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High blood sugar levels, rather than problems related to insulin, are linked to the first steps of coronary artery disease in younger adults with diabetes.
High blood sugar levels, rather than problems related to insulin, are linked to the first steps of coronary artery disease in younger adults with diabetes, according to a study in the Journal of the American College of Cardiology (vol. 41, no. 8).
Researchers enrolled 18 participants with type 1 (insulin-deficient) diabetes, 17 participants with type 2 (insulin-resistant) diabetes and 11 healthy participants as a control group. The two groups of diabetic patients were similar in age and control of their blood sugar levels. Researchers observed blood flow in the hearts of participants using positron emission tomography imaging, and then used adenosine and cold stress to trigger different types of blood vessel dilation. Researchers found that the coronary arteries of participants responded similarly to tests, regardless of whether they had type 1 diabetes or type 2 diabetes.
"We noticed that the two groups were very similar in a number of different measurements we performed with PET imaging with respect to blood flow, coronary resistance and so on," said Marcelo F. Di Carli, a co-researcher on the study. "So our interpretation of the data is that, because the only thing these two groups have in common is hyperglycemia, then the hyperglycemia is probably the primary culprit for the abnormalities that one sees."
This study is a bridge between experimental evidence of the toxic effects of glucose on the inner lining of blood vessels and clinical studies showing that controlling blood sugar levels postpones the complications of diabetes, including atherosclerosis and heart attacks. The coronary blood vessel impairment seen in this study foreshadows health problems that may appear many years later.
"We know diabetic patients have higher rates of heart attack and other problems, but the process begins much earlier in life, so that's another feature that's kind of scary, because even when patients are in their 30s you can already see these impaired coronary blood flows as an early sign of atherosclerosis," Di Carli said.
Rory Hachamovitch, director of nuclear cardiology at the University of Southern California Medical Center in Los Angeles, who was not part of this research team, said these findings will bring new attention to the role of glucose.
"There has been an increasing awareness of the importance of insulin resistance as primary driver of premature atherosclerosis in diabetes mellitus, as well as in patients with 'pre-diabetic' states," he said. "The role of hyperglycemia in the pathophysiology of macrovascular disease, on the other hand, was not felt to be significant. The results of the study by Di Carli et al. indicate that glycemic control needs to be considered along with prevention or reversal of insulin resistance in the management of patients." PR