There are a number of ways to take GH and when combining with Insulin it complicates it a bit. First off GH reduces glucose uptake which is why it increases blood sugar. GH also promotes gluconeogenesis, which is when the body makes glucose from more complex hydrocarbons like fatty acids. This also increases blood sugar as well as reduces fat. Gluconeogenesis occurs more when the glucose supply is low (low blood sugar, i.e. empty stomach).
So where are we at, we used some GH and now we have reduced some fat into glucose but our glycogen uptake is hindered by it as well. This is where insulin comes into play. Injecting insulin at this point forces the glycogen uptake to occur in the muscles, liver, and kidneys which allows for immediate nutrient transport post workout.
Chemically this is the most anabolically efficient way to do it, the problem is that many people feel fatigue doing it this way and they opt to take the GH after the 'slin because the reduction process of the carbon substrates (fats, acids, alcohols etc) combined with the hypoglycemia help balance each other.
Ideally on paper you could inject GH 15 minutes preworkout and a fast acting insulin at the start and drink a high mono and polysaccharide complex throughout the workout, but for anyone who had ever tried to lift post 'slin injection... it's just too hard to balance it perfectly and be able to actually lift.
Basically what I'm saying is doing it the "best way" is not a good way to do it, so it really doesn't matter. Doing it in reverse, with the GH following the insulin will work well but you will see less fat reduction. I will try to elaborate on this more but I have to get going at the moment.