Maternally inherited diabetes and deafness (MIDD) is a form of diabetes that typically goes hand in hand with hearing loss, specifically of high tones. MIDD is a rare form of diabetes that accounts for approximately 1% of all diabetic cases. The diabetes in MIDD is categorized by high blood sugar levels (hyperglycemia) which results from a shortage of insulin – the hormone which adjusts the amount of sugar in the blood.
Mitochondrial DNA is inherited only from the mother (due to the degradation of mitochondria in the spermatic cells upon fertilization). Thus, the mutation can only be transferred through the mother; however both sexes can harbour the mutation and manifest the disease. In MIDD, the diabetes and hearing loss mostly develop in mid-adulthood, although the age at which it occurs varies from childhood to late adulthood. Typically, hearing loss occurs before diabetes.
Sensorineural deafness is the other main characteristic in MIDD and is due to involvement of the cochlea. It exists in about 75% of diabetic patients, from early adulthood. It commonly heralds the diagnosis of diabetes; it’s more common, more serious and rapidly progressive in men, as compared to women. Initially, it affects higher frequencies and later, all frequencies.
Hearing loss varies from person to person, but a hearing aid is required. MIDD may have other multi-organ disabilities: for instance, muscular and cardiac problems, pigmented retinopathy and nephropathy with complications.
The presence of diabetes mellitus, deafness and a family history in maternal relatives should raise a red flag of MIDD and genetic testing should be pursued so one can then undertake personalized management and genetic counseling. MIDD patients are initially treated with diet or/and oral hypoglycemic agents, however progression to insulin is rather quick within 2 years from diagnosis.
E194 – Diabetes mellitus and deafness – www.diabetic.today