To the controary, Dlace!

Insulin controls blood sugar, which, if out of countrol, will damage kidneys, hearts and eyes, to name a few. So, no, insulin will not damage internal organs.

What are the signs of a bad kidney or a kidney going bad!

Well...most of the signs would be difficulty urinating, or not urinating at all, nausea, etc. Tests can be run (and should be, if you're diabetic) on your kidneys for microalbumin. If there is albumin in the urine this can mean problems. Check with your doc, though...I'm not a doc, just a fellow diabetic.

Insulin is a hormone that is produced by the body to break down and use carbs. No, natural insulin or synthetic insulin does not damage the body, as Gina-MI said.

The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) lists the following as some of the signs and symptoms of kidney disease:

frequent headaches or tiredness
itchy all over your body
more or less than normal urination
hematuria or blood in the urine
urine that appears pink
urine that appears foamy
edema or swelling in the hands and feet or numbness
loss of appetite
nausea and vomiting
trouble concentrating
drowsiness
darkening skin
muscle cramps

I got this list from HERE. You can visit this website for more information. They expand on a few of these (like muscle cramping and the swelling piece).