Maternal immunization with oxidized lipoproteins prior to pregnancy protects against atherogenic in utero programming by gestational hypercholesterolemia and enhances beneficial lymphocyte-dependent immune responses in offspring. To determine whether in utero programming and immunomodulation also affect insulin resistance (IR) and type 2 diabetes, we investigated the effects of immunization on glucose and insulin responses in LDL receptor-deficient mice fed regular or 60% sucrose diets, as well as in offspring fed 0.5% cholesterol or 60% sucrose diets. IR was assessed by fasting glucose and insulin levels, oral glucose tolerance tests, glucose clamps, pancreatic immunohistochemistry and plasma free fatty acid concentrations. Immunizations improved glucose responses in both genders and protected both immunized mice and their offspring against IR and type 2 diabetes. Protection occurred even under euglycemic conditions, but was greatest in obese males exposed to very obesogenic/diabetogenic conditions. Hyperinsulinemic euglycemic clamps confirmed that maternal immunization protected mainly by reducing IR, but pancreatic immunocytochemistry also indicated some protection against beta cell damage. Maternal immunization was associated with marked regulation in offspring of 4 genes relevant to diabetes and 19 genes of importance for oxidative stress, as well as increased hepatic activities of key antioxidant enzymes. These findings establish that targeted immunomodulation may be used to protect immunized subjects and their offspring against IR and type 2 diabetes, and thus to reduce cardiovascular risk. They also support the notion that in utero programming influences offspring disease not by a single mechanism, but by multiple systemic effects.