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Pathology - Year 2 AC > Week 7 - Diabetes Mellitus > Flashcards

Week 7 - Diabetes Mellitus Flashcards

1
Q

What type of hormone is insulin?

A

Peptide hormone

-51 amino acids

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2
Q

Where is insulin produced?

A
  • B cells of the islets of Langerhans of the pancreas

- also produce glucagon and pancreatic polypeptide

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3
Q

How does insulin take affect and what effect does it have?

A
  • released in to blood stream from the B-cells of the islets of Langerhans in the pancreas
  • bind to cell membrane receptors of target cells
  • regulates glucose uptake and metabolism
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4
Q

Which cells require insulin and why?

A
  • skeletal muscle cells and fat cells require insulin to absorb glucose
  • both types can accumulate large carbohydrate reserves
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5
Q

Which cells don’t require glucose and why?

A
  • neurons and a variety of other cells don’t require insulin to absorb glucose
  • can’t accumulate significant carbohydrate reserves
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6
Q

What are the actions of insulin?

A
  • uptake of glucose by cells
  • uptake of amino acids by cells
  • increased glycogen synthesis
  • increased synthesis and esterification of fatty acids
  • decreased lipolysis, proteinolysis and gluconeogenesis
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7
Q

How is insulin release controlled?

A

Mainly direct feed back

  • B-cells absorb glucose via glucose transporter GLUT2
  • complex metabolic pathway releases pre-synthesised insulin

Some autonomic control

Also released by cholecystokinin derived from enteroendocrine cells of intestinal mucosa

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8
Q

What are the acute consequences of insulin deficiency?

A
  • hyperglycaemia
  • ketosis (raised ketone levels)
  • acidosis (excessive blood acidity)
  • hyperosmolar state
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9
Q

What are the chronic consequences of insulin deficiency?

A
  • CV disease
  • nephropathy
  • neuropathy
  • retinopathy
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10
Q

What types of diabetes mellitus are there?

A
  • type 1
  • type 2
  • gestational
  • secondary (direct consequence of something e.g. giving steroids)
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11
Q

Explain diabetes mellitus type 1

A

Autoimmune destruction of B-cells

  • probably triggered by viral infection (coxsackie/rubella)
  • susceptibility partly dependant on HLA gene subtypes (HLA-DR3/DR4)
  • classically starts in childhood, though adult onset is not rare
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12
Q

What are the classical symptoms of type 1 diabetes?

A
  • polyuria (production of abnormally large volumes of dilute urine)
  • polydipsia (abnormally great thirst)
  • hunger
  • weight loss

(Can be seen in DM type 2 but often camouflaged by other symptoms)

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13
Q

How does polyuria occur as a symptom in DM type 1?

A
  • normal for glucose to be secreted into the urine in the glomerulus at normal concentrations (all of this glucose is reabsorbed in the proximal renal tubule)
  • threshold for reabsorption is about 10mmol/l - higher concentrations lead to glycosuria (excess sugar in the urine)
  • glycosuria leads to osmotic polyuria
  • polyuria leads to polydipsia
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14
Q

Explain DM type 2

A

Pathophysiology complicated:

  • peripheral insulin resistance
  • B-cell response to glucose delayed or absent
  • insulin concentrations normal or high

Strong association with lifestyle

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15
Q

What is gestational diabetes?

A
  • insulin resistance, probably triggered by hormonal changes of pregnancy
  • genetic predisposition
  • resolves with delivery
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16
Q

What are the risk factors for gestational diabetes?

A
  • maternal age
  • family history of DM type 2
  • African or North American native
  • previous gestational diabetes
  • previous baby over 4kg
  • smoking
17
Q

What are the dangers of gestational diabetes for the mother?

A
  • greater risk of DM type 2 later in life
  • hypertension
  • pre-eclampsia or eclampsia (condition which one or more convulsions occur in a pregnant women suffering from high BP)
  • obstructed labour
18
Q

What are the dangers of gestational diabetes for the child?

A
  • risk of DM type 2 later in life
  • risk of obesity later in life
  • macrosomia - big body
  • neonatal hypoglycaemia
  • neonatal jaundice
  • respiratory distress syndrome
19
Q

What can cause secondary diabetes mellitus?

A
  • chronic pancreatitis
  • cystic fibrosis
  • pancreatic surgery
  • haemachromatosis
  • endocrine disease e.g. Cushing’s syndrome
  • drug therapy e.g. corticosteroids
20
Q

How is diabetes diagnosed biochemically?

A

Criteria:
-fasting plasma glucose level at or above 7.0mmol/l

  • plasma glucose at or above 11.1mmol/l two hours after a 75g oral glucose load
  • random plasma glucose at or above 11.1mmol/l
  • glucose tolerance test
21
Q

What are the acute presentations of diabetes mellitus?

A 
Ketoacidosis
Hyperosmolar non-ketotic state
Hypoglycaemia (insulin overdose, can lead to coma and death) 
Diabetic foot (can lead to general sepsis and death)
22
Q

What is ketoacidosis?

A
  • rapid breakdown of fat and protein releases ketones (including acetone) and acids in to the bloodstream
  • DM type 1 and rarely type 2
  • can lead to coma and death
23
Q

What is hyperosmolar non-ketotic state?

A
  • severe dehydration
  • DM type 2
  • can lead to coma and death
24
Q

What are the chronic presentations of diabetes mellitus?

A
  • macrovascular (ischaemic heart disease, stroke, peripheral vascular disease)
  • microvascular (retinopathy, neuropathy, nephropathy)
  • cataracts
25
Q

What is diabetic retinopathy?

A

Proliferation of blood vessels in the retina
-retinal haemorrhages

Macular oedema
-fluid exudation into retina

Microaneurysms

Hyperglycaemia alone can cause visual disturbance, but this isn’t diabetic retinopathy

26
Q

What is diabetic neuropathy?

A

Microangiopathy of vasa nervosum
-(peripheral numbness or tingling, occasional neuropathic pain, muscle weakness, autonomic neuropathy (vomiting, diarrhoea, constipation, incontinence, impotence, anorgasmia, postural hypotension))

Microangiopathy of glomerular capillaries

  • pathology: nodular and diffuse glomerulosclerosis
  • clinical: chronic renal failure or nephrotic syndrome; hypertension
27
Q

What are the two types of diabetes and what are they caused by?

A

Diabetes mellitus

  • deficiency to insulin
  • resistance to effects of insulin

Diabetes insipidus
-deficiency of ADH

28
Q

What is angiopathy?

A

Disease of blood vessels

So microangiopathy is disease of blood vessels affecting small blood vessels in the body

Pathology - Year 2 AC (19 decks)

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