Can Glucose Be Monitored Accurately at the Site of Subcutaneous Insulin Delivery?

Abstract

Because insulin promotes glucose uptake into adipocytes, it has been assumed that during measurement of glucose at the site of insulin delivery, the local glucose level would be much lower than systemic glucose. However, recent investigations challenge this notion. What explanations could account for a reduced local effect of insulin in the subcutaneous space? One explanation is that, in humans, the effect of insulin on adipocytes appears to be small. Another is that insulin monomers and dimers (from hexamer disassociation) might be absorbed into the circulation before they can increase glucose uptake locally. In addition, negative cooperativity of insulin action (a lower than expected effect of very high insulin concentrations)may play a contributing role. Other factors to be considered include dilution of interstitial fluid by the insulin vehicle and the possibility that some of the local decline in glucose might be due to the systemic effect of insulin. With regard to future research, redundant sensing units might be able to quantify the effects of proximity, leading to a compensatory algorithm. In summary, when measured at the site of insulin delivery, the decline in subcutaneous glucose level appears to be minimal, though the literature base is not large. Findings thus far support (1) the development of integrated devices that monitor glucose and deliver insulin and (2) the use of such devices to investigate the relationship between subcutaneous delivery of insulin and its local effects on glucose. A reduction in the number of percutaneous devices needed to manage diabetes would be welcome.

Glucose Sensing Using Functionalized Amorphous In–Ga–Zn–O Field-Effect Transistors

“…Extremes in blood glucose levels can lead to major health issues, where high blood sugar (hyperglycemia) can cause complications such as macrovascular and kidney disease, and low blood sugar (hypoglycemia) can lead to seizures and loss of consciousness. , Glucose sensors are a critical component of an artificial pancreas and have been extensively studied over the past several decades. , For these applications the sensors need to be sensitive and reliable while measuring glucose concentrations over the normal physiological range (i.e., 2–30 mM in the interstitial fluid and 0.1–0.4 mM in tear fluid − ). The recent development of continuous glucose sensors allows real-time monitoring of sugar levels and continuous subcutaneous infusion of insulin/glucagon to assist in maintaining glycemic control. , …”

Emerging Technologies for Diabetes Care

“…Initial concerns that proximity of insulin infusion near tissues in which glucose sensing was performed have been largely mollified. 56 Questions concerning this remain, however, in regard to the impact of larger boluses or novel insulins.…”

An Amperometric Glucose Sensor Integrated into an Insulin Delivery Cannula: In Vitro and In Vivo Evaluation

“…However, our review of literature on this topic found that the magnitude of uptake into fat cells is almost certainly much less than the magnitude of insulininduced uptake into muscle cells. 21 The recent reports of several workers have been very instructive in understanding the quantitative aspects of this issue. These investigators, during their evaluation of the effect of local insulin on glucose measurement, found that this effect on glucose uptake was transient and minimal, no greater than about 15%.…”