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Questions and Answers
What is the primary function of glucagon in the body?
What is the primary function of glucagon in the body?
Which cells in the pancreas secrete glucagon?
Which cells in the pancreas secrete glucagon?
What metabolic processes are promoted by glucagon to increase blood glucose levels?
What metabolic processes are promoted by glucagon to increase blood glucose levels?
Which of the following is NOT a criterion for diagnosing diabetes according to the American Diabetes Association?
Which of the following is NOT a criterion for diagnosing diabetes according to the American Diabetes Association?
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What primarily causes the insulin deficiency in Type 1A Diabetes Mellitus?
What primarily causes the insulin deficiency in Type 1A Diabetes Mellitus?
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Which factor is associated with the increasing rates of diabetes in youth?
Which factor is associated with the increasing rates of diabetes in youth?
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What is the primary consequence of the destruction of 80-90% of pancreatic beta cells?
What is the primary consequence of the destruction of 80-90% of pancreatic beta cells?
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Which environmental factor is NOT related to the risk of developing type 1A diabetes mellitus?
Which environmental factor is NOT related to the risk of developing type 1A diabetes mellitus?
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What happens to potassium levels in the presence of insulin deficiency?
What happens to potassium levels in the presence of insulin deficiency?
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What is the primary reason for osmotic diuresis in individuals with hyperglycemia?
What is the primary reason for osmotic diuresis in individuals with hyperglycemia?
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What is a consequence of insulin deficiency on fat metabolism?
What is a consequence of insulin deficiency on fat metabolism?
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Which of the following conditions is most likely associated with nonimmune-mediated Type 1B diabetes mellitus?
Which of the following conditions is most likely associated with nonimmune-mediated Type 1B diabetes mellitus?
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What role do alpha cells play in the context of reduced insulin secretion?
What role do alpha cells play in the context of reduced insulin secretion?
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What is the effect of decreased glucose uptake in cells due to insulin deficiency?
What is the effect of decreased glucose uptake in cells due to insulin deficiency?
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What mechanism leads to decreased glucose uptake into cells in insulin resistance?
What mechanism leads to decreased glucose uptake into cells in insulin resistance?
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What is a common lipid profile observed upon diagnosis in most type 2 diabetics?
What is a common lipid profile observed upon diagnosis in most type 2 diabetics?
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What is the result of nonenzymatic glycosylation in chronic hyperglycemia?
What is the result of nonenzymatic glycosylation in chronic hyperglycemia?
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What clinical indicator reflects average blood glucose levels over a period of 2 to 3 months?
What clinical indicator reflects average blood glucose levels over a period of 2 to 3 months?
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What can cause injury to beta cells in the pancreas in diabetes?
What can cause injury to beta cells in the pancreas in diabetes?
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What is the effect of capillary basement membrane thickening in diabetes?
What is the effect of capillary basement membrane thickening in diabetes?
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What is a consequence of increased capillary permeability in diabetes?
What is a consequence of increased capillary permeability in diabetes?
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What leads to increased glucagon secretion contributing to hyperglycemia?
What leads to increased glucagon secretion contributing to hyperglycemia?
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What is the relationship between obesity and the incidence of type 2 diabetes mellitus?
What is the relationship between obesity and the incidence of type 2 diabetes mellitus?
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Which ethnic group has the highest reported increase in incidence of type 2 diabetes mellitus?
Which ethnic group has the highest reported increase in incidence of type 2 diabetes mellitus?
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What condition is associated with a significant increase in the risk of developing type 2 diabetes mellitus?
What condition is associated with a significant increase in the risk of developing type 2 diabetes mellitus?
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What is hyperinsulinemia and its effect on insulin receptors?
What is hyperinsulinemia and its effect on insulin receptors?
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Which factor is NOT considered a part of metabolic syndrome?
Which factor is NOT considered a part of metabolic syndrome?
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How does genetics influence type 2 diabetes mellitus?
How does genetics influence type 2 diabetes mellitus?
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What age group is most commonly affected by type 2 diabetes mellitus?
What age group is most commonly affected by type 2 diabetes mellitus?
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What role do adipokines play in relation to insulin sensitivity?
What role do adipokines play in relation to insulin sensitivity?
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What is a consequence of the shunting of glucose to the polyol pathway in non-insulin dependent tissues?
What is a consequence of the shunting of glucose to the polyol pathway in non-insulin dependent tissues?
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Which of the following is primarily caused by retinal ischemia?
Which of the following is primarily caused by retinal ischemia?
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How does inappropriate activation of protein kinase C affect the body?
How does inappropriate activation of protein kinase C affect the body?
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What is a key factor in the formation of diabetic retinopathy?
What is a key factor in the formation of diabetic retinopathy?
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What leads to the formation of cataracts in the lens of the eyes?
What leads to the formation of cataracts in the lens of the eyes?
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Which mechanism is NOT related to microvascular disease effects caused by chronic hyperglycemia?
Which mechanism is NOT related to microvascular disease effects caused by chronic hyperglycemia?
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What effect does the production of oxygen free radicals have in tissues?
What effect does the production of oxygen free radicals have in tissues?
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Which of the following best describes a consequence of increased arterial smooth muscle proliferation?
Which of the following best describes a consequence of increased arterial smooth muscle proliferation?
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What is the first clinical sign of nephropathy?
