A stepwise approach toward closed-loop blood glucose control for intensive care unit patients: results from a feasibility study in type 1 diabetic subjects using vascular microdialysis with infrared spectrometry and a model predictive control algorithm

Accuracy and stability of an arterial sensor for glucose monitoring in a porcine model using glucose clamp technique

Intravascular glucose sensors have the potential to improve and facilitate glycemic control in critically ill patients and might overcome measurement delay and accuracy issues. This study investigated the accuracy and stability of a biosensor for arterial glucose monitoring tested in a hypo- and hyperglycemic clamp experiment in pigs. 12 sensors were tested over 5 consecutive days in 6 different pigs. Samples of sensor and reference measurement pairs were obtained every 15 minutes. 1337 pairs of glucose values (range 37–458 mg/dl) were available for analysis. The systems met ISO 15197:2013 criteria in 99.2% in total, 100% for glucose <100 mg/dl (n = 414) and 98.8% for glucose ≥100 mg/dl (n = 923). The mean absolute relative difference (MARD) during the entire glycemic range of all sensors was 4.3%. The MARDs within the hypoglycemic (<70 mg/dl), euglycemic (≥70–180 mg/dl) and hyperglycemic glucose ranges (≥180 mg/dl) were 6.1%, 3.6% and 4.7%, respectively. Sensors indicated comparable performance on all days investigated (day 1, 3 and 5). None of the systems showed premature failures. In a porcine model, the performance of the biosensor revealed a promising performance. The transfer of these results into a human setting is the logical next step.

Diabetes Mellitus and Sepsis: A Challenging Association

Sepsis is a life-threatening organ dysfunction caused by a deregulated host response to infection. This inappropriate response to micro-organism invasion is characterized by an overwhelmed systemic inflammatory response and cardiovascular collapse that culminate in high mortality and morbidity in critical care units. The occurrence of sepsis in diabetes mellitus (DM) patients has become more frequent, as the prevalence of DM has increased dramatically worldwide. These two important diseases represent a global public health concern and highlight the importance of increasing our knowledge of the key elements of the immune response related to both conditions. In this context, it is well established that the cells taking part in the innate and adaptive immune responses in diabetic patients have compromised function. These altered responses favor micro-organism growth, a process that contributes to sepsis progression. The present review provides an update on the characteristics of the immune system in diabetic and septic subjects. We also explore the beneficial effects of insulin on the immune response in a glycemic control-dependent and independent manner.

Optimal blood glucose control in severely burned patients: a long way to go, but one step closer

Over the past years there has been a significant decrease in mortality and morbidity in patients suffering from severe burns due to improved burn wound management and approaches in critical care. Survival is no longer the exception, but unfortunately death still occurs. One of the key elements concerning state-of-the-art burn care is blood glucose control and insulin therapy; it is well known that burn-induced hyperglycaemia is associated with adverse clinical outcomes. However, controversy for insulin therapy and tight glycaemic control in critically ill and burn patients exists. The increased incidence of hypoglycaemia is the dominant argument against this treatment, because hypoglycaemia is also associated with an increased risk for death in critically ill patients. Taking all current data together, insulin therapy appears both a friend and a foe in the treatment of ICU patients. In order to overcome the limits of tight glycaemic control resulting from hypoglycaemic episodes, current efforts have been directed towards the development of protocols allowing for implementation of clinically feasible and safe guidelines. Among the strategies addressing this problem are closed loop techniques, which are supported by studies demonstrating their capability of exerting tight glycaemic control without the risk of developing hypoglycaemic episodes. Although closed loop techniques have become readily available, we require further evidence to ensure their safety in various ICU environments, notably in ICUs dealing with burn patients. Nonetheless, it is important to emphasise that glycaemic control and adequate insulin therapy are crucial factors for the final outcome (survival) and require our attention.

Microdialysis--a versatile technology to perform metabolic monitoring in diabetes and critically ill patients

Continuous subcutaneous glucose monitoring has been tested in type 1 diabetes (T1D). Since in critically ill patients vascular access is granted vascular microdialysis may be preferential. To test this hypothesis comparative accuracy data for microdialysis applied for peripheral venous and subcutaneous glucose monitoring was obtained in experiments in T1D patients. Twelve T1D patients were investigated for up to 30 h. Extracorporeal vascular (MDv) and subcutaneous microdialysis (MDs) was performed. Microdialysis samples were collected in 15-60 min intervals, analyzed for glucose and calibrated to reference. MDv and MDs glucose levels were compared against reference. Median absolute relative difference was 14.0 (5.0; 28.0)% (MDv) and 9.2 (4.4; 18.4)% (MDs). Clarke Error Grid analysis showed that 100% (MDv) and 98.8% (MDv) were within zones A and B. Extracorporeal vascular and standard subcutaneous microdialysis indicated similar performance in T1D. We suggest microdialysis as a versatile technology for metabolite monitoring in subcutaneous tissue and whole blood.