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354: Pathobiology > 5. Diabetes Mellitus > Flashcards

5. Diabetes Mellitus Flashcards

1
Q

define diabetes mellitus

A

a group of metabolic diseases characterised by hyperglycaemia resulting from defects in insulin secretion, insulin action or both

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2
Q

where is insulin secreted

A

from beta cels of the islets of langerhans

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3
Q

what are incretins

A

a group of metabolic hormones that stimulate a decrease in blood glucose levels.

they are released after eating and augment the secretion of insulin

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4
Q

what is the incretin effect

A

the phenomenon where glucose consumed orally elicits higher insulin secretory responses than intravenous glucose.

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5
Q

how is glucose reabsorbed

A

using SGLT receptors

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6
Q

what is the renal glucose threshold, what does this mean?

A

10 mmol
- anything over 10 mmol ends up in the urine

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7
Q

name 3 other factors that contribute to hyperglycaemia (increased blood glucose)

A

increased glucose reabsorption
decreased glucose uptake into cells
increased glucagon secretion

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8
Q

where is glucagon secreted from

A

alpha cells

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9
Q

describe the structure of insulin

A

52 amino acids with A and B chains linked by disulphide bonds

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10
Q

how is insulin synthesised, and what is it cleaved into

A

synthesised as pre-proinsulin and cleaved into proinsulin

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11
Q

diabetes has an increasing global burden, what has happened to cases in the last 25 years

A

almost doubled!!

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12
Q

what 2 things does insulin inhibit

A

inhibits gluconeogenesis and lipolysis

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13
Q

what is the role of insulin

A

facilitates glucose transport into muscle and fat cells

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14
Q

name 6 clinical symptoms of DM

A

fatigue
wounds that won’t heal
sudden weight loss
frequent urination
sexual problems

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15
Q

why do people with DM experience sudden weight loss

A

muscle and fat is broken down for energy

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16
Q

why do people with DM frequently urinate, what does this lead to?

A

an excess of blood glucose (hyperglycaemia) results in glucose expulsion in the urine (takes the urine with it)

this then causes dehydration - the patient drinks more to replace the lost water

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17
Q

why do people with DM experience wounds that won’t heal

A

high sugar increases inflammation and decreases immunity

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18
Q

what does glucagon inhibit

A

insulin and gastric inhibitory polypeptide (GIP)

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19
Q

what triggers the release of insulin

A

glucose
GIP
parasympathetic stimulation

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20
Q

what triggers the release of glucagon

A

low glucose
sympathetic stimulation
adrenaline

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21
Q

which branch of the nervous system coordinates the fight or flight response

A

sympathetic

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22
Q

what is an A1C measure used for diagnosing diabetes

A

a good indication of how glucose has been in the past 3 months, Hb binds to glucose and it can remain in the blood stream for up to 3 months

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23
Q

what is the A1C threshold for diabetes

A

> 6.5%

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24
Q

what is the prevalence of type 1 diabetes

A

1 per 430-530 people aged 19+

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25
Q

what is the average age for diagnosis of DM

A

10-14 years

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26
Q

name the 5 types of diabetes

A

type 1
type 2
gestational diabetes
mody diabetes
lada diabetes

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27
Q

which type of diabetes is an autoimmune disease

A

type 1

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28
Q

which type of diabetes develops the quickest

A

type 1

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29
Q

when is type 1 diabetes typically diagnosed

A

in young children

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30
Q

when is type 2 diabetes typically diagnosed

A

in adults

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31
Q

describe what happens in gestational diabetes

A

pregnancy hormones redirect glucose to the growing foetus rather than the mother

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32
Q

is gestational diabetes pathological

A

normally no - in most cases it reverses following birth

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33
Q

what type of diabetes does gestational diabetes increase the risk for later in life

A

type 2 DM

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34
Q

how can gestational diabetes be treated

A

through diet and exercise and in some cases insulin

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35
Q

what is mody diabetes

A

presents similar to type 2 diabetes but in a young person

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36
Q

what is lada diabetes

A

presents similar to type 1 diabetes but in an older person

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37
Q

which has a strong genetic risk factor: mody or lada diabetes

A

mody diabetes

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38
Q

which one is an autoimmune disease: mody or lada diabetes

A

lada diabetes - a latent autoimmune diabetes of adulthood

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39
Q

what is the concordance rate for type 1

A

50%

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40
Q

by how many times higher is the risk of developing T1DM if you have a first degree relative with the condition

