My Uncle Went Into Septic Shock And Had To Have

My uncle went into septic shock and had to have a toe and small portion of his foot removed. He's a diabetic (not sure which type). I also know that secretly, he occasionally (only very recently, and not daily by any means) was abusing methamphetamine via his insulin syringes. He's a nurse and has plenty of medical background. What I want to know is, was his septic shock due to diabetes complications, or did the infrequent meth abuse cause this?