ORIGINAL ARTICLE Sympathovagal balance and 1-h postload plasma glucose in normoglucose tolerant hypertensive patients Maria Perticone 1 • Eliezer J. Tassone 2 • Paola E. Scarpino 2 • Paola Naccarato 2 • Desire ´e Addesi 2 • Serena di Cello 2 • Angela Sciacqua 2 • Raffaele Maio 2 • Michele Andreucci 3 • Salvatore Carrao 4 • Anna Licata 4 • Giorgio Sesti 2 • Francesco Perticone 2 Received: 31 December 2014 / Accepted: 11 March 2015 Ó Springer-Verlag Italia 2015 Abstract Aims Normoglucose tolerant (NGT) subjects with a 1-h postload plasma glucose (PLPG) value C155 mg/dL have an increased risk of type-2 diabetes and subclinical organ damage. Heart rate variability (HRV) reflects cardiac au- tonomic balance, frequently impaired in course of diabetes. At this time, no data support the association between 1-h PLPG and HRV; thus, we investigated the possible asso- ciation between 1-h PLPG and HRV. Methods We enrolled 92 never-treated hypertensive subjects (56 women, 36 men), aged 55 ± 9.8 years. During OGTT, the patients underwent electrocardiographic recordings to evaluate HRV in the time domain (SDNN). Insulin sensitivity was assessed by Matsuda index. Results Among participants, 56 were NGT, 20 had im- paired glucose tolerance (IGT), and 16 had type-2 diabetes. According to the 1-h PLPG cutoff point of 155 mg/dL, we divided NGT subjects into: NGT \ 155 (n = 38) and NGT C 155 (n = 18). Glucose tolerance status was asso- ciated with a significant (P \ 0.0001) increase in PLPG and insulin and the reduction in Matsuda index. In all groups, the SDNN values significantly (P \ 0.0001) de- creased during the first hour of OGTT. A complete re- covery in NGT groups was observed at the end of the second hour; in IGT and type-2 diabetes, SDNN remained significantly lower with respect to baseline values. At multiple regression analysis, Matsuda index resulted in the only determinant of SDNN modification, explaining the 12.3 % of its variability. Conclusions Our data demonstrate that during OGTT, sympathovagal balance is acutely affected by both glucose and insulin modifications. Particularly, NGT C 155 sub- jects behave in the same way of IGT and type-2 diabetes patients. Keywords Insulin resistance Á Heart rate variability Á Glucose tolerance Á Essential hypertension Introduction Cardiovascular diseases, particularly coronary heart dis- ease and ischemic stroke, are the most important cause of morbidity and mortality in subjects with type-2 diabetes [1, 2]. In addition, type-2 diabetes-related metabolic dis- orders lead to the appearance and progression of sensitive and autonomic neuropathy in addition to micro- and macro-vascular damage. Specifically, diabetic autonomic neuropathy (DAN) is a serious and common complication of type-2 diabetes that, despite its significant negative impact on survival and quality of life, remains a poorly recognized and understood clinical condition [3–5]. Damage of the autonomic nerve fibers that innervate the Managed by Antonio Secchi. & Francesco Perticone perticone@unicz.it 1 Department of Experimental and Clinical Medicine, University Magna Graecia of Catanzaro, Campus Universitario di Germaneto, V.le Europa, 88100 Catanzaro, Italy 2 Department of Medical and Surgical Sciences, University Magna Græcia of Catanzaro, Campus Universitario di Germaneto, V.le Europa, 88100 Catanzaro, Italy 3 Department of Health Science, University Magna Græcia of Catanzaro, Catanzaro, Italy 4 Biomedical Department of Internal Medicine and Speciality, University of Palermo, Palermo, Italy 123 Acta Diabetol DOI 10.1007/s00592-015-0740-1