Point-of-care Glucose Detection for Diabetic Monitoring and Management

Sandeep Kumar Vashist, John H.T Luong

• Publisher: CRC Press
• Year: 2017
• ISBN:
  9781315349183
• Edition: 1
• Topic: Medicine
• Subtopic: Public Health, Administration & Care

This book unravels the role of Point-of-Care (POC) glucose monitoring as an essential part of diabetes management. It provides the reader with an in-depth knowledge and understanding of diabetes management, including:

• the need for POC glucose monitoring

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• the glucose detection technologies (invasive, noninvasive and continuous) being used in the POC devices

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• the analytical performance, characteristics, pros and cons of the POC devices developed to date

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• the importance and role of glycated hemoglobin (HbA1c) monitoring for diabetes management

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• the various POC devices and analyzers for the determination of HbA1c.

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This is the first book to provide complete up-to-date information on POC glucose detection technologies and devices for diabetic monitoring and management. It will be an important reference for healthcare professionals, biomedical engineers, researchers, economists and policy makers. This book also serves as an asset and teaching aid for professionals and researchers in diabetic monitoring and management.

CHAPTER 1

Diabetes: a growing epidemic and the need for point-of-care testing

Sandeep Kumar Vashist and John HT Luong

CHAPTER SUMMARY

Diabetes has been declared as a global epidemic and emergency by the International Diabetes Federation (IDF), as the current incidence level has surpassed all previously projected numbers. Indeed, it has reached a catastrophic level, which substantiates the need for all essential steps for more effective diagnosis, monitoring, and management. The diabetic patient needs to perform continual monitoring of blood glucose, followed by intervention and management to cope with this disease. Ideally, the current high cost of consumables and miniaturised blood glucose meters (BGMs) must be reduced significantly, particularly for patients in developing nations. Continuous glucose monitoring systems offer the potential for real-time monitoring of glucose levels. However, current non-invasive glucose monitoring (NGM) technologies have not matched the desired clinical accuracy to replace the BGM. Together with advanced optical methods, the ongoing trend towards smartphone-based mobile healthcare is further facilitating the monitoring of physical activity and basic healthcare parameters, which contributes to the prevention, or delays the onset, of this debilitating disease.

Keywords: diabetes; glucose; point-of-care testing; blood glucose meters; non-invasive glucose monitoring devices; continuous glucose monitoring systems.

CONTENTS

Introduction

Glucose and insulin relationship

Diabetes: Facts and figures

Point-of-care glucose monitoring

Other short-term glycaemic indicators

Conclusions

References

INTRODUCTION

Diabetes is a global emergency and the topmost concern for governments and public health authorities worldwide.¹ The unprecedented increasing incidence during the last decade together with the unsustainable economic burden substantiates the need for taking all essential measures to suppress its further growth. In general, insulin deficiency and its associated glucose disorder can be attributed to diabetic consequences. A total lack of insulin is referred to as type 1 diabetes, which was formerly called juvenile onset or insulin-dependent diabetes. Endocrine pancreas cells, spreading over the pancreas surface like small islands, produce insulin, glucagon, and other hormones. They are known as islets of Langerhans, after the pathologist who discovered these islet cells. In type 1, the body’s immune system destroys the islet, which eventually eliminates the synthesis of insulin. Thus, cells cannot absorb sugar (glucose), which they need to produce energy. Type 1 might account for 5 to 10 out of 100 diabetic patients. In type 2 diabetes, the level of insulin is low or the patients cannot use insulin effectively, and this accounts for the vast majority of people who have diabetes, 90–95%. As type 2 diabetes progresses, the pancreas may make less and less insulin; that is, insulin deficiency, whereas insulin resistance is referred to as the state where the body is unable to use insulin. Type 2 diabetes (adult onset or non-insulin-dependent diabetes) can develop at any age but becomes more apparent during adulthood. However, an increasing number of children are being diagnosed with the disease. Type 1 cannot be prevented, while type 2 can be prevented or delayed with a healthy diet and physical activity. Even with proper treatment, diabetes remains the leading cause of blindness and kidney failure, a critical risk factor for heart disease, stroke, and foot or leg amputations. There is a severe form of diabetes, known as brittle diabetes, which is characterised by increasing and decreasing blood sugar levels at rapid rates. Brittle diabetes is almost exclusive to type 1 diabetes (also called a subtype of type 1 or diabetes complication); however, people with type 2 diabetes are not immune to this glucose fluctuation.

