A 42-year-old male with a 15 year history of type 1 diabetes p | Neurology collections 2020

A 42-year-old male with a 15 year history of type 1 diabetes presents with a two month history of deteriorating
pain and stiffness of the right shoulder.
On examination he has painful limitation of internal rotation and can abduct the right arm to only 90 degrees.
Flexion is relatively unimpaired. There is some weakness of movement of that shoulder with slight wasting of

shoulder muscles. He has some reduced vibration sensation in both hands.
Which of the following is the most likely diagnosis?