"Normal" Plasma Glucose Isn't Necessarily Safe

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Normal fasting plasma glucose levels and type 2 diabetes in young men, by A. Tirosh and colleagues. N Engl J Med 353:1454–1462, 2005.

What is the problem and what is known about it so far?

A few years ago, the American Diabetes Association changed the definition of impaired fasting plasma glucose (a condition in which the body doesn't handle glucose properly) from 110 mg/dL to 100 mg/dL. Fasting plasma glucose is the level of glucose in the bloodstream when a person's stomach is empty. Levels above 100 are now considered to be abnormal (or impaired). This isn't diabetes, but it does mean that it's more likely that the person may develop diabetes in the future.

It is not known if people in the "normal" range indeed have a lower chance of developing diabetes.

Why did the researchers do this particular study?

Researchers wanted to see if people who have a fasting plasma glucose within the "normal" range also had some risk of getting type 2 diabetes.

Who was studied?

The study included 13,163 male Israeli military personnel who were 25 years or older, all of whom had a fasting plasma glucose of 100 mg/dL or lower during their first visit.

How was the study done?

Researchers had detailed medical information on each participant, including lab tests, a personal and family history, and other information. Participants were followed from 1992 to 2004. Researchers looked for cases of diabetes in this group.

What did the researchers find?

Overall, they found that men with a fasting plasma glucose level of 87 or higher were more likely to get diabetes than people with lower levels.

Men with a glucose level of 91 to 99 and a triglyceride (fat in blood) level of 150 mg/dL or higher were more than eight times more likely to get diabetes than those with lower levels.

Also, having a body mass index (BMI, a measure of height in relation to weight) of 30 or more, plus a glucose level of 91 to 99, increased the chance of getting diabetes by eight times.

What were the limitations of the study?

The study was limited to healthy young men serving in the military, so the results may not apply to the general population. Also, researchers did not measure other factors, such as insulin, that are linked to getting diabetes.

What are the implications of the study?

When it comes to fasting plasma glucose levels, even having a result in the normal range doesn't mean that one is safe from getting diabetes. Considering things like body mass index and triglyceride levels, along with glucose, may help identify men most likely to get diabetes.