C H A P T E R 3 8
Agents to control blood glucose levels
573
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
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
(
).
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.
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
INSULIN
insulin
SULFONYLUREAS AND OTHER
ORAL HYPOGLYCAEMIC
AGENTS
Sulfonylureas
glibenclamide
gliclazide
glimepiride
glipizide
Other oral hypoglycaemic
agents
Alpha-glucosidase
inhibitors
acarbose
Biguanide
metformin
Dipeptidyl peptidase-4
inhibitor
alogliptin
linagliptin
saxagliptin
sitagliptin
vildagliptin
Glucagon-like peptide 1
liraglutide
Incretin mimetic
exenatide
Sodium-glucose
co-transporter 2
canagliflozin
dapagliflozin
Thiazolidinediones
pioglitazone
rosiglitazone
GLUCOSE-ELEVATING AGENT
glucagon
