Diabetes Mellitus Overview
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Questions and Answers

What is the primary function of glucagon in the body?

  • To decrease plasma lipids
  • To increase plasma glucose levels (correct)
  • To stimulate insulin production
  • To promote protein synthesis

Which cells in the pancreas secrete glucagon?

  • Acinar cells
  • Beta cells
  • Alpha cells (correct)
  • Delta cells

What metabolic processes are promoted by glucagon to increase blood glucose levels?

  • Glycogenolysis and lipogenesis
  • Protein synthesis and lipolysis
  • Glycolysis and ketogenesis
  • Gluconeogenesis and lipolysis (correct)

Which of the following is NOT a criterion for diagnosing diabetes according to the American Diabetes Association?

<p>FPG &gt; 180 mg/dl (D)</p> Signup and view all the answers

What primarily causes the insulin deficiency in Type 1A Diabetes Mellitus?

<p>Absolute β-cell destruction (C)</p> Signup and view all the answers

Which factor is associated with the increasing rates of diabetes in youth?

<p>Childhood obesity (B)</p> Signup and view all the answers

What is the primary consequence of the destruction of 80-90% of pancreatic beta cells?

<p>Decreased insulin secretion (A)</p> Signup and view all the answers

Which environmental factor is NOT related to the risk of developing type 1A diabetes mellitus?

<p>Exercise (D)</p> Signup and view all the answers

What happens to potassium levels in the presence of insulin deficiency?

<p>Hyperkalemia occurs (C)</p> Signup and view all the answers

What is the primary reason for osmotic diuresis in individuals with hyperglycemia?

<p>Saturation of glucose carrier molecules (B)</p> Signup and view all the answers

What is a consequence of insulin deficiency on fat metabolism?

<p>Increased ketone production (B)</p> Signup and view all the answers

Which of the following conditions is most likely associated with nonimmune-mediated Type 1B diabetes mellitus?

<p>Chronic pancreatitis (D)</p> Signup and view all the answers

What role do alpha cells play in the context of reduced insulin secretion?

<p>They increase glucagon secretion (C)</p> Signup and view all the answers

What is the effect of decreased glucose uptake in cells due to insulin deficiency?

<p>Cell starvation risk (A)</p> Signup and view all the answers

What mechanism leads to decreased glucose uptake into cells in insulin resistance?

<p>Decreased insulin sensitivity (C)</p> Signup and view all the answers

What is a common lipid profile observed upon diagnosis in most type 2 diabetics?

<p>Low HDL and high triglycerides (A)</p> Signup and view all the answers

What is the result of nonenzymatic glycosylation in chronic hyperglycemia?

<p>Binding of glucose to proteins, lipids, and nucleic acids (A)</p> Signup and view all the answers

What clinical indicator reflects average blood glucose levels over a period of 2 to 3 months?

<p>HgbA1c test (D)</p> Signup and view all the answers

What can cause injury to beta cells in the pancreas in diabetes?

<p>Chronic presence of amyloids (C)</p> Signup and view all the answers

What is the effect of capillary basement membrane thickening in diabetes?

<p>Decreased gas exchange (B)</p> Signup and view all the answers

What is a consequence of increased capillary permeability in diabetes?

<p>Reduced oxygen availability (B)</p> Signup and view all the answers

What leads to increased glucagon secretion contributing to hyperglycemia?

<p>Insulin resistance (B)</p> Signup and view all the answers

What is the relationship between obesity and the incidence of type 2 diabetes mellitus?

<p>Obesity is associated with a ten-fold increase in the incidence of type 2 diabetes mellitus. (C)</p> Signup and view all the answers

Which ethnic group has the highest reported increase in incidence of type 2 diabetes mellitus?

<p>American Indian (B)</p> Signup and view all the answers

What condition is associated with a significant increase in the risk of developing type 2 diabetes mellitus?

<p>Polycystic ovarian syndrome (A)</p> Signup and view all the answers

What is hyperinsulinemia and its effect on insulin receptors?

<p>Leads to chronically high insulin levels, causing receptor down-regulation. (B)</p> Signup and view all the answers

Which factor is NOT considered a part of metabolic syndrome?

<p>Normal blood pressure (C)</p> Signup and view all the answers

How does genetics influence type 2 diabetes mellitus?

<p>Multiple types of mutations involved in insulin synthesis and receptors are identified. (C)</p> Signup and view all the answers

What age group is most commonly affected by type 2 diabetes mellitus?

<p>Individuals over 40 years old (B)</p> Signup and view all the answers

What role do adipokines play in relation to insulin sensitivity?