A

15 x higher

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41
Q

list 2 viruses that can cause type 1 DM

A

cosackie B
mumps (causes pancreatitis)

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42
Q

name 2 dietary factors that can cause type 1 DM

A

cows milk, caffeine, nitrates

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43
Q

name 2 lifestyle factors that can cause type 1 DM

A

exposure toxins
stress

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44
Q

what geographical factor also increases risk of DM

A

increasing latitude (distance away from the equator)

45
Q

what happens to islet cells targeted by antibodies in T1DM

A

these become fibrotic

46
Q

name 3 autoantibodies implicated in DM type 1 pathology

A

antibodies to:
insulin
glutamic acid decarboxylase (GAD)
zinc transporter 8

47
Q

what are the most frequent risk factors for type 2

A

obesity
hypertension
strong family history

48
Q

what happens to insulin in type 2

A

cells become insulin resistant

49
Q

what is the concordance rate of T2DM

A

90%

50
Q

if you gain how much weight over 18 years, your risk of T2DM will double

A

7-11 kg

51
Q

why has the global burden of diabetes increased

A

increased westernisation and urbanisation - the western diet ubiquitous in dietary emulsifiers

52
Q

how does obesity cause type 2 dm

A

inflammation

53
Q

name 2 cytokines that increase inflammation in type 2 DM

A

adiponectin
TNF-alpha

54
Q

what is adiponectin

A

an adipocyte derived cytokine

55
Q

what happens if infliximab is administered to obese rodents

A

blocking TNF-alpha antibodies improves glucose utilisation

56
Q

what happens to rheumatoid arthritis patients treated with infliximab

A

lower incidence of diabetes

57
Q

name a chemokine molecule that increases inflammation in obesity

A

CXCL5

58
Q

what is the action of CXCL5

A

it binds to CXCR2 to reduce insulin-stimulated glucose uptake in the muscle

59
Q

what is evidence for the role of CXCL5 in obesity

A

serum levels of CXCL5 is higher in obese individuals and T2DM obese patients compared to healthy individuals of a normal weight

60
Q

how can you differentiate between type 1 and type 2 DM - provide 2 methods

A

islet autoantibody testing - positive result in T1 and lada

serum c-peptide - if it is low it shows there is insufficient insulin (<0.2 mol/l)

61
Q

what is monogenic diabetes

A

diabetes that arises from specific genetic mutations

62
Q

name a mutation found in monogenic diabetes

A

mutations in glucokinase

63
Q

how many diabetes cases does monogenic diabetes account for

A

2%

64
Q

name 2 acute complications of DM

A

hypoglycaemia
diabetic ketoacidosis

65
Q

name the 2 types of chronic complications of DM

A

microvascular and microvascular

66
Q

what condition is diabetic ketoacidosis common in

A

type 1 DM

67
Q

describe the process of ketoacidosis

A

when there is lowered insulin there is increased lipolysis which increases the concentrations of FFAs

ketosis is where these FFAs are broken down to produce energy as well as ketones - the accumulation of ketones leads to acidosis as the pH decreases

68
Q

name 2 ketones

A

acetone and butyric acid

69
Q

what are the 3 types of microvascular chronic complications

A

diabetic nephropathy
neuropathy
retinopathy

70
Q

what is diabetic nephropathy

A

where concentrations of microalbuminuria rise and proteinuria happens.

glomerular death occurs and so does renal failure

71
Q

what is diabetic neuropathy

A

loss of sensation of injury

72
Q

what can form as a result of diabetic neuropathy

A

foot ulcers - pain of standing on an object is not detected by nociceptors due to damaged blood vessels, pressure depends the stone into the tissue which can become infected

73
Q

what is diabetic retinopathy

A

the thinning out of vasculature and eventual haemorrhage

74
Q

what does hyperglycaemia result in the production of

A

advanced glycation end products

75
Q

what do advanced glycation end products do

A

bind to receptors to induce a pro inflammatory cascade of cytokines and adhesion molecules.

they can also alter the function of proteins to result in vascular changes or endothelial permeability changes.

