Ten untreated type II (non-insulin-dependent) diabetic subjects were given 15, 25, 35, and 50 g glucose orally. Plasma glucose, insulin, C-peptide, glucagon, urea nitrogen, α-amino acid nitrogen, and lactate concentrations were measured, and net 5-h postprandial areas were calculated. The net glucose-area response to the ingested glucose dose (with the 0-time value as a constant baseline) was best described by a second-order polynomial equation, whereas insulin-area response was best described by a third-order equation. In a separate study, 5 untreated type II diabetic subjects were given only water, and the same metabolites and hormones were measured. Data from this study indicated that the baseline was not constant during the 5 h of study but decreased progressively. The net glucose-area and insulin-area responses to ingested glucose dose (with the decreasing baseline) were then best described by third-order equations. Glucagon, α-amino acid nitrogen, and lactate concentrations were exquisitely sensitive to a rise in glucose and insulin concentrations. These were all decreased with the lowest concentration of glucose used. At this dose of glucose, the increase of insulin was only 15 μU/ml.