Onion juice can cure many diseases including diabetes and cholesterol.

onion juice can reduce the excess amount of sugar and cholesterol from blood:

According o recent research scientists in the light of experiments have concluded that in the bulb like layers of onion they found "Matt Foreman" a medicine helps to reduce the excess amount of glucose and cholesterol in diabetic patients. 

Many experiments are conducted by experts on  rats in this regard and concluded that we need to know the mechanism that how onions juice reduces the amount of glucose in blood.