13. DIABETES MELLITUS Flashcards

1
Q

Diabetes mellitus

A

deficiency of insulin

resistance to effects of insulin

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2
Q

Diabetes insipidus

A

deficiency of antidiuretic hormone

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3
Q

Insulin (1)

A

peptide hormone
51 amino acids
produced in ß-cells of the islets of Langerhans of pancreas; they also produce glucagon and pancreatic polypeptide
released into bloodstream
binds to cell membrane receptors of target cells
regulates glucose uptake and metabolism, and a whole host of other stuff

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4
Q

Insulin (2)

A

skeletal muscle cells and fat cells require insulin to absorb glucose; both types can accumulate large carbohydrate reserves

neurons and a variety of other cells do not require insulin to absorb glucose; they cannot accumulate significant carbohydrate reserves

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5
Q

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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6
Q

Control of insulin release

A

mainly direct feedback
ß-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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7
Q

Acute consequences of insulin deficiency

A

hyperglycaemia
ketosis
acidosis
hyperosmolar state

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8
Q

Chronic consequences of insulin deficiency

A

cardiovascular disease
nephropathy
neuropathy
retinopathy

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9
Q

Types of diabetes mellitus

A

Type 1
Type 2
Gestational
- WHO classification

Secondary

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10
Q

Diabetes mellitus type 1

A

autoimmune destruction of ß-cells
probably triggered by viral infection
Coxsackie or rubella viruses
susceptibility partly dependent on HLA gene subtypes (HLA-DR3/DR4)
classically starts in childhood, though adult onset not rare

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11
Q

Diabetes mellitus type 2 (1)

A
former names 
   non insulin dependent diabetes mellitus (NIDDM)
   obesity related diabetes mellitus
   adult-onset diabetes mellitus
   etc, etc
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12
Q

Diabetes mellitus type 2 (2)

A

pathophysiology complicated
peripheral insulin resistance
ß-cell response to glucose delayed or absent
insulin concentrations normal or high
strong association with lifestyle
up to 20% prevalence in the elderly in the USA

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13
Q

Gestational diabetes

A

genetic predisposition
insulin resistance, probably triggered by hormonal changes of pregnancy
resolves with delivery

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14
Q

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
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15
Q

Dangers of gestational diabetes

mother

A

greater risk of DM type 2 later in life
hypertension
pre-eclampsia or eclampsia
obstructed labour

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16
Q

Dangers of gestational diabetes

child

A
risk of DM type 2 later in life
   risk of obesity later in life
   macrosomia
   neonatal hypoglycaemia
   neonatal jaundice
   respiratory distress syndrome
17
Q

Secondary diabetes mellitus

A
chronic pancreatitis 
   cystic fibrosis
   pancreatic surgery
   haemachromatosis
   endocrine disease
   eg Cushing’s syndrome
   drug therapy
   eg corticosteroids
18
Q

Diabetes mellitus type 1 (2)

A
classical symptoms
   polyuria
   polydipsia
   hunger
   weight loss
  can be seen in DM type 2, but often camouflaged by other symptoms
19
Q

polyuria

A

it is normal for glucose to be secreted into the urine in the glomerulus
at normal concentrations, all of this glucose is resorbed in the proximal renal tubule
threshold for resorption is about 10mmol/l; higher concentrations lead to glycosuria
glycosuria leads to osmotic polyuria
polyuria leads to polydipsia

20
Q

Biochemical diagnosis of diabetes mellitus

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

21
Q

Acute presentations of diabetes mellitus (1)

A

ketoacidosis
rapid breakdown of fat and protein releases ketones (including acetone) and acids into bloodstream
DM type 1 and rarely type 2
can lead to coma and death

22
Q

Acute presentations of diabetes mellitus (2)

A

hyperosmolar nonketotic state
severe dehydration
DM type 2
can lead to coma and death

hypoglycaemia
insulin overdose, generally accidental
can lead to coma and death

diabetic foot
can lead to generalised sepsis and death

23
Q

Chronic presentations of diabetes mellitus

A
Macrovascular
   ischaemic heart disease
   stroke
   peripheral vascular disease
   Microvascular
   retinopathy
   neuropathy
   nephropathy
   Cataract
24
Q

Diabetic retinopathy

A

proliferation of blood vessels in the retina
retinal haemorrhages
macular oedema
fluid exudation into retina

NB Hyperglycaemia alone can cause visual disturbance, but this is not diabetic retinopathy

25
Q

Diabetic retinopathy

A
microangiopathy of vasa nervosum
   peripheral numbness or tingling
   occasional neuropathic pain
   muscle weakness
   autonomic neuropathy
  vomiting, diarrhoea, constipation 
  impotence, incontinence, anorgasmia
  postural hypotension
26
Q

Diabetic nephropathy

A

microangiopathy of glomerular capillaries

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

27
Q

Infections in diabetes mellitus

A
overall risk ratio 		1.21
   osteomyelitis 		4.39	
   septicaemia		2.45
   post-op infections	2.02
   rectal abscess		1.97	
   pyelonephritis		1.95