Diabetes Dx & Pathophys Flashcards

1
Q

diabetes - defined

A

*a disease characterized by hyperglycemia resulting from defects in insulin secretion, insulin action, or both
*various types of diabetes:
-type 1 = beta cell destruction; no insulin secretion
-type 2 = insulin resistance; defect in insulin action
-gestational = beta cell dysfunction and insulin resistance during pregnancy
-miscellaneous = drug induced, exocrine pancreatic disease, monogenic diabetes (MODY), LADA

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2
Q

diabetes - clinical presentation

A
  1. often asymptomatic
  2. the 3 P’s: polyuria, polydipsia, polyphagia
    -excess glucose causes osmotic diuresis → polydipsia
    -glucose cannot enter cells → low energy → polyphagia
  3. weight loss (body is unable to utilize glucose as fuel; muscle & fat are broken down as alternatives)
  4. blurry vision, distal paresthesias
  5. diabetic ketoacidosis (DKA) or hyperosmolar hyperglycemic state (HHS)
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3
Q

diabetes - diagnosis

A
  1. 8hr fasting plasma glucose 126+ mg/dL
  2. 2hr glucose tolerance test 200+ mg/dL (check fasting plasma glucose, drink 75g glucose drink, then recheck glucose 2hrs later)
  3. random plasma glucose 200+ AND hyperglycemia sx present
  4. HbA1c 6.5% or higher
    *note - cannot rely on just one test: either repeat the same test or perform another to officially make the dx
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4
Q

hemoglobin A1c (HbA1c) - overview

A

*glucose attaches to Hb by nonenzymatic glycosylating in a high glucose environment (more glucose in blood → more glucose attaches to Hb)
*A1c represents the average glucose over a 3-month period (average lifespan on an RBC)
*assumes stable Hb (blood transfusions, hemoglobinopathies, etc can change HbA1c)

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5
Q

why do we treat diabetes?

A

*diabetes, when uncontrolled, can lead to multiple complications over time
*heart disease is the leading cause of death for pts with diabetes

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6
Q

type 1 diabetes - overview

A

*characterized by autoimmune destruction of the pancreatic beta cells, resulting in absent insulin secretion
*most cases are diagnosed before age 18

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7
Q

type 1 diabetes (T1DM) - pathogenesis

A

*beta cell destruction is mediated by both T and B lymphocytes:
-T lymphocytes - infiltrate the islets and destroy the beta cells (insulitis)
-B lymphocytes - autoantibody-mediated destruction of beta islet cells
*antibodies also target glutamic acid decarboxylase (GAD), an enzyme that controls insulin release from the beta cells
*a type IV cell-mediated hypersensitivity reaction

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8
Q

type 1 diabetes (T1DM) - presentation

A

*often symptomatic at the time of dx as patients present with severe hyperglycemia
*polyuria, polydipsia, polyphagia

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9
Q

type 1 diabetes (T1DM) - diagnosis

A

*diagnose with previous screening tests (fasting glucose, glucose tolerance test, HbA1c, etc) AND:
-anti-glutamic acid decarboxylase antibodies (GAD)
-other antibodies: islet cell cytoplasmic antibodies, insulin antibodies, etc

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10
Q

type 1 diabetes (T1DM) - associations

A

*associated with mutations in HLA antigens: HLA-DR3 and HLA-DR4 but T1DM has a weaker genetic component than T2DM
*associated with other autoimmune conditions: hypothyroidism, vitiligo, celiac disease

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11
Q

type 1 diabetes (T1DM) - prognosis

A

*without insulin, T1DM is fatal
*now, good prognosis

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12
Q

type 2 diabetes (T2DM) - overview

A

*a “relative” insulin deficiency; a mismatch between insulin production and requirements driven by insulin resistance
*insulin resistance:
-a decrease in tissue responsiveness to insulin
-increased insulin levels required to maintain normal glucose

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13
Q

type 2 diabetes (T2DM) - pathophysiology

A

*cause of insulin resistance unclear but correlates with obesity, sedentary lifestyle, high triglycerides, inflammation, and cytokines
*beta cells compensate initially with excess insulin secretion, but continued hyperglycemia can impair beta cell function and they fail → T2DM; a vicious cycle

