The “Ulm Zucker Uhr System” and its Consequences

Summary

The “Ulm Zucker Uhr System” comprises a microdialysis probe, a biosensor (Glucosensor Unitec Ulm s.c.), a sender transferring telemetrically the glucose concentrations, and a receiving indicator. The “Zucker Uhr” or “Sugar Watch” looks and operates like a normal wrist watch. We now present the functioning pre-prototype of the first portable system, which

1) is continuously measuring in s.c. tissue the Tissue Glucose (T.G.) concentration in the intercellular fluid on-line enzymatically by combining an enzymatic and an electrochemical (amperometric) technique, 2) is transferring in the patient via the “Zucker Uhr” once per minute the actual tissue glucose concentration, i.e. 1,440 values/24 hours or even 2880 values/48 hours,

3) is actually alarming the patient by optical and acoustic means, when the tissue glucose is too high (hyperglycemia) or too low (hypoglycemia),

4) is storing digitally all values and, therefore, permitting the dialogue between doctor and patient as to his diabetes control in view of his 24 h glucose profile, which is visual on a computer screen.

The advantage for the patient is on the one hand the elimination of the multiple pricking in the finger tips for providing capillary blood, and on the other hand, permitting the preview of the limitation and perhaps the complete elimination of the microangiopathy of the retina, kidneys and nervous system. The trend of the T.G. decreases is readily recognizable, which indicates immediately the dangerous hypoglycemia. Likewise, over 48 hours, the hyperglycemic periods are transmitted and recorded which are not measured and reflected by the Hb_A1 a nd HbA_1c conventional measurements.

The three periods of development of the system are seen in

1) the providing of complete information as to the T.G. profile under conditions of daily life (on-line home monitoring), with ready warning before hypoglycemia, and at the same time permitting the complete control of the sugar metabolism actually and as documentation,

2) the partial regulation in the control of the insulin infusion via pumps by the sugar profile in the tissue, and

3) the complete glucose controlled insulin infusion in a portable device, which contains the sensor and the insulin pump.

Problems still exist regarding the self-implantable microdialysis probe and the provision of electrical energy, independent from the network for 24-48 hours, the calibration operated by the patient himself, and the miniaturization of the whole system.

Key-Words

Glucosensor - Artificial Pancreas - Tissue Glucose Home Monitoring - Hypoglycemia Awareness - Glucose Controlled Insulin Infusion - Type I Diabetes - Open and Closed Loop Systems