With diabetes and age, you do have sensory neural hearing loss, and hearing aid is the only answer. As far as fluctuation in hearing level is concerned, wax, allergy, common cold, can all cause fluctuation in hearing, due to a change in the conductive element of hearing. In case the hearing loss documented by repeated audiometry is fluctuating (more than 10-20 dB at the same center on repeated occasions), then further investigations are warranted.