Insulin and Glucose Regulation
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Questions and Answers

What percentage of diabetics have Insulin-dependent diabetes mellitus (IDDM)?

  • 30-40%
  • 5-10%
  • 20-30%
  • 10-20% (correct)

    • At what percentage of β-cell destruction do symptoms of IDDM appear?

  • 70%
  • 90-100%
  • 80-90% (correct)
  • 50%

    • What is the main cause of hyperglycemia in IDDM?

  • Increased peripheral utilization
  • Increased gluconeogenesis and glycogenolysis (correct)
  • Increased glycolysis
  • Decreased insulin production

    • What is the consequence of high glucagon: insulin ratio in IDDM?

    <p>Increased lipolysis and mobilization of FA from adipose tissue</p> Signup and view all the answers

    What is a characteristic of LDL particles in IDDM?

    <p>Smaller and denser</p> Signup and view all the answers

    What is the percentage of diabetics that have NIDDM?

    <p>80-90%</p> Signup and view all the answers

    What is a complication of untreated IDDM?

    <p>Ketoacidosis</p> Signup and view all the answers

    What is the age range of IDDM patients?

    <p>Children and young adults</p> Signup and view all the answers

    What is the earliest detectable abnormality in diabetic nephropathy?

    <p>Microalbuminuria</p> Signup and view all the answers

    What is the incidence of Gestational Diabetes Mellitus (GDM) in pregnancies?

    <p>1-5% of pregnancies</p> Signup and view all the answers

    What is the term for a form of autoimmune diabetes diagnosed in individuals older than the usual age of onset of type 1 diabetes?

    <p>LADA (Latent Autoimmune Diabetes in Adults)</p> Signup and view all the answers

    What is a complication of diabetes mellitus?

    <p>Diabetic retinopathy</p> Signup and view all the answers

    What is the term for carbohydrate intolerance with onset or first recognition during pregnancy?

    <p>Gestational Diabetes Mellitus (GDM)</p> Signup and view all the answers

    What is the result of long-standing hyperglycemia?

    <p>Chronic complications of diabetes mellitus</p> Signup and view all the answers

    What is the effect of insulin on the liver?

    <p>Inhibits gluconeogenesis and glycogenolysis</p> Signup and view all the answers

    What is a macrovascular complication of diabetes mellitus?

    <p>Atherosclerosis</p> Signup and view all the answers

    What percentage of women with Gestational Diabetes Mellitus (GDM) are found to have type 2 diabetes after pregnancy?

    <p>5-10%</p> Signup and view all the answers

    What is the precursor of insulin in the process of its synthesis?

    <p>Preproinsulin</p> Signup and view all the answers

    What is the main cause of diabetes mellitus?

    <p>Defect in insulin secretion or action</p> Signup and view all the answers

    What is the effect of insulin on muscle cells?

    <p>Stimulates glucose uptake</p> Signup and view all the answers

    What is the classification of diabetes mellitus characterized by a relative or absolute deficiency in insulin?

    <p>Insulin-dependent diabetes mellitus</p> Signup and view all the answers

    What is the effect of insulin resistance on metabolic alterations?

    <p>Aggravates the metabolic alterations</p> Signup and view all the answers

    What is the function of pancreatic β-cells?

    <p>They secrete insulin in response to hyperglycemia</p> Signup and view all the answers

    What is the effect of counter-regulating hormones on glucose concentrations?

    <p>Provides sufficient energy substrates at low glucose concentrations</p> Signup and view all the answers

    What is the percentage of cardiac output that flows through the kidneys at rest?

    <p>25%</p> Signup and view all the answers

    What is the primary route of elimination for urea?

    <p>Kidneys</p> Signup and view all the answers

    What is the amount of fluid filtered into Bowman's capsule per minute?

    <p>120 ml</p> Signup and view all the answers

    Why is creatinine not a perfect substance for measuring GFR?

    <p>It does not meet all the ideal criteria</p> Signup and view all the answers

    What is the relationship between serum creatinine and GFR?

    <p>Inversely proportional</p> Signup and view all the answers

    Why is serum creatinine not a sensitive indicator of kidney function?

    <p>Because it only increases when kidney function drops by half</p> Signup and view all the answers

    What is the source of creatinine in the body?

    <p>Skeletal muscle</p> Signup and view all the answers

    What is the theoretical concept that measurement of GFR is based on?

    <p>Clearance</p> Signup and view all the answers

    What is a characteristic of patients with DM1 in regards to insulin and C-peptide concentrations?

    <p>They have low concentrations of insulin and C-peptide.</p> Signup and view all the answers

    What is the role of autoimmune markers in patients with T1DM?

    <p>They are present in patient's blood for months or years before the onset of the disease.</p> Signup and view all the answers

    What is the purpose of monitoring blood glucose in diabetic patients?

    <p>To reduce the incidence of chronic complications of DM.</p> Signup and view all the answers

    What is the significance of HbA1c in diabetic patients?

    <p>It is an indirect indicator of glycemia over the life of erythrocytes.</p> Signup and view all the answers

    What is the limitation of urinary glucose test in diabetic patients?

