Stiff Person Syndrome and Brittle Type 1 Diabetes: Report of 2 Cases

Stiff person syndrome (SPS) and type 1 diabetes (T1D) are heterogeneous disorders characterized by antibodies (Abs) against glutamic acid decarboxylase (GAD).

We describe 2 patients with T1D and autoimmune thyroid disease who presented with muscle rigidity and intermittent spasms that affected gait and with elevated circulating anti-GAD titers. Classic SPS and stiff limb syndrome were diagnosed, respectively. Muscle spasms resolved with immunotherapy and muscle relaxants in both patients, and the ability to ambulate without an assistive device was restored in 1 patient. Patients also had brittle diabetes with high glycemic variability, requiring the use of flash glucose monitoring with an insulin pump and a second-generation basal insulin analog, respectively.

GAD Ab-associated syndromes include SPS, T1D, and other endocrinopathies. The clinical heterogeneity implies variable susceptibility of γ-aminobutyric acid-ergic neurons and pancreatic beta cells to anti-GAD or other autoantibodies.

Our case series represent the heterogeneity in natural history, clinical course, and response to therapy in patients with Abs against GAD-spectrum disorders.