People who have sugar intolerence

High glycaemic is partly to do with the processing and partly to do with the natural chemical structure of the starches and sugars themselves - some are much faster to breakdown or convert to blood glucose than others. The rating system was invented for diabetics after scientific research. Regular rice, white potatoes, modern finely ground wheat flour and corn/ maize are all pretty high glycaemic index so convert to blood sugar quickly and easily. Consider eating more variety of beans and lentils, jumbo or steel cut oats, barley, sweet potatatoes, brown basmati rice.

Not all proteins are expensive and they can easily be padded out with extra veg and beans or lentils if you use chopped or ground meat rather than whole pieces (steaks, whole chicken breasts) or organ meats like liver. For health you should be eating oily fish regularly (canned is cheapest), nuts and seeds for healthy fats and minerals, reduced fat dairy for minerals (cottage cheese, Greek yoghurt). All these supply protein as well as other nutrients that can be of benefit in blood sugar control and weight management.

I am on a tight budget and find it helpful to price up foods in groups by serving based on supplying, say, 30g of protein or an equal weight for fruits and vegetables (I use 80-100g because that is a UK serving). Be sure you are getting enough produce in the full range of colours - blue/ purple, dark green, red, orange/ yellow, considering that the antioxidants in some are believed to help with blood sugar control, for example grapefruit and certain berries (I have canned and frozen respectively for convenience and price). Fruit generally tends to be more expensive than vegetables, fresh more expensive than frozen.