I've Googled for various permutations of "great depression" +/- heath care +/- diabetes treatment with various levels of success, so I have a general idea of what diabetes treatment was like back then. I've also read up on George Woolf, but he was a moneymaking jockey and could afford treatments!
Is it possible that he can afford insulin? I can't find anything on how much insulin cost back then, but I assume it was expensive, since it was a relatively new medical breakthrough.
I hope that's enough info. Please let me know if you need anything else!
ETA: Edited for clarity, since I realized that I specified his diabetes only in the subject.