If one feels low on energy most of the day, excess sugar could be causing energy spikes and crashes. High sugar levels cause body to lose more fluids, leading to constant thirst, said Dr Manjusha Agarwal, senior consultant, internal medicine, Gleneagles Hospital. "Skin changes...can also indicate increased sugar in body," stated Dr Vijay Negalur, HOD, diabetology, KIMS Hospitals.