Ok this thread seems to have moved into completely different realms. I've been looking at various diets
There were many diets, some very low, some very high carb Some very unpleasant. Most were very low calorie .
Rollo's diet mentioned earlier apparently included 'plain blood puddings',' fat rancid old meat' and it is thought he dosed with Antimony or other substance to make the patient vomit . Of his two Officers one, Rollo said was cured of glycosuria ie he had no sugar in the urine. ( how long for we don't know)The other couldn't tolerate the diet, stopped and died 3 months later. (Bittersweet, J Feudtner)
Another low carb diet ( actually meat only ) was used by an Italian doctor Cantani. He locked his patients up so that they would stick to the diet. I haven't been able to find if he killed or cured them. Apparently in Malta it was introduced but the death rate stayed exactly the same during the period it was used (but there were actually only a handful of cases in 19th century Malta)
There was Carl Van Noorden's oatmeal diet comprising 250g of oats, made into a porridge with water with 350-300g butter,and 100g of 'vegetable albumin' for which egg white could be substituted beaten in afterwards. This was eaten for each meal; with perhaps a little coffee or sour wine to 'relieve the monotony' Gradually the 'normal' diabetic diet was reintroduced with meat, veg, more oats to furnish carbs.
The telling thing in this account though is of a lady of 50 with what is called a malignant type of diabetes that was progressing. Her weight had been reduced to 68lbs (ie under 5 stone) A Dr Herrick writing about it here in 1908 says that it didn't do much in mild cases but he thought that it helped ward of coma and increased carbohydrate tolerance in more severe cases . However it was as he said unappetising .
http://jama.jamanetwork.com/article.aspx?articleid=181594
How about Arthur Scott Donkin's skim milk treatment for diabetes 1871? (haven't read it but there is a whole book here )
https://archive.org/details/skimmilktreatme01donkgoog
And apparently there was even a sugar feeding diet, a potato diet and a vegetable cure diet (haven't found details of them).
This discusses all the various diets briefly
http://www.medscape.com/viewarticle/760941_3
Here is a source of many other old books about diabetes , some of them medical treatises but there are several other diabetes cookery books from the 1920s and 30s
One book I also noted is by R Lawrence (founder of Diabetes UK , a doctor and a T1 diabetic) The Diabetic Life was the standard 'manual' for both patients and doctors in the UK from the mid 1920s to as late as the 1950s) . .
http://onlinebooks.library.upenn.edu/webbin/book/browse?type=lcsubc&key=Diabetes -- Periodicals&c=x