<p>They can stimulate insulin resistance when present in high quantities. (B)</p> Signup and view all the answers

What is a consequence of the shunting of glucose to the polyol pathway in non-insulin dependent tissues?

<p>Increased osmotic pressure leading to cellular swelling (B)</p> Signup and view all the answers

Which of the following is primarily caused by retinal ischemia?

<p>Retinopathy (B)</p> Signup and view all the answers

How does inappropriate activation of protein kinase C affect the body?

<p>Increases basement membrane thickening (C)</p> Signup and view all the answers

What is a key factor in the formation of diabetic retinopathy?

<p>Thickening and clotting of blood vessels (C)</p> Signup and view all the answers

What leads to the formation of cataracts in the lens of the eyes?

<p>Glucose shunting through the polyol pathway (B)</p> Signup and view all the answers

Which mechanism is NOT related to microvascular disease effects caused by chronic hyperglycemia?

<p>Shunting of fatty acids (D)</p> Signup and view all the answers

What effect does the production of oxygen free radicals have in tissues?

<p>Causes endothelial cell injury (B)</p> Signup and view all the answers

Which of the following best describes a consequence of increased arterial smooth muscle proliferation?

<p>Thickening of arterial walls leading to hypertension (C)</p> Signup and view all the answers

What is the first clinical sign of nephropathy?

<p>Proteinuria/alubinuria (C)</p> Signup and view all the answers

Which consequence is associated with chronic renal failure (CRF)?

<p>Fluid retention leading to hypertension (A)</p> Signup and view all the answers

What is a risk factor that contributes to the development of atherosclerosis?

<p>Dyslipidemia (A)</p> Signup and view all the answers

Which of the following is a potential consequence of atherosclerosis?

<p>Cerebral infarction (stroke) (C)</p> Signup and view all the answers

What is a primary mechanism of neuronal injury in neuropathies?

<p>Shunting of glucose via the polyol pathway (C)</p> Signup and view all the answers

Which symptom is most commonly associated with sensory neuropathies?

<p>Tingling and burning sensations (D)</p> Signup and view all the answers

How does autonomic neuropathy typically manifest in patients?

<p>Alterations in bowel function (D)</p> Signup and view all the answers

What cellular event is involved in the damage to neurons in neuropathies?

<p>Demyelination of neurons (C)</p> Signup and view all the answers

Flashcards

Glucagon function

Increases blood glucose levels by promoting glycogenolysis and gluconeogenesis.

Glucagon secretion trigger

Decreased blood glucose levels.

Diabetes Mellitus

A group of disorders related to insulin activity, causing glucose intolerance and protein/lipid metabolism issues.

Type 1 Diabetes

Autoimmune disease resulting in insufficient insulin production, often leading to absolute insulin deficiency.

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HbA1c

A blood test measuring average blood glucose levels over several months.

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Fasting Plasma Glucose (FPG)

Blood glucose level measured after an 8-hour fast.

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2-hr plasma glucose

Blood glucose level measured 2 hours after consuming a glucose drink.

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Symptoms of high blood sugar

Classic symptoms leading to diabetes diagnosis can include hyperglycemia or hyperglycemic crisis.

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Type 1A Diabetes Mellitus (DM)

A type of diabetes caused by an autoimmune attack on pancreatic beta cells, preventing insulin production.

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Type 1B Diabetes Mellitus

A type of diabetes characterized by β-cell destruction with no evidence of an autoimmune disease. Often, a result of other diseases.

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Beta Cell Destruction

The process of damaging pancreatic beta cells reducing insulin production resulting in elevated blood glucose.

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Hyperglycemia

High blood glucose levels in the body, a hallmark of uncontrolled diabetes.

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Osmotic Diuresis

Increased urination due to high glucose in the blood, which prevents water reabsorption in the kidneys.

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Hyperkalemia

High potassium levels in the blood, a potential complication of diabetes due to reduced insulin.

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Ketones

Acidic molecules produced when the body uses fat for energy instead of glucose due to lack of insulin.

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Renal Threshold (Tm)

The point where glucose is no longer completely reabsorbed into the blood from filtered urine.

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Type 2 Diabetes Mellitus (T2DM) risk factors

Factors increasing the likelihood of developing T2DM. These incorporate genetic predisposition, obesity, age, ethnicity, family history, PCOS, and metabolic syndrome.

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Genetic Risk for T2DM

T2DM has a strong genetic component, with mutations affecting insulin synthesis, receptors, and cellular responsiveness.

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Obesity and T2DM

A significant risk factor; individuals with obesity (BMI > 30) have an increased chance of developing T2DM due to related chronic conditions.

