A Case Report of Latent Autoimmune Diabetes Arising After Isotretinoin Treatment: Real Association or Coincidence? A Hypothesis on Pathophysiology

Background: Latent autoimmune diabetes in adults (LADA) is the most common form of adult-onset autoimmune diabetes. Isotretinoin is a very effective treatment for severe acne. There are various reports on the effect of isotretinoin on autoimmunity. We present a case of LADA, probably related to isotretinoin treatment. To the best of our knowledge, this case was the second case of LADA that occurred after isotretinoin treatment. Here we discuss a hypothesis on the pathophysiology of how isotretinoin can induce LADA. Case Presentation: A 55-year-old female was diagnosed with type 2 diabetes mellitus (T2DM) one month after the end of a nine-month isotretinoin treatment period. At the time of diagnosis, the patient’s fasting blood glucose level was 257 mg/dL and HbA1c level was 10.3%. Then, she was followed-up for T2DM for two years. Since the patient did not comply with classical T2DM characteristics and C-peptide level was 0.4 ng/ml (0.78-5.18), autoantibody test was performed. The patient was found positive for anti-glutamic acid decarboxylase antibody (>2000 IU/mL). Her oral antidiabetic drug treatment was discontinued and insulin degludec and insulin aspart therapy was started. Three months after this adjustment, HbA1c level decreased to 7.2%. Except 25-hydroxycholecalciferol which was low (10.9 ng/mL), all other laboratory parameters were within normal range. Conclusion: Isotretinoin is known to have some immunomodulating effects. There are some case reports on the relationship between isotretinoin and autoimmune diseases. The negative immune environment that developed due to the long-standing moderate-severe VitD deficiency may have taken a turn toward autoimmunity upon isotretinoin treatment. This hypothesis on how isotretinoin can cause autoimmune diabetes needs to be validated.