The notion behind taking insulin with
HGH is to counter the hyperglycemic effect of
HGH.
HGH raises blood sugar levels, and when those levels go up, the body is required to secrete more insulin to cope with it. These constantly higher-than-normal insulin levels may harm insulin sensitivity over time - AKA insulin-resistance.
By assisting the body with exogenous insulin, it may help shuttle more glucose from the blood into the cells, especially muscle cells. Insulin itself is an anabolic hormone, although in human clinical studies it does not appear to increase protein synthesis by itself, but it does have strong anti-catabolic effects.
Generally, and especially in your case, I would stay away from incorporating insulin.
What may be beneficial for many users, especially those on higher dosages of
HGH, is adding IGF-1, AKA insulin-like growth factor. IGF-1 may help balance blood sugar levels with fewer risks and better anabolic potential than insulin, and it may also be more beneficial from a metabolic standpoint. Insulin directly promotes fat accumulation along with its other effects.
I highly recommend this read concerning GH and IGF-1, as well as insulin sensitivity:
GH and IGF1 in Growth and Repair