OGT Interpreting OGTT Results and Glucose Tolerance Classifications 1 — Questions and Answers
Question 1: What fasting plasma glucose level is classified as impaired fasting glucose (IFG) according to ADA criteria?
- 100–125 mg/dL (Correct answer)
- 70–99 mg/dL
- 126–140 mg/dL
- 140–199 mg/dL
Correct answer: 100–125 mg/dL
ADA defines IFG as a fasting plasma glucose of 100–125 mg/dL, representing a prediabetic state below the 126 mg/dL diabetes threshold.
Question 2: A 2-hour plasma glucose of 155 mg/dL following a 75g oral glucose load is classified as:
- Normal glucose tolerance
- Impaired glucose tolerance (IGT) (Correct answer)
- Diabetes mellitus
- Hypoglycemia
Correct answer: Impaired glucose tolerance (IGT)
A 2-hour glucose of 140–199 mg/dL after a 75g OGTT is classified as impaired glucose tolerance (IGT), a prediabetic state.
Question 3: Which 2-hour OGTT plasma glucose value meets the ADA diagnostic threshold for diabetes mellitus?
- 180 mg/dL
- 190 mg/dL
- 199 mg/dL
- 200 mg/dL (Correct answer)
Correct answer: 200 mg/dL
A 2-hour plasma glucose ≥200 mg/dL after a 75g OGTT is diagnostic for diabetes mellitus per ADA guidelines.
Question 4: According to ADA guidelines, the term 'prediabetes' encompasses which glucose abnormalities?
- Only impaired fasting glucose (IFG)
- Only impaired glucose tolerance (IGT)
- Both IFG and IGT (Correct answer)
- Borderline diabetes and reactive hypoglycemia
Correct answer: Both IFG and IGT
The ADA uses 'prediabetes' as an umbrella term covering both impaired fasting glucose (IFG) and impaired glucose tolerance (IGT), either separately or together.
Question 5: A patient's OGTT 2-hour value is 145 mg/dL. What is the typical first-line intervention?
- No intervention; repeat in 5 years
- Immediate insulin therapy
- Dietary modification and increased physical activity (Correct answer)
- Oral hypoglycemic agents
Correct answer: Dietary modification and increased physical activity
Impaired glucose tolerance (2-hour glucose 140–199 mg/dL) is managed first with lifestyle interventions—diet and exercise—to prevent progression to diabetes.
Question 6: Which laboratory value, when combined with the 2-hour OGTT result, provides the most complete picture of glucose tolerance?
- Random plasma glucose
- Fasting plasma glucose (Correct answer)
- Urine glucose
- Serum ketones
Correct answer: Fasting plasma glucose
Fasting plasma glucose combined with the 2-hour OGTT value assesses both basal insulin secretion and post-challenge glucose clearance comprehensively.
Question 7: A patient has a fasting glucose of 102 mg/dL and a 2-hour OGTT glucose of 195 mg/dL. How should this result be classified?
- Normal glucose tolerance
- IFG only
- IGT only
- Both IFG and IGT (combined prediabetes) (Correct answer)
Correct answer: Both IFG and IGT (combined prediabetes)
A fasting glucose of 100–125 mg/dL (IFG) combined with a 2-hour glucose of 140–199 mg/dL (IGT) means the patient meets criteria for both prediabetic states simultaneously.
OGT Interpreting OGTT Results and Glucose Tolerance Classifications 1
What fasting plasma glucose level is classified as impaired fasting glucose (IFG) according to ADA criteria?