Systemic lupus erythematosus and pulmonary tuberculosis in a patient developing acute-onset type 1 diabetes

A 73-year-old Japanese woman was admitted to our hospital with anorexia, weight loss, and fever. A few weeks prior to admission, she became aware of anorexia. She was leukopenic, complement-depleted, and positive for antinuclear antibodies and anti-double stranded DNA antibodies. She was also found to have chronic airway inflammation on computed tomography. At the time of admission, she had multiple erythematous plaques on face and neck. She had blood glucose 343 mg/dL, HbA1c 12.7%, serum C-peptide 0.74 ng/mL, urinary C-peptide 17 μg/day, and urinary ketone 3+; and was positive for anti-glutamic acid decarboxylase antibodies and anti-zinc transporter 8 antibodies. Her human leukocyte antigen type was DRB1* 09:01-DQB1* 03:03, which is a susceptibility haplotype for acute-onset type 1 diabetes (T1D). Therefore, she was diagnosed as having concomitant T1D and SLE. Initial treatment with insulin and prednisolone alleviated her symptoms. However, sputum culture revealed Mycobacterium tuberculosis 23 days later, and she was treated with a multidrug regimen. The timing of onset of the SLE and T1D was estimated to be 4-7 weeks prior to admission. No imaging findings were available prior to 3 weeks of admission, making it difficult to determine the timing of onset of pulmonary tuberculosis (TB). In summary, SLE and T1D are both autoimmune diseases, but rarely occur together. Environmental and genetic factors are involved in the development of T1D and SLE, but TB is rarely thought of as a causative environmental factor. In the present case, SLE, T1D, and TB may have interacted during their respective onsets.