Here's an infographic I have posted on my fridge to help.
Common Foods on the Glycemic Index
Eating several time small portions throughout the day of foods that don't spike your blood sugar levels: no white flour, white rice, etc.
Do eat lentils, for instance, because not only do they not spike your blood sugar levels, they are also alkaline rather than acidic.
This is something else I have posted on my fridge:
Alkaline-Acid Food Charts to Help Balance Your pH - Greenopedia
The more alkaline food you eat, the better.