Regional Medical Laboratory

To remain consistent with the American Diabetes Association’s (ADA) recommended criteria for diagnosing diabetes, Regional Medical Laboratory has made changes to our orderable tests, reference ranges and interpretive data.

Screening and Diagnosis of Gestational Diabetes

The screening test for gestational diabetes is a serum or plasma glucose level one hour after a 50 gram glucose challenge. The patient is not required to be fasting prior to the 1-hour screening test. The orderable test is GLUC 1 HR. Glucose levels greater than 135 mg/dL should be followed by a 3-hour glucose tolerance test.
Gestational diabetes is diagnosed if two or more values of a 3-hour glucose tolerance test are above the reference range. The orderable test is GTT PREG

Fasting: 70-95 mg/dL
Post 1-hour: 70-180 mg/dL
Post 2-hour: 70-155 mg/dL
Post 3-hour: 70-140 mg/dL

Diagnosis of Diabetes in non-Pregnant Individuals

The American Diabetes Association states to diagnose diabetes in a non-pregnant individual, one of the following criteria must be met:

1. Random plasma glucose greater than 200 mg/dL with symptoms (polyuria, polydypsia, and unexplained weight loss) repeated to confirm on a subsequent day.
2. Fasting plasma glucose greater than 126 mg/dL repeated to confirm on a subsequent day.
3. 2-hour plasma glucose greater than 200 mg/dL post 75-gram glucose challenge repeated to confirm on a subsequent day. The patient must be fasting. The orderable test is GLUC 2 HR.

A result of 135 to 200 mg/dl post 75 gram glucose challenge is diagnostic of impaired glucose tolerance (pre-diabetes).

If you have any questions, you may contact Dr. Cindi R. Starkey, M.D., Ph.D at (918) 744-2553 or 1-800-722-8077, or by email at cindi.starkey@ascension.org.