Low blood glucose concentrations early postpartum are associated with low blood insulin concentrations, postpartum metabolic disorders, and infertility. The hypothesis was that short-term feeding of a rumen protected carbohydrate (RPC; 56% soybean meal, 40% soluble carbohydrates, 3.2% urea, and 0.8% minerals) would increase blood insulin concentrations by increasing glucose supply from the gastrointestinal tract. Lactating dairy cows (4 Holstein and 1 Guernsey; 17 ± 2 DIM; 30.9 ± 4.6 kg milk and 13.7 ± 2.6 kg DMI per day) were jugular catheterized, barn housed, and milked 2×. During the first 24 h (d 1), cows were fed a nutritionally balanced TMR (corn silage, haylage, wet brewer grains, dry corn, alfalfa hay, rumen protected and unprotected soybean meal, soyhulls, and premix). After 24 h (d 2, 3, and 4), cows were fed the TMR with the RPC added at 10% of diet DM. On d 5, cows were switched to control TMR. Blood was sampled every 2 h for d 1 to 5 through a jugular catheter. Plasma was isolated and analyzed for insulin, glucose, β-hydroxybutyrate (BHB) and nonesterified fatty acids (NEFA). Data were analyzed for the effects of day, time, and day by time with cow as a random effect (Proc GLM of SAS). There was an effect of day (P < 0.001) on plasma insulin concentrations (0.23, 0.24, 0.31, 0.40, and 0.36 ng/mL; SEM = 0.027; d 1 to 5, respectively). The increase in blood insulin was associated with a decrease in plasma glucose (54.4, 55.7, 51.0, 50.9, and 51.3 mg/dL; SEM = 0.7; d 1 to 5) and an increase (P < 0.001) in plasma BHB (1.64, 1.78, 2.01, 2.19, and 1.97 mmol/L; SEM = 0.06; d 1 to 5; P < 0.001). There was no effect of day on plasma NEFA but there was an effect of time (P < 0.001). Milk produced and DMI were similar (P > 0.10) for d 1 to 5. In conclusion, short-term feeding of the RPC increased blood insulin concentrations. The increase in blood insulin was associated with a decrease in blood glucose and an increase in BHB. Feeding RPC to early postpartum dairy cows effectively alleviated depressed insulin and shifted associated metabolite concentrations.