One-Hour Postload Plasma Glucose Levels and Diastolic Function in Hypertensive Patients

Abstract

OBJECTIVE To address whether glucose tolerance status, and in particular 1-h postload plasma glucose levels, may affect diastolic function in 161 never-treated hypertensive white subjects. Impaired left ventricular relaxation, an early sign of diastolic dysfunction, represents the first manifestation of myocardial involvement in diabetic cardiomyopathy. A plasma glucose value ≥155 mg/dL for the 1-h postload plasma glucose during an oral glucose tolerance test (OGTT) is able to identify subjects with normal glucose tolerance (NGT) at high risk for type 2 diabetes and with subclinical organ damage. RESEARCH DESIGN AND METHODS Subjects underwent OGTT and standard echocardiography. Diastolic function was assessed by pulsed Doppler transmitral flow velocity and tissue Doppler imaging. Insulin sensitivity was assessed by Matsuda index. RESULTS Among the participants, 120 had NGT, 26 had impaired glucose tolerance (IGT), and 15 had type 2 diabetes. According to the 1-h postload plasma glucose cutoff point of 155 mg/dL, we divided NGT subjects as follows: NGT <155 mg/dL (n = 90) and NGT ≥155 mg/dL (n = 30). Those with NGT ≥155 mg/dL had higher left atrium dimensions (P < 0.0001) and isovolumetric relaxation time (IVRT) (P = 0.037) than those with NGT <155 mg/dL. By contrast, early/late transmitral flow velocity and all tissue Doppler parameters were significantly lower in those with NGT ≥155 mg/dL than in those with NGT<155 mg/dL. At multiple regression analysis, 1-h glucose was the major determinant of left atrium area, IVRT, septal e′, septal e′-to-a′ ratio, lateral e′, and lateral e′-to-a′ ratio. CONCLUSIONS The main finding of this study is that 1-h postload plasma glucose is associated with left ventricular diastolic dysfunction. Subjects with NGT ≥155 mg/dL had significantly worse diastolic function than those with NGT<155 mg/dL.