Dieting Advice

My husband was diagnosed with type 2 diabetes last year, he weighed 249 lbs in sept 09 , but for the last 8.9 years has had a huge big belly!!!he does,nt drink at all, but it is rock hard, more so after eating, he has lost nearly 2 stone since sept 09, all of his body has gone very thin looking except for his belly which still measures 50 inches round,before he lost this weight he has asked the gp several times about his large stomach, but he just said it was the insulin???
I and my husband area bit confused about this as he has only been on the insulin for 12 months, he now wont go back to the gp { even though he has lost this weight with no change in diet} about his stomach, have you any ideas or advice please, as I can see he is worried, but does,nt want to go to gp as he feels he is bugging them .

Hi thank you for your reply, he was taking 180 units a day, but he has now told me he has,nt taken any since october 09, as his doctor told him that it was the unsulin keeping the weight on particularly round his belly,{ which as I said before he has had for a few years now} he is still taking the metformin,
So now he is losing weight like never before, but his belly is still as big,
I think he is really worried because his mum died a while ago of pancreatic cancer.
The problem is we cant just go to our gp and demand a scan etc, any more advice please.
Thank you , Carol