Children exposed to a maternal Western-style diet in utero have an increased risk of developing type 2 diabetes. Understanding the mechanisms and an investigation of possible interventions are critical to reversing this phenomenon. We examined the impact of maternal Western-style diet consumption on the development of islet vascularization and innervation, both critical to normal islet function, in fetal and juvenile offspring. Furthermore, we assessed whether improved dietary intake or resveratrol supplementation could ameliorate the harmful consequences of Western-style diet consumption during pregnancy. Adult female Japanese Macaques were maintained on a control or Western-style diet for 4-7 years. One cohort of dams was switched back onto a control diet while another cohort received resveratrol supplementation throughout gestation. Pregnancies were terminated in the early third trimester by C-section or offspring were born naturally and sent to necropsy at 1 year of age. Western-style diet consumption resulted in impaired fetal islet capillary density and sympathetic islet innervation. Furthermore, this reduction in vascularization persisted in the juvenile offspring. This effect is independent of changes in the expression of key angiogenic markers. Diet reversal normalized islet vascularization to control offspring levels while resveratrol supplementation caused a significant increase in capillary density above controls. These data provide a novel mechanism by which maternal Western-style diet consumption leads to increased susceptibility to type 2 diabetes in the offspring. Importantly, an improved maternal diet may mitigate these harmful effects. However, until the long-term consequences of increased vascularization can be determined, resveratrol use during pregnancy is not advised.