monitoring is showing up
the limitations of HbA1c,
which is just a summary of
control over a three-month
" Time in range (TIR) generally refers to
the time spent in an individual's target
glucose range (usually 3.9-10mmol).
TIR measurements add valuable
information to assess the level of current
glycaemic control in addition to what
is known from the HbA1c. However,
clinicians, researchers, and regulators
now know that time in target range
alone is not an adequate description
of overall glycaemic control. It is also
necessary to quantify the times below
and above target range, using a few
severity thresholds for each level. Thus, time in 'ranges' (TIRs) provide a more useful
metric for clinical and research purposes.
TIRs are useful for a research comparison of interventions and can help
patients understand whether the amount of clinically significant hypoglycaemia or
hyperglycaemia they are experiencing is improving over time. Isolating and counting
the time in hypoglycaemia and hyperglycaemia into level 1 (monitor and take action if
needed) and level 2 (immediate action required due to the more potentially clinically
significant nature of the glucose levels) can guide the urgency and degree of clinical
Because the function of CGM use is to monitor glucose levels with the ultimate
goal of improving glycaemic control, it makes clinical sense to combine TIRs data
with other measures. HbA1c level and time in level 2 (clinically significant/immediate
action required) hypoglycaemia is one such combined measure. Time in target range
combined with time in level 2 hypoglycaemia is another such combined measure.
Ideally, the way to use TIR measurements is to assess and report the percentages
of time in ranges (target, hypoglycaemia, and hyperglycaemia). Different TIRs in
conjunction with a measure of glycaemic variability should be reported as key
diabetes control metrics in clinical studies.
CGM & TIR
continued over HEALTH ECONOMICS &
TIME IN RANGE
According to an article on Diabettech, "In order for the discussion about using
CGM and TIR to become standard in diabetes care, in order to move into the
mainstream CGM technology has to come down in price. Manufacturers need
to sell their products as Gap not Gucci. We get that it's not cheap to develop
the products, but if, instead of having a consumer base of 3% of the global
T1D population, you had 40% of the population, then the cost could become
a lot lower."
To read the full article, click http://bit.ly/diabettech_tir
reading of 7% might be spending a lot of
time in hypo and having a miserable time.
Also it is only designed to measure mean
[average] glucose. It's hard for users to
correlate an HbA1c target with day-today
readings via blood tests, or even
via CGM. Time in range is much more
understandable, and therefore in many
ways more useful for patients. It's good
to be able to tell them that not all blood
tests will be bullseyes."
The fact remains that not all diabetics
are getting access to (or are paying for)
CGM, but you can get pretty much the
same results using blood tests to see
how much time you spend in range. Says
Choudhary, "An HBA1c of 8% has a mean
Variability - going up, going
down - is problematic.
Improve on that, and it all
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