Normal Blood Sugar May Belie Diabetes Risk

All Blood Sugar Levels Aren't Equal, Study Shows

From the WebMD Archives

Oct. 5, 2005 - When it comes to predicting type 2 diabetes risk, not all normal fasting blood sugar levels are equal, new research shows.

Fasting blood sugar levels that are currently considered in the normal range may actually be predictive of diabetes in otherwise healthy men. Higher yet normal-range blood sugar levels may predict diabetes risk, along with body weight, family history of the disease, or blood fat levels, according to the study published in the Oct. 6 issue of The New England Journal of Medicine.

The findings make it clear that what is normal for one person may not be normal for another when it comes to blood sugar testing, researcher Amir Tirosh, MD, of Israel's Sheba Medical Center, tells WebMD.

"Independently, this test doesn't tell the whole story," he says. "The thinking has been that there is a single cutoff point for what is normal, but this doesn't seem to be the case. It depends on the individual."

Soldiers Followed

Fasting blood sugar testing is widely used to diagnose type 2 diabetes and identify people at high risk for developing the disease. The test measures the amount of sugar in the blood, called glucose, after an overnight fast.

A blood sugar level of up to 100 mg/dL is considered normal, while people with levels between 100 and 125 mg/dL are considered to have impaired fasting glucose or prediabetes. Diabetes is typically diagnosed when the fasting blood glucose levels rise to 126 mg/dL or higher.

In the newly reported study, healthy, nondiabetic male Israeli soldiers were followed for 12 years. Blood samples were analyzed for fasting blood glucose levels. During that time, 208 of the approximately 13,000 men with initially normal blood sugar levels developed type 2 diabetes.

Despite normal blood sugar levels, those who were obese, had a family history of diabetes, and had high levels of blood fats (triglycerides) were nine times as likely as men with none of these risk factors to develop diabetes.

The researchers also show that men with the highest normal-range blood sugar, even levels of 90 mg/dL, had a higher risk.


Implications for Treatment

The findings could have implications for determining when to treat people at risk with blood sugar-lowering medications.

And they note that a one-level-fits-all approach to blood sugar testing is too simplistic, says diabetes specialist Ronald Arky, MD, of Harvard Medical School.

"Blood glucose means very little if you don't considered obesity, sedentary lifestyle, smoking, family history, and other diabetes risk factors along with it," he tells WebMD.

In an editorial accompanying the study, Arky wrote that the lessons learned about cholesterol and cardiovascular disease can help guide doctors in better understanding blood sugar and diabetes.

Revised guidelines released just over a year ago lower target cholesterol levels, but only for patients with the greatest risk of having a heart attack or stroke.

The new research shows that the same individualized approach is called for when counseling patients about their diabetes risk, Arky and Tirosh tell WebMD.

"We know what the risks are," Tirosh says. "By better recognizing them we may be able to prevent or at least delay diabetes with lifestyle modification and drug therapy."

Better and earlier identification of young adults at risk for diabetes may be warranted, given the success of interventions aimed at delaying the onset of diabetes among high-risk individuals, write the researchers.

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SOURCES: Tirosh, A. The New England Journal of Medicine, Oct. 6, 2005, vol 353: pp 1454-1462. Amir Tirosh, MD, PhD, department of internal medicine, Sheba Medical Center, Tel-Hashomer, Israel. Ronald A. Arky, MD, Charles S. Davidson Distinguished Professor of Medicine, Harvard Medical School.
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