56 terms

Free Online NCLEX Review for the Complete Idiot. LVN/LPN. Diabetes #3. Monitoring and Control of Diabetes.

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what substances should be measured to gauge diabetic control?
random glucose
Glycated haemoglobin (HbA1c)
ketones
lipid: triglycerides, LDL, HDL, total cholesterol
renal function
urine protein
where should random glucose readings be taken from?
veins or capillaries
what other substances are affected by diabetes?
CRP
homocysteine
leptin
adiponectin
GLP-1
what are the three main reasons for testing blood glucose in diabetes?
-to adjust therapy to maintain normal glucose levels
-interpreting symptoms and signs
-to assess risks of tissue complications
what samples can be taken to measure glucose? (6)
urine
whole blood
plasma
capillary
arterial
interstitial
when does glycosuria occur? what values?
when renal threshold is exceeded
about 10mmol/l
how did egyptians used to test glucose levels (1500BC)?
tasting urine
what does Fehling's test do? when was this used?
reduces CuSo₄ which precipitates as Cu₂O in the presence of an aldehyde in urine
1850
when was benedict's solution first used for measuring urine sugar?
1907
when was the clinitest first used to measure urine sugar?
1941
what are the problems with measuring urine glucose?
-retrospective
-renal threshold can differ between patients and also individually
-fluid intake affects the urine concentration
how much lower is whole blood glucose compared to plasma glucose? why?
10-15%
it is affected by haematocrit
how does glycolysis in the RBC affect glucose concentration?
falls by 0.5mmol over 3 hours
how can glycolysis be inhibited? does this cancel out the drop in glucose concentration?
fluoride oxalate
no- there is still a 0.2-0.3 mmol/l drop
what measurement of glucose do labs usually use?
plasma glucose
what measurement of glucose do meters usually take?
whole blood glucose but convert it to a plasma glucose equivalent
what is the reaction catalysed by glucose oxidase?
Glucose + O₂--> gluconic acid + H₂O₂
how is the glucose oxidase reaction usually detected?
electrochemically as current flow
what is the reaction catalysed by peroxidase?
H₂O₂ + reduced dye --> oxidised dye (therefore coloured) + H₂O
why is the glucose oxidase reaction measured?
to monitor capillary glucose
how much blood is take in a capillary glucose measurement?
0.25ul
what is the error rate of capillary glucose to plasma glucose?
10-15%
how much is spent in the UK per year on capillary glucose monitoring strips?
over £100 million
How many times a day should patients with unstable blood glucose test?
over 4 times
How many times a day should patients with empowered T1DM test?
4 times
How many times a day should patients with unstable T2DM test?
4 times
How many times a day should patients with not empowered T1DM test?
1-2 times
How many times a day should patients with T2DM on insulin and suphonyureas test?
1-2 times
How many times a day should patients with T2DM which is controlled by diet/metformin/glitazone test?
don't need to
two tests which measure long term glucose control?
HbA1c
Serum fructosamine
how far back does an HbA1c test reflect?
2-3 months
how far back does a serum fructosamine test reflect?
6-8 weeks
(or 2 weeks-lifetime span of albumin??)
how does glucose attach to Hb?
covalently
how is HbA1c measured?
HPLC= high performance liquid chromatography
what is the reference range of HbA1c in non- diabetic people?
4-6%
what patients might an HbA1c test be inaccurate?
haemoglobin variants
HbS or HbC carriers
what type of conditions affect HbA1c?
ones which affect RBC turnover
How much of the HbA1c value is from glucose control in the previous month?
50%
what shape relationship does HbA1c have with the mean blood glucose over the life of RBC?
linear
what are the old and new measurements for HbA1c? when did it change? when will we stop co-reporting?
old (DCCT) = percentage
new (IFCC) = mmol/Mmol
June 2009
stop in 2011
what does 5% HbA1c equate to in the enw measurements?
10%
31mmol/Mmol
86 mmol/Mmol
what is fructosamine?
glycated albumin
how long is the lifetime of serum albumin?
2 weeks
when is fructosamin testing particularly useful? example?
when glucose control is changing quickly e.g. in diabetic pregnancy
how is serum fructosamine usually measured?
colorimetric assay
what is the reference range for serum fructosamine?
200-285 umol/l
3 ketone bodies which are measured in diabetes?
-acetone
-3 (orß)-hydroxybutyric acid
-acetoacetic acid
how are the ketone bodies formed in diabetes?
lack of insulin means triglycerides are broken down to fatty acids and glycerol.
Fatty acids are converted to acetyl coA which is converted to acetoacetic acid which can then be converted to both acetone and 3 (-hydroxybutyric acid.
what test are the strips and tablets for testing ketone bodies based on? what is it?
Rothera's test
nitroprusside/glycine turns purple in the presence of acetoacetic acid/acetone
what isn't detected in ketone body test strips/tablets?
3-hydroxybutyric acid
what is looked for when testing for renal function?
proteinuria
microalbuminuria (e.g. unrin albumin:creatinine)
plasma creatinine
what is serum cholesterol a risk factor for in diabetes?
coronary heart disease
what should levels of:
cholesterol
triglyceride
HDL
and
LDL be?
<4 mM
<1.7 mM
>1.1 mM
<2 mM
how is continuous glucose monitoring carried out?
subcutaneously implanted enzyme electrode where glucose oxidase is immobilised
what is a problem with continuous glucose monitoring?
measures tissue glucose which lags behind blood glucose by 5- 15 minutes
what are advantages to continuous glucose monitoring?
can have a alarm to warn of high/low blood sugars
provides "real time" readings
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