Insulin is a growth hormone and is known to promote fat storage, I injected into my belly for along time and have a marked increase in fatty tissue there, not much ha ;)
Long acting insulin is typically given in larger doses and will pool under the skin for longer than a small dose, further promoting fat storage. It could also beginnings of lipohypertrophy. If you are injecting large doses into your stomach stop doing it, and perhaps split these large injections into different sites.
I did something about it and lost 5 inches off my waist, unfortunately there is no easy way to do this, belly fat is always the last to go for some reason ;O)
I restricted my calorie intake to no more than 1500 calories a day, I drank 3 litres of a water a day, I ran hard four times a week and I did stomach crunches, 6 months later it had gone.
There is a wealth of information on the net. The PX90 stuff is good.
My advice is really look at your diet..
Look at joining a site like this, log everything you eat for one month, use it to work out your recommended daily calorie intake for your diet and don't go above it.
The best thing for dropping weight quickly are exercises like running, interval running is especially good. Cycling and spinning classes are also great.
If you have an iphone or a smart phone, there are many apps that will get you from the couch to 10k in a few weeks. Google is your friend!
All comes down to expending more calories than you consume and creating a deficit. Discipline and hard work also go along way.
Good luck, if you PM I can provide you with links to exercise downloads decent sites, I have have around 1,000 exercise and fitness related pdfs I can compress and email you should you want them.