Wrong about LCHF being a relatively new innovation. It was the only treatment available to diabetics as long ago as the 1800s. There have been several threads about this, with quotes from books written at the time. I have one published in 1936
Cookery and Household Management
Printed 1936
Diabetes
Those suffering from this ailment require carefully to avoid all foods containing sugar and starch. The following Must be avoided:
Milk, sugar, flour, cornflour, oatmeal, rice, sago, macaroni, the various pulse foods, fruits containing a high percentage of sugar, potatoes, beets, carrots, peas, parsnips, broad beans, spanish onions.
The following are allowed:
meat, soups, fish, poultry, game and meat of all kinds. Also eggs, butter, cream, cheese, certain vegetables. Light dry wines. Weak unsweetened spirits. Tea, coffee and cocoa which may be sweetened with saccharine. There may be plentiful use of butter, cream, fat and oils if the digestion will allow.