Clinical Research
Myocardial Metabolism
Effects of Hepatic Triglyceride Content on Myocardial Metabolism in Type 2 Diabetes

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Objectives

The purpose of this study was to investigate the relationship between hepatic triglyceride content and both myocardial function and metabolism in type 2 diabetes mellitus (T2DM).

Background

Heart disease is the leading cause of mortality in T2DM. Central obesity and hepatic steatosis, both hallmark abnormalities in T2DM, have been related to increased risk of heart disease.

Methods

Sixty-one T2DM patients underwent myocardial perfusion and substrate metabolism measurements by positron emission tomography, using [15O]water, [11C]palmitate, and [18F]-2-fluoro-2-deoxy-d-glucose. In addition, whole-body insulin sensitivity (M/I) was determined. Myocardial left ventricular function and high-energy phosphate metabolism were measured using magnetic resonance imaging and [31P]-magnetic resonance spectroscopy, respectively. Hepatic triglyceride content was measured by proton magnetic resonance spectroscopy. Patients were divided according to hepatic triglyceride content (T2DM-low ≤5.56% vs. T2DM-high >5.56%).

Results

In addition to decreased M/I (p = 0.002), T2DM-high patients had reduced myocardial perfusion (p = 0.001), glucose uptake (p = 0.005), and phosphocreatine/adenosine triphosphate (PCr/ATP) ratio (p = 0.003), compared with T2DM-low patients, whereas cardiac fatty acid metabolism and left ventricular function were not different. Hepatic triglyceride content correlated inversely with M/I (Pearson's r = −0.620, p < 0.001), myocardial glucose uptake (r = −0.413, p = 0.001), and PCr/ATP (r = −0.442, p = 0.027). Insulin sensitivity correlated positively with myocardial glucose uptake (r = 0.528, p < 0.001) and borderline with myocardial PCr/ATP (r = 0.367, p = 0.072), whereas a positive association was found between cardiac glucose uptake and PCr/ATP (r = 0.481, p = 0.015).

Conclusions

High liver triglyceride content in T2DM was associated with decreased myocardial perfusion, glucose uptake, and high-energy phosphate metabolism in conjunction with impaired M/I. The long-term clinical implications of hepatic steatosis with respect to cardiac metabolism and function in the course of T2DM require further study.

Key Words

cardiomyopathy
diabetes mellitus
hepatic
magnetic resonance imaging
positron emission tomography

Abbreviations and Acronyms

CAD
coronary artery disease
CVD
cardiovascular disease
[18F]FDG
[18F]-2-fluoro-2-deoxy-d-glucose
LV
left ventricular
MBF
myocardial blood flow
MFAE
myocardial fatty acid esterification
M/I
whole-body insulin sensitivity
MMRglu
myocardial metabolic rate of glucose uptake
[31P]-MR
phosphorus-31 magnetic resonance
PCr/ATP
phosphocreatine/adenosine triphosphate
T2DM
type 2 diabetes mellitus

Cited by (0)

This investigator-initiated study was supported by Eli Lilly. Dr. Diamant reports receiving consulting and lecture fees from Eli Lilly, Merck, Novartis, Novo Nordisk, Pfizer, and Sanofi-Aventis and research grants from Eli Lilly, GlaxoSmithKline, Merck, Novartis, and Novo Nordisk. Dr. Heine is employed by Eli Lilly as of January 2008. Drs. Rijzewijk, Jonker, Diamant, and Lamb contributed equally to this work. Michael Davidson, MD, served as Guest Editor for this paper.