During an oral glucose tolerance test the serum or plasma insulin will change over time, with an initial rise followed by a decline. The area under curve for insulin over time correlates with pancreatic beta-cell insulin secretion. The easiest way to measure the area under the curve is to measure the area for each trapezoidal region.



(1) baseline insulin in pmol/L (or µU/mL)

(2) insulin measured at constant intervals following administration of the oral glucose solution


area under each segment of time in pmol • min / L =

= ((concentration in pmol/L at start) + (concentration in pmol/L at end)) / 2 * (minutes in interval)


total area under the curve in pmol • min / L =

= SUM(area under all of the segments)


This total area can be adjusted for a variety of factors.


If we consider the baseline insulin as marking the patient's unstimulated state, then the insulin response to the glucose load is:


insulin response to glucose load in pmol • min/L =

= (total area under curve) - ((baseline insulin) * (total time in minutes))


Sometimes the insulin response is adjusted for the patient's body mass index (BMI).


insulin response adjusted for BMI in pmol•min•m^2 / (L • kg) =

= (area under curve in pmol•min/L) / (body mass index in kg per m^2)


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