Insulin-dependent type-1 diabetes (T1D) is driven by autoimmune beta-cell failure, whereas systemic resistance to insulin is considered the hallmark of insulin-independent type-2 diabetes (T2D). In contrast to this canonical dichotomy, insulin resistance appears to precede the overt diabetic stage of T1D and to predict its progression, implying that insulin sensitizers may change the course of T1D. However, previous attempts to ameliorate T1D in animal models or patients by insulin sensitizers have largely failed. Sensitization to insulin by MEthyl-substituted long-chain DICArboxylic acid (MEDICA) analogs in T2D animal models surpasses that of current insulin sensitizers, thus prompting our interest in probing MEDICA in the T1D context. MEDICA efficacy in modulating the course of T1D was verified in streptozotocin (STZ) diabetic rats and autoimmune non-obese diabetic (NOD) mice. MEDICA treatment normalizes overt diabetes in STZ diabetic rats when added-on to sub-therapeutic insulin, and prevents / delays autoimmune T1D in NOD mice. MEDICA treatment does not improve beta-cell insulin content or insulitis score, but its efficacy is accounted for by pronounced total body sensitization to insulin. In conclusion, potent insulin sensitizers may counteract genetic predisposition to autoimmune T1D, and amplify sub-therapeutic insulin into an effective therapeutic measure for the treatment of overt T1D.