    <p>It correlates with glycemia only in patients with normal GFR.</p> Signup and view all the answers

    What is the significance of glycated proteins in diabetic patients?

    <p>They are involved in the development of some chronic complications of diabetes.</p> Signup and view all the answers

    What is the current method of choice for monitoring blood glucose in diabetic patients?

    <p>Self-monitoring using a glucometer.</p> Signup and view all the answers

    What is the effect of high glucose concentration on proteins?

    <p>It leads to non-enzymatic glycation of proteins.</p> Signup and view all the answers

    Serum urea levels increase in conditions where

    <p>renal clearance decreases</p> Signup and view all the answers

    Which of the following conditions is NOT associated with increased serum urea levels?

    <p>Starvation</p> Signup and view all the answers

    What is the ratio of BUN: creatinine in pre-renal disease?

    <p>20:1</p> Signup and view all the answers

    What is the advantage of creatinine clearance over plasma creatinine?

    <p>It removes the variables of diet and muscle mass</p> Signup and view all the answers

    What is the characteristic of cystatin C that makes it a useful marker of renal function?

    <p>It is reabsorbed and metabolized by the proximal renal ducts</p> Signup and view all the answers

    Why is serum creatinine not a perfect substance for measuring GFR?

    <p>It is affected by muscle mass and diet</p> Signup and view all the answers

    What is the significance of the BUN: creatinine ratio in differentiating pre-renal from renal causes?

    <p>It is useful in differentiating pre-renal from renal causes</p> Signup and view all the answers

    Why is creatinine clearance a more sensitive indicator of renal function than plasma creatinine?

    <p>It is less affected by muscle mass and diet</p> Signup and view all the answers

    What is the primary function of the glomeruli in the nephron?

    <p>Filtration of water and low molecular weight substances</p> Signup and view all the answers

    What is the main function of the kidney in terms of calcium metabolism?

    <p>Activation of vitamin D</p> Signup and view all the answers

    What is the purpose of renal function tests?

    <p>To screen for, detect, evaluate, and monitor acute and chronic kidney diseases</p> Signup and view all the answers

    What is the functional unit of the kidney?

    <p>Nephron</p> Signup and view all the answers

    What percentage of urea is eliminated via kidneys?

    <p>85%</p> Signup and view all the answers

    What is the significance of proteinuria in urine examination?

    <p>Indicates glomerular leak and is the first sign of glomerular injury</p> Signup and view all the answers

    What is the purpose of estimating glomerular filtration rate (GFR)?

    <p>To assess kidney function</p> Signup and view all the answers

    What is the primary route of elimination for urea?

    <p>Kidneys</p> Signup and view all the answers

    What is the source of creatinine in the body?

    <p>Skeletal muscle</p> Signup and view all the answers

    What is the significance of urinary protein in urine examination?

    <p>Indicates glomerular leak and is the first sign of glomerular injury</p> Signup and view all the answers

    What is the role of the kidney in erythropoiesis?

    <p>Produces erythropoietin</p> Signup and view all the answers

    Why is serum creatinine not a sensitive indicator of kidney function?

    <p>All of the above</p> Signup and view all the answers

    What is the theoretical concept that measurement of GFR is based on?

    <p>Clearance</p> Signup and view all the answers

    What is the relationship between serum creatinine and GFR?

    <p>Inversely proportional</p> Signup and view all the answers

    What is the amount of fluid filtered into Bowman's capsule per minute?

    <p>120 ml</p> Signup and view all the answers

    What percentage of cardiac output flows through the kidneys at rest?

    <p>25%</p> Signup and view all the answers

    Study Notes

    Counter-Regulating Hormones

    • Increase in concentration in blood at low glucose concentrations
    • Provide energy substrates from glycogenolysis, gluconeogenesis, lipolysis, and ketogenesis

    Insulin

    • Pancreatic β-cells function as glucose sensors, secreting insulin in response to hyperglycemia
    • Reduce insulin secretion if blood glucose decreases
    • Synthesis involves preproinsulin, proinsulin, and insulin (51 AK) with C-peptide (connecting peptide)
    • Functions:
      • Stimulate glucose uptake in muscle cells and enhance glycogenesis
      • Stimulate glucose uptake in adipose tissue cells and enhance lipogenesis
      • Inhibit gluconeogenesis and glycogenolysis in the liver

    Diabetes Mellitus

    • Systemic metabolic disorder characterized by chronic hyperglycemia with disturbances in CHO, fat, and protein metabolism
    • Caused by relative or absolute deficiency in insulin and/or insulin resistance
    • Complications:
      • Acute: diabetic ketacidosis, hyperosmolar hyperglycemic nonketotic, diabetic lactic acidosis, hypoglycemic coma
      • Chronic: macrovascular (atherosclerosis), microvascular (diabetic retinopathy, cataract, diabetic neuropathy, diabetic nephropathy)

    Insulin-Dependent Diabetes Mellitus (IDDM)