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14
Q

type 2 diabetes (T2DM) - epidemiology

A

*diagnosed in adulthood, usually > 40yo
*age of onset is shifting to younger adults/kids with obesity on the rise

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15
Q

type 2 diabetes (T2DM) - associations

A

*obesity increases the risk of metabolic syndrome: constellation of visceral or intra-abdominal adiposity, insulin resistance, hyperinsulinemia, glucose intolerance, HTN, HLD, and low HDL
*metabolic syndrome, in turn, increases the risk of T2DM and CVD

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16
Q

type 2 diabetes (T2DM) - presentation

A

*often asymptomatic early in dx, or BG only mildly elevated; as disease progresses and more profound hyperglycemia develops, sx develop
*signs of insulin resistance:
-acanthosis nigricans (hyperpigmentation in skin folds; high circulating insulin levels cross react with IGF-1 receptors in skin)
-skin tags
-central adiposity

17
Q

gestational diabetes - overview

A

*diabetes that is diagnosed during pregnancy
*increasing insulin resistance with progression of pregnancy, but mother’s pancreas is unable to secrete enough insulin to match her needs, causing hyperglycemia

18
Q

gestational diabetes - pathophysiology

A

*driver of insulin resistance and insulin secretion in pregnancy: human placental lactogen
*increased insulin resistance = pregnant women is less able to use glucose, causing postprandial glucose levels to increase and there is increased lipolysis in her body
*the glucose that she is not able to take up in her cells are instead taken up and used by the fetus

19
Q

gestational diabetes - risk factors

A

*age 25-30 or older
*Hispanic, African American, Native American, Asian, Pacific Islander
*obesity (BMI > 30)
*excessive gestational weight gain
*history of glucose intolerance, PCOS, prior GDM
*previous birth of a large infant (>9lbs)
*multiple gestations
*family history of diabetes

20
Q

gestational diabetes - maternal complications

A

*preeclampsia (HTN, protein in urine, potentially fatal)
*polyhydramnios (excess amniotic fluid):
-fetal malposition
-maternal respiratory compromise
-placental abruption
-preterm contractions/labor
-uterine atony
-umbilical cord prolapse

21
Q

gestational diabetes - fetal complications

A

*macrosomia (large for gestational age infants)
-risk of shoulder dystocia, brachial plexus injuries, clavicle fractures
*premature birth
*post-delivery complications:
-hypoglycemia, hypocalcemia, iron deficiency anemia, polycythemia, hyperbilirubinemia

22
Q

gestational diabetes - screening

A

*screen at 24-28 wks (1hr oral glucose tolerance test or 2hr OGTT)

23
Q

gestational diabetes - treatment

A

*lifestyle/diet changes
*insulin
*metformin or glipizide

24
Q

monogenic diabetes (MODY)

A

*aka maturity-onset diabetes of the young (MODY)
*onset of diabetes in late childhood or before the age f 25
*negative testing for diabetes autoantibodies
*defect is in glucose-stimulated insulin secretion
*autosomal dominant diabetes inheritance
*pts are usually not obese and do not have signs/symptoms of insulin resistance
*pts may not require insulin therapy

25
Q

drug-induced diabetes

A

*most commonly associated with glucocorticoids (prednisone, dexamethasone, hydrocortisone)
*glucocorticoids causes a supraphysiologic hypercortisolemic state which induces insulin resistance (steroid induced diabetes)
*checkpoint inhibitors such as monoclonal antibodies against PD-1 and CTLA-4 are associated with development of autoimmune diabetes

26
Q

latent autoimmune diabetes in adults (LADA)

A

*type 1 diabetes diagnosed later in life
*similar pathophys with autoimmune destruction of pancreatic beta islet cells; generally GAD antibodies are checked
*often misdiagnosed as T2DM b/c pts initially retain some beta islet cell function, but diminishes over time

27
Q

prediabetes

A

*impaired fasting glucose or impaired glucose tolerance but not to the degree of overt diabetes
*diagnosis:
-fasting plasma glucose 100-125 mg/dl
-oral glucose tolerance results 140-199 mg/dl
-HbA1c 5.7-6.4%
*focus on dietary modifications, weight loss (if applicable), and regular moderate intensity exercise as first line approach