Abstract. – Background and Objectives: Glycemic control has been suggested to im- prove prognosis in diabetic patients, but recent trials failed to show benefits from intensive glycemic control. Hypoglycaemic episodes or large variability in glucose blood levels causing a sympatho-vagal imbalance of cardiac auto- nomic function (CAF) might play a role in this re- sult. In our study we assessed whether blood glucose fluctuation may be related to variations in CAF during daily life in diabetic patients with coronary artery disease (CAD). Materials and Methods: Twelve patients with type 2 diabetes mellitus with CAD (65±4 years, 2 women) underwent simultaneous 48-hour ECG Holter monitoring and continuous interstitial glu- cose measurements. The highest and lowest glu- cose levels for each 3-hour segments of the day were identified and heart rate variability (HRV) pa- rameters were measured on Holter recordings on 5-minute intervals centred on these times. Results: Overall, 294 glucose levels were available for analysis. In the whole population several HRV indices were significantly lower in correspondence of the lowest glucose blood lev- els and this difference was much more evident in patients who were not taking beta-blockers, than in patients who were taking beta-blockers. A significant, although mild, correlation was found between glucose blood levels and several time-and frequency domain HRV variables in pa- tients not taking beta-blockers, but not in these on beta-blockers therapy. Discussion: Our data suggest that, in type 2 dia- betic patients with CAD, hypoglycaemic episodes are associated with depressed HRV and that beta- blocking agents are able to contrast this relation. These interesting results merit to be investigated in a larger population of patients. Key Words: Diabetes mellitus, Heart rate variability, Continuous glucose monitoring. European Review for Medical and Pharmacological Sciences 2010; 14: 203-207 Low glucose blood levels are associated with abnormal cardiac sympatho-vagal balance in type 2 diabetic patients with coronary artery disease F. INFUSINO, D. PITOCCO*, F. ZACCARDI*, G. SCAVONE, I. COVIELLO, R. NERLA, R. MOLLO, A. SESTITO, A. DI MONACO, L. BARONE, C. PISANELLO, G. GHIRLANDA*, G.A. LANZA, F. CREA Institute of Cardiology and *Institute of Medical Pathology and Diabetology, School of Medicine, Catholic University of the Sacred Heart, Rome (Italy) Corresponding Author: Gaetano A. Lanza, MD; e-mail: g.a.lanza@rm.unicatt.it 203 Background Diabetes is associated with an increased risk of morbidity and mortality, with cardiovascular disease accounting for up to two-thirds of all deaths in the diabetic population 1 . Hyper- glycemia can influence long-term prognosis of these patients favouring the development and progression of microvascular and macrovascular complications 2-6 . Thus an intensive glycemic control has been suggested to improve prognosis in patients with diabetes. However, recent trials failed to demonstrate a significant reduction in cardiovascular events with an intensive glycemic control 7,8 . These data might be related to an in- creased incidence of hypoglycaemic episodes or large variability in glucose blood levels. Previous studies reported that episodes of hypoglycemia may indeed impair cardiac autonomic function causing sympathetic activation and vagal with- drawal 9,10 , which, in patients with coronary artery disease (CAD), may trigger or favour ischemic or arrhythmic events 11-13 . In this study we assessed whether continuous blood glucose fluctuation may be related to variations in cardiac autonomic function during daily life in diabetic patients with evidence of CAD. Methods Population We enrolled 12 consecutive patients (mean age 65±4 years, 2 women) affected by type 2 dia- betes mellitus and a well-known history of ob- structive CAD for at least 2 years, always docu- mented by coronary angiography. The main clini-