A case of slowly progressive type 1 diabetes mellitus with reduced insulin requirement during the administration of disease-modifying anti-rhuematic drugs

Introduction: This report describes a 53-year-old female with slowly progressive insulin-dependent (type 1) diabetes mellitus (SPIDDM) and rheumatoid arthritis (RA) in whom treatment for RA reduced her insulin requirement. Case Description: A routine laboratory examination in March 2004 showed hyperglycemia, which had worsened 5 months later. At this initial examination, her fasting blood glucose and HbAlc levels were 238 mg/dL and 13.1 %, respectively, and she was positive for anti-GAD and anti-IA-2 antibodies. She was diagnosed with SPIDDM and started on insulin therapy, which improved her glycemic control. Following a diagnosis of RA in February 2006, she was started on the immunomodulator leflunomide, which gradually reduced her insulin requirement from 23 U/day to 19 U/day. After starting administration of the tumor necrosis factor (TNF)-alpha inhibitor infliximab in June 2007, she experienced frequent episodes of hypoglycemia. Infliximab was discontinued, and, in December 2008, she started treatment with a combination of methotrexate and leflunomide. She began treatment with adalimumab in April 2015. Her insulin requirement has gradually but progressively decreased to 11 U/day. Her glycemic control remains excellent, with an HbAlc concentration of 5.8 % in August 2015. Conclusion: TNF-alpha inhibitors and/or immunomodulators for RA may preserve the beta cell function, reducing the insulin requirement in patients with SPIDDM.