How does a person with diabetes feel if sick?

How does a person with diabetes feel if sick?

Not quite sure what you are asking here!
But I think you mean: How do you know a person with diabetes is feeling unwell?

People with Diabetes suffer many problems as it affects the whole body. symptoms tend to develop rapidly, over a couple of weeks, and are more severe. In type 2 diabetes, symptoms develop slowly and are usually milder.
The symptoms consist of:

Increased thirst (could drink an ocean dry kind of thirst)
passing water frequently, especially at night (Hence the amount of fluid drunk)
tiredness and fatigue
loss of weight
genital itching or recurrent thrush

Hope this was helpful