Stiff-person syndrome (SPS) is highly associated with anti-
glutamic acid decarboxylase (GAD) antibody. However, GAD
antibodies alone appear to be insufficient to cause SPS, and they possibly are involved in only part of its pathophysiology. It is suspected that the symptoms of SPS get precipitated by external stimuli. Here, we briefly introduce the case of a patient with latent
autoimmune diabetes who developed SPS through the action of subcutaneously injected
insulin. A 43-year-old man was diagnosed with diabetes and initially well-controlled with oral
hypoglycemic agents but progressed to requiring
insulin within 1 year of diagnosis. Two months after the initiation of basal
insulin therapy, he presented with abdominal stiffness and painful
muscle spasms, involving the lower limbs, which resulted in
walking difficulty, and thus, he refused
insulin injections thereafter. He had been treated with oral anti-diabetic agents instead of
insulin for 10 years until premixed
insulin twice daily was started again due to poor diabetes control. Immediately after
insulin injection, abdominal muscle rigidity and
spasms were noted. When
insulin was not administered, frequent episodes of
diabetic ketoacidosis occurred. Serum GAD antibody test was positive and there was no positivity for islet antigen-2 antibody. A
glucagon stimulation test demonstrated relative
insulin deficiency, indicative of
latent autoimmune diabetes in adults (LADA). Tolerable
muscle rigidity was achieved when the dosage of basal
insulin was split into two separate daily
injections with lower amounts of units per injection. This case highlights a different form of
autoimmune diabetes in SPS. To our knowledge, this is the first report of SPS described shortly after the initiation of
insulin therapy that required basal
insulin to achieve tolerable muscle symptoms and better
glucose control, without the development of
diabetic ketoacidosis.