Needed to read PDF's

Adobe Reader |
Continuous Glucose Monitoring
(CGM)
Overview
Continuous glucose monitoring (CGM) devices help you manage diabetes
with fewer fingerstick checks. A sensor just under your skin
measures your glucose levels 24 hours a day. A transmitter sends
results to a wearable device or cell phone so you can track changes
to your glucose level in real time. Learning how to use a CGM takes
time, but it can help you more easily manage your health.
Continuous glucose monitors (CGMs) have significantly
evolved, offering improved accuracy, reliability, and
user-friendliness. These devices are key tools for
continuous glucose monitoring and diabetes management. When
selecting the best continuous glucose monitor, understanding
the differences between real-time and intermittently scanned
CGMs is essential.
What is continuous glucose monitoring (CGM)?
CGMs continually monitor your blood glucose (blood sugar),
giving you real-time updates through a device that is
attached to your body. They have become popular and more
accurate over the years and are now considered a viable
treatment option for people with diabetes.
Advances in Continuous Glucose Monitor (CGM) technology have
made our lives easier, and that goes for people with
diabetes as well. Insulin administration and blood glucose
(blood sugar) monitoring have transformed from multiple
finger pricks in a day to a few swipes on a cell phone. With
a continuous glucose monitor (CGM), one can see in real time
if they’re trending high or low and take preventative
measures against hypo and hyperglycemia. Real time CGM
monitoring has led to tremendous outcomes for people with
diabetes who, without a CGM, may have experienced
potentially life-threatening complications.
With the benefits and ease of use that a CGM provides, it
would be natural to assume everyone with diabetes has one,
or at least has access to one. That however is not the case,
studies show that poorer, older, Black and Brown Americans
and Americans on Medicaid have less access to CGMs than
their counterparts. This is a health disparity we can’t
ignore. People with diabetes have the right to access the
latest technologies. Federal and state government officials
can and should take steps to drive improved and more uniform
coverage policies for diabetes technology and supplies
within.
What is interstitial fluid?
Interstitial fluid is the fluid in the spaces around
your cells. It comes from substances that leak out
of your blood capillaries.
One of these substances is glucose (sugar).
The sensor in a CGM goes just under your skin where
this fluid is — not in a blood
vessel. It measures the glucose in your
interstitial fluid.
Glucose hits your bloodstream first and then leaks
into your interstitial fluid. So, there’s a lag
between your blood glucose level and interstitial
glucose level. This means there may be a few minutes
delay in your CGM sensor glucose readings compared
with fingerstick (manual) blood glucose readings.
Popular CGM's |

FreeStyle Libre 3 |

Dexcom G7 |

FreeStyle Libre 2 |

Dexcom G6 |
-
With the brand-new Freestyle Libre 3, get
readings every minute. That's 1,440 readings per
day.
-
The world’s smallest, thinnest,
and most discreet, sensor—smaller
than two stacked pennies.
-
Sensor lifespan 15 Days
|
-
Uses Dexcom’s tiniest sensors yet - 60 percent
smaller than before
-
Unmatched accuracy and
warmup speed
-
Compatible with a fully-redesigned app
-
Approved for people with diabetes aged two years
and older
- Clarity App for sharing with your doctor
- Follow App for sharing with your family
-
Sensor lifespan 10 Days + 12-hour grace
period
|
-
Check your glucose levels up to 288 times per
day.
-
Glucose readings can be viewed on the FreeStyle Libre
2 reader or
on your smartphone with the FreeStyle Libre 2
app.
-
Sensor lifespan 15 Days
|
-
A small wearable sensor sends your number to
your smartphone every
five minutes. Known for accuracy, you don’t need
to use fingersticks.
-
Set your own glucose alerts to
notify you before you're too high or too low.
The Urgent Low Soon Alert can warn you up to 20
minutes before a low - even at night.
- Clarity App for sharing with your doctor
- Follow App for sharing with your family
-
Sensor lifespan 10 Days + 12-hour grace
period
|

