One-hour postload plasma glucose levels and diastolic function in hypertensive patients

Area of Science:

• Cardiology
• Endocrinology
• Diabetology

Background:

• Diastolic dysfunction, characterized by impaired left ventricular relaxation, is an early indicator of myocardial involvement in diabetic cardiomyopathy.
• A 1-hour postload plasma glucose level ≥155 mg/dL during an oral glucose tolerance test (OGTT) can identify individuals with normal glucose tolerance (NGT) at high risk for type 2 diabetes and subclinical organ damage.

Purpose of the Study:

• To investigate the association between glucose tolerance status, specifically 1-hour postload plasma glucose levels, and diastolic function in never-treated hypertensive white subjects.
• To determine if elevated 1-hour postload glucose levels in individuals with normal glucose tolerance are associated with subclinical left ventricular diastolic dysfunction.

Main Methods:

• 161 never-treated hypertensive white subjects underwent an oral glucose tolerance test (OGTT) and standard echocardiography.
• Diastolic function was assessed using pulsed Doppler transmitral flow velocity and tissue Doppler imaging.
• Insulin sensitivity was evaluated using the Matsuda index.

Main Results:

• Among participants, 120 had NGT, 26 had impaired glucose tolerance (IGT), and 15 had type 2 diabetes.
• NGT subjects with 1-hour postload glucose ≥155 mg/dL (n=30) exhibited significantly larger left atrium dimensions and longer isovolumetric relaxation time (IVRT) compared to those with <155 mg/dL (n=90).
• Early/late transmitral flow velocity and tissue Doppler parameters were significantly lower in NGT subjects with ≥155 mg/dL 1-hour postload glucose, indicating worse diastolic function. 1-hour glucose was a major determinant of diastolic function parameters.

Conclusions:

• Elevated 1-hour postload plasma glucose levels are associated with left ventricular diastolic dysfunction, even in individuals with normal glucose tolerance.
• Hypertensive individuals with normal glucose tolerance and 1-hour postload plasma glucose ≥155 mg/dL demonstrate significantly impaired diastolic function compared to those with lower levels.