BACKGROUND: A complex interplay between genetic and environmental factors contributes to disease etiology of most of the autoimmune disorders. Type 1 diabetes mellitus (T1DM) and celiac disease (CD) are polygenic autoimmune diseases that have high propensity to coexist due to shared etiological factors like genetics and clinico-pathological overlaps. SUMMARY: The mean prevalence rate for coexistence of these diseases is 8%, and this value is a gross underestimation as reported from biopsy-proven symptomatic cases. The prevalence rate will rise when studies will excavate bottom layers of the "celiac iceberg" to detect potential and silent celiac cases. The concomitant presence of both these disorders is a complex situation immunologically as well as clinically. There is an accentuated breakdown of tolerance and proinflammatory cytokine storm that leads to the progression of organ-specific autoimmunity to systemic. No immunomodulating drugs are advocated as exogenous insulin supplementation and gluten exclusion are recommended for T1DM and CD respectively. Nevertheless, these pose certain challenges to both the clinicians and the patients, as gluten free diet (GFD) has been described to have an impact on glycemic control, bone health, and vascular complications. Also intermittent gluten intake by these patients due to non-compliance with GFD also stimulates the autoreactive immune cells that result in an augmented immune response. Key Messages: Large public health studies are needed to estimate the prevalence of all forms of CD in T1DM patients. Strict global guidelines need to be formulated for the disease management and prognosis, and there is also a need for an extensive research on each front to thoroughly understand the co-occurrence of these diseases.