabetes.

OBJECTIVE: Given the controversial aspects of orthostatic hypotension (OH) testing in diabetes, we evaluated the diagnostic role for cardiac autonomic neuropathy (CAN) and for nondipping of OH, defined according to a fall in systolic blood pressure (BP) > or = 30 (30-OH) or > or = 20 mmHg (20-OH). METHODS: 164 diabetic patients underwent 24 hours BP monitoring, three heart rate cardiovascular tests, and OH test. RESULTS: Compared to 30 mmHg, the 20 mmHg criterion increased the frequency of OH from 11 to 19.5%. Both 30-OH and 20-OH were associated with CAN (chi (2) = 30.5, P < 0.0001, and chi (2) = 45.1, P < 0.0001, respectively) and nondipping (chi (2) = 31.7, P < 0.0001, and chi (2) = 17.2, P = 0.0001, respectively). ROC curve for orthostatic systolic BP fall provided an AUC of 0.79 +/- 0.04 (95% CI 0.70-0.86) for diagnosing CAN and of 0.77 +/- 0.05 (95% CI 0.66-0.86) for diagnosing nondipping. Both 30-OH and 20-OH showed a low sensitivity and high specificity for CAN [sensitivity 31%, specificity 98%, Likelihood Ratio for a positive result (LR(+)) 17.1; and sensitivity 50%, specificity 95%, LR(+) 9.3, respectively], and for nondipping (sensitivity 40%, specificity 96%, LR(+) 8.9, and sensitivity 47%, specificity 87%, LR(+) 3.5, respectively), having 30-OH a higher LR(+) in both cases. INTERPRETATION: OH had only moderate diagnostic accuracy, with high specificity and low sensitivity, for CAN, diagnosed on the basis of heart rate cardiovascular tests, and-as a novel finding-also for nondipping. A different definition of OH did not substantially affect its diagnostic characteristics, with just a slightly greater ability of the 30 mmHg criterion to estimate the probability of CAN and nondipping.