University of Illinois Extension

Diagnosing Diabetes in Youth

There are several tests available to help diagnose diabetes in youth. A fasting blood glucose level is taken after fasting for 8-12 hours (usually in the morning). A casual blood glucose level can be taken at anytime. A 2-hour oral glucose tolerance test measures the blood glucose level every 30 minutes and up to 2 hours after drinking a glucose solution. This is to see how fast the blood glucose returns to normal. Finally, hemoglobin A1c levels can be used to diagnose diabetes.

Youth may be diagnosed with diabetes if they meet any of the following criteria:

  • Fasting blood glucose > 126 mg/dL
  • Casual blood glucose > 200 mg/dL
  • 2-hour oral glucose tolerance test > 200 mg/dL
  • Hemoglobin A1c > 6.5%

Youth may be diagnosed with pre-diabetes or impaired glucose tolerance if they meet the following criteria:

  • Fasting blood glucose > 100 mg/dL
  • 2-hour oral glucose tolerance test 100-125 mg/dL