Assessment of skin permeability to topically applied drugs by skin impedance and admittance.

Objective: Pharmacokinetic and pharmacodynamic studies of topically applied drugs are commonly performed by sampling of interstitial fluid with dermal open flow microperfusion and subsequent analysis of the samples. However, the reliability of results from the measured concentration-time profile of the penetrating drug suffers from highly variable skin permeability to topically applied drugs that is mainly caused by inter- and intra-subject variations of the stratum corneum. Thus, statistically significant results can only be achieved by performing high numbers of experiments.

Monitoring tissue oxygen heterogeneities and their influence on optical glucose measurements in an animal model.

The purpose of this study was to characterize the heterogeneity of oxygen partial pressure in different adipose tissue zones and to assess the possibility of compensating these heterogeneities during optical glucose measurements. In this proof of concept study, the heterogeneity of oxygen partial pressure was determined in the adipose tissue of a pig by using 48 oxygen sensors in 3 zones of the abdominal region at two different blood oxygen levels. Sensor oxygen values correlated well with reference blood oxygen values and we identified heterogeneities in oxygen partial pressure among the defined zones of the abdominal region.

Evaluation of subcutaneous glucose monitoring systems under routine environmental conditions in patients with type 1 diabetes.

Continuous and flash glucose monitoring (GM) systems have been established in diabetes care. We compared the sensor performance of 3 commercially available GM systems. A total of 12 patients with type 1 diabetes were included in a single-centre, open-label study in which the sensor performance of the Abbott FreeStyle libre (Abbott), Dexcom G4 Platinum (Dexcom) and Medtronic MiniMed 640G (Medtronic) systems over 12 hours was compared during mimicked real-life conditions (meals, exercise, hypo- and hyperglycaemia).

First application of a transcutaneous optical single-port glucose monitoring device in patients with type 1 diabetes mellitus.

The combination of continuous glucose monitoring (CGM) and continuous subcutaneous insulin infusion can be used to improve the treatment of patients with diabetes. The aim of this study was to advance an existing preclinical single-port system for clinical application by integrating the sensors of a phosphorescence based CGM system into a standard insulin infusion set. The extracorporeal optical phase fluorimeter was miniaturised and is now comparable with commercial CGM systems regarding size, weight and wear comfort.

Integrated catheter system for continuous glucose measurement and simultaneous insulin infusion.

A new measurement system enables combination of continuous glucose monitoring (CGM) and insulin infusion. A sensor system comprising an optical glucose biosensor and an optical oxygen sensor is integrated into the insulin infusion catheter of an insulin pump. Both sensors rely on near infrared (NIR) phosphorescent porphyrin dyes, wherefore the signals can be read out transcutaneous and non-invasively with a custom-built phase fluorometer measurement module.