    • Type I or juvenile-onset diabetes
    • Characterized by absolute deficiency of insulin due to massive autoimmune attack on β-cells
    • Symptoms: polyuria, polydipsia, polyphagia
    • Patients rely on exogenous insulin to restore metabolic control and avoid life-threatening ketoacidosis
    • Complicated by ketoacidosis

    Non-Insulin-Dependent Diabetes Mellitus (NIDDM)

    • Type II or adult-onset diabetes
    • Most common type, constituting 80-90% of diabetic cases
    • Complications: same as IDDM, plus hypertriglyceridemia, hypercholesteremia, and low HDL

    Gestational Diabetes Mellitus (GDM)

    • Carbohydrate intolerance with onset or first recognition during pregnancy
    • Incidence: 1-5% of pregnancies
    • Patients often revert to normal glucose tolerance after delivery
    • Requires treatment to normalize maternal blood glucose levels during pregnancy

    Other Types of DM

    • Latent Autoimmune Diabetes in Adults (LADA): a form of autoimmune diabetes diagnosed in individuals older than the usual age of onset of type 1 diabetes
    • Laboratory monitoring of diabetic patients:
      • Monitoring of blood glucose: reduces incidence of chronic complications
      • HbA1c: assesses long-term compensation of a diabetic, indirect indicator of glycemia over life of erythrocytes
      • Urinary glucose test: correlates with glycemia only in patients with normal GFR
      • GFR: accurate measurement requires a substance with constant production and removal rate, such as creatinine
      • Creatinine: breakdown product of creatine and creatine phosphate, inversely proportional to GFR, but not sensitive and influenced by muscle mass and liver function
      • Blood Urea Nitrogen (BUN): formed in the liver as the end product of protein metabolism, eliminated via kidneys and GI tract

    Serum Urea Levels

    • Increase in conditions where renal clearance decreases (acute and chronic renal failure/impairment)
    • Also increase in other conditions not related to renal diseases, such as:
      • Upper GI bleeding
      • Dehydration
      • Catabolic states
      • High protein diets
    • Decrease in:
      • Starvation
      • Low-protein diet
      • Severe liver disease

    BUN: Creatinine Ratio

    • Useful to differentiate pre-renal from renal causes when BUN is increased
    • In pre-renal disease, the ratio is close to 20:1
    • In intrinsic renal disease, the ratio is closer to 10:1
    • Upper GI bleeding can be associated with a very high BUN to creatinine ratio (sometimes >30:1)

    Creatinine Clearance

    • More sensitive than plasma creatinine at picking up small changes in renal function
    • Removes the variables of diet and muscle mass
    • Inconvenient, requiring 24hr urine collection plus serum sample
    • Calculation: Evaluation of glomerular function

    Cystatin C

    • Small polypeptide produced by all nucleated cells at a constant rate
    • Stable concentration in blood
    • Renal handling of cystatin C differs from creatinine
    • Not affected by:
      • Infections
      • Inflammatory or neoplastic states
      • Body mass
      • Diet
      • Drugs
    • Useful for monitoring progression of renal disease, assessing therapeutic response, and estimating cardiovascular risk

    Glomerular Filtration Rate (GFR)

    • Volume of blood filtered across glomerulus per unit time
    • Measurement based on a theoretical concept of clearance
    • Requires a substance that is:
      • Freely filtered by glomeruli
      • Not secreted or reabsorbed in tubules
      • Produced and removed from the body with a constant rate
    • Creatinine is close to fulfilling these criteria

    Creatinine

    • Breakdown product of creatine and creatine phosphate
    • Released from skeletal muscle at a steady rate
    • Not metabolized or excreted from the body other than by the kidney
    • Can measure its clearance from plasma or excretion in urine
    • Inversely proportional to GFR
    • Limitations:
      • Not sensitive (serum creatinine only increases above normal when kidney function drops by half)
      • Influenced by:
        • Muscle mass size
        • Food intake (meat)
        • Liver function (synthesis of creatine)

    Blood Urea Nitrogen (BUN)

    • Nitrogen-containing compound formed in the liver as the end product of protein metabolism
    • About 85% of urea is eliminated via kidneys; the rest is excreted via the GI tract
    • Hormonal functions:
      • Produces erythropoietin, which helps promote erythropoiesis in bone marrow
      • Plays a role in calcium metabolism by activating vit.D

    Renal Function Test (RFT)

    • Group of tests used to assess the functions of the kidney
    • Used to:
      • Screen for, detect, evaluate, and monitor acute and chronic kidney diseases
      • Monitor the response of kidneys to treatment or progression of renal disease
      • Evaluate kidney function in patients with other conditions that can harm the kidneys, such as diabetes or high blood pressure

    Nephron

    • Functional unit of the kidney
    • Each of the approximately one million nephrons is made up of five main functional segments
    • The principal function of the glomeruli is to filtration, which is permeable to water and low molecular weight substances, but impermeable to macromolecules like proteins.

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    Description

    This quiz covers the role of insulin in regulating blood glucose levels, including the production and secretion of insulin in response to hyperglycemia and hypoglycemia.

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