What is the standard glucose load for the 2-hour OGTT in adults?

• A. 50 g
• B. 75 g or 1.75 g/kg body weight
• C. 100 g
• D. 125 g

Answer: (B)

The amount given during a 2-hour OGTT in adults is designed to provide a consistent glucose challenge. The standard load is 75 grams of glucose dissolved in water, taken after an overnight fast. This fixed dose has been validated to differentiate normal glucose tolerance from impaired tolerance and diabetes when the 2-hour plasma glucose is measured. Some guidelines also allow dosing by body weight, using 1.75 grams of glucose per kilogram of body weight up to a maximum of 75 grams, to tailor the challenge for different body sizes. The other suggested amounts are not used for the standard 2-hour test; 100 g is associated with a different, longer oral glucose tolerance protocol, and 125 g is not a standard dose.