Normal Blood Sugar May Belie Diabetes Risk
All Blood Sugar Levels Aren't Equal, Study Shows
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."
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.