Has anyone ever been insulin dependant and developed a diarrhea that is like butter ?

My mom has been insulin dependant for several years.  About one year ago she developed this diarrhea that looks like butter and is uncontrollable.  She was taking Novalog 70/30 at the time of onset however she has tried several different insulins and now it is very hard to control sugar.  Also her protein levels are so low they say she is malnourished and needs to eat more protein.  She eats protein all the time she is losing it some how and it is not through her urine. They have done urinalysis and other tests.  She has also started swelling in her legs and they say that is also due to the low protein levels.  Can people be allergic to insulin? Any ideas or answers?