In addition to the risk of low blood sugars (hypoglycemia which can lead to coma) in diabetics there is also a risk that someone might try something like this a

In addition to the risk of low blood sugars (hypoglycemia which can lead to coma) in diabetics there is also a risk that someone might try something like this and then forgo other treatment (say insulin or metformin) without properly monitoring to see if they still need.