WEDNESDAY, March 3 (HealthDay News) -- The newer hemoglobin A1C test predicts diabetes as well as the traditional fasting blood sugar test, but it beats that old standard in predicting a patient's future risk of heart disease and stroke, new research shows.

After adjusting for common cardiovascular disease risk factors, the study found that while A1C levels high enough to diagnose diabetes were associated with nearly twice the risk of coronary heart disease, no such association was found with fasting glucose readings high enough to trigger a diabetes diagnosis.

The A1C test is also known as a glycated hemoglobin test, and using a small blood sample, it measures your average blood sugar levels for the past two to three months.

"Our data show that glycated hemoglobin is a really potent risk factor for diabetes and cardiovascular disease. If you have abnormal glycated hemoglobin results, you should be targeted for diabetes and cardiovascular disease interventions," said the study's lead author, Elizabeth Selvin, an assistant professor of epidemiology and medicine in the department of epidemiology at the Johns Hopkins Bloomberg School of Public Health in Baltimore.

In January, the American Diabetes Association (ADA) recommended that doctors could begin using the A1C test for diagnosis of diabetes. Previously, the test wasn't recommended because it hadn't been standardized from lab to lab. The ADA set the level for diagnosis of diabetes at 6.5 percent or higher, and the diagnosis of pre-diabetes for levels of 5.7 to 6.4 percent.

The A1C percentage is the amount of a person's hemoglobin that is glycated or glycosylated.

For the current study, Selvin and her colleagues measured A1C from more than 11,000 stored blood samples from the Atherosclerosis Risk in Communities Study, which began in 1990. None of the study volunteers had diabetes or cardiovascular disease at the time the blood samples were taken.

The researchers then compared the A1C levels to fasting blood sugar levels and to the 15 years of overall health follow-up information gathered for the previous study.

During that time, 2,251 people were diagnosed with diabetes, nearly 1,200 were diagnosed with heart disease and 358 people had an ischemic (non-bleeding) stroke, according to the study.

As expected, the researchers found that elevated A1C levels were associated with an increased risk of being diagnosed with diabetes. Those with an A1C of less than 5 percent had a 48 percent reduced risk of diabetes, while people whose A1Cs were between 5 and 5.5 percent had a normal risk of diabetes. From there, however, the risk quickly went up. Those with an A1C of 5.5 to 6 percent had an 86 percent increased risk of diabetes. For those between 6 and 6.5 percent, the risk more than quadrupled. For people with levels above 6.5 percent, the odds of being diagnosed were more than 16 times higher than for someone with levels under 5.5 percent. These results were similar to those for fasting glucose levels, the study authors noted.

Where fasting glucose and A1C differed greatly, however, was in the prediction of future heart disease and stroke risk. While fasting glucose failed to predict future risk, the study found that A1C levels accurately did so.

People with A1Cs under 5.5 percent had an average risk of heart disease and stroke, but for people with an A1C between 5.5 and 6 percent, the risk went up 23 percent. For those with an A1C between 6 and 6.5 percent, the risk of cardiovascular disease jumped to 78 percent. When A1C went over 6.5 percent, the risk of cardiovascular disease went up nearly twofold.

Results of the study are published in the March 4 issue of the New England Journal of Medicine.

"This is a test that's been around for a long time, and the old dictum was that it couldn't be used to predict cardiovascular disease," said Dr. Rafael Gonzalez, director of cardiology at Scott & White Healthcare in Round Rock, Texas. "But this study shows it may be a great marker -- the higher the A1C, the greater the risk. This tells us we may need to be more aggressive with prevention in people with higher levels, maybe push for lower LDL (bad) cholesterol, emphasize lifestyle factors," he explained.

"Diabetes is like high blood pressure -- the consequences don't come right away. And, sometimes that makes people think, 'Why do I need to be on this medicine?' So, this is further evidence, and may be a good way to get people's attention," Gonzalez added.

More information

Learn more about the A1C test from the U.S. National Library of Medicine.

TUESDAY, March 2 (HealthDay News) -- Knowing you're on the cusp of developing diabetes apparently isn't enough to make most people take steps to prevent it.

New research, published in the April issue of the American Journal of Preventive Medicine, found that only about half of those with prediabetes said they had tried to drop pounds or boost their exercise level in the preceding year.

An estimated one-third of U.S. residents 20 years and older are prediabetic, experts say, but more than 92 percent are not aware of it.

The study involved a survey of 1,402 people with prediabetes who were interviewed and given glucose tests. Of that group, just 7 percent said that they had been diagnosed with prediabetes and only 48 percent of them had been tested for diabetes or high blood sugar in the preceding three years.

Overall, the researchers said, people with prediabetes are generally older, more likely to be men and often have such heart disease risk factors as higher weight, waist size, systolic blood pressure and triglyceride levels. No ethnicity or race is more likely to have the condition, however, they said.

"Reversing the growing diabetes problem will require multiple levels of interventions, including promotion of healthy lifestyles and increased availability of evidence-based community prevention programs for people at high risk," the researchers wrote. "More efficient identification and awareness of prediabetes is a key first step to implementing these changes."

The researchers include representatives from Emory University, the U.S. Centers for Disease Control and Prevention and the U.S. National Institute of Diabetes and Digestive and Kidney Diseases.

More information

The American Diabetes Association has more on prediabetes  .

FRIDAY, Feb. 26 (HealthDay News) -- New measurements for determining dangerous blood sugar levels for pregnant women and their unborn babies mean that two to three times as many women will be diagnosed with gestational diabetes, a new study suggests.

Instead of 5 percent to 8 percent of pregnant women being diagnosed with gestational diabetes, the new measurements mean that more than 16 percent would be diagnosed with the condition, said study author Dr. Boyd Metzger, a professor of metabolism and nutrition at Northwestern Feinberg School of Medicine.

The current gestational diabetes measurements are based on blood sugar levels that identified women at high risk for developing diabetes in the future, but didn't take into account other risks to the mother or baby, including increased risk of overweight babies with high insulin levels, early deliveries, cesarean deliveries, and potentially life-threatening preeclampsia (high blood pressure that affects the pregnant women and her unborn child).

Metzger and an international group of researchers studied more than 23,000 women in nine countries and concluded that a fasting blood sugar level of 92 or higher, a one-hour level of 180 or higher on a glucose tolerance test, or a two-hour level of 153 or higher on a glucose tolerance test pose a serious threat to mother and baby.

Previously, those levels were considered in the safe and normal range.

"At these levels, the frequency of having an overweight baby is almost double, the frequency of having preeclampsia is almost double, and the frequency of early delivery is 40 percent greater. These are really substantial differences," Metzger said.

The study appears in the March issue of Diabetes Care.

More information

The U.S. National Institute of Child Health and Human Development has more about gestational diabetes.