 |

 |

 |

 |
How does a continuous glucose monitor (CGM) work?
You can choose among a handful of CGM devices
available today. Each works pretty much the same
way. The main differences are in a device’s
features, look and feel.
But all CGMs have three basic components:
-
Sensor: The sensor is a tiny piece of
material that measures real-time glucose levels
in your interstitial fluid. You’ll insert the
sensor under your skin with an applicator. It
uses a needle to pierce your skin. You remove
the needle, and it leaves the sensor in place.
Sensors typically last seven to 15 days,
depending on the brand. The implantable CGM
system lasts for months. It’s a small pellet
(about 18 millimeters long) that a healthcare
provider inserts under the skin of your upper
arm.
-
Transmitter: All CGM systems use a
transmitter to wirelessly send the glucose data
from the sensor to a device where you can view
it. For some CGM systems, the transmitter is
reusable and attaches to each new sensor. For
other CGM systems, the transmitter is part of
the disposable sensor.
-
Smartphone app, receiver or insulin pump:
This technology displays your real-time glucose
level and shows a graph of the history of your
levels. It can also show whether your glucose
level is trending up or down — and how
drastically. Most CGMs offer smartphone apps for
viewing data. Some offer handheld devices if you
don’t use a smartphone. Some CGM devices can
also send the glucose information to a
compatible insulin pump.
In general, here’s how a CGM works:
- You insert a small sensor just under your skin,
usually on your belly or arm. An applicator
makes this part quick and easy to do. Adhesive
tape holds the sensor in place.
- You’ll either connect the CGM transmitter to the
sensor or the sensor and transmitter will
already be connected when you insert it. You
must charge some transmitters before connecting
them to the sensor. You may also want to place
additional adhesive over the transmitter and
sensor to keep it in place on your skin.
- Depending on the type of CGM, there’ll be a
“warm-up” time before the sensor will share
data. This typically ranges from 30 minutes to
two hours.
- Most CGMs start sharing glucose data
automatically after the warm-up. Some require a
fingerstick blood glucose calibration before
they start sharing data.
- You’ll then see your current glucose level on
your smartphone app, receiver or insulin pump
for as long as the sensor lasts. You can set
certain alarms and settings for your app,
receiver or pump to alert you to when your
glucose is out of range. These ranges vary from
person to person.
- Once the sensor expires (or fails), you’ll start
the process over again.
You can download CGM data (trends and history) to a
computer at any time. Some CGM systems will send
data continuously. You can also share the
information with your healthcare provider.
Are CGMs easy to use?
CGM devices are complex little machines. They do
require some upfront time to understand their
technical aspects.
For example, you’ll need to learn how to:
- Insert the sensor properly.
- Calibrate the device with fingerstick blood
glucose readings (if necessary).
- Set device alarms.
- Transfer data to a computer (for long-term
analysis) or your phone.
- Respond to and make changes to your care plan
based on the collected data.
It takes time and patience to understand how a CGM
device works. But you don’t have to do it alone.
Once you’ve decided to get a CGM — and have a
prescription for it — a qualified professional will
help you learn how to use it safely. Your provider
may recommend taking a diabetes education class or
speaking one-on-one with a certified
diabetes care and education specialist (CDCES).
Do I still have to do fingerstick checks while using
a CGM?
Using a CGM should drastically decrease the number
of times you need to do a fingerstick. But it’s
still important to have a fingerstick meter and
unexpired supplies on hand. If your CGM fails or
falls off unexpectedly, you can use the fingerstick
meter to check your glucose level until you can
apply a new sensor.
Fingerstick checks can also act as a backup tool to
confirm CGM results. Like all technology, CGMs can
be inaccurate. If your CGM reading seems
questionable, it’s always a good idea to do a
fingerstick check to be sure. For example, a
fingerstick check may give you peace of mind if your
CGM device shows rising or falling numbers, but you
feel OK. It can also provide answers if you don’t
feel well, but the CGM says your glucose levels are
in range.
You may also need to do fingerstick checks to
calibrate (set up or adjust) a CGM device.
CGM & Time in Range
Continuous glucose monitors (CGM), as the name suggests, continually
monitor the glucose (sugar) in your blood through an external device
that’s attached to your body, and gives real-time updates. They’ve
become popular and more accurate over the years, and with that
improvement has come a new way to manage your blood glucose—enter
time in range (TIR).
What is time in range?
Time in range is the amount of time you spend in the target blood
glucose (blood sugar) range—between 70 and 180 mg/dL for most people.
The time in range method works with your CGM’s data by looking at the
amount of time your blood glucose has been in target range and the times
you’ve been high (hyperglycemia)
or low (hypoglycemia).
Time in range is often depicted as a bar graph showing the percentage of