76
Q

name three macrovascular chronic complications

A

stroke
heart damage
atherosclerosis

77
Q

what percentage of newly presenting patients with type 2 DM already have one or more complication at diagnosis

A

50%

78
Q

what 5 methods can be used to monitor glycaemic control

A
  1. symptoms
  2. urinalysis
  3. capillary glucose
  4. HbA1c
  5. interstitial glucose
79
Q

which method for monitoring glycemic control has become redundant

A

urinalysis

80
Q

how is capillary glucose measured

A

using a finger prick

81
Q

what is capillary glucose critical for monitoring

A

type 1

82
Q

what does HbA1c measure

A

the amount of glucose attached to RBCs - provides an indication of what someones blood glucose has been doing over the past 3 months

83
Q

what two tools can be used to measure interstitial glucose

A

continuous glucose monitoring

flash glucose monitoring

84
Q

how does continuous glucose monitoring work

A

sensor monitors interstitial glucose levels - the date is transmitted to a monitor which beeps when it is either too low or too high. it then is transmitted to an insulin pump which corrects glucose levels

85
Q

what is the benefit of continuous glucose monitoring

A

it is a closed loop system - blood sugar is automatically fixed by the pump

86
Q

how far behind blood glucose levels is interstitial glucose levels

A

interstitial levels are 15 minutes behind blood glucose

87
Q

describe how flash glucose monitoring works

A

sensor is worn on the arm, the date is transmitted to a device when it is passed over the sensor. the monitor will show a glucose trend which can warn of hypoglycaemia

88
Q

which is more expensive, continuous glucose monitoring or flash glucose monitoring

A

continuous glucose monitoring

89
Q

how long can the sensor be worn on the arm for

A

up to 14 days

90
Q

what are the typical treatments of type 1 diabetes

A

insulin
glycemic control
screening to prevent complications

91
Q

where was insulin originally derived from

A

pigs and cows

92
Q

how is insulin extracted nowadays

A

the gene for human insulin is expressed in bacteria or yeast

93
Q

most patients are on a basal-bolus regime, what does this mean>

A

they are given a long acting insulin analogue
and a prandial rapid acting insulin

the prandial insulin dose is adjusted according to the carbohydrate content of meals and blood sugar levels.

94
Q

to improve patient outcomes, what lifestyle changes are encouraged

A

physical exercise
smoking cessation and lowering alcohol intake

95
Q

what are biguanides

A

drugs that increase glucose uptake and utilisation by target tissues and reduce insulin resistance

they also suppress hepatic glucose production

96
Q

what is the only available biguanide

A

metformin

97
Q

what is a side effect of metformin

A

weight loss

98
Q

what is the mode of action of sulfonylureas

A

works on beta cells to increase insulin secretion - it does this by closing K+ channels on the membrane and depolarising them

99
Q

what happens when beta pancreatic cells are depolarised

A

calcium channels open which leads to an increased fusion of insulin granular with the cell membrane = secretion of proinsulin

100
Q

what is the side effect of sulfonylureas

A

weight gain - it prompts people to eat more

101
Q

name 2 inhibitors used to treat type 2 DM

A

DPP-IV inhibitors
SGLT2 inhibitors

102
Q

what must be present for DPP-IV inhibitors to work

A

food

103
Q

how does DPP-IV inhibitors work

A

inhibits the DPP-IV enzyme, causing levels of incretin hormones GLP-1 and GIP to increase.

this prompts beta-cell insulin secretion and reduces postprandial hyperglycaemia

104
Q

how does GLP-1 work (an incretin hormone)

A

lowers blood glucose by stimulating insulin secretion and reducing glucagon concentrations

105
Q

what drug also works on GLP-1 and what does it do

A

GLP-1 agonists used in the treatment of T2DM
it delays gastric emptying, inhibits glucagon production and stimulates insulin secretion.

106
Q

what plastic response can worsen hyperglycemia

A

when there is more glucose in the blood, the expression of SGLT2 can be up-regulated. this worsens the response as more glucose gets reabsorbed

107
Q

how do SGLT2 inhibitors work

A

decrease glucose reabsorption leading to greater excretion

108
Q

what is a side effect of SGLT2 inhibitors

A

can cause dehydration as glucose is osmolarity active and takes water with it as its excreted.

354: Pathobiology (10 decks)

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