From the Guidelines
The results of the Oral Glucose Tolerance Test (OGTT) are used to diagnose impaired glucose tolerance (IGT) and diabetes, with normal fasting glucose below 100 mg/dL and normal 2-hour post-glucose level below 140 mg/dL, and prediabetes indicated by fasting glucose of 100-125 mg/dL or 2-hour level of 140-199 mg/dL. The OGTT is necessary to diagnose impaired glucose tolerance (IGT) 1. According to the guidelines, an OGTT can be carried out if FPG and HbA1c are inconclusive 1. The test results are crucial in detecting glucose metabolism problems before symptoms appear, allowing for earlier intervention to prevent complications like cardiovascular disease, neuropathy, and retinopathy 1. Some key points to consider when interpreting the results of the OGTT include:
- Normal fasting glucose is below 100 mg/dL
- Normal 2-hour post-glucose level is below 140 mg/dL
- Prediabetes is indicated by fasting glucose of 100-125 mg/dL or 2-hour level of 140-199 mg/dL
- Diabetes is diagnosed when fasting glucose is 126 mg/dL or higher, or when the 2-hour level is 200 mg/dL or higher If the results are abnormal, lifestyle modifications including weight loss, regular exercise, and a balanced diet are recommended first-line interventions, and medications like metformin may be prescribed for prediabetes or diabetes 1. It is essential to note that the OGTT is more sensitive and modestly more specific than fasting plasma glucose (FPG) to diagnose diabetes, but it is poorly reproducible and rarely performed in practice 1. However, the FPG is the preferred screening and diagnostic test due to ease of use, acceptability to patients, and lower cost 1. In individuals with established CVD, screening using HbA1c and/or fasting glucose is recommended, and an OGTT can be carried out if FPG and HbA1c are inconclusive 1. Overall, the OGTT is a valuable tool in diagnosing and managing glucose metabolism problems, and its results should be interpreted in the context of individual patient factors and clinical guidelines.
From the FDA Drug Label
The FDA drug label does not answer the question.
From the Research
Results of the Oral Glucose Tolerance Test (OGTT)
The results of the OGTT can be used to diagnose prediabetes and type 2 diabetes. The test measures the body's ability to regulate blood sugar levels after consuming a sugary drink.
- The 1-hour post-load plasma glucose level during an OGTT can be used to predict the risk of progressing to type 2 diabetes, with a level of ≥155 mg/dl (8.6 mmol/L) being highly predictive of future risk 2.
- The 2-hour glucose concentration during an OGTT can be used to diagnose impaired glucose tolerance (IGT) and type 2 diabetes, with a level of ≥7.8 mmol/L indicating abnormal glucose tolerance 3.
- Lifestyle interventions, such as increasing physical activity and decreasing caloric intake, can improve insulin sensitivity and glucose tolerance in individuals with IGT, but may not have a significant effect on individuals with normal glucose tolerance (NGT) 4.
- Combination therapy with pioglitazone and exenatide can improve beta-cell function and produce superior glycemic control compared to basal/bolus insulin in patients with poorly controlled type 2 diabetes, with an OGTT used to assess the efficacy of the treatment 5.
- Insulin sensitivity during an OGTT can be improved with pharmacological agents such as metformin and thiazolidinedione, which can also improve glucose control and reduce endothelial dysfunction in type 2 diabetic patients 6.