Cardiac steatosis in diabetes mellitus: a 1H-magnetic resonance spectroscopy study.
BACKGROUND
The risk of heart failure in type 2 diabetes mellitus is greater than can be accounted for by hypertension and coronary artery disease. Rodent studies indicate that in obesity and type 2 diabetes mellitus, lipid overstorage in cardiac myocytes produces lipotoxic intermediates that cause apoptosis, which leads to heart failure. In humans with diabetes mellitus, cardiac steatosis previously has been demonstrated in explanted hearts of patients with end-stage nonischemic cardiomyopathy. Whether cardiac steatosis precedes the onset of cardiomyopathy in individuals with impaired glucose tolerance or in patients with type 2 diabetes mellitus is unknown.


RESULTS
To represent the progressive stages in the natural history of type 2 diabetes mellitus, we stratified 134 individuals (age 45+/-12 years) into 1 of 4 groups: (1) lean normoglycemic (lean), (2) overweight and obese normoglycemic (obese), (3) impaired glucose tolerance, and (4) type 2 diabetes mellitus. Localized (1)H magnetic resonance spectroscopy and cardiac magnetic resonance imaging were used to quantify myocardial triglyceride content and left ventricular function, respectively. Compared with lean subjects, myocardial triglyceride content was 2.3-fold higher in those with impaired glucose tolerance and 2.1-fold higher in those with type 2 diabetes mellitus (P<0.05). Left ventricular ejection fraction was normal and comparable across all groups.


CONCLUSIONS
In humans, impaired glucose tolerance is accompanied by cardiac steatosis, which precedes the onset of type 2 diabetes mellitus and left ventricular systolic dysfunction. Thus, lipid overstorage in human cardiac myocytes is an early manifestation in the pathogenesis of type 2 diabetes mellitus and is evident in the absence of heart failure.
McGavock
Jonathan M
JM
Department of Internal Medicine, Divisions of Hypertension, University of Texas Southwestern Medical Center at Dallas, Dallas, Tex, USA.
Lingvay
Ildiko
I
Zib
Ivana
I
Tillery
Tommy
T
Salas
Naomi
N
Unger
Roger
R
Levine
Benjamin D
BD
Raskin
Philip
P
Victor
Ronald G
RG
Szczepaniak
Lidia S
LS
D000328:Adult; D003924:Diabetes Mellitus, Type 2 / Q000150:complications / Q000175:diagnosis* / Q000378:metabolism; D005260:Female; D006331:Heart Diseases / Q000150:complications / Q000175:diagnosis* / Q000378:metabolism; D006801:Humans; D050356:Lipid Metabolism / Q000502:physiology*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000150:complications / Q000175:diagnosis / Q000378:metabolism; D011522:Protons; D014280:Triglycerides / Q000378:metabolism
D011522:Protons; D014280:Triglycerides