time over a specific amount of time when your blood glucose was low, in
range, and high. This data is helpful in finding out which types of
foods and what activity level causes your blood glucose to rise and
fall.
Most people with type 1 and type 2 diabetes should aim for a time in
range of at least 70 percent of readings—meaning 70 percent of readings,
you should aim for roughly 17 out of 24 hours each day to be in range
(not high or low). Some may have different targets. Talk with your
doctor to figure out the right blood glucose levels and time in range
targets are right for you.
What does the research say?
Because CGMs are relatively new, we’re still learning about the
long-term results of time in range. Here’s what we do know: the more
time you spend in range, the less likely you are to develop certain
diabetes complications.
However, a lot more research needs to be done. What we understand about
the link between time in range and diabetes complications comes from
data before CGMs were in use. The good news is, as more people start
using CGMs, we anticipate more data for research will be collected and
more information will be available for the long-term effect of spending
more time in your target range.
Time in range versus A1C
A1C is a measure of your average blood glucose for the previous
three months—but it doesn’t document the daily highs and lows that
people may have. The introduction of time in range is a result of the
improvements in diabetes management (specifically CGMs) and what we find
out from your A1C, the current gold standard for determining diabetes
management.
Without knowing the details of your highs and lows, your doctor might
prescribe medication in a dose that lowers your blood glucose into
hypoglycemia territory, creating a situation where you need to correct
medications over time. Being able to know your average blood glucose
levels as well as the highs and lows time in range provides a bigger
picture of what’s needed to manage your diabetes.
Does that mean A1C is on the way out? No. It has been and likely will
remain the standard measure of diabetes management because it’s well
established that A1C
can be used to predict and help prevent diabetes complications.
Who should use time in range?
People with type 1 diabetes and those with type 2 who use insulin and
have tight blood glucose goals will benefit the most from reviewing
their time in range data. That’s because they’re most likely to have
blood glucose levels outside their target range.
Research has yet to establish how often people should check their time
in range status. However, many people with diabetes find daily and
weekly summaries to be helpful. The more times you check your blood
glucose levels each day, the more you’ll know about how long you are in
range.
If you have type 2 diabetes, but do not use insulin, your health care
provider may still advise you to use a CGM periodically to measure how
much time your glucose is in range.
Still interested in understanding your time in range? Talk to your
doctor about using a professional CGM for about two weeks to figure out
your time in range patterns. Your doctor may recommend that you do this
to confirm that your time in range since it gives more information than
standard blood glucose meters.
One roadblock to the widespread use of time in range for diabetes
management is the limited number of people who use a CGM. Though the
numbers have dramatically increased in recent years, we still believe a
minority of people with diabetes are using one.
With insurance coverage of CGMs improving and with Medicare covering
CGMs for anyone who uses an insulin pump, injects insulin multiple times
a day, or checks their blood glucose at least four times a day—there
will likely be more and more people who begin to use them.
At the end of the day though, time in range data is meaningless unless
both patients and their diabetes care team take the time to check it.
As for what time in range target you should aim for, remember: there’s
no universal time in range goal. Yours will depend on your diabetes
management needs and lifestyle, and your doctor can help you determine
the right range for you.
Can people without diabetes use a CGM?
CGMs are mainly for people with diabetes. But
healthcare providers may recommend CGMs for other
conditions that impact glucose levels, like:
Talk to your healthcare provider if you think a CGM
may benefit your health.
What are the advantages of using a CGM to manage
diabetes?
Using a CGM device can make it easier to manage
diabetes. Several studies show that people with Type
1 and Type 2 diabetes who use a CGM have fewer
episodes of low blood sugar and a lower A1C.
A CGM device can:
-
Show you a bigger picture of how diabetes
affects you: CGM measures glucose
levels every few minutes. That data shows a more
complete picture of how your glucose levels
change over time. This information can help you
and your healthcare provider better understand
how things like food, activity, stress and
illness impact your glucose levels.
-
Lead to more personalized care: CGM
doesn’t give the whole story of all the ways
diabetes affects you. It tells you when glucose
goes up or down, not why. But you and your
provider can download CGM data from your device
and review it for patterns and trends. Together,
you and your provider can personalize your care
based on what you learn.
-
