If you are a type 2 diabetic and you just don't hear as well as you used to, the real problem might be blood sugar control. Both high and low blood sugars can permanently damage hearing.
Although severe hypoglycemia is relatively uncommon for type 2's, diabetics who take an overdose of insulin great enough to lose consciousness often have permanent damage to both hearing and vision. A single episode of hypoglycemia with loss of consciousness is enough to cause permanent hearing loss. Even children and teens who pass out from insulin shock can have permanent hearing loss. It's important for all diabetics to learn the symptoms of hypoglycemia and to keep blood sugar testing equipment close at hand--because the only way any diabetic can no for sure he or she is experiencing hypoglycemia is to test blood sugar levels.
The effects of high blood sugars are slower and more insidious. A variety of conditions contribute to the loss of the ability to hear high frequency pitches as we get older. Uncontrolled type 2 diabetes, however, affects the ability to hear low- and mid-range frequencies, too. Diabetics who develop neuropathy can be up to nearly 3 times as likely as the general population to lose their hearing after 10 to 15 years of the disease.
Preserving your hearing is one more good reason to keep blood sugar levels in check. Avoid both highs and lows to avoid ever needing a hearing aid.
Bainbridge KE, Cheng YJ, Cowie CC. Potential mediators of diabetes-related hearing impairment in the
population: National Health and Nutrition Examination Survey 1999-2004. Diabetes Care. 2010 Apr;33(4):811-6. Epub 2010 Jan 22. U.S.