It has been observed that in prediabetics and
diabetics, fat storage following a meal is impaired. This results in high
levels of circulating fatty acids following a meal, which may be taken up by
the heart muscle.
Studies have shown that increased uptake of fatty
acids by the heart muscle impairs cardiac function. It increases the oxidation
of the cardiac muscle and reduces its contracting ability.
A study was carried out to assess the effects of
dietary fats on cardiac muscle in individuals who showed impaired glucose
tolerance (IGT+). The study subjects included 9 IGT+ individuals and 17 IGT−
individuals for the purpose of comparison.
Following a fasting period, an intravenous catheter
was placed in one arm for infusions and another was placed in a vein of the
other arm for blood sampling.
A standard liquid meal was given to each participant.
In the first protocol, oral 18FTHA was administered to study whole-body dietary
fatty acid partitioning in various organs with the help of PET and CT scan.
In the second part of the study, [11C]acetate was
administered 90 min after the start of meal intake followed by PET scan to
study the blood flow and oxidative metabolism of the cardiac muscle.
All the subjects underwent ECG to check cardiac
In the study, IGT+ participants were usually older,
and had higher body mass index (BMI) and waist circumference. They had higher
plasma insulin levels, (non-esterified fatty acid) NEFA and triglyceride
found that dietary fatty acid uptake by the heart muscle was increased by 63%
in IGT+ subjects
. This increase did not depend on other factors like age, body fat,
central obesity markers, or sex. The increased uptake was not observed in the
liver, skeletal muscles and thigh subcutaneous fat tissue. In fact, a reduced
tracer uptake of 54 and 58% was observed in the anterior abdominal subcutaneous
tissue and the fat around the kidneys, respectively.
The study also
found a significant reduction in cardiac function, as estimated using
parameters like left ventricular stroke volume, ejection fraction, and cardiac
output in IGT+ participants. In
addition, blood flow to the heart muscle and oxidative metabolism, which could
damage the heart muscle and is implicated in the development of heart disease
in diabetics, was higher in IGT+ participants.
The study thus concludes that excessive exposure of
the heart to dietary fatty acids could be the reason behind the development of
heart disease in diabetic patients.
1. Increased Myocardial Uptake of Dietary Fatty Acids Linked to Cardiac
Dysfunction in Glucose-Intolerant Humans; Sebastien Labbe et al; Diabetes
November 2012vol. 61 no. 11 2701-2710