Alert you to highs and lows: Most CGM
devices send an alert when your glucose levels
rise or fall a certain amount. With this
information, you can make changes quickly. You
may be able to treat or prevent high
blood sugar or low blood sugar episodes
before they turn into bigger issues.
-
Reduce how many fingerstick checks you need: CGMs
significantly reduce how many fingerstick checks
you’ll need to do each day.
-
Money Saving: Potentially save money through
improved diabetes management and fewer events, like
hypoglycemia (low blood glucose) leading to emergencies.
People with type 1 and type 2
diabetes who use a CGM have fewer instances of hypoglycemia
and a lower A1C.
Types Of CGM's
Real-Time CGMs
Real-time CGMs consist of three main components: a sensor (inserted
under the skin, usually on the arm or abdomen), a transmitter that
attaches to the sensor, and a smartphone or handheld receiver that
displays real-time glucose data.
The Pros |
The Cons |
-
Offers alerts. The most significant benefit of
all real-time CGM systems is having audible alarms that
can warn you if your blood sugar (blood glucose) is
getting too high. This allows time for adjustments that
could lessen the impact of high or low blood sugar or
avoid it altogether.
-
Transmits data continuously. With real-time CGM
devices, data is constantly pushed to a receiver or
smartphone without the need for additional action, such
as a finger prick.
-
Shares data. The ability to share data with
family members and friends is another important feature.
It acts as a safety net, especially when traveling. For
example, if you don’t wake up to a low glucose alarm
during the night, someone else will be alerted and can
get in touch with you.
-
Eliminates finger sticks. While not all
real-time CGMs offer this benefit, some allow you to
make treatment decisions—how much insulin to dose, for
instance—without the need for finger-stick confirmation.
Plus, some are factory calibrated, eliminating the
hassle and pain of calibrating with finger sticks.
|
-
Requires setup. To use the alarm and alert
features, you have to program your settings, such as
your low glucose threshold and target ranges. This can
get a little complicated, especially if you don’t read
the instructions. However, the manufacturers offer
online video tutorials to guide you through the process.
Your diabetes care team, particularly your diabetes
educator, can help you learn to use your device.
-
Alerts can be tiresome. Some people complain
about the repeated alarms (real or false). It can become
so bothersome—or embarrassing, depending on where you
are or who you’re with—that they simply turn off the
alarms altogether. However, this is mainly a problem
with the older CGM systems, which are not as accurate as
the newer ones.
-
Devices can be expensive. Although they are
covered by most insurance companies and Medicare, they
may not be affordable if you have to pay out of pocket.
If cost is an issue, know that many device manufacturers
offer patient assistance programs.
You can find
resources and contact information at InsulinHelp.org
|
Intermittently Scanned CGMs
This system requires you to scan the device to get your glucose data. It
uses two components: a combined glucose sensor/transmitter (inserted in
your upper arm) and a separate touchscreen reader device. The sensor
continuously samples and measures glucose levels, generates a new
glucose value every minute, and records the reading every 15 minutes for
10 to 14 days of sensor wear time, depending on the model.
The Pros |
The Cons |
-
Convenient and easy to use. The sensor, which
is about the size of two stacked quarters, is painless
to apply, comfortable to wear, and easy to use. And you
can scan the transmitter through your clothes, a real
benefit when you want to be discreet.
-
Affordable. They are much less expensive than
real-time CGM devices, and they are covered by most
insurance companies and Medicare.
-
Shares data. Your glucose values can be shared
in real time with up to 20 family, friends, caregivers,
or health care providers using their smartphones.
-
Eliminates finger sticks. Like the real-time
CGMs, some intermittently scanned CGMs can be used to
make treatment adjustments without the need for
finger-stick confirmation, and some are factory
calibrated, eliminating the hassle and pain of daily
calibration with finger sticks.
|
-
Offers no alerts. There is a lack of alerts to
warn about current or upcoming glucose problems. Without
the chime of a CGM alarm, people with low blood sugar
(hypoglycemia) unawareness may not know they’re low
until their judgment is impaired. This also means you
won’t be woken by a low-glucose alarm—a downside for
anyone concerned about overnight lows.
-
Requires intent. You have to remember to wave
the reader over the transmitter, which might not happen
on days when you’re busy or distracted, or at night. And
there’s a price for forgetting: The sensor can provide
glucose values for 10 to 14 days (depending on the
model) if you scan at least every eight hours. If not,
the glucose information that is older than eight hours
will be overwritten and not available for
decision-making or download.
-
One version takes 12 hours to warm up. When a
new sensor is inserted, the device will not show any
glucose data for the first 12 hours. During this time,
you will need to do finger-stick checks.
-
Offers no option to calibrate. You cannot
