I was on /r/keto and saw a cool picture about diabetic cookery in 1917. So I googled a little bit further and I found this site that had the 1917 diabetic cookery. I looked at a bunch of the recipes and there is very low carb count recipes, a table with carb % for veggies, fruits, and nuts and also food that is “forbidden”
From a quick glance through the pages, it looks like a majority of the recipes would be good for Keto also.
Also kind of neat that this cook book existed in 1917 where today’s “normal” diabetic recipes are high carb, low fat.

It’s so much fun to read all the recipes and the amount of butter she recommends really jumps off the page!
I wonder what a “moderate oven” would have been considered though. My best guess would be 350F as a starting point for experiments. It’s funny to see the use of almond flour too! Love it!