This study evaluated the effect of meal ingestion on intraperitoneal insulin absorption in type I diabetic patients with an implanted pump for long-term intraperitoneal insulin delivery. On four separate occasions, patients (n = 7) were administered 15 IU insulin as a 20-minute square-wave infusion using their implanted device; hypoglycemia was prevented by intravenous infusion of 10% dextrose at a variable rate. Two studies were performed during fasting conditions (n = 2 fasting tests) and two studies after the administration of an 800-kcal standard meal (n = 2 postprandial tests). An insulin peak of 630 +/- 545.4 pmol/L (mean +/- SD) in fasting tests and 696 +/- 420.5 pmol/L in postprandial tests was reached in the peripheral circulation after 45 +/- 11.7 and 45 +/- 14.7 minutes, respectively, with no significant difference between the two experimental conditions. Areas under the insulin curves were not significantly different in fasting and postprandial tests (51,500 +/- 34,278 v 50,916 +/- 20,558 pmol/L.min-1, respectively; NS). In type I diabetic patients receiving long-term intraperitoneal insulin therapy, the increase in splanchnic blood flow following ingestion of a standard meal does not accelerate the appearance of insulin in the peripheral circulation.