Early exposure to certain cow’s milk proteins has been thought to be an environmental factor in the genesis of autoimmunity in type 1A (autoimmune) diabetes. Excluding dairy products from the diet would not lead to insulin independence at this stage.
In any case, given the acute onset, the negative islet cell antibody test, and the now rather small insulin requirements, I think that your son could well have what is now called type 1B idiopathic diabetes. The underlying pathology is not well understood yet though some may be due to another form of autoimmunity and some linked to chromosomal changes. It is uncommon in Caucasian families, but comprises just over 50% of new onset cases in Hispanic and African American children. Perhaps most importantly, in about half, insulin requirements slowly diminish, and these children can control blood sugars with oral medication, sometimes with just diet and exercise. Long term though, it is likely that they will again become insulin dependent.
DOB