First clinical evaluation of a new long-term subconjunctival glucose sensor.

BACKGROUND To evaluate the feasibility of an implantable subconjunctival glucose monitoring system (SGMS) for glucose monitoring in humans, we investigated the in vivo performance of the sensor in a clinical trial with five patients. METHODS The new SGMS consists of an implantable ocular mini implant (OMI) and a hand-held fluorescence photometer. The implantable subconjunctival glucose sensor is composed of a fluorescence resonance energy transfer system based on Concanavalin A chemistry, embedded in a nelfilcon polymer hydrogel disk. Blood glucose changes in humans were induced by oral glucose intake and insulin injections. RESULTS The in vivo response of the new SGMS was tested in a first human clinical study with five diabetes patients. The OMI was well tolerated in the eyes of the patients. The SGMS exhibited high correlation coefficients (>0.88) with blood glucose changes and a good stability of the sensor response to glucose for the study period of 2 weeks. Lag times were in the range of 5-10 min. A total of 98% of all data pairs was in the clinical acceptable ranges A and B of the consensus error grid. CONCLUSIONS For the first time, the possibility to measure glucose in vivo in the subconjunctival interstitial fluid for a period of 2 weeks was demonstrated in a human clinical trial.