Insulin therapy by insulin pump: continuous or conventional self-blood glucose monitoring?

Use of portable pumps is increasing to achieve intensive insulin treatment. Beside unpredictable insulin absorption and insufficient reactivity to changes of insulin flow rate due to the subcutaneous route, this therapy is however limited by the lack of information on blood glucose level provided by self-blood glucose monitoring. Thus, patient interpretation only leads to speculative adaptation of pump flow rate. The lack of alert toward the risk of hypoglycernia or hyperglycemic ketogenic deviations can lead to the occurrence of deleterious metabolic distorsions, among which severe hypoglycemia stands in first rank. Starting experiences of continuous recording of interstitial glucose level by portable systems using glucose-oxidase allow on short time durations the identification of daily periods of poor metabolic control. Retrospective availability of information gives the possibility of more adequate treatment adaptations than conventional capillary blood glucose monitoring, but does not allow immediate prevention of metabolic events. Only devices providing real time or near-real time information to the patient can fulfill this function. However, the absence of tight parallelism between variations of interstitial and blood glucose levels may lead to erroneous decisions. A true continuous real time information on blood glucose level on long-term seems only expectable from implantable glucose sensors. Still under investigation, these systems should be able to insure vigilance toward the risk of hypo- and hyperglycemia on weekly or monthly periods. Initially used as complementary to capillary self-monitoring, their reliability should allow their use as substitutes for conventional monitoring, except for measurements aimed at signal calibration. Pump control by the sensor signal is conceivable if it corresponds to a direct continuous, real time measurement of blood glucose, and subject to a simultaneous improvement of insulin infusion modes.