169-LB: Type 1 Diabetes Mellitus and Stiff-Person Syndrome

Abstract

Introduction: Type 1 diabetes mellitus (T1DM) is often associated with other autoimmune diseases. One of them is Stiff-Person Syndrome (SPS), a rare neurological disorder characterized by muscle spasms and progressive muscle stiffness, which most often affects females. Glutamic acid decarboxylase antibodies (anti-GAD) are associated with the pathogenesis of this disease as well as T1DM. These antibodies cause a deficit in the synthesis of γ-aminobutyric acid (GABA) that is essential both in the function as neurotransmitter and in the secretion of insulin in pancreatic β cells. Clinical case: We present the case of a 32-year-old female patient diagnosed with T1DM at 18 years old. Currently under intensive functional insulin therapy and flash glucose monitoring (FGM). Since 2019 with subcutaneous insulin infusion system. At the age of 26, the patient reports dystonia in the left lower limb with subsequent involvement of the contralateral lower limb, upper limbs, trunk and face. Collaboration was made with the Neurology department. Among the laboratory findings, of note: positive serum anti-GAD65 (5437 U/mL; <1) and positive cerebrospinal fluid anti-GAD65 (126.23 U /mL; <1). The diagnosis of SPS was made. The patient started human immunoglobulin therapy with progressive clinical improvement. Estimated HbA1c from FGM was 6,8 % at February, 2021. Discussion: The association between T1DM and SPS is frequent. In this case, a patient with a known history of T1DM was presented, but cases of diagnosis of T1DM in patients with SPS have also been described. About 43% of patients have T1DM at the time of diagnosis of SPS. Anti-GAD are involved in the pathophysiology of these two diseases and anti-GAD titers are much higher in cases of association with SPS (about 50 to 100 times). In the treatment of patients with T1DM, physicians should be alert to the onset of other autoimmune diseases and active surveillance is essential for early diagnosis. Disclosure C. A. Araújo: None. C. Baptista: None. I. Paiva: None. A. Morgadinho: None.