> my guess is that what we'll ultimately find is that the benefits of GLP-1 therapy are primarily due to reduced blood sugar

This is my guess as well. It's been eye opening correlating on/off GLP-1s, wearing a CGM (blood glucose monitor), and seeing how that data changes depending on what I eat and how that further impacts what I eat an hour or three later.

Tightly controlled blood sugar was life changing to me - and I wasn't diabetic or at risk to become so.