What is the first clinical sign of nephropathy?
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Which consequence is associated with chronic renal failure (CRF)?
Which consequence is associated with chronic renal failure (CRF)?
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What is a risk factor that contributes to the development of atherosclerosis?
What is a risk factor that contributes to the development of atherosclerosis?
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Which of the following is a potential consequence of atherosclerosis?
Which of the following is a potential consequence of atherosclerosis?
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What is a primary mechanism of neuronal injury in neuropathies?
What is a primary mechanism of neuronal injury in neuropathies?
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Which symptom is most commonly associated with sensory neuropathies?
Which symptom is most commonly associated with sensory neuropathies?
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How does autonomic neuropathy typically manifest in patients?
How does autonomic neuropathy typically manifest in patients?
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What cellular event is involved in the damage to neurons in neuropathies?
What cellular event is involved in the damage to neurons in neuropathies?
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Study Notes
Pancreas: Endocrine vs. Exocrine
- Insulin is secreted by beta cells in the islets of Langerhans.
- Insulin functions to influence carbohydrate, lipid, and (partially) protein metabolism, primarily through anabolism.
- Insulin's half-life is very short, about 15 minutes.
Insulin Synthesis
- Insulin mRNA is initially translated as a single-chain precursor called preproinsulin.
- Removal of a peptide during insertion into the endoplasmic reticulum forms proinsulin.
- Proinsulin comprises an amino-terminal B chain, a carboxy-terminal A chain, and a connecting C peptide.
- Insulin is activated by removing the C peptide, leaving the bonded A and B chains.
- C-peptide levels are useful in measuring residual beta-cell function.
- Low C-peptide levels can help distinguish type 1 diabetes mellitus (T1DM) from type 2 diabetes mellitus (T2DM).
Insulin Secretion
- Increased glucose, amino acids, and fatty acids stimulate insulin secretion.
- Plasma glucose is the most potent trigger.
- High insulin levels inhibit further insulin release.
Action on Cells
- Insulin receptors are on the cell's plasma membrane.
- CNS neurons are largely independent, relying less on insulin for glucose uptake.
- Insulin receptors have two alpha subunits and two beta subunits, with the beta subunits possessing tyrosine kinase activity.
- Insulin binds to its receptor and stimulates the activation of intracellular enzymes (e.g., protein kinase B and MAP kinase).
- Insulin directly stimulates glucose uptake via the tyrosine kinase pathway, with glucose transporter proteins (GLUT4) required for facilitated diffusion.
- Glucose is a large molecule, requiring facilitated diffusion into cells.
General Physiological Effects
- Insulin controls postprandial plasma glucose and inhibits glucose-producing pathways.
- Insulin promotes glucose storage as glycogen, which has a lowered osmotic pressure to prevent cell swelling.
- Insulin helps in the synthesis of fatty acids and triglycerides, and the transport of amino acids, promoting protein synthesis and cell growth.
Glucagon
- Glucagon is a peptide hormone produced by alpha cells in the pancreas.
- Glucagon release is stimulated by decreased plasma glucose levels.
- Glucagon increases blood glucose by promoting glycogenolysis and gluconeogenesis; it also promotes lipolysis and ketogenesis.
- Glucagon is an insulin antagonist.
Diabetes Mellitus
- Diabetes mellitus is a group of metabolic disorders characterized by chronic glucose intolerance, alterations in insulin activity, and alterations in protein and lipid metabolism.
Epidemiology of Diabetes
- Risk of diabetes is higher among certain racial and ethnic groups (American Indians/Alaska Natives, non-Hispanic blacks, Hispanics).
- Risk is also influenced by education level (an indicator of socioeconomic status).
Type 1 Diabetes Mellitus
- Characterized by absolute insulin deficiency due to beta-cell destruction.
- Mainly autoimmune-mediated (Type 1A) in which autoantibodies and cytotoxic T cells target beta cells, followed by a loss of 80-90% of the beta cells.
- Type 1B may arise from non-immune mechanisms.
- Genetics and environmental factors, such as viruses, can contribute.
Type 2 Diabetes Mellitus (T2DM)
- Risk factors include genetics, obesity (BMI > 30), age > 40, and certain ethnicities (American Indian, Hispanic or Latino, Pacific Islander, and Black populations).
- Approximately 80-90% of adults with T2DM have a BMI of greater than or equal to 25.
- T2DM is linked to obesity through a ten-fold increase in incidence related to obesity.
- Truncal obesity is strongly associated with T2DM development.
- Also includes central obesity, high blood pressure (HTN), elevated blood fats, high serum triglyceride levels, and low HDL.
Pathophysiology of T2DM
- High-calorie diets, notably high carbohydrate and sugar intake, result in increased insulin secretion (hyperinsulinemia).
- Persistent high insulin levels lead to downregulation of insulin receptors.
- Cells become insulin resistant, meaning they don't respond effectively to insulin.
- Adipokines (released by adipose tissue) contribute to insulin resistance.
- Decreases glucose uptake by cells results in hyperglycemia.
- Glucagon release is increased which contributes to hyperglycemia.
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Description
This quiz covers essential concepts related to diabetes mellitus, including the roles of glucagon and insulin, the demographics of diabetes prevalence, and the criteria for diagnosis. Gain insights into metabolic processes, particularly how they relate to blood glucose levels and insulin deficiency.
