Maternally inherited diabetes and deafness (MIDD) is a rare form of diabetes, affecting an estimated 0.1-0.2% of patients with diabetes in the UK. Affected women pass the condition on to both daughters and sons. However, affected men cannot pass the condition on to any of their offspring. It has high penetrance, with more than 85% of carriers developing diabetes during their lifetime. Bilateral sensorineural hearing loss occurs in most cases. The hearing loss typically develops in early adulthood and often precedes the onset of diabetes.