Progressive myelopathy associated with spinal epidural lipomatosis in three non-obese patients with type 1 diabetes mellitus.

•Spinal epidural lipomatosis (SEL) is a rare condition without known association with DM1.•SEL may cause myelopathy that is potentially amenable to surgical intervention.•We report three non-obese patients with DM1 and SEL who developed progressive myelopathy.•All patients had intramedullary lesions adjacent to the area of maximal lipomatosis.•We suggest that patients with DM1 and myelopathy of unknown cause should be evaluated for SEL.