GLUCOSE CLAMPS WITH THE BIOSTATOR - A CRITICAL REAPPRAISAL

The Biostator makes it possible to perform glucose clamp experiments a lmost automatically Thus, blood glucose concentrations can be maintain ed at (or close to) a target level with substantially less effort than with the manual clamp technique. The automatisation also avoids a pot ential bias on the part of the investigator. However, as with the non- automated manual clamp technique, blood glucose concentrations do not remain exactly at the target value, as they show a considerable scatte r around the target value. This scatter is generated by the time const ants of the Biostator, i.e. the whole closed-loop system, and the auto regressive properties of the glucose clamp algorithm used. In order to describe the quality of glucose clamps over time more precisely, ''cu mulative sums'' as an alternative to the usual coefficient of variatio n can be used. Practical work with the Biostator is burdened with tech nical difficulties and considerable costs in comparison to the manual clamp technique. Deficits concerning data storage and presentation cap ability of the Biostator have been overcome by an appropriate programm e for an external computer. The use of the Biostator for the glucose c lamp technique is not mandatory, but, the use of this machine makes it possible to perform glucose clamp studies under standardised and repr oducible conditions.