Type 1 Diabetes Mellitus (T1DM) is an autoimmune disorder characterized by the destruction of pancreatic β-cells, leading to significant endogenous insulin deficiency. In this context, inflammation plays a crucial role in the pathogenesis of the disease. Traditionally, insulin resistance has been associated with Type 2 Diabetes Mellitus (T2DM); however, recent studies have shown that it also occurs in a significant proportion of T1DM patients. Regarding the prevalence of Non-Alcoholic Fatty Liver Disease associated with metabolic dysfunction (MASLD), variations are observed depending on the studied population and diagnostic method used, although there has been a global increase in this condition in T1DM patients. MASLD is closely linked to insulin resistance, both hepatic and peripheral, suggesting that MASLD progression is associated with worsening insulin resistance. The relationship between both pathologies is bidirectional, as the presence of one can accelerate the progression of the other. When both coexist, the natural history of both diseases is altered, increasing the risk of complications and worsening patient prognosis.