Blood glucose disposition rate after intravenous glucose infusion is considered to reflect mainly the rate of cellular glucose uptake, the rate of glucose degradation process and gluconeogenesis. excluding the influense of glucose absorption.
When it is hypothesized that the elevated blood glucose is disposed by constant rate (one-compartment theory), the following formula will be realized.
Ct = A (1— k)t Ct = blood glucose level at t-minutes after infusion
A = initial glucose level after infusion
k = constant glucose disposition index / min
log Ct = log A (1—k) t= log A + t log (1 — k)
This formula demonstrates that logarithm of blood glucose concentration (Ct) is a one-dimensional (linear) function of time t with a slope log (1 — k), and blood glucose disposition index k can be calculated from this slope.
To examine the validity of this hypothesis, 1.5 ml / kg of 20% glucose (0.3g / kg) was infused at rest within 3 minutes into an antecubital vein and plasma glucose was determinned at 1, 3, 5, 10, 15, 20, 30 and 40 min after the cessation of infusion.
In 10 healthy subjects, linear regression coefficient between logarithm of plasma glucose and time t was significantly higher (r= 0.992 ± 0.006, p<0.001) during 5 to 40 min. Calculated k index ranged from 0.78 to 4.54% / min and the correlation between the 1st and the 2nd measurements (n=5) within a week was also significantly high (0.92±0.06, p<0.01). These results highly support the validity of basic formula (one-compartment theory) and practical procedure to measure k index.
The effects of warm water bathing (42 C, 10min) was examined in 7 subjects keeping warmth by blankets. After bathing, k value remained in nearly the same in 4 subjects, decreased in 2 and increased in 1. Although more detailed studies are needed, the effect of single bathing on glucose disposition seems to be not so significant.