What does this test include?
This combined test follows glucose after a standardized oral glucose drink and measures insulin at three time points. It shows both glucose tolerance and the insulin response under the laboratory protocol.
Why might it be ordered?
- For a clinician-directed investigation of glucose regulation and insulin response.
- When standard glucose measurements do not fully answer the metabolic question.
What sample is needed?
Several blood samples are collected before and after the glucose drink. Obtain the exact written schedule, including which three samples include insulin.
How should you prepare?
Confirm the full protocol. Maintain your usual carbohydrate-containing diet and normal activity for the preceding days, then complete the required overnight fast. Remain seated and do not eat, smoke or exercise during the test. Ask how to handle medicines and never change them on your own.
How are the results reported?
Glucose is interpreted using protocol-specific thresholds. Insulin curves do not have one universally accepted diagnostic cutoff, so the timing, paired glucose and clinical context are essential.
Sources and editorial status
This patient-facing text is an editorial draft. It should be approved by a laboratory physician before official publication.