If you can do it, it might be worth showing us a scan of the page you are referring to.
My best bet is that that G and the GP are not related.
G in a circle sounds like a warning of a Glider Field in the proximity of the approach. The GP probably has a number next to (or near) it and indicates the check altitude for the Glidepath at that point. With Jepp charts this is normally written as GS, but again, without knowledge of the chart type that you are referring to, its hard to guess.
-2Donkeys