McKenna's Pharmacology for Nursing, 2e

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C H A P T E R 3 8 Agents to control blood glucose levels

sodium-glucose co-transporter 2 (SGLT2): protein that promotes reabsorption of glucose in the proximal tubule of the nephron sulfonylureas: oral hypoglycaemia agents used to stimulate the pancreas to release more insulin

Sodium-glucose co-transporter 2 canagliflozin dapagliflozin Thiazolidinediones

INSULIN insulin

Other oral hypoglycaemic agents Alpha-glucosidase inhibitors acarbose Biguanide metformin Dipeptidyl peptidase-4

linagliptin saxagliptin sitagliptin vildagliptin Glucagon-like peptide 1 liraglutide Incretin mimetic exenatide

SULFONYLUREAS AND OTHER ORAL HYPOGLYCAEMIC AGENTS Sulfonylureas glibenclamide gliclazide glimepiride glipizide

pioglitazone rosiglitazone

inhibitor alogliptin

GLUCOSE-ELEVATING AGENT glucagon

H ypoglycaemic agents, as the name implies, are used to treat diabetes mellitus , the most common of all met- abolic disorders. It is estimated that almost 1 million people in Australia have been diagnosed with diabetes mellitus, and there are many others not yet diagnosed. Furthermore, diabetes mellitus has been reported as three times more common in the Indigenous Austral- ian population than the non-Indigenous (AIHW, 2013). As a major problem that significantly impacts on the health of Australians, diabetes mellitus is one of the nine National Health Priority Areas identified by the Aus- tralian government. For more information on diabetes mellitus in Australia, see www.aihw.gov.au/diabetes. In New Zealand, the Ministry of Health has a big focus on diabetes prevention and active diabetes management, especially of type 2 diabetes, resulting in increased funding for diabetes services over the last few years (www.diabetes.org.nz). Diabetes mellitus is a complicated disorder that alters the metabolism of glucose, fats and proteins, affect- ing many end organs and causing numerous clinical complications. It is part of the metabolic syndrome, a collection of conditions that predispose to cardiovascu- lar disease (Chapter 46). Treatment of diabetes is aimed at tightly regulating the blood glucose level through diet and the use of insulin or other glucose-lowering drugs. Maintaining serum glucose within a therapeutic range is very important to the nervous system. The nerves in the central nervous system (CNS) receive glucose by dif- fusion. The presence of too much glucose, which is a large molecule, takes water into the CNS and can cause swelling and nerve instability. The presence of too little glucose results in less energy for the nerves to use to function and loss of cell membrane integrity. Maintain- ing a therapeutic glucose level is a complicated process that involves diet, exercise and drug management. At times, the blood glucose level is lowered too much, producing a state of hypoglycaemia. When this occurs, glucose-elevating agents need to be used to quickly return the serum glucose levels to a therapeutic range.

Considerations related to the use of insulin and other oral hypoglycaemic agents based on age are highlighted in Box 38.1. Nurses, midwives and diabetic educators play a major role in education and management for indi- viduals with diabetes and their families. GLUCOSE REGULATION Glucose is the leading energy source for the human body. Glucose is stored in the body for rapid release in times of stress. As a result, blood glucose levels can be readily maintained so that the neurons always receive a constant supply of glucose to function. The body’s control of glucose is intricately related to fat and protein metabolism, balancing energy conservation with energy consumption to maintain homeostasis in a variety of situ- ations. Many factors have an impact on this balance and the body’s ability to adapt and to maintain metabolism. Endocrine: Hormonal control of blood glucose The pancreas The pancreas is both an endocrine gland, producing hormones, and an exocrine gland, releasing sodium bicarbonate and pancreatic enzymes directly into the common bile duct to be released into the small intestine, where they neutralise the acid chyme from the stomach and aid digestion. The endocrine part of the pancreas produces hormones in collections of tissue called the islets of Langerhans. These islets contain endocrine cells that produce specific hormones. The alpha cells release glucagon in direct response to low blood glucose levels. The beta cells release insulin in direct response to high blood glucose levels. Delta cells produce somatostatin in response to very low blood glucose levels; somatostatin blocks the secretion of both insulin and glucagon. These hormones work together to maintain the blood glucose level within normal limits.