Final answer:
The 1hr glucose challenge test and the glucose tolerance test are tools used to diagnose diabetes mellitus. A normal person's blood glucose will return to baseline levels within 2.5 hours after ingestion during a GTT. In diabetes, glucose levels remain elevated, indicating intolerance.
Step-by-step explanation:
Difference Between 1hr Glucose Challenge Test and Glucose Tolerance Test
The 1hr glucose challenge test and the glucose tolerance test (GTT) are important diagnostic tools for assessing how well an individual's body manages glucose, and they are often used for screening and diagnosing diabetes mellitus. The 1hr glucose challenge test is a preliminary screening, whereas the GTT is more detailed and is used when diabetes is suspected but not confirmed by the simple challenge test.
Glucose Tolerance Test (GTT)
For the GTT, patients are instructed to consume a carbohydrate-rich diet for three days prior to the test. Fasting blood glucose is measured, and then the patient ingests a specified dose of glucose. Blood glucose levels are then monitored at regular intervals to assess glucose tolerance. In a normal person, the fasting blood glucose level should be at the lower limit, around 75 mg/100 ml. After ingesting glucose, the blood glucose level peaks and then decreases back to normal within about 2.5 hours.
Insulin Tolerance Test
Similarly, an insulin tolerance test may be conducted with patients on a high-carbohydrate diet. Fasting blood glucose is assessed, followed by an intravenous dose of insulin. The individual's blood glucose is measured at intervals to see how it is affected by insulin. In a normal person, blood glucose will fall then return to normal after about 2.5 hours.
- In people with diabetes mellitus, blood glucose does not return to normal within 2.5 hours after glucose ingestion, indicating a tolerance issue.
- Hypoglycemia relative to the baseline may occur during an insulin tolerance test in cases of Insulin Dependent Diabetes Mellitus (IDDM).
- Hyperglycemia is noted during the glucose tolerance test when confirming diabetes mellitus.