Diabetes Self-Management Blog

A routine blood test may be able to identify people with prediabetes as well as the fasting plasma glucose (FPG) test, the method currently used by some doctors for screening, according to a recent study funded in part by the US Centers for Disease Control. An estimated 57 million adults in the United States have prediabetes (a condition in which blood glucose levels are elevated, but not enough for a diagnosis of diabetes) and the vast majority don’t know it.

The FPG test screens for diabetes by measuring the level of glucose in a person’s blood plasma after a period of fasting (not eating or drinking anything other than water). The test is performed after a person has fasted for at least 8 hours; people with a fasting plasma glucose level less than 126 mg/dl but greater than or equal to 100 mg/dl are classified as having prediabetes. Because the FPG test sometimes requires a second doctor’s visit for retesting, and because people often forget to arrive with an empty stomach, obtaining accurate results by the method can be difficult. The A1C test, currently used to check the level of blood glucose control over the previous 2–3 months in people with diabetes, only requires a single visit and is accurate regardless of whether a person has eaten prior to the visit. Based on blood test results from the 1,750 people included in the study, the A1C test is effective at pinpointing people who have prediabetes, and who are therefore at increased risk of developing Type 2 diabetes. (In 2010, the American Diabetes Association began recommending that the A1C test be used to diagnose Type 1 or Type 2 diabetes.)

According to Ronald T. Ackerman, MD, MPH, lead author of the study “If you have high blood pressure or heart disease, or multiple other risk factors such as obesity, are over the age of 45, had a past episode of diabetes during pregnancy, or have a family history of the disease, your physician can administer a simple blood test which will show if you are pre-diabetic. If you are pre-diabetic, losing as little as 10 to 15 pounds through diet and exercise can cut in half your chances of getting diabetes, greatly improving your health and lowering your need for health care.”

In a 2006 study, Dr. Ackermann suggested that it would be cost effective for Medicare to pay for diabetes prevention services starting at age 50 rather than waiting until age 65, when many people have already developed the condition. Since then, UnitedHealth Group, a nationwide carrier, has begun paying for a diabetes prevention program offered by the YMCA. The services are only covered, however, when a blood test has shown a person to have prediabetes.

To learn more about the research, read the article “Routine Blood Test May Identify People With Pre-Diabetes, Cutting Later Treatment Costs” or see the study’s abstract in the American Journal of Preventive Medicine. And for more information about the A1C test, click here.


  1. Too bad we don’t live in never-never land. In June 1991, I had a FBG of 138 (cut off was 140 at the time), an in September, 131. However, in November, I had an A1c of 4.8. My FBGs would be diagnosable today, but not my A1c.
    As it was, it took another 3 years for me to be definitively diagnosed, and I was only lucky that I didn’t come up with any complications. But I DID get extremely symptomatic, and it took forever to get a treatment that worked (insulin)
    The A1c will miss low-glycators like me, as well as those with unusual forms of hemoglobin.
    It strikes me as an enormous mistake to use the A1c alone as a diagnostic tool — it will catch some, but miss others, and people don’t need to be falsely reassured when complications are looming around the corner.

    Posted by Natalie Sera |
  2. You stated that FPG sometimes requires a second doctor’s visit for retesting. I think it need more study to require an evidence data base. But it’s a great help to detect prediabetes.

    Posted by Stefanie Bill |

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