Diabetes Flashcards

1
Q

List 3 differences between Type I and Type II DM

A
  • Type I is insulin dependant, Type II is non-insulin dependant
  • Type I is defined by an absolute lack of insulin, Type II can still produce insulin but cells are less responsive
  • Type I can cause ketoacidosis
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2
Q

What can cause a rise in blood glucose?

A
  • Inability to produce insulin due to β cell failure or autoimmune destruction
  • Insulin resistance of cells so glucose cannot be utilised
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3
Q

Name 4 typical symptoms of hyperglycaemia

A
  • Polyuria
  • Polydipsia
  • Urogenital infections
  • Blurring of vision
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4
Q

What are the symptoms of inadequate energy utilisation?

A
  • Tiredness
  • Lethargy
  • Weakness
  • Unexplained weight loss (due to increased metabolism of fatty acids)
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5
Q

What tests could you perform to help diagnose diabetes?

A
  • Fasting blood glucose
  • Oral glucose tolerance test
  • HbA1c (Type II only)
  • Need symptoms and 1 abnormal test (2 if asymptomatic) to be diagnosed
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6
Q

What is the advantage of performing a HbA1c test on a person with Type II DM?

A
  • GLYCATION of Haemoglobin in RBC due to high plasma glucose
  • Lifespan of RBC is ~120 days
  • Gives % reading of blood glucose levels (glucose saturation) over the past 120 days
  • Can monitor if diet/lifestyle modifications in Type II are effective
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7
Q

What are the diagnostic criteria that define diabetes?

A
  • Fasting venous plasma glucose of >7mmol/L
  • Random venous plasma glucose of >11.1mmol/L
  • HbA1c of >6.5%
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8
Q

Why can HbA1c NOT be used to diagnose Type I diabetes?

A

Patients have a short history of symptoms (onset is about 2-3 weeks)

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9
Q

What defines Type I diabetes mellitus?

A
  • Autoimmune destruction of β cells in islets of pancreas so no insulin production
  • Insulin deficiency
  • Hyperglycaemia
  • Lipolysis leads to increased production of ketone bodies which can cause KETOACIDOSIS (fatal)
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10
Q

Explain why Type II diabetes can be as a result of insulin resistance AND insulin deficiency

A
  • Insulin resistance of cells means glucose cannot be utilised so plasma levels rise
  • β cells secrete more insulin to compensate for high blood glucose
  • Eventually β cells wear out (exhaustion) which leads to relative lack of insulin
  • Type II diabetics can also require the administration of insulin
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11
Q

List 3 factors (other than β cell failure) that can contribute to the cause of diabetes

A
  • Drug induced e.g. Steroids
  • Genetic defects of β cell or insulin action
  • Pancreatitis (acute or chronic)
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12
Q

Explain the presentation of Type I diabetes in a patient

A
  • Patient usually
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13
Q

Describe the effects of insulin on cell metabolism

A
  • PROMOTES glycogenesis, lipogenesis, protein synthesis

- INHIBITS glycogenolysis, lipolysis, proteolysis, gluconeogenesis

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14
Q

Explain how insulin deficiency can lead to weight loss and ketoacidosis

A
  • Absolute lack of insulin so cells cannot utilise glucose
  • Signals stress response so lipolysis is activated to produce ketone bodies for brain metabolism (as glucose is unable to enter)
  • Fat metabolised so patient loses weight
  • Ketone bodies can accumulate in blood altering the buffering mechanisms and causes ketoacidosis - fatal
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15
Q

What factors can diagnose Type I diabetes straight away?

A
  • Elevated venous plasma glucose >10mmol/L
  • Presence of KETONES (smell acetone on breath)
  • High blood pressure
  • Family history
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16
Q

How is Type I diabetes treated?

A
  • Exogenous insulin injections (MUST)
  • Subcutaneous insulin injections several times per day
  • Fluids (saline, water)
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17
Q

What percentage of people with Type II overweight or obese?

A

90%

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18
Q

Describe the aetiology of Type II diabetes

A
  • Insulin resistance due to obesity
  • β cell failure which leads to relative lack of insulin
  • Genetic and environmental factors
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19
Q

Describe how obesity can lead to insulin deficiency

A
  • First leads to insulin resistance
  • Secretion of more insulin due to increase in circulating fatty acids (need to be stored)
  • Pancreatic exhaustion
  • Hyperglycaemia causes pancreas to secrete more insulin
  • Eventually β cell failure occurs
  • Can also have amyloid type deposits in islets which leads to β cell failure
20
Q

Explain why diet modification is the primary treatment method for Type II diabetes

A
  • Has been shown to drastically reduce blood glucose within a short period of time
  • Coupled with moderate exercise this is very effective
  • If diet changes and exercise do not work, drugs can be administered
21
Q

What are the effects of a hypo-calorific diet on insulin resistance?

A
  • Under hypo-calorific conditions fat is metabolised first from the LIVER (followed by other ectopic and subcutaneous sites)
  • Decrease in fat around liver results in normal hepatic insulin sensitivity
  • Glucose can slowly be utilised more so fasting glucose levels decrease
22
Q

Explain why a patient presenting with Type II diabetes may not have a presence of ketones

A
  • Still producing some insulin

- Fatty acid oxidation is inhibited by insulin so no ketones produced

23
Q

Describe the presentation of a patient with Type II diabetes

A
  • Most are >40 yrs however increasing in younger population
  • Variable and slower rise in blood glucose
  • Polyuria, Polydipsia, weight loss, lack of energy, persistent infections, blurred vision
  • NO KETONES
  • May be ASYMPTOMATIC
24
Q

What happens if Type I diabetes is left untreated?

