Lecture 5: The Endocrine Pancreas Flashcards
D1 cells of the endocrine pancreas secrete what; what is the effect of this secretory product?
- VIP
- Induces glycogenolysis and hyperglycemia
- Stimulates GI secretions –> secretory diarrhea
Which value of HbA1C is considered diagnositc for diabetes?(≥
≥6.5%

A fasting plasma glucose of ≥ ______ mg/dL is considered diagnostic for diabetes.

A fasting plasma glucose of ≥ 126 mg/dL is considered diagnostic for diabetes.
A random plasma glucose ≥ ______ mg/dL is considered diagnostic for diabetes.
A random plasma glucose ≥ 200 mg/dL is considered diagnostic for diabetes.
What are 4 genetic syndromes associated w/ diabetes?
- Down syndrome
- Klinefelter syndrome
- Turner syndrome
- Prader-Willi syndrome
Fasting plasma glucose levels are determined primarily by what?
Hepatic glucose output
What is the major insulin-responsive site for postprandial glucose utilization and is critical for preventing hyperglycemia and maintaining glucose homeostasis?
Skeletal muscle
What 2 classes of drugs have been created for pt’s with T2DM based on the incretin effect?
- GLP-1 receptor agonists
- DPP-4 inhibitors (↓ breakdown of incretins)
Which form of diabetes is associated with amyloid deposition in pancreatic islets?
Type 2 DM
What are 2 mitogenic functions of insulin?
- Initiation of DNA synthesis in certain cells
- Stimulation of cell growth and differentiation
Insulin signaling facilitates the trafficking and docking containing which insulin-sensitive glucose transporter to the plasma membrane?
GLUT-4

What is the most important susceptibility locus associated with T1DM; what chromosome is it on?
HLA gene cluster on chromosome 6p21

Which 2 HLA loci are associated with T1DM?
- HLA-DR3
- HLA-DR4
Individuals with what concurrent HLA halotypes have the highest inherited risk for T1DM?
DR3 or DR4 concurrently w/ a DQ8

The classic manifestations of T1DM (hyperglycemia and ketosis) occur after more than _______% of the beta-cells have been destroyed
The classic manifestations of T1DM (hyperglycemia and ketosis) occur after more than 90% of the beta-cells have been destroyed

What is the fundamental immune abnormality underlying the pathogenesis of T1DM?
Failure of self-tolerance in T cells specific for islet antigens
What are the 3 circulating islet autoantibodies observed in the majority of pt’s with T1DM as well as asymptomatic family members at risk for progression to overt disease?
- anti-insulin
- anti-GAD
- anti-ICA512
Which type of diabetes (T1DM or T2DM) has a stronger genetic component?
T2DM —> disease concordance >90% in monozygotic twins
What are the 2 cardinal metabolic defects that characterize T2DM?
- ↓ response of peripheral tissues, especially skeletal m., adipose, and liver to insulin = insulin resistance
- Inadequate insulin secretion in the face of insulin resistance and hyperglycemia = β-cell dysfunction

Excess FFA’s within macrophages and β cells in the setting ↑ central obesity can activate what; contribute to insulin resistance how?
Inflammasome leads to secretion of IL-1β = release of pro-inflammatory cytokines —> insulin resistance
Maturity-onset diabetes of the young (MODY) resembles what type of diabetes?
T2DM
How does maturity-onset diabetes of the young (MODY) resemble T2DM?
- ↑ blood insulin
- NO autoantibodies
- NON-ketotic

Maturity-onset diabetes of the young (MODY) is most often associated with loss-of-function mutations in which gene?
Glucokinase (GCK)
Rare insulin receptor mutations which impair tissue response to insulin can cause what 2 disease states?
- Type A insulin resistance —> acanthosis nigricans
- Lipoatrophic diabetes —> hyperglycemia + loss of subcutaneous adipose tissue
Women w/ pregestational diabetes (where hyperglycemia was present before conception) have an increased risk for what fetal complications?
- Stillbirth
- Congenital malformations

Poorly controlled diabetes arising later in pregnancy, regardless of prior history, can lead to what problems for the infant?
- Excessive weight at birth (macrosomia)
- Problems later in life including obesity and diabetes