recalibrate the sensor when glucose values don’t match
your finger-stick results. When your sensor and
finger-stick glucose readings don’t match, it may mean
your meter is inaccurate. Or it could indicate that your
blood sugar is rapidly rising or falling. But it could
also point to an inaccurate CGM sensor. Without the
ability to recalibrate the sensor, you may need to
insert a new sensor before its indicated wear time has
expired.
|
How to choose?
Take the time to investigate both options and talk to your
doctor and diabetes educator, who can provide valuable
guidance and insights about the type of CGM system that may
be right for you. They can also help you make the transition
to a CGM and provide training to help you learn how to
interpret and use your data to make appropriate treatment
decisions and achieve your blood sugar goals.
What are the limitations of CGMs?
CGMs are extremely helpful tools. But they have some
limitations. Like all technology, CGM systems can
run into issues, be inaccurate or fail. Your CGM
trainer will go over issues to look out for and how
to troubleshoot them.
Certain medications and supplements can also affect
the accuracy of certain CGM sensors, including:
- Acetaminophen (Tylenol® or Panadol®).
- Hydroxyurea, a medication for sickle
cell anemia.
- Vitamin C (ascorbic acid).
These medications and supplements may make your CGM
read your glucose level as higher or lower than it
actually is. It’s important to check with the
manufacturer of your CGM device to see what may
affect the accuracy of it.
What are the drawbacks of CGMs?
Some things that you may see as drawbacks of CGMs
include:
-
Cost: CGMs and the supplies they
require can be expensive compared to just using
fingerstick checks. The cost varies based on
your healthcare insurance plan.
-
Information overload: While the
extensive information that CGMs provide can be
very helpful, it can also be overwhelming. For
some, this could worsen diabetes distress or
burnout. It may also trigger disordered
eating.
-
Alarm fatigue: Depending on your
settings, you may get several alarms a day from
your CGM. This can become distressing and lead
to burnout. It may also disrupt your sleep.
-
It’s always attached to your body: All
CGMs are an extra piece of hardware attached to
your body. This can take time to get used to.
There are many discreet ways to cover them up if
you want to.
-
Issues with adhesives: Some people
experience allergic
reactions to the skin adhesives CGM devices
use.
Consider making an appointment with a CDCES if
you’re facing any of these challenges.
They can
teach you tips and tricks to make a CGM easier to
use.
Obstacles to Accessing CGMs
One obstacle with CGMs is the cost of access to diabetes
technology. Many people with diabetes who have put off
getting an insulin pump or CGM, do so because they are too
expensive.
Another major obstacle is due to strict Medicaid coverage
policies they are not accessible for people who need them.
In fact, people with diabetes on Medicaid, especially in
minority communities who use Medicaid, are the least likely
to use a CGM.
This is concerning since people with diabetes are more than
twice as likely to receive their health care from Medicaid
as those without diabetes.
Individuals who meet the coverage criteria for a CGM and want to learn more about them
should talk to their health care provider to ensure it is
the right tool for the management of their diabetes.
Updated Medicare Coverage Requirements for CGMs
Medicare has eliminated the
four-time-daily fingerstick testing requirement for
continuous glucose monitor (CGM) coverage! Read on to learn
about how the American Diabetes Association championed this
effort and what it means for your Medicare coverage moving
forward.
When should I contact my healthcare provider?
Reach out to your diabetes healthcare provider if
you have any questions about how to use a CGM device
safely.
Very high or low blood sugar levels can be dangerous
when left untreated for too long. In the most severe
cases, this can lead to seizures, coma or
even death. You can avoid these complications by
keeping blood sugar levels in a healthy range. Call
your provider if you have any symptoms you’re
worried about.
Can you get a CGM without a doctor?
Currently, there’s one CGM that’s available over the
counter (OTC). That means you don’t need a
healthcare provider or prescription to get it. Other
CGM manufacturers are also in the process of making
OTC CGMs.
OTC CGMs may not be suitable for people who use
insulin to manage diabetes or who experience
significant low blood sugar episodes. Make sure you
understand the capabilities and limitations of OTC
CGMs before using them.
One Final Note..
CGM technology has been a game-changer for people with
diabetes, as it offers a hugely improved ability to keep
track of glucose levels on a constant basis. Unlike
traditional fingerstick meters that only provide a snapshot
of blood sugars in the moment, CGM systems provide a more
complete picture of how one’s blood sugars are trending both
in the moment and over time. CGMs are being connected to insulin delivery devices these
days, to create combo systems that can automatically adjust
insulin doses based on the glucose data being streamed via
Bluetooth. As these “closed loop” systems become more
discreet and lower cost, they’re bringing much more
lifestyle flexibility and better health outcomes for people
with diabetes
|