Hi thanks for contacting HCM... Noted your husband having chronic diarrhea .... So here yes you have to consult gastroenterologist for detail physical examination and investigation.... Here as you have diabetis it can lead chronic diarrhea ....so diabetis need to be controlled.... Also rule out hyperthyroidism by serum thyroid profile.... Rule put HIV from blood by ELISA test.... Chronic diarrhea can be by chronic infective etiology.... So stool routine microscopic examination and stool culture examination done... By concentration method stool examined for parasitic detection.... According to cause management done.... If still cause not clear then yes colonoscopy and biopsy done to rule out non specific colitis , Whipple disease , tropical sprue etc ....like condition... Hope your concern solved... Maintain hydration.... Take care. Dr.Parth