”The 2014 CODATA Recommended Values of the Fundamental Physical Constants” ( Last update: June 25 2015). Available: http://physics.nist.gov/constants
This constant is necessary to quantify  gravitational force between two bodies and presumably it must ride on the global Universe’s mass allocated in the full Universe’s volume at a definite moment.
Investigating its dimensions we notice:
G = m3 / (sec2 * Kg ).
We make this hypothesis :