The relation of glucose metabolism to left ventricular mass and function and sympathetic nervous system activity in obese subjects with metabolic syndrome.

Laboratories of Human Neurotransmitters, Baker IDI Heart and Diabetes Institute, PO Box 6492, St. Kilda Road Central, Melbourne, Victoria, Australia. A. Nora.Straznicky@bakeridi.edu.au

The Journal of clinical endocrinology and metabolism 2013 Feb

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Altered cardiac structure and function have been reported in prediabetic and diabetic populations; however, the contribution of the sympathetic nervous system (SNS) to these changes has yet to be delineated. Our objective was to examine interrelationships between glucose metabolism, left ventricular mass and function, and SNS activity in obese metabolic syndrome subjects. Unmedicated impaired glucose tolerant (IGT) (n = 31) or treatment-naive type 2 diabetic (T2D) (n = 25) subjects, matched for age (mean 58 ± 1 years), gender, body mass index (32.2 ± 0.5 kg/m(2)), and blood pressure, participated. They underwent echocardiography and assessments of whole-body norepinephrine kinetics, muscle sympathetic nerve activity, and insulin sensitivity by euglycemic clamp (M value). T2D subjects had higher left ventricular mass index (LVMI) (93.6 ± 3.5 vs 77.2 ± 3.4 g/m(2), P = .002) and Doppler-derived isovolumetric relaxation and deceleration times (both P < .05) and lower early/late transmitral inflow velocities (E/A) (P = .02) compared with IGT. Total muscle sympathetic nerve activity and arterial norepinephrine concentration were higher in the T2D group (by 18% and 32%, respectively, both P ≤ .05), whereas plasma norepinephrine clearance was reduced (1.94 ± 0.11 vs 2.26 ± 0.10 L/min, P = .02). M value correlated inversely with left ventricular septal thickness (r = -0.46, P = .007). Whole-body noradrenaline spillover rate correlated with LVMI in the T2D subgroup (r = 0.47, P = .03). In the pooled cohort, LVMI was independently predicted by pulse pressure (r = 0.38, P = .004) and E/A ratio by 2-hour glucose (r = -0.38, P = .005). Transition from IGT to T2D is associated with cardiac enlargement and diastolic dysfunction, which relate to metabolic, hemodynamic, and SNS alterations.

Citation

Nora E Straznicky, Mariee T Grima, Carolina I Sari, Sofie Karapanagiotidis, Chiew Wong, Nina Eikelis, Katrina L Richards, Geraldine Lee, Paul J Nestel, John B Dixon, Gavin W Lambert, Markus P Schlaich, Elisabeth A Lambert. The relation of glucose metabolism to left ventricular mass and function and sympathetic nervous system activity in obese subjects with metabolic syndrome. The Journal of clinical endocrinology and metabolism. 2013 Feb;98(2):E227-37