I think controlling carbs (and thus some weight) is important in the beginning. But when the pancreas fails, then not much can be accomplished and injectable insulin has to be the solution.

Eating sensibly will allow for less insulin, but people at the end of their lives often, only have food as a comfort. So getting thru that barrier would be difficult.

The pancreas can be damaged by drugs..some cause pancreatitis. Autoimmune disease can attack the pancreas too. Many new drugs also cause diabetes... the atypical antipsychotics, and new evidence that Paxil + Pravachol (statin)taken together does too! So one can diet forever and if they are damaged this way, the diet will have only limited effectiveness.
So many variables can lead to diabetes.

It is great you could do what you did Mel. But you are correct that people vary in their will and determination. Some will fight and not even take certain nutrients in the face of a severe deficiency! I think TV is a big culprit too. The new flat screen TV we just got makes food look SO good. OH.... I find it hard to fight that myself!