Insulin responses to mixed meals: comparison of an artificial beta cell and normal beta cells

The peripheral glucose and free insulin levels seen following a mixed meal in six insulin-dependent diabetic patients whose insulin was administered by a glucose-controlled insulin infusion system (GCIIS) were compared to those of normal subjects who received the same mixed meal or who were given separately carbohydrate, protein, or fat in amounts equivalent to those contained in the mixed meal. Patients treated with the GCIIS achieved nearly normal glucose levels immediately after the mixed meal, but this was accompanied by marked hyperinsulinemia. In the period from 120 to 240 minutes after the start of the mixed meal, the GCIIS duplicates the insulin levels produced by the normal pancreas after a glucose meal and, with appropriate algorithm constants, closely approximates those seen after a mixed meal.