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Take Heart Articles
Glucose Tolerance Testing
03/29/2006
Here is a startling observation: Diabetic individuals without known coronary artery disease have the same cardiovascular prognosis as non-diabetics with coronary artery disease. With 75 percent of diabetic individuals dying from cardiovascular disease, more studies indicate the importance of early detection of diabetes and glucose intolerance, by administering a glucose tolerance test and measuring fasting insulin levels.

“If looked for, two-thirds of coronary patients will have a problem with their glucose metabolism. In these patients, there is a high residual risk that even statin therapy and cholesterol-lowering drugs will not address. Glucose intolerance increases one’s risk for heart disease,” says Dr. Joe Hollins, Palmetto Health Heart Hospital cardiologist.

A glucose tolerance test will distinguish between the normal blood insulin pattern and the patterns in diabetes. Blood insulin levels may be abnormally high in patients with insulin resistance and “pre-diabetes.” “Studies are mounting up in support of putting glucose tolerance testing into more common practice,” says Hollins.

Deaths and non-fatal myocardial infarctions (MI) occur more prevalently in individuals with abnormal glucose metabolism. More and more physicians in Great Britain, for example, are requiring their cardiac patients take a glucose tolerance test. One study in particular, through the European Society of Cardiology, indicated that abnormal glucose regulation quadrupled the cardiovascular event rate in patients.

“Blood glucose is a critical variable in predicting future coronary events,” says Hollins. “It should be measured along with cholesterol and blood pressure, as part of an aggressive diagnostic routine to determine cardiac risk.”

“Only about one-third of people who have heart disease do not have problems with their glucose. The rest, do. It makes perfect sense to have glucose checked,” says Hollins. “More studies are showing that diabetes is not just a sugar problem. It is a cardiovascular problem.”

Diabetes often goes unnoticed and undiagnosed because an individual may be asymptomatic. Unfortunately, glucose metabolic issues are usually already present before the diabetes is detected. The increasing prevalence of the disease is attributed to an aging population, increasing rates of obesity, declining levels of physical activity, and a high-carbohydrate, calorie dense diet.

It is important that individuals manage their diabetes. However, traditional treatments focused only on stabilizing elevated glucose levels have proven disappointing in reducing cardiovascular events. Managing diabetes plays one part in controlling other modifiable risk factors associated with insulin resistance, which are high triglycerides, low HDL (“good”) cholesterol, and the pattern of small dense LDL (“bad”) cholesterol.

“The best management includes a comprehensive approach to glycemic control by improving insulin sensitivity, reducing cardiovascular risks, preventing and treating diabetes-related complications, as well as educating cardiac and diabetic patients on the relationship between diabetes and heart disease,” says Dr. Hollins.

WHAT IS A GLUCOSE TOLERANCE TEST?
After fasting overnight, you will have a series of three samples of blood taken over the course of a few hours. In nondiabetic people, the glucose concentration rises to about twice the normal level within the first hour and returns to normal within two hours. With diabetes, the blood glucose rises to a much higher level than normal and the return to normal may take three hours or more.