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Endocrine Care: Jin-Shang Wu, Yi-Ching Yang, Thy-Sheng Lin, Ying-Hsiang Huang, Jia-Jin Chen, Feng-Hwa Lu, Chih-Hsing Wu, and Chih-Jen Chang Epidemiological Evidence of Altered Cardiac Autonomic Function in Subjects with Impaired Glucose Tolerance But Not Isolated Impaired Fasting Glucose J Clin Endocrinol Metab 2007; 92: 3885-3889 [Abstract] [Full text] [PDF]

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IS CARDIAC AUTONOMIC FUNCTION ALTERED IN IMPAIRED GLUCOSE TOLERANCE AND NOT IN IMPAIRED FASTING GLUC

Antonio Perciaccante, Alessandra Fiorentini, Rosita Valente, Angelo De Stefano, Luigi Tubani   (20 August 2007)

IS CARDIAC AUTONOMIC FUNCTION ALTERED IN IMPAIRED GLUCOSE TOLERANCE AND NOT IN IMPAIRED FASTING GLUC 20 August 2007
Antonio Perciaccante, MD Department of Clkinical Medicine, University, Alessandra Fiorentini, Rosita Valente, Angelo De Stefano, Luigi Tubani Send letter to journal: Re: IS CARDIAC AUTONOMIC FUNCTION ALTERED IN IMPAIRED GLUCOSE TOLERANCE AND NOT IN IMPAIRED FASTING GLUC antonioperciaccante{at}libero.it Antonio Perciaccante, et al.	We read with interest the article by Wu et al. (1) on cardiac autonomic function, as assessed by heart rate variability, in subjects with impaired glucose tolerance (IGT), impaired fasting glucose (IFG), normal glucose tolerance (NGT) and diabetes mellitus (DM). Their results have shown no difference in HF power and LF power between IFG and NGT. The multivariate analysis showed that none of the indices of cardiac autonomic function was related to isolated IFG in the reference group of NGT. In a previous study (2) we observed that both HF and LF power expressed in absolute units were reduced in insulin resistant subjects with NGT, IFG, IGT and DM compared with non insulin resistant subjects with NGT. We found no difference between insulin resistant subjects with NGT and IFG. The analysis of HF and LF expressed in normalized units showed a difference also between insulin resistant subjects with NGT and insulin resistant subjects with IFG. In contrast to Wu et al., we reported cardiac autonomic function also in subjects with IFG and in insulin resistant subjects with NGT. Other studies (3,4) have also reported an impaired cardiac autonomic activity in insulin resistant subjects with NGT. The fact that Wu et al. did not evaluated the presence of insulin resistance in subjects with NGT and have not evaluated HF and LF in normalized units might explain the differences in our findings. The Task Force of the European Society of Cardiology and the North American Society of Pacing and Electrophysiology (5) suggests to measure LF and HF power components also in normalized units that emphasizes the controlled and balanced behavior of the two branches of the autonomic nervous system and tends to minimize the effect on the values of LF and HF components of the changes in total power. The conclusion of Wu et al. that LF power is a major quantitative marker of sympathetic modulation must be questioned. Interpretation of the LF component is controversial, as it is considered by some as a marker of sympathetic modulation when expressed in normalized units, and by others as a parameter that includes both sympathetic and vagal influences (5). References 1. Wu JS, Yang YC, Lin TS, Huang YH, Chen JJ, Lu FH, Wu CH, Chang CJ 2007 Epidemiological Evidence of Altered Cardiac Autonomic Function in Subjects with Impaired Glucose Tolerance, but not Isolated Impaired Fasting Glucose. J Clin Endocinol Metab doi:10.1210/jc.2006-2175 2. Perciaccante A, Fiorentini A, Paris A, Serra P, Tubani L 2006 Circadian rhythm of the autonomic nervous system in insulin resistant subjects with normoglycemia, impaired fasting glycemia, impaired glucose tolerance, type 2 diabetes mellitus. BMC Cardiovasc Disord 6:19 3. Laitinen T, Vauhkonen IK, Niskanen LK, Hartikainen JE, Lansimies EA, Uusitupa MI, Laakso M 1999 Power spectral analysis of heart rate variability during hyperinsulinemia in nondiabetic offspring of type 2 diabetic patients: evidence for possible early autonomic dysfunction in insulin-resistant subjects. Diabetes 48:1295-1299 4. Frontoni S, Bracaglia D, Baroni A, Pellegrini F, Perna M, Cicconetti E, Ciampittiello G, Menzinger G, Gambardella S 2003 Early autonomic dysfunction in glucose-tolerant but insulin-resistant offspring of type 2 diabetic patients. Hypertension 41:1223-1237 5. Task Force of the European Society of Cardiology and the North American Society of Pacing and Electrophysiology 1996 Heart rate variability: standards of measurement, physiological interpretation and clinical use. Circulation 93:1043-1065