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Glucose tolerance test



Urine sample
Urine sample
Fasting glucose tolerance test
Fasting glucose tolerance test
Oral glucose tolerance test
Oral glucose tolerance test


Glucose tolerance test

Alternative Names:

Oral glucose tolerance test
Normal Values:

For a 75-gram oral glucose tolerance test used to check for type 2 diabetes, normal (nondiabetic) blood values are:

  • fasting: 60 to 110 mg/dL
  • 1 hour: less than 200 mg/dL
  • 2 hours: less than 140 mg/dL. Between 140-200 mg/dL is considered impaired glucose tolerance or pre-diabetes. This group is at increased risk for developing diabetes. Greater than 200 mg/dL is diagnostic of diabetes mellitus


For a 50-gram oral glucose tolerance test used to screen for gestational diabetes, normal blood values at 1 hour are less than 140 mg/dL.

For a 100-gram oral glucose tolerance test used to screen for gestational diabetes, normal blood values are:

  • fasting: less than 95 mg/dL
  • 1 hour: less than 180 mg/dL
  • 2 hour: less than 155 mg/dL
  • 3 hour: less than 140 mg/dL
Note: mg/dL = milligrams per deciliter
What abnormal results mean:

Greater than normal levels of glucose may indicate

High glucose levels may be related to another clinical problem (for example, Cushing's syndrome).




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