I have just released version 0.1 of mrtgsql.

mrtgsql – a MRTG to SQL logging and reporting tool for MRTG
Copyright (c) 2004 Max Clark
mrtgsql is composed of two programs: mrtgsql which inserts data from the MRTG .log files into a database, and mrtgreport which reports usage on the interfaces in total GB and the 95th percentile.

Grab it from Github: mrtgsql