Point-of-care testing (POCT) is the only option for diabetics to check their blood glucose levels and fluctuation. Patients can then keep their blood glucose levels within the desired physiological range by dietary and healthcare interventions. Otherwise, subsequent life-threating diabetic complications are unavoidable, which account for significant healthcare costs. A wide range of POC glucose monitoring devices has been developed such as BGMs, NGM devices and CGMS. The most widely used devices are the BGMs, while CGMS are more appropriate for those who require continuous glucose monitoring (CGM). Although various NGM devices and concepts have been developed, a clinically precise and robust NGM device has not been achieved so far. This chapter provides an overview of diabetes and the POCT of glucose.

GLUCOSE AND INSULIN RELATIONSHIP

Human beings require about 160–200 g of glucose per day as an energy source for cellular metabolism and brain functions. Indeed, two-thirds of glucose (about 100–130 g) is specifically needed by the brain to cover its high energy requirements. As a dense network of neurons, or nerve cells, which are constantly active, the brain depends on a continuous supply of glucose from the bloodstream. After food ingestion, glucose is absorbed and released into the bloodstream by the small intestine and the stomach. Glucose per se cannot penetrate into the cells directly and thus circulates in the bloodstream. Beta cells, the predominant type of cells in the islets of Langerhans, are sensitive to glucose levels and regulate the pancreas to release insulin, corresponding to the blood glucose level. Insulin is then secreted into the blood where it travels throughout the body and helps regulate blood sugar. Beta cells also secrete amylin and C-peptide together with insulin. Thus, beta cells in the pancreas play three important tasks: producing, storing and releasing the hormone insulin. Insulin attaches itself to the insulin receptor (IR), a transmembrane receptor, resulting in an ‘open’ channel that allows the passage of glucose. The IR belongs to the large class of tyrosine kinase receptors and is activated by insulin and free insulin-like growth factors (IGF-I and IGF-II). A ‘substrate’ protein that is phosphorylated by the insulin receptor is known as IRS-1 (insulin receptor substrate 1). IRS-1 binding and phosphorylation lead to an increase in the high-affinity glucose transporter (Glut4) molecules on the outer membrane of insulin-responsive tissues, including muscle cells and adipose tissue. Glut4 is transported from cellular vesicles to the cell surface, where it then can mediate the transport of glucose into the cell. Indeed, insulin plays three important roles: (i) it helps muscle, fat, and liver cells absorb glucose from the bloodstream, lowering blood glucose levels, (ii) it stimulates the liver and muscle tissue to store excess glucose as glycogen, and (iii) it lowers blood glucose levels by reducing glucose production in the liver.

Insulin is a peptide, consisting of 51 amino acids in two peptide chains. Preproinsulin is the primary translational product of the insulin gene, a biologically inactive precursor of insulin. This 110 amino acid peptide is converted into proinsulin by signal peptidases, which remove its signal peptide from its N-terminus. Proinsulin is then converted into the bioactive hormone insulin by removal of the C-peptide. In addition, amylin, a 37 residue peptide hormone, is co-secreted with insulin (1:100 ratio) from the pancreatic beta cells, which are also deficient in diabetic people. Amylin inhibits glucagon secretion, delays gastric emptying and acts as a satiety agent. It acts as a short-term regulator of blood glucose level by diminishing the rate of glucose entering the bloodstream. The C-peptide helps to prevent neuropathy and other vascular complications by assisting in the repair of the arterial muscular layers. Insulin stimulates glycogen synthesis and inhibits glycogen breakdown.

In contrast, glucagon, a peptide hormone produced by alpha cells of the pancreas, raises the concentration of glucose in the bloodstream. Its effect is opposite to that of insulin, which lowers the glucose. The pancreas A cells release glucagon when the concentration of glucose in the bloodstream falls too low. Glucagon binds to the glucagon receptors of the liver and causes it to convert stored glycogen, which is released into the bloodstream. Thus, glucagon and insulin are part of a feedback system that keeps blood glucose levels at a stable level (Fig. 1.1).

About 5% of people, particularly children and young adults, have type 1 diabetes as their bodies cannot produce insulin because their body’s immune system (i.e. white blood cells called T cells) attacks and destroys the beta cells. Unfortunately, type 1 diabetes is not diagnosed until all beta cells have already been destroye...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Table of Contents
• Preface
• Contributors
• 1 Diabetes: a growing epidemic and the need for point-of-care testing
• 2 Blood glucose monitoring devices
• 3 Non-invasive analytics for point-of-care testing of glucose
• 4 Continuous glucose monitoring systems
• 5 Glycated haemoglobin (HbA1c) monitoring for diabetes diagnosis, management and therapy
• 6 Diabetes management software and smart applications
• 7 Performance requirements, analytical accuracy and clinical accuracy of self-monitoring of blood glucose: a clinical perspective
• 8 Concluding remarks
• Index