NUR 239 Lecture Notes - Lecture 23: Diabetes Mellitus Type 2, Circadian Rhythm, Insulin Resistance

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NUR 239/Pathophysiology and Pharmacotherapeutics in Nursing I
Unit 5/Porth Chapters 33 and Frandsen 41
Complete the following study guide and submit on Reggie Net by the due date on the Course Calendar
Key Terms (Porth Chapter 33) Diabetes Mellitus and the Metabolic Syndrome - define the following terms:
Insulin resistance: The diminished ability of cells to respond to the action of insulin transporting glucose
(sugar) from the bloodstream into muscle and other tissues. Insulin resistance typically develops with
obesity and heralds the onset of type 2 diabetes.
Metabolic Syndrome: Cluster of biochemical and physiological abnormalities associated with the
development of CV Disease and Type 2 diabetes.
Type 2 Diabetes: Long-term metabolic disorder that is characterized by high blood sugar, insulin
resistance, and relative lack of insulin. Common symptoms include polyuria, polydipsia, and
unexplained weight loss.
Glycogen: Excess glucose stored in the liver and skeletal muscles and is used as an energy reserve
Glycogenolysis: Process used by the cells to convert glycogen (stored glucose) into glucose- this occurs
when the body doesn’t have enough circulating blood glucose from carb ingestion.
Gluconeogenesis: Process the liver uses to convert amino acids and fats into glucose; fats come from
stored adipose tissue broken down into fatty acids and glycerol.
o The glycerol is used but the fatty acids accumulate in the blood and are converted to ketones
(DKA)
o High levels of ketones in the blood can affect the brain causing poor concentration, confusion,
and disorientation
o The brain can only use glucose - Low levels of blood glucose result in hypoglycemia.
o High ketones leads to ketoacidosis resulting in fruity odor detected in the saliva, breath and
sweat.
Glucagon: produced by the alpha cells in the pancreas, helps maintain blood glucose between meals and
during times of fasting
Counterregulatory Hormones: Hormones that can affect blood glucose include catecholamines
(epinephrine), growth hormones, and glucocorticoids are called counterregulatory hormones.
DKA: Characterized by hyperglycemia, ketosis, and metabolic acidosis, an acute life-threatening
complication of uncontrolled diabetes
Somogyi Effect: A cycle of insulin induced post-hypoglycemic episodes. In people with diabetes,
insulin induced hypoglycemia produces a compensatory increase in blood levels of catecholamines,
glucagon, cortisol, and growth hormone. These counter-regulatory hormones cause blood glucose to
become elevated and produce some degree of insulin resistance. The hypoglycemic episode may occur
at night.
Dawn Phenomenon: Increased levels of fasting blood glucose or insulin requirement between 5 and 9
am without antecedent hypoglycemia. Occurs in both type 1 and type 2 DM. Possible contributing
factors are changes in the circadian rhythm is altered in people with DM and growth hormone. A change
in the circadian rhythm for glucose tolerance and an inappropriate increase in counter-regulatory
hormones can lead to the dawn phenomenon in DM patients.
Key Learning Objectives - Answer the follow questions (Porth Chapter 33 Diabetes Mellitus and the
Metabolic Syndrome):
Names the two types of tissue in the pancreas (p. 794).
o Acini and islets of Langerhans. The acini secrete digestive juices into the duodenum, whereas the
islets of Langerhans, which account for only 1-2% of the volume of the pancreas, secrete
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NUR 239/Pathophysiology and Pharmacotherapeutics in Nursing I
Unit 5/Porth Chapters 33 and Frandsen 41
Complete the following study guide and submit on Reggie Net by the due date on the Course Calendar
hormones into the blood. Each islet is composed of beta cells that secrete insulin and amylin,
alpha cells that secrete glucagon, and delta cells that secrete somatostatin.
Describe the actions of Insulin.
o Insulin is the only hormone known to have a direct effect in lowering blood glucose levels. The
actions of insulin are three-fold: 1) promotes glucose uptake by target cells and provides for
glucose storage as glycogen, 2) prevents fat and glycogen breakdown, 3) inhibits
gluconeogenesis and increase protein synthesis.
See Table 33-1 (p. 795), describe the actions of Insulin on glucose, fats, and proteins. Describe the
actions of Glucagon on glucose, fats, and proteins.
o Glucose promotes glycogen breakdown and increases gluconeogenesis. It activates adipose cell
lipase, making increased amounts of fatty acids available to the body for use as energy. It also
increases amino acid uptake (protein) by liver cells and their conversion to glucose by
gluconeogenesis.
Name the Counterregulatory hormones and describe what they do.
o They counteract the storage functions of insulin in regulating blood glucose levels during periods
of fasting, exercise, and other situations that either limit glucose intake or deplete glucose stores.
Epinephrine: Catecholamine that helps to maintain blood glucose levels during periods of
stress. It has the potent effect of stimulating glycogenolysis in the liver, thus causing
large quantities of glucose to be released into the blood. It inhibits insulin release from
the beta cells and decreases the movement of glucose into muscle cells, while at the same
time increasing the breakdown of muscle glycogen stores.
Growth Hormone: Has many metabolic effects; increases protein synthesis in all cells of
the body, metabolizes fatty acids from adipose tissue, and antagonizes the effects of
insulin. It decreases cellular uptake and use of glucose, thereby increasing the level of
glucose. The increased blood glucose level stimulates further insulin secretion by the beta
cells. The secretion of growth hormone normally is inhibited by insulin and increased
levels of blood glucose. During periods of fasting, when both blood glucose levels and
insulin secretion fall, growth hormone levels increase. Exercise, such as running and
cycling, various stresses, including anesthesia, fever, and trauma, also increase growth
hormone levels.
Glucocorticoid Hormone: Glucocorticoid hormones are synthesized in the adrenal cortex
along with other corticosteroid hormones, are critical to survival during periods of fasting
and starvation. They stimulate gluconeogenesis by the live, sometimes producing a 6- to
10-fold increase in hepatic glucose production. They also moderately decrease tissue use
of glucose. There are several steroid hormones with glucocorticoid activity; the most
important of these is cortisol, which accounts for apx. 95% of all glucocorticoid activity.
What is the relationship between stress and cortisol (p. 799)?
o Almost any type of stress (physical or emotional) causes an immediate increase in
adrenocorticotropic hormone (ACTH) secretion by the anterior pituitary gland, followed within
minutes by greatly increased secretion of cortisol by the adrenal gland.
Describe the differences between type 1 and type 2 diabetes.
o Type 1: Characterized by destruction of the pancreatic beta cells; accounts for 5-10% of those
with diabetes, subdivided into type 1A immune-mediated diabetes & type 1B idiopathic (non-
immune related) diabetes.
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Document Summary

Key terms (porth chapter 33) diabetes mellitus and the metabolic syndrome - define the following terms: Insulin resistance: the diminished ability of cells to respond to the action of insulin transporting glucose (sugar) from the bloodstream into muscle and other tissues. In people with diabetes, insulin induced hypoglycemia produces a compensatory increase in blood levels of catecholamines, glucagon, cortisol, and growth hormone. These counter-regulatory hormones cause blood glucose to become elevated and produce some degree of insulin resistance. The hypoglycemic episode may occur at night: dawn phenomenon: increased levels of fasting blood glucose or insulin requirement between 5 and 9 am without antecedent hypoglycemia. Occurs in both type 1 and type 2 dm. Possible contributing factors are changes in the circadian rhythm is altered in people with dm and growth hormone. A change in the circadian rhythm for glucose tolerance and an inappropriate increase in counter-regulatory hormones can lead to the dawn phenomenon in dm patients.

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