That study abstract really isn't that informative.
We know that these guys were taking 850mg Metformin 2x a day.... and one group was taking hGH, one group was taking a placebo.
We know that the guys taking hGH + Metformin increased their IGF-1 levels, and lost fat.
We don't know 3 things:
1) We don't know what happened to the IGF-1 levels in the Metformin group without hGH. (did it increase, or stay the same, or decrease?)
2) In the Metformin group with HGH, how much more would their IGF-1 levels be without Metformin present? (maybe it would be further increased, or maybe it would be about the same... we don't know)
3) What was the average hGH dose that these people were taking? (in i.u.'s)
Maybe the full study addresses these questions.