Dr. Nataly Lerner, Dr. Michal Shani and Shlomo Vinker of Tel Aviv University's Sackler Faculty of Medicine say 26 million Americans have diabetes, while another 79 million are thought to have "prediabetes," meaning they are at risk of developing type-2 diabetes.
"Our study supports the idea that the A1c test, used to diagnose type-2 diabetes, can also be used at a much earlier stage to screen for the disease in the high risk population, like overweight patients," Lerner says in a statement.
In healthy people, glucose is absorbed from the blood for use by various tissues. But the cells of people with type-2 diabetes are resistant to insulin, which is produced by the pancreas and is central to regulating carbohydrate and fat metabolism in the body.
These individuals have higher-than-normal blood glucose levels. People with prediabetes have blood glucose levels somewhere between normal and diabetic, the researchers say.
Blood glucose can be directly tested in several ways, but these tests only provide a snapshot. To get a picture of blood glucose levels over time, doctors test for levels of glycated hemoglobin, or A1c, in the blood. When blood glucose levels are high, more A1c is formed. So A1c serves as a biomarker, indicating average blood glucose levels over a two- to three-month period, the researchers say.
The A1c test has long been used to monitor type-2 diabetes. The American Diabetes Association and World Health Organization have added the test to their guidelines as a criterion for diagnosing type-2 diabetes.
An A1c level of 6.5 percent or more is an indicator of the disease and an A1c level of between 5.7 and 6.4 percent is an indicator of prediabetes, Lerner says.