Well, remember that all of these claims were being reassessed because of a directive and some new clarification language that was added to the clarification letters which said that adults with type 1 would not generally qualify unless they had one or more chronic conditions in addition to their diabetes. The ones who would have been accepted prior to the review presumably had other chronic conditions that caused them to be approved. These people were all denied on the basis of that clarification letter, so they would normally have been approved prior to May 2017.
On October 2nd, 2018. See this statement in context.