<i>Aim:</i> To determine the effects of simultaneously ingesting glucose and fat on postchallenge glycemia and lipidemia in 12 healthy young Japanese women. <i>Methods:</i> Three test trials were administered in a randomized crossover design: glucose (1 g/kg, G trial); fat cream (0.35 g/kg as fat; F trial); glucose + fat cream (GF trial). Blood samples were taken before and at 0.5, 1, 2, 4, and 6 h post-ingestion. <i>Results:</i> The GF trial's serum glucose peak value was lower than the G trial's, and its remnant lipoprotein-cholesterol (RLP-C) increase was less than the F trial's. The GF trial's apolipoprotein (Apo) B48 increase happened faster than the F trial's. The G and GF trials' insulinogenic index (I/G30) values were negatively correlated with the area under the curve (AUC) of glucose for 2 h. Fasting insulin level and HOMA-IR were positively (and QUICKI and I/G30 were negatively) correlated with the AUC of insulin for 2 h. The F and GF trials' fasting TG, RLP-C, ApoB48, and ApoC-III levels were positively correlated with the AUC of TG and RLP-C for 6 h. The fasting ApoB48 level predicted the AUC of ApoB48 for 6 h. <i>Conclusion:</i> The glucose peak was ameliorated by co-ingesting fat. I/G30 predicted an early postchallenge (0–2 h) glucose rise. The fasting insulin level, HOMA-IR, QUICKI, and I/G30 predicted an insulin rise. The RLP-C rise by fat ingestion was ameliorated by co-ingesting glucose. Fasting TG, RLP-C, ApoB48, and ApoC-III levels predicted postchallenge TG and RLP-C rises. The fasting ApoB48 level predicted postchallenge apoB48, i.e., a rise in intestinal lipoprotein.