A dosage form of glucose and a method of performing an oral glucose tolerance test or challenge test on a patient are disclosed. The dosage form of glucose may be a drinkable gel formulation and include water, a primary gelling agent, and a pH adjuster. The water, the primary gelling agent, and the pH adjuster may be present in amounts which ensure proper hydration and a formation of a firm gel with a bloom grade of at least 100, which can be sheared to make it more fluid, such that it is a drinkable gel.