A review of the relationship between T1DM and major depressive disorder suggested that patients with T1DM have increased levels of cytokines IL‐4, IL‐6, IL‐10, and TNF‐α as a result of beta cell destruction and hyperglycemia, and that increased plasma IL‐6, IL‐1, and TNF‐α induce symptoms associated with major depressive disorder [28]. This evidence concerns the gene TNF and major depressive disorder.