I assume you mean lower your BG, Some say Bitter gourd can lower BG however Ive never seen ANY proof of that.
I know of no food that lowers BG. I do know that carbohydrates raise BG... ALL carbohydrates will raise your BG. brown rice is a carb and will raise BG, so is wheat, potato, sugar and most fruits.
Google LCHF Way Of Eating (WOE)
Eat low carb / ketogenic diet. Avoid or strictly sugars, grains, starchy vegetables, and sweet fruits.
Use a blood glucose meter to determine the effect of your diet on your blood sugar. This will help you fine tune what foods do and don't affect your blood sugars, and to what degree.