Long-Acting Glucagon-Like Peptide-1 Receptor Agonist-Induced Rheumatoid Arthritis in a Patient with Type 2 Diabetes Mellitus

Case Presentation: We report a case of a male patient with rheumatoid arthritis (RA) diagnosed during treatment with a long-acting glucagon-like peptide-1 (GLP-1) receptor agonist (once-weekly dulaglutide injection). At 3 months after dulaglutide initiation, he began experiencing left shoulder pain that continued despite treatment by an acupuncturist, indicating that the pain was not due to periarthritis scapulohumeralis. His HbA1c level was 7.3% at the 3-month follow-up. At the 6-month follow-up visit, the HbA1c level was 8.2%, the low-density lipoprotein cholesterol level was 132 mg/dL, and he expressed right shoulder pain. After 3 months, the HbA1c level was 9.0%, and his bilateral shoulder pain worsened, due to which he could not use his arms well. Routine laboratory testing revealed no other abnormalities at that time. However, several inflammatory and serological RA markers were detected, including an erythrocyte sedimentation rate of 73 (normal range, <10) mm/h, a C-reactive protein level of 1.89 (normal range, 0.0–0.14) mg/dL, a rheumatoid factor level of 26 (normal range, 0–15) IU/mL, and an anti-cyclic citrullinated protein antibody level of 195 (normal range, <4.5) U/mL. However, tests for antinuclear antibodies, anti-SS-A/Ro antibodies, and anti-RNP antibodies showed negative results. He was diagnosed with RA, and salazosulfapyridine (500 mg/day) was started. At 1 month after RA treatment initiation, his shoulder pain began showing improvement and improved HbA1c levels from 9.0% to 8.0%. Discussion: Thus, this case report suggests an association between RA and GLP-1. Based on a literature search in PubMed, we believe that this case report is the first to demonstrate that a patient with type 2 diabetes mellitus treated with a long-acting GLP-1 receptor agonist had RA. However, further research is needed to determine whether RA is one of the adverse effects of long-acting GLP-1 receptor agonists. Conclusion: During treatment with long-acting GLP-1 receptor agonists, it is necessary to consider the possibility of RA as a differential diagnosis when patients complain of persistent joint pain.