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

  • Being more than 20 percent above ideal body weight or having a body mass index (BMI) of greater than or equal to 27. BMI is the ratio of weight in kilograms to height in meters squared (kg/m2 ). (Your doctor or dietitian can provide information on your BMI.)
  • Having a mother, father, brother, or sister with diabetes.
  • Being African American, Alaska Native, American Indian, Asian American, Hispanic American, or Pacific Islander American.
  • Giving birth to a baby weighing more than 9 pounds or having diabetes during pregnancy.
  • Having blood pressure at or above 140/90 millimeters of mercury (mmHg).
  • Having abnormal blood lipid levels, such as high density lipoprotein (HDL) cholesterol less than 35 mg/dL or triglycerides greater than 250 mg/dL.
  • Having abnormal glucose tolerance when previously tested for diabetes.

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.

  • A casual plasma glucose level (taken at any time of day) of 200 mg/dL or greater when the symptoms of diabetes are present.
  • A fasting plasma glucose value of 126 mg/dL or greater.
  • An OGTT value in the blood of 200 mg/dL or greater measured at the 2-hour interval.

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:

  • Younger than 25 years of age.
    • At normal body weight.
    • Without a family history of diabetes.
    • Not members of a high-risk ethnic group.

    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.