How is the diagnosis of T2DM most frequently made?
After routine blood testing in asymptomatic pt
Classic triad of T1DM?
- Polyuria
- Polyphagia, BUT losing weight!
- Polydipsia

Autoantibodies associated with T1DM are present more often in which ethnicity, therefore are more reliable indicators of disease?
>90% of Caucasians

What is the most common precipitating factor of diabtetic ketoacidosis; what are some other factors which may contribute?
- Failure to take insulin (non-compliance) = most common
- Intercurrent infections –> Pneumonia and UTI’s
- illness
- Trauma
- Certain drugs

What is the triad of diabetic ketoacidosis?
- HYPERglycemia
- Ketonemia
- Metabolic acidosis
The pathogenesis of DKA is associated with the release of what into circulation and how does this contribute?
- Release of epinephrine
- Which blocks residual insulin action and stimulates the secretion of glucagon
- ↑ glucagon –> ↑ gluconeogenesis and ↑ blood glucose levels —> exacerbating hyperglycemia —> osmotic diuresis and dehyrdration

Insulin deficiency stimulates what enzyme responsible for the production of ketone bodies?
Hormone sensitive lipase –> breaks down adipose tissue —> ↑ FFA’s which are esterified to fatty acyl CoA and oxidized by hepatic mitochondria to produce ketone bodies
What are the clinical signs/sx’s of pt in DKA?
- Fatigue + N/V + severe abdominal pain
- Fruity odor
- Deep, labored respirations (also known as Kussmaul breathing)

Which acute hyperglycemia crisis is more common in T2DM and how does it occur?
- Hyperglycemic hyperosmotic syndrome (HHS)
- Prolonged hyperglycemia –> sustained osmotic diuresis + severe dehydration in a pt who does not drink enough water to compensate for urinary losses

How does HHS differ from DKA?
- More severe HYPERglycemia (600-1200 mg/dL)
- HYPERosmolality (>350 mOsm/L)
- NO ketones

What is the most common acute metabolic complication in both T1DM and T2DM; how does it present clinically?
- HYPOglycemia from either missing a meal, excessive exertion, or too much insulin administration
- Presents as: dizziness + confusion + sweating + palpitations + tachycardia
Which GF released as a result of the AGE-RAGE signaling axis within the vascular compartment is implicated in diabetic retinopathy?
VEGF

The accumulation of what in the lens of pt with chronic hyperglycemia contributes to cataract formation?
Sorbitol
In tissues that do not require insulin for glucose transport (i.e., nerves, lens, kidneys, and blood vessels), what reaction occurs in the presence of excess intracellular glucose; which cofactor is used for this reaction?
- Glucose metabolized by aldose reductase —> Sorbitol
- This reaction uses NADPH as cofactor; which compromises GSH regeneration; ↑ susceptibility to oxidative stress
What are 5 effects on the vasculature produced by advanced glycation end products (AGEs) formed in the presence of chronic hyperglycemia?
- ↑ release cytokines + GF’s –> TGF-β and VEGF
- Generation of ROS’s
- Procoagulant activity
- Proliferation of smooth m.
- Cross-linking of matrix proteins –> pro-atherogenic

An increase in the number and size of the pancreatic islets is a characteristic morphological feature in which pt’s?
NON-diabetic newborns of diabetic mothers
What is the morphological hallmark of diabetic macrovascular disease?
Accelerate atherosclerosis involving the aorta and large- and medium-sized arteries
Which vascular lesion associated with HTN is seen both more prevalent and more severe in diabetics than in non-diabetics?
Hyaline atherosclerosis

What 3 lesions are encountered in diabetic nephropathy?
- Glomerular lesions
- Renal vascular lesions, mainly arteriolosclerosis
- Pyelonephritis, including necrotizing papillitis

What are the 3 most important glomerular lesions encountered in diabetic nephropathy?
- Capillary BM thickening
- Diffuse mesangial sclerosis
- Nodular glomerulosclerosis

The diffuse mesangial slcerosis associated with diabetic nephropathy is caused by an increase in what?
Diffuse ↑ in mesangial MATRIX

