To a diabetic, Food is poison.
One has to avoid saturated fats with an even number of atoms less than 18 in their carbon chains, avoid.
One has to know by heart the carbohydrate contents of most foods and avoid anything which contains more than 15% Carb by gram weight.
That is no mean feat.
So one has to eat a low carb, higher Good fat, higher right protein diet.
Fat puts up insulin resistance and the wrong type of protein will be turned into sugar by gluconeogenesis.
Carb puts up blood sugar.
To a diabetic, Food is poison