Insulin Tolerance Test (4 Hour)

OVERVIEW:

This test entails the measurement of a fasting insulin followed by a glucose challenge of 100mg/dL (Glucolatm), with five subsequent insulin measurements at hour, 1, 2, 3, and 4 hour postglucose. The test is best utilized (but not necessarily), in conjunction with glucose measurements at each point in time (4-hour glucose tolerance test) as well. Meridian Valley Laboratory does not perform the GTT in-house, but we can run the test, if desired, as a send-out for an additional cost. Alternatively, you can fax the glucose data for a patient to be plotted with the MVL insulin data at no extra charge.

CLINICAL SIGNIFICANCE:

The 4 Hour Glucose/Insulin Tolerance Test ((G)ITT) is offered by MVL on the strength of a study reported in 1975 by Dr. Joseph Kraft, who ran GITT tests on 3,650 patients, most of whom were referred on suspicion of having diabetes.1 When only the glucose data were considered, 1,713 people were found to be normal. However, when both the glucose and insulin data were considered for these same 1,713 people, 1,023 or 60% of them were found to have abnormal insulin secretion patterns consistent with what is now called insulin resistance.

Moreover, consideration of insulin data was able to clarify the situation when glucose results were equivocal, as was the case for another 1,227 of the 3,650 people. Only ten percent of the 1,227 equivocal tests had normal insulin patterns, adding another 1,105 patients to the insulin-resistant tally. All told, only 710 people of the original 3,650 were found to be normal by both criteria. Inclusion of the insulin data made a difference, i.e. resulted in the reclassification of normal or equivocal tests to abnormal sugar regulation in 2,128 cases.

This test can be invaluable for detecting pre-diabetic conditions years before diabetes may otherwise have been indicated.

Glucose Insulin Tolerance Test

BENEFITS:

• Lowest Cost — no other laboratory offers the test at a comparable price.
• Reproducible — State of the art clinical methodology
• Excellent preventive medicine test
• Speed — 5 to 7 business day sample turnaround
• Results — Easy to read graph of insulin versus time
• Free return shipping
• Call to Order Collection Kits

1. Kraft, J.R., (1975) Detection of Diabetes Mellitus In Situ (Occult Diabetes). Laboratory Medicine 6:2, 10-22.