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REGUB: Path of T1DM (i) (Intro (diabetes = several distinct chronic…
REGUB: Path of T1DM (i)
Intro
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diabetes = several distinct chronic diseases characterised by adequate effect of insulin (key regulatory hormone)
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defects in secretion, action or both
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inadequate effect of insulin involves totality of carb, fat + protein metabolism
'diabetes' = passing through, referring to polyuria
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morbidity = huge health burden - significant resources used, economic cost
commonest cause of ESRD, adult blindness, non-traumatic LL amputation
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in US pop 6% have DM, further 2+% undated
incidence/prevalence of T2DM rising (longer lives, more prediabetic cases living long enough to progress)
greatest % increase in MICs - most people live here, westernisation
T2DM = disease of affluence/altered lifestyles, industrialised countries, ageing pop
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there is a continuous relationship between levels of blood glucose + risk of DM comps (e.g. retinopathy)
all tests reliable in the prediction of comps, but not a black + white cutoff for dx (comps still possible with pre-diabetes)
Dx
random plasma glucose > 11.1mmol/l + osmotic symptoms of hyperglycaemia (polyuria, polydipsia, weight loss)
OR 2hr post-75g glucose load (oral GTT - fast overnight for @ least 8 hrs, then a glass of lucozade, standardised load, see how body handles the glucose load), measure plasma glucose after 2 hrs (+ve if > 11.1, normal <7.8)
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OR HbA1C (glycated Hb > 48mmol/mol (new units) or 6.5% (old units) - good for HICs, no fasting required - most acceptable, most expensive, requires more technology, unsuitable if acutely unwell or for dx of T1DM (rapid disease evolution) or for haemoglobinopathy or haemolysis
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blood glucose most accurately measured in venous blood (special tube with fluoride added = paralysis RBC metabolism so cells don't use the glucose in the blood)
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FPG easier, cheaper, more acceptable
OGTT cumbersome, now rare as a primary test
Point of care testing
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suitable for use @ bedside or @ home (self-management, glycemic control)
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HbA1C
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glycosylation of Hb = non-enzymatic reaction, rate only related to conc of blood glucose
previously % of Hb which glycated, now mmol of glycated Hb per mol Hb (hard units, agreed standard)
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Glycosuria
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1% of pop have inherited low renal threshold for tubular reabsorption of glucose (false +ves as these people easily spill glucose into urine), there also can be false -ves
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Pre-diabetes
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HbA1c 37-48/5.7-6.4% (ADA), 42-48/6-6.4% (WHO)
adult pop testing: 2% undxed DM, 5% pre-diabetes
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risk may be modulated by diet, weight loss, exercise, weight-losing drugs/surgery
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Progression of DM
established DM (T1 or 2) is typically preceded by a phase of abnormal glucose homeostasis as the disease progresses
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longer duration of progression in T2, increasingly may be recognised as prediabetes
progression in T2 can be modified or even reversed - diet, exercise, weight loss, drugs, surgery