A child with mitochondrial DNA deletion presenting diabetes mellitus as an initial symptom

Children with mitochondrial disease may present with diabetes mellitus (DM) without autoimmune antibodies as an initial manifestation, however, it is difficult to make a precise diagnosis in early stages. We present a 2-year-old male patient with mitochondrial disease who showed insulin-dependent DM without autoimmune antibodies as an initial symptom. He later presented with progressive motor deterioration, hearing disability, ptosis, external ophthalmoplegia, and retinitis pigmentosa at 6 years and 6 months. T2- and diffusion-weighted imaging revealed high signal lesions in the subcortical white matter, anterior thalamus, globus pallidus, and brainstem. MR spectroscopy showed elevated lactate and low N-acetylaspartate in the affected white matter. Genetic analysis revealed a single large-scale mitochondrial DNA deletion at 7117-13994, leading to a diagnosis of mitochondrial DNA deletion syndrome associated with insulin-dependent DM. Although the frequency of DM in pediatric mitochondrial disease is low, mitochondrial disease, especially due to mitochondrial DNA deletion, should be considered as a differential diagnosis in those with insulin-dependent DM without autoimmune antibodies, and MRI and MR spectroscopy are recommended for an early diagnosis.