Type 1 Diagnosis

Because the onset of symptoms of type 1 diabetes is usually fast and severe, diagnosis is often made in a hospital or emergency room. However, the blood tests for diabetes diagnosis can also be given in a healthcare professional's office or lab.

These tests, and the values for diabetes diagnosis, are as follows:

• An A1C value of 6.5% or more.
• A random plasma glucose value of 200 mg/dl (11.1 mmol/l) or more (in the presence of diabetes symptoms).
• A fasting plasma glucose value of 126 mg/dl (7 mmol/l) or more.
• An oral glucose plasma glucose value of 200 mg/dl (11.1 mmol/l) or higher at 2 hours post-glucose load.

If your blood sugar is not significantly elevated, a second follow-up test may be ordered to confirm the diagnosis. In addition, your healthcare professional may also prescribe additional blood tests to differentiate between a type 1 and type 2 diabetes diagnosis. These include a c-peptide test, which measures levels of this protein created when insulin is produced. Your healthcare professional may also order antibody tests, including tests to measure islet cell antibodies (ICA), insulin auto-antibodies (IAA), and/or glutamic acid decarboxylase (GAD). These tests determine if your body has produced antibodies against insulin. Such autoimmune activity is specific to type 1 diabetes.

Reviewed by Joy Pape, RN, BSN, CDE, WOCN, CFNC 06/13.