¹Department of Internal Medicine, Endocrinology, Tor Vergata University, Rome, Italy

Correspondence: Dr V Spallone, Department of Internal Medicine, University of Tor Vergata, Via Montpellier, 81, 00133 Rome, Italy. E-mail: vispa@mclink.it

Received 26 September 2006; Revised 26 November 2006; Accepted 18 December 2006; Published online 15 February 2007.

Abstract

This study investigated whether nondipping (defined as a day–night change in blood pressure (BP) 0%) could be assumed as a diagnostic index for autonomic neuropathy, and assessed its accuracy in discriminating between type I diabetic patients with and without autonomic neuropathy. In 87 type I diabetic patients with normal renal function (age 3611, duration 179 years, serum creatinine 67.215.9 mol/l), four cardiovascular tests and 24-h BP monitoring were performed, and the percentage day–night change () in systolic (SBP) and diastolic BP (DBP) was calculated. Sixteen patients had SBP and/or DBP 0%. In a multiple logistic regression with adjustment for sex, age, and body mass index, the odds ratio for having autonomic neuropathy was seven times higher in patients with SBP 0% as opposed to those without (odds ratio 6.97, CI 1.4–34.9, P=0.018). Using Receiver Operating Characteristic (ROC) analysis, BP showed an acceptable accuracy in discriminating between patients with and without autonomic neuropathy (area under the ROC curve 0.690.06 and 0.720.05 for SBP and DBP, respectively). Adequate cutoff values were 0% for SBP (sensitivity, 26%; specificity, 95%; positive predictive value, 87%) and 5% for DBP (sensitivity, 26%; specificity, 92%; positive predictive value, 81%). In type I diabetic patients with normal renal function, a value of SBP 0% identifies the presence of autonomic neuropathy with a very high chance. Nondipping at the cutoff proposed could be considered an adjunctive marker of autonomic neuropathy provided with a high specificity and low sensitivity.