The glomerular lesions of diabetic nephropathy that take the form of ovoid or spherical, often laminated, nodules of matrix situated in the periphery of the glomerulus are known as what?
Intercapillary glomerulosclerosis or Kimmelstiel-Wilson disease

Grossly what will the surface of the kidney and cortical tissue show in a patient with long-standing diabetes leading to nephrosclerosis?
- Diffuse granular transformation of the surface
- Marked thinning of the cortical tissue
- Overall contraction in size

Which arterioles of the kidney (afferent or efferent) are affected by hyaline arteriolosclerosis in long-standing diabetic nephropathy?
BOTH the afferent and efferent arterioles
Which special pattern of acute pyelonephritis is much more prevalent in diabetics than in nondiabetics?
Necrotizing papillitis (or papillary necrosis)
What is the gold standard for urine albumin testing?
Urine Albumin: Creatinine Ratio (UACR)

The most profound histopathologic changes of diabetes are seen in what part of the eye?
Retina = Retinal vasculopathy of diabetes

What is the fundamental lesions of diabetic retinopathy and how is it induced?
Neovascularization due to hypoxia-induced overexpression of VEGF

What is the most frequent pattern of involvement seen with diabetic neuropathy?
Distal symmetric polyneuropathy of the LE’s that affects BOTH motor and sensory function

Diabetics have enhanced susceptibility to what type of infections?
- Skin i.e., cellulitis
- Tuberculosis
- Pneumonia
- Pyelonephritis

Intrracellular hyperglycemia stimulates the de novo synthesis of DAG from glycolytic intermediates, which causes excessive activation of what; what are the downstream effects of this?
- Excessive PKC activation
- Leads to ↑ production of VEGF, TGF-β, and the procoagulant, PAI-1
Somatic alterations in which 3 major genes or pathways have been identified as factors associated w/ sporadic pancreatic neuroendocrine tumors?
- MEN1
- LOF mutations, PTEN and TSC2 —> ↑ mTOR signaling pathway
- Inactivating mutations of ATRX and DAXX
Deposition of amyloid is a characteristic histologic feature of which type of pancreatic neuroendocrine tumor?
Insulinoma

Levels of what can be useful in making the diagnosis of an insulinoma?
Urine C peptide levels
Insulinomas are associated with what clinical signs and sx’s; these sx’s are usually precipitated by what?
- HYPOglycemic episodes when blood glucose falls below 50 mg/dL
- Confusion + stupor + loss of consciousness
- Episodes precipitated by fasting or exercise
Which type of pancreatic neuroendocrine tumor is generally benign and is associated with the lowest rate of metastasis (10%)?
Insulinoma

How do MEN-1-associated gastrinomas differ morphologically from sporadic gastrinomas?
- MEN-1-associated are often multifocal
- Sporadic are usually single
What is the triad of gastrinomas which constitute Zollinger-Ellison Syndrome?
- Pancreatic islet cell tumor
- HYPERsecretion of gastric acid
- Severe peptic ulceration

Patients with Zollinger-Ellison syndrome with metastasis where have a shortened life expectancy?
Liver; progressive tumor growth causes liver failure within 10 years
What are the 4 D’s of Glucagonomas?
- Diabetes (mild)
- Dermatitis (necrolytci migratory erythema)
- Depression
- DVT’s

What is the characteristic rash associated with glucagonomas called and where on the body is this rash seen?
- Necrolytic migratory erythema
- Groin + lower extremities

δ-cell tumors (somatostatinomas) are associated with what 4 clinical manifestations?
- Diabetes
- Cholelithiasis (gallstones)
- Steatorrhea
- HYPOchlorhydria

Since somatostatin functions as a paracrine regulator, what 3 things are reduced when somatostatin levels are high?
- Reduced insulin
- Reduced gallbladder motility
- Reduced exocrine pancreatic secretions

VIPomas are associated with what syndrome and what are the clinical manifestations?
- WDHA syndrome
- Watery diarrhea
- HYPOkalemia
- Achlorhydria

20% of patients with VIPomas will also have what presenting sx?
FLUSHING