A
  • Severe hyperglycaemia
  • KETOACIDOSIS
  • Coma/DEATH
25
What happens if Type II diabetes is left untreated?
- Gradual worsening of symptoms e.g. Inadequate energy utilisation leading to sedentary behaviour - Onset or worsening of complications related to diabetes e.g. Severe morbidity, mortality, susceptibility to CVDs
26
Explain the treatment methods of Type II diabetes
- PRIMARY treatment includes diet modification (low kcal) and moderate exercise - If hyperglycaemia persists, can use drugs such as biguanides (Metformin), sulphonylureas and INSULIN - Requires patient education for monitoring blood glucose
27
Describe the action of sulphonylureas
- Increase insulin release from (remaining) β cells | - Reduce insulin resistance
28
Explain how the autoimmune destruction of β cells can be triggered
- Genetic predisposition associated with genetic markers HLA DR3 and HLA DR4 - Environmental trigger e.g. Viral infection that triggers immune response (activation of T lymphocytes and macrophages)
29
Explain how increased plasma glucose can lead to Polyuria and Polydipsia
- Glucose normally reabsorbed in PCT after ultrafiltration in glomerulus - Reabsorption is ISOSMOTIC (same osmotic pressure) - Increased plasma glucose filtered out is not all absorbed so some glucose remains in nephron - EXTRA OSMOTIC LOAD - Less water reabsorbed to maintain isosmotic character so extra water is excreted along with glucose - Leads to increased thirst as DEHYDRATION occurs
30
Explain why people with hyperglycaemia are more susceptible to urogenital and thrush infections
- Increased glucose concentration attracts bacteria | - Growth environment for broth turbidity/Biofilms
31
Describe the presentation of a patient with KETOACIDOSIS
- Severely ill - Hyperventilation (KUSSMAUL BREATHING) - Prostration (elevated chest and abdomen) - Nausea/vomiting - Dehydration - Abdominal pain
32
Describe how you could test for the presence of ketones
- Presence in urine using a KETOSTIK | - Smell of acetone on breath
33
Explain why a person with diabetes may have blurred vision
- Hyperglycaemic | - Increased plasma glucose causes lens of eye to swell, affecting the refractive index of the eye
34
Describe the steps of an oral glucose tolerance test
- Take fasting blood sample from patient - Administer 75g glucose orally e.g. 395ml Lucozade - Take another sample of blood after 2 hrs of administration - If plasma glucose is >11.1mmol/L indicates hyperglycaemia
35
Explain how persistent hyperglycaemia may leave some tissues susceptible to ROS damage
- Uptake of glucose in some tissues is regulated by extracellular concentration e.g. Peripheral nerves, eye and kidney - If plasma glucose is high, it leads to increased intracellular concentration - Excess glucose metabolised by ALDOSE REDUCTASE into SORBITOL - NADPH ---> NADP+ in the process - Depletion of NADPH stores leaves cells more susceptible to oxidative damage as it is needed to recycle glutathione
36
How does GLYCATION differ from GLYCOSYLATION?
GLYCATION is non-enzymatic
37
Describe how glycation can affect protein function
- Glucose binds to free amino acid residues on proteins | - Change in overall NET CHARGE and 3D structure of protein so disrupts functioning
38
What is diabetes mellitus?
- Blood glucose is too high (HYPERGLYCAEMIA) due to either absolute lack of insulin or decrease in cell sensitivity to insulin - Can lead to problems such as ketoacidosis and micro/macrovascular damage - Can cause premature death from CVD
39
Explain the significance of the HbA1c test
- GLYCATION of Haemoglobin in blood at terminal valine due to elevated blood glucose - RBC have a lifespan of ~120 days - Related to the average blood glucose over the preceding 120 days from when it was taken - Can indicate how well blood glucose has been monitored in diabetics
40
List 3 MICROVASCULAR complications associated with diabetes
- Diabetic retinopathy - Diabetic neuropathy - Diabetic nephropathy
41
Explain why it is essential that the feet of diabetics are checked regularly
- Feet particularly vulnerable in diabetics - Poor circulation - Damage to nerves - Increased risk of infection - Failure to examine feet and detect changes may result in amputation (e.g. Gangrene)
42
What visual problems may be associated with diabetes?
- Glaucoma -> osmotic effects of glucose draw water into eye - Cataracts -> production of sorbitol depletes NADPH stores which is needed for protection from ROS damage - Retinopathy - damage to blood vessels (may rupture causing bleed; leakage leads to formation of protein exudates on retina) - All can lead to BLINDNESS
43
Describe the cause and detection of diabetic nephropathy
- Damage to glomeruli due to high blood glucose - Damage from infection of urinary tract - Detected by increased amount of proteins such as ALBUMIN in urine
44
Explain how diabetic neuropathy can affect the feet of diabetics
- Damage to periphery nerves by increased intracellular concentration of glucose - Depletion of NADPH stores, production of SORBITOL (causes osmotic damage to cells) - Leads to loss of sensation and changes due to alteration of autonomic nervous system - Damage to feet may go undetected
45
Explain how sorbitol is produced and what it's effects on the tissue is
- In some cells glucose uptake is determined by extracellular concentration - In patients with hyperglycaemia the intracellular concentration of glucose increases (due to increased uptake) so glucose is converted to SORBITOL using aldose reductase - Sorbitol causes OSMOTIC DAMAGE to cells and tissues
46
What are the MACROVASCULAR complications of diabetes?
- Increased risk of STROKE - Increased risk of MYOCARDIAL INFARCTION - Poor circulation to periphery - particularly in feet