The study, led by Dr Saverio Stranges, Associate Professor of Cardiovascular Epidemiology at Warwick Medical School, looked at levels of oxidative stress in the body (a toxic effect which causes cell damage).
The researchers found high levels of oxidative stress in people with coronary heart disease, previously thought to be a marker of the heart condition, could instead indicate a condition of glucose abnormality, such as overt type 2 diabetes.
The research team took blood samples to contrast oxidative stress levels in people with coronary heart disease, people with type 2 diabetes and healthy control subjects.
Previous studies have shown people with type 2 diabetes and people with coronary heart disease have high levels of oxidative stress.
Dr Stranges' team expected to produce similar results, but they found that those stress levels were low in people with coronary heart disease but without type 2 diabetes.
Further investigation showed people from this group with high levels also had overt type 2 diabetes.
The research used data taken from the Western New York Health Study. This was a case-control study of myocardial infarction and cardiovascular risk factors among residents of Erie and Niagara Counties, New York.
Dr Stranges said: "The results were intriguing. We expected to find high levels of oxidative stress in people with a clinical heart condition, such as myocardial infarction, and people with diabetes. As we thought, the levels were high for diabetics, but there were some discrepancies for people with heart disease.
"Our findings suggest the observed associations of increased oxidative stress in individuals with heart disease may be dependent on underlying abnormalities in glucose metabolism."