Elevated Glucose Associated with Undetected Heart Damage

Elevated levels of glycated hemoglobin (HbA1) are associated with minute levels of the protein troponin T (cTnT), a blood marker for heart damage.

A high-sensitivity blood test has been used to detect levels of cTnT showed that the concentrations were tenfold lower than those found in patients diagnosed with a heart attack.

Scientists at the Johns Hopkins Bloomberg School of Public Health (Baltimore, MD, USA) tested the hypothesis that in persons without clinically evident chronic heart disease (CHD) or heart failure, chronic hyperglycemia, assessed by HbA1c, would be independently associated with subclinical myocardial injury measured by elevated cTnT. The cTnT was measured using a novel high-sensitivity assay; Elecsys Troponin T (hs-cTnT) with a lower limit of detection of 3.0 ng/L. Elevated hs-cTnT was defined as levels above 4 ng/L in a healthy subpopulation, which were 20 to 70 year old.

The scientists followed 9,662 participants from the Atherosclerosis Risk in Communities (ARIC) study. None of the participants had coronary heart disease or history of heart failure. Higher levels of HbA1c were associated in a graded fashion with elevated levels of high-sensitivity cTnT. This relationship was present at HbA1c levels even below the threshold used to diagnose diabetes. Using conventional tests, troponin T can be detected in 0.7% of the population and is associated with heart attacks and death. With the high-sensitivity Elecsys Troponin T test (Roche Diagnostics; Indianapolis, IN, USA) low levels of troponin were found in 66% of the study population.

Jonathan Rubin, MD, a lead author of the study, said, "Our study hints at other potential pathways by which diabetes and elevated glucose are associated with heart disease. Mainly, glucose might not only be related to increased atherosclerosis, but potentially elevated glucose levels may directly damage cardiac muscle." The study was published on January 31, 2012, in the Journal of the American College of Cardiology.

Related Links:
Johns Hopkins Bloomberg School of Public Health
Roche Diagnostics