If she is taking insulin, than there is a extra amount of insulin for her to take that is told to her by her Dr./nurse for high blood sugars and when she is sick. Have them tell you how much more insulin she needs and write it down and keep it on the refrigerator.
Drinking cold water will bring down high blood sugars slowly for type 1 and type 2. Being active. Go for a brisk walk will bring down high blood sugars.