One way of interpreting the data collected during a glucose tolerance test is to measure the area under the glucose time curve, based on glucose measurements collected at 30 minute intervals.
Duration of Test
Glucose Measurements
Number of Subregions (n –1)
1 hour
0 (baseline), 30, 60 minutes
2
2 hour
0, 30, 60, 90, 120 minutes
4
3 hour
0, 30, 60, 90, 120, 150, 180 minutes
6
where:
• The initial glucose reading is done on a fasting specimen.
• Glucose readings are in mg/dL. It can be expressed in mmol/L, with adjustments to area under curve to min*mol/L.
• The oral glucose load administered may vary (50, 75 or 100 grams).
• The molecular weight of glucose is 180.16.
area in each subregion =
= (area of rectangular subportion) + (area of triangular subportion)
= ((30 minutes) * (minimum of 2 readings)) + (0.5 * (30 minutes) * (difference between 2 readings))
area under curve in min*mg/dL =
= SUM(areas for all subregions)
area under curve in min*g/dL =
= (area under curve in min*mg/dl) / 1000
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