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Age and T2DM

T2DM onset frequently occurs after age 40, though, increasingly, younger people are affected.

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Hyperinsulinemia

Chronically high insulin levels due to over-activation of the body's insulin-producing mechanisms.

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Insulin Resistance

A condition where cells fail to respond adequately to insulin, potentially due to receptor down-regulation.

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Adipokines and T2DM

High levels of adipokines, secreted by adipose tissue, promote insulin resistance.

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Metabolic syndrome

A cluster of conditions increasing the risk for T2DM, including central obesity, high blood pressure, elevated blood sugars, high triglycerides, and low HDL.

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Dyslipidemia

Abnormal levels of lipids in the blood, characterized by low HDL (good cholesterol) and high triglycerides.

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Adipokines

Hormones produced by fat cells that can contribute to beta cell injury and diabetes.

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Amyloids

Protein strands that infiltrate the pancreas and can destroy the insulin-producing cells.

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Nonenzymatic Glycosylation

A harmful process where glucose binds to proteins, lipids, and nucleic acids, causing cell damage and long-term complications.

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Advanced Glycosylation End-Products (AGEs)

Harmful complexes formed when glucose irreversibly binds to proteins, lipids, and nucleic acids.

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HgbA1c Test

A blood test that measures the average blood glucose levels over the past 2-3 months by measuring the amount of glucose bound to hemoglobin in red blood cells.

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Nephropathy in Diabetes

Damage to the kidneys caused by diabetes, characterized by proteinuria, glomerular changes, and eventual chronic kidney failure.

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Atherosclerosis & Diabetes

Diabetes accelerates atherosclerosis, the hardening of arteries, due to increased LDL deposition and endothelial damage caused by AGEs.

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Neuropathy in Diabetes

Damage to nerves caused by diabetes, leading to numbness, tingling, and impaired motor function.

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AGEs and Diabetes

Advanced Glycation End products (AGEs) are harmful molecules that accumulate in diabetes, leading to vascular and nerve damage.

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Consequences of Diabetic Nephropathy

Diabetic nephropathy leads to chronic kidney failure, characterized by increased creatinine, fluid retention, anemia, and metabolic acidosis.

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Consequences of Diabetic Atherosclerosis

Atherosclerosis in diabetes can affect the heart (heart attack, heart failure), brain (stroke), and other organs.

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Consequences of Diabetic Neuropathy

Diabetic neuropathy affects sensory, motor, and autonomic nerves, causing numbness, impaired movement, and dysfunction in bodily functions.

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Polyol Pathway in Diabetic Neuropathy

In diabetic neuropathy, glucose is shunted via the polyol pathway, leading to neuronal swelling and damage.

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Arterial Smooth Muscle Proliferation

The thickening of arterial walls due to increased smooth muscle cell growth, contributing to hypertension. This process is driven by factors like oxygen free radicals, which injure endothelial cells and promote vasoconstriction.

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Oxygen Free Radicals in Hypertension

Oxygen free radicals, highly reactive molecules, damage endothelial cells lining the arteries and surrounding tissues, contributing to the development of hypertension. Their effects include vasoconstriction and promoting blood clotting.

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Nitric Oxide (NO) and Hypertension

Nitric Oxide (NO) is a vasodilator (a substance widening blood vessels). In hypertension, its inactivation leads to vasoconstriction, further contributing to the increase in blood pressure.

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Polyol Pathway: What is it?

The polyol pathway is a pathway in cells that utilizes glucose when insulin is not available for glucose transport. It occurs in tissues like neurons and is activated in hyperglycemia.

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Polyol Pathway: What are the consequences?

Excessive glucose shunting to the polyol pathway causes osmotic pressure build-up, leading to cellular swelling and damage, ultimately contributing to complications like cataracts, neurological problems and hemolysis.

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Inappropriate Protein Kinase C Activation

Protein Kinase C (PKC) is an enzyme that regulates various cellular processes. In hyperglycemia, its inappropriate activation contributes to insulin resistance, increased capillary permeability, basement membrane thickening and vasoconstriction.

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Microvascular Disease: What causes it?

Chronic hyperglycemia causes damage to tiny blood vessels (microvasculature) due to three main mechanisms: formation of advanced glycation end products (AGEs), glucose shunting through the polyol pathway and inappropriate protein kinase C activation.

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Diabetic Retinopathy: What is it?

Diabetic retinopathy is a complication of diabetes that affects the retina in the eye. It is caused by retinal ischemia (reduced blood flow) due to vessel thickening and clotting, ultimately leading to vision loss and blindness.

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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.

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