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Coronary artery disease linked to decreased beta-cell function
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In patients with ischemic coronary artery disease, enhanced systemic glucose oxidation, decreased insulin secretion and increased pericardial adipose tissue may serve as protective physiologic adaptations, according to study results.
“The overall clinical implication of the present study is that our results underscore the urgent need of clinical trials that define the optimal and safest glycemic range in different CAD stages, and especially in situations of myocardial ischemia,” the researchers wrote.
Patricia Iozzo, MD, PhD, of the Institute of Clinical Physiology, National Research Council in Pisa, Italy, and colleagues evaluated patients with myocardial ischemic CAD (n = 8), patients with CAD alone (n = 14) and patients without CAD (n = 8) to determine whether CAD is an independent predictor of metabolic abnormalities and whether the interaction is influenced by myocardial ischemia.
Researchers measured insulin sensitivity and secretion and substrate oxidation during fasting and oral glucose tolerance testing and used MRI, magnetic resonance spectroscopy, PET and CT for characterization of CAD, cardiac function, pericardial and abdominal adipose tissue, and myocardial, liver and pancreatic triglycerides contents.
Lower triglyceride and C-peptide levels and higher lactate levels were found among the ischemic CAD group compared with the no-CAD group. Compared with the no-CAD group, both CAD groups had down-regulated glucose sensitivity.
In the ischemic CAD group, oxygen consumption did not change from fasting to OGTT, whereas it was significantly increased in the other groups. Researchers observed elevated fasting glucose oxidation rate and depressed fatty acid oxidation rate in the ischemic CAD group. Significant changes from the fasting state to OGTT were found for all groups.
Compared with the CAD-alone group, the ischemic CAD group had higher calcium score and lower myocardial perfusion involving all left-ventricular regions.
Compared with the no-CAD group, the ischemic CAD group had increased epicardial and pericardial fat. Liver and pancreatic fat contents did not differ between the two CAD groups; however, triglyceride content in the heart was increased in the ischemic CAD group. Links were found between triglyceride levels in the liver, pancreas and heart with mass of abdominal intra-peritoneal or retroperitoneal visceral adipose tissue.
“Our results reveal important metabolic adaptations occurring in patients with CAD,” the researchers wrote. “The current findings highlight the existence of an independent relationship between CAD and beta-cell function, which is strengthened in the situation of myocardial ischemia, whereas our data do not support the concept that CAD per se leads to whole body insulin resistance.” – by Amber Cox
Disclosure: The researchers report no relevant financial disclosures.
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