In this paper we have compared the postprandial increase in triglyceride (TG) rich lipoproteins of intestinal origin in 10 patients with noninsulin-dependent diabetes mellitus (NIDDM) and 10 subjects with normal glucose tolerance. The two groups were matched for age, sex distribution, body mass index, and plasma TG concentration. Breakfast was consumed at 0800 h and lunch at 1200 h, at which time vitamin A was also administered. Blood was sampled frequently from 1200 h to 2400 h, and measurements made of glucose, insulin, and TG concentrations. Furthermore, the retinyl palmitate (RP) content of plasma, the Sf > 400 lipoprotein fraction, and the Sf 20-400 lipoprotein fraction was also determined, and differences compared by two-way analysis of variance. Fasting and postprandial (from 1200 h to 2400 h) TG concentrations in the plasma and the two lipoprotein fractions were not significantly different in normal subjects and patients with NIDDM. In addition, the postprandial RP concentration of the two groups was not different in the chylomicron containing Sf > 400 lipoprotein fraction. However, the postprandial Sf 20-400 RP concentration was significantly higher (P < 0.001) in patients with NIDDM, estimated as hourly values over time, peak value, or total integrated response area. Significant correlation coefficients (r = 0.60-0.75, P < 0.08 < 0.02) were seen in patients with NIDDM between the total integrated insulin response and both the TG and RP responses in the Sf > 400 and Sf 20-400 fractions. In addition, fasting high density lipoprotein-cholesterol concentration in patients with NIDDM was significantly correlated with the postprandial TG response in the Sf > 400 (r = -0.64, P < 0.05) and the Sf 20-400 (r = -0.68, P < 0.05) lipoprotein fractions. In summary, the postprandial RP concentration in the Sf 20-400 lipoprotein fraction was higher than normal in patients with NIDDM. In addition, associations have been defined in patients with NIDDM between postprandial insulin response, fasting TG and high density lipoprotein-cholesterol concentrations, and magnitude of postprandial increase in TG-rich lipoproteins of intestinal origin.