Determination of Insulin Requirements in Brittle Diabetic Patients by the Artificial Pancreas

Abstract

An extracorporeal system (called the artificial pancreas) infused insulin and/or glucose at rates regulated by feedback control of the continuously monitored blood glucose. This system was capable of restoring the circadian blood glucose profile of 11 brittle diabetics to within a physiologic range. These patients made two stays of one week each in the hospital, during which the M-value and the MAGE index (used as indexes of blood glucose control and of glycemic fluctuations) were measured. The first stay was just before their connection to the artificial pancreas, while the patients were being given their usual insulin dosage; the second stay occurred one to nine months later. The day after connection of the artificial pancreas, the patients received a new insulin regimen, calculated according to the daily insulin profile infused by the artificial pancreas, consisting of two daily injections of a mixture of short-acting and intermediate-acting insulins. This regimen was essentially characterized by an increased proportion of regular insulin in the daily dose of from 31.2 ± 5.8 per cent (mean ± S.E.M.) before to 56.1 ± 3.0 per cent after artificial pancreas, p < 0.01, and a reduction of the percentage of the dose given in the morning of from 68.1 ± 5.9 to 52.6 ± 2.8 per cent, p < 0.025. These changes of insulin dosage caused a noticeable decrease of the M-value, from 69.5 ± 8 to 53.1 ± 4.4 (p < 0.02), but the MAGE index was not significantly affected (187 ± 20 versus 162 ± 14). Thus, the artificial pancreas could be helpful in the clinical management of brittle diabetics by providing a more precise estimate of the patient's insulin needs (particularly those of short-acting insulin), leading to a better control of blood glucose.