How to reduce sugar in chocolate chip cookies without losing the texture
You can toast your sugar. Stella Parks on Serious Eats and in her cookbook Bravetart explains that toasted sugar undergoes thermal decomposition that make a more complex, less sweet flavor and (importantly to your question) is lower in the glycemic index: 


  Not only does toasted sugar taste less sweet, it has less sucrose, fewer calories, and a lower glycemic index than plain sugar. How much lower would depend on the extent of thermal decomposition


Toast sugar by putting white sugar on a baking sheet in the oven at 300&deg;F for one to five hours. Stir occasionally. You will likely need to place the resulting toasted sugar mass in a food processor to break it up. It can be used 1:1 for the sugar in the original recipe.