Why did dog die?

My dog, Runway, died suddenly early sunday morning, at about 1:00am. I am wondering if you have any input of why? Tuesday and wednesday he had thrown up once each day and then thursday my uncle brought him to our vet. The vet thought just upset stomach, gave some amoxicillin and metoclopramide to calm stomach, becuase the dog also wouldnt eat and was losing weight noticeably. friday came along and he wasnt getting any better, i stayed up with him all night and he threw up about 7-8 times and would go outside and not come back in. at this point he was very out of it, down, couldnt walk well and just looked terrible. we brought him to emergency e.r vet at 5am and they kept him. we brought back blood work and xrays from previous vet and the alkp, ast and one other were high, and also the glucose was high. at that time they thought he had diabetes. said they would put him on insulin and keep him for a few days to make sure he was good. so we thought so big deal. that night about 7pm the vet called and said the insulin didnt work and she was going to do more blood work and call us back. she called back at about 930pm and said the ast levels were up to 2,000 (from 119) and not sure if he would make it through night. then they called again at 1245am saying he died. before all this he was in great shape, ran around, and was an awesome awesome dog. please give me some peace of mind and let me know if you have ever heard of anything like this and what it can be. I dont have any cash on my paypal account or i would have just paid to ask you a question, but if you can atleast respond to my email sometime, i will be more than happy to send money your way via paypal tomorrow after i get out of work. thank you very much,

kevin m.