A pregnant female presented with a family history of diabetes. Her glucose tolerance test (GTT) is positive. All of the following are TRUE about GTT, EXCEPT:
Glucose tolerance test (GTT): After an 8-12 h overnight fast, a fasting blood glucose sample is drawn, and the patient ingests a 75-g oral glucose load (100 g for gestational DM screening, 1.75 mg/kg ideal body weight in children up to 75 g). The glucose load is consumed within 5 minutes. Blood is drawn at 30 min, 1, 2 and 3 h after glucose load. An oral glucose tolerance test is normal if the fasting venous plasma glucose value is less than 100 mg/dL (5.6 mmol/L) and the 2-hour value falls below 140 mg/dL (7.8 mmol/L). A fasting plasma glucose value of 126 mg/dL (7 mmol/L) or higher or a 2-hour value of greater than 200 mg/dL (11.1 mmol/L) is diagnostic of diabetes mellitus. Reactive hypoglycemia can be evaluated using the oral GTT. Ref: German M.S. (2011). Chapter 17. Pancreatic Hormones and Diabetes Mellitus. In D.G. Gardner, D. Shoback (Eds), Greenspan's Basic & Clinical Endocrinology, 9e.
It is useful in reactive hypoglycemia
Fasting of 8-12 hours is required
Most impoant sample is at 2 hours
Patient is instructed to drink glucose within 10 minutes