Which condition will lead to erroneous results when preparing for an oral glucose tolerance test (OGTT)?

The preparation for an oral glucose tolerance test (OGTT) is critical for ensuring accurate results. A significant factor affecting these results is the diet of the patient leading up to the test, particularly carbohydrate intake.

Restricting carbohydrate intake to below 150 g/day for three days prior to the test can lead to inaccurate results. When a patient has a very low carbohydrate intake, their body's insulin response and glucose metabolism may not reflect their true physiological state under normal dietary conditions. The body may adapt to the low carbohydrate availability, resulting in an altered level of insulin sensitivity and potentially leading to a false indication of glucose tolerance. This lack of adequate carbohydrate consumption can hinder the body's ability to respond appropriately during the test, skewing the OGTT results.

In contrast, remaining ambulatory, fasting appropriately, and administering the glucose load correctly under the specified conditions are essential and do not typically lead to erroneous results. Maintaining a standard diet before the test—especially one that includes adequate carbohydrates—ensures that the body's normal physiological responses to glucose can be assessed accurately.