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. 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

Greater than normal levels of glucose may indicate

• Diabetes
• Gestational diabetes

High glucose levels may be a manifestation of another clinical problem (for example, Cushing's syndrome).