American Board of Internal Medicine (ABIM) Certification Practice Exam

Which condition is characterized by elevated A1c levels despite well-controlled preprandial blood glucose?

1. Type 1 diabetes

2. Diabetic ketoacidosis

3. Postprandial hyperglycemia

4. Chronic kidney disease

The correct answer is: Postprandial hyperglycemia

The condition characterized by elevated A1c levels despite well-controlled preprandial blood glucose is indeed postprandial hyperglycemia. This scenario occurs when a patient's blood glucose levels spike significantly after meals, while their fasting glucose remains within target ranges. The A1c test reflects average blood glucose levels over the previous two to three months. If a patient manages to keep their fasting or pre-meal glucose levels stable, but experiences sharp rises in glucose after consuming food, it can lead to an elevated A1c. This indicates that while the patient has control over their blood sugar before eating, they struggle with the glucose response post-mealtime. In understanding other conditions: Type 1 diabetes often presents with both high preprandial and postprandial glucose levels, particularly in poorly controlled cases. Diabetic ketoacidosis is an acute condition related to insufficient insulin, characterized by markedly high blood glucose levels, ketosis, and acidosis, which does not fit this question's context. Chronic kidney disease can lead to alterations in glucose metabolism but doesn't specifically cause an isolated rise in postprandial blood sugar alongside well-controlled fasting levels. Thus, postprandial hyperglycemia is the condition that best explains elevated A1c levels