Great find and great story. Oh man, the dudes he played with and/or against ... Nap Lajoie, Ty Cobb, Tris Speaker, Eddie Collins... Epic .... Bummer of an end to his life story though...
Yes, he really suffered with what appears to have been what today is called Type 1 diabetes. It used to be called juvenile diabetes, because it occurs most often in children and young adults, but now is called Type 1 because, like in Dr. Kahler's case, it sometimes presents first in adulthood.
Ken Johnson, D.O., the OU-HCOM dean, did reply to my message to him about Kahler, and said he was very excited to learn about him. He copied several subordinates, one of whom was supposed to follow up. So far I've heard nothing more.