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Flashcards in DIABETES MELLITUS Deck (28)
1

Diabetes mellitus

deficiency of insulin
resistance to effects of insulin

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Diabetes insipidus

deficiency of antidiuretic hormone

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Insulin

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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Insulin and Skeletal muscle cells and fat cells

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

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insulin and neurons

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

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Actions of insulin

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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Control of insulin release

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

8

Acute consequences of insulin deficiency

hyperglycaemia
ketosis
acidosis
hyperosmolar state

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Chronic consequences of insulin deficiency

cardiovascular disease
nephropathy
neuropathy
retinopathy

10

Diabetes mellitus type 1

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

11

Diabetes mellitus type 2 former names

former names
non insulin dependent diabetes mellitus (NIDDM)
obesity related diabetes mellitus
adult-onset diabetes mellitus

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Diabetes mellitus type 2

pathophysiology complicated
peripheral insulin resistance
ß-cell response to glucose delayed or absent
insulin concentrations normal or high
strong association with lifestyle

13

gestational diabetes

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

14

Risk factors for gestational diabetes

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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Dangers of gestational diabetes- mother

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

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Dangers of gestational diabetes - child

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

17

Secondary diabetes mellitus

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

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Diabetes mellitus type 1 - classical symptoms

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

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Polyuria

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

Biochemical diagnosis of diabetes mellitus

criteria
fasting plasma glucose level at or above 7.0 mmol/l
plasma glucose at or above 11.1mmol/l two hours after a 75 g oral glucose load
random plasma glucose at or above 11.1 mmol/l

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Acute presentation of diabetes mellitus - keto acidosis

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

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Acute presentation of diabetes mellitus -hyperosmolar nonketotic state

severe dehydration
DM type 2
can lead to coma and death

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Acute presentation of diabetes mellitus- hypoglycaemia

insulin overdose, generally accidental
can lead to coma and death

24

Acute presentation of diabetes mellitus - diabetic foot

can lead to generalised sepsis and death

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Chronic presentations of diabetes mellitus

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

26

Diabetic retinopathy

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

27

Diabetic neuropathy

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

28

Diabetic nephropathy

microangiopathy of glomerular capillaries
pathology: nodular and diffuse glomerulosclerosis
clinical: chronic renal failure or nephrotic syndrome; hypertension