Diabetes Diagnosis

An American Diabetes Association expert committee recently recommended a change in the names of the two main types of diabetes because the former names caused confusion. The type of diabetes that was known as Type I, juvenile-onset diabetes, or insulin-dependent diabetes mellitus (IDDM) is now type 1 diabetes. The type of diabetes that was known as Type II, noninsulin-dependent diabetes mellitus (NIDDM), or adult-onset diabetes is now type 2 diabetes. The new names reflect an effort to move away from basing the names on treatment or age at onset.

A lower number to diagnose diabetes. The expert committee also recommended a lower fasting plasma glucose (FPG) value to diagnose diabetes. The new FPG value is 126 milligrams per deciliter (mg/dL) or greater, rather than 140 mg/dL or greater. This recommendation was based on a review of the results of more than 15 years of research. This research showed that a fasting blood glucose of 126 mg/dL or greater is associated with an increased risk of diabetes complications affecting the eyes, nerves, and kidneys. When diagnosis was based on a blood glucose value of 140 mg/dL or greater, these complications often developed before the diagnosis of diabetes. The experts believe that earlier diagnosis and treatment can prevent or delay the costly and burdensome complications of diabetes.

The prior criteria for diagnosing diabetes relied heavily on performing an oral glucose tolerance test (OGTT). In this test, the person must come in fasting, drink a glucose syrup, and have a blood sample taken 2 hours later. This complicated procedure made detection and diagnosis of diabetes a difficult and cumbersome process, and the expert committee recommended that it be eliminated from clinical use. The change to using fasting plasma glucose for determining the presence of diabetes will make detection and diagnosis of diabetes more routine. The fasting value can be easily obtained during routine physician visits, in clinics, at the place of employment, and other situations. Currently, about 5 to 6 million adults in the United States have diabetes but do not know it. The simpler testing method of measuring fasting glucose should help identify these people so they can benefit from treatment sooner.

People at high risk for diabetes. The experts suggest that adults age 45 years and older be tested for diabetes. If their blood-glucose is normal at the first test, they should be tested at 3-year intervals. People under age 45 should be tested if they are at high risk for diabetes. These high-risk factors include:

The committee states that diabetes can be detected by any of three positive tests. To confirm the diagnosis, there must be a second positive test on a different day.

As mentioned above, the committee recommended that the OGTT not be used.

Testing for diabetes during pregnancy. The expert panel also suggested a change in the testing for diabetes during pregnancy, stating that women at low risk for gestational diabetes do not need to be tested. This low-risk group includes women who are:

All women who are not in the low-risk category should be tested for gestational diabetes during the 24th to 28th weeks of pregnancy. The testing procedure requires drinking a glucose drink and measuring blood glucose 1 hour later. If the blood glucose value is 140 mg/dL or greater, the woman should be evaluated further.