Continuous glucose sensor
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As some of the old timers will recall, I was in the first
batch of humans implanted with a continuous glucose sensor
with a radio link to a belt receiver. Few, if any, of the
first batch were successful due to what were, in retrospect,
silly mistakes in implant procedure. That is why you have to
actually do the tests. I heard that the results in the
second batch were very good. Posted below is the abstract of
a paper which I believe to be based on that second batch.
Before you read it and get too excited, here are the results
of a poll take at a Diabetes Technology Meeting where they
had been presented with the results of the trial. Nobody
should be holding their breath for quick implementation of a
closed loop system, the eventual goal.
http://www.diabetes123.com/d_0j_129.htm
__________ Quote start___________ In the final session of
the conference, participants were asked to vote, using a hand-
held electronic voting device, on several questions related
to diabetes and technology. When asked when an artificial
pancreas would be available for widespread clinical use, the
results of the voting was:
2 years - 1% 4 years - 12% 6 years - 25% 10 years - 45%
Never - 17%
Panel members overseeing the voting session felt more
optimistic, generally feeling that some sort of continuous
sensor control of a pump was about six years away from
clinical availability. _______________Quote
End__________________
Diabetes Care. 2004 Mar;27(3):734-8.
Improved glucose excursions using an implantable real-time
continuous glucose sensor in adults with type 1 diabetes.
Garg SK, Schwartz S, Edelman SV.
Department of Medicine and Pediatrics, Barbara Davis Center
for Childhood Diabetes, University of Colorado Health
Sciences Center, Denver, Colorado 80262, USA.
satish.garg@uchsc.edu
OBJECTIVE: The capability of emerging glucose sensor
technology to continuously monitor glucose levels may
provide ways to achieve glycemic targets while reducing
hypoglycemia. RESEARCH DESIGN AND METHODS: A first-
generation, long-term continuous glucose sensor (DexCom, San
Diego, CA) was implanted subcutaneously in 15 patients with
type 1 diabetes. Safety, efficacy, and potential benefits
were evaluated during a blinded control period and in a
study period during which patients had real-time access to
the glucose data. RESULTS: The bias differences between self-
monitored blood glucose (SMBG) and sensor data were <15% at
2.8, 4.4, 5.6, 8.3, and 11.1 mmol/l. No procedure or device-
related adverse events were observed. Of 15 patients, 13
(87%) had functional sensors during the 12-h simulated home
use study with 96% of points in the A and B regions of the
Clarke error grid, an R value of 0.88, and a mean absolute
relative difference of 16% when retrospectively compared
with SMBG. In actual home use, during the blinded control
period (50 +/- 16 days) data were not displayed to the
patient, whereas during the unblinded study period (44 +/-
17 days) the data were presented to the patient, and alerts
were set at 3.1, 5.6, and 11.1 mmol/l. Patients spent a
median of 47% less time below 3.1 mmol/l (P<0.05) and 25%
less time above
13.3 mmol/l (P<0.05) during the nonblinded study period
compared with the blinded control period. CONCLUSIONS:
The availability of real-time continuous glucose values
may help patients reduce their hyperglycemic excursions
and lower the risk of hypoglycemia.
--
-------
Charly Coughran ccoughran@DELETE-TO-RESPOND-UCSD.EDU
The only post I am interested in tonight. Some of you will
profit from some of the advasnces. Too late, too slow for
some of us. Guy
On Mon, 21 Jun 2004 19:24:21 +0000 (UTC), Charly Coughran
<ccoughran@REMOVE-TO-DELETE-UCSD.EDU> wrote:
>
>As some of the old timers will recall, I was in the first
>batch of humans implanted with a continuous glucose sensor
>with a radio link to a belt receiver. Few, if any, of the
>first batch were successful due to what were, in
>retrospect, silly mistakes in implant procedure. That is
>why you have to actually do the tests. I heard that the
>results in the second batch were very good. Posted below is
>the abstract of a paper which I believe to be based on that
>second batch.
>
>Before you read it and get too excited, here are the
>results of a poll take at a Diabetes Technology Meeting
>where they had been presented with the results of the
>trial. Nobody should be holding their breath for quick
>implementation of a closed loop system, the eventual goal.
>http://www.diabetes123.com/d_0j_129.htm
>
>__________ Quote start___________ In the final session of
>the conference, participants were asked to vote, using a
>hand-held electronic voting device, on several questions
>related to diabetes and technology. When asked when an
>artificial pancreas would be available for widespread
>clinical use, the results of the voting was:
>
>
>2 years - 1% 4 years - 12% 6 years - 25% 10 years - 45%
>Never - 17%
>
>Panel members overseeing the voting session felt more
>optimistic, generally feeling that some sort of continuous
>sensor control of a pump was about six years away from
>clinical availability. _______________Quote
>End__________________
>
>Diabetes Care. 2004 Mar;27(3):734-8.
>
>Improved glucose excursions using an implantable real-time
>continuous glucose sensor in adults with type 1 diabetes.
>
>Garg SK, Schwartz S, Edelman SV.
>
>Department of Medicine and Pediatrics, Barbara Davis Center
>for Childhood Diabetes, University of Colorado Health
>Sciences Center, Denver, Colorado 80262, USA.
>satish.garg@uchsc.edu
>
>OBJECTIVE: The capability of emerging glucose sensor
>technology to continuously monitor glucose levels may
>provide ways to achieve glycemic targets while reducing
>hypoglycemia. RESEARCH DESIGN AND METHODS: A first-
>generation, long-term continuous glucose sensor (DexCom,
>San Diego, CA) was implanted subcutaneously in 15 patients
>with type 1 diabetes. Safety, efficacy, and potential
>benefits were evaluated during a blinded control period and
>in a study period during which patients had real-time
>access to the glucose data. RESULTS: The bias differences
>between self-monitored blood glucose (SMBG) and sensor data
>were <15% at 2.8, 4.4, 5.6, 8.3, and 11.1 mmol/l. No
>procedure or device-related adverse events were observed.
>Of 15 patients, 13 (87%) had functional sensors during the
>12-h simulated home use study with 96% of points in the A
>and B regions of the Clarke error grid, an R value of 0.88,
>and a mean absolute relative difference of 16% when
>retrospectively compared with SMBG. In actual home use,
>during the blinded control period (50 +/- 16 days) data
>were not displayed to the patient, whereas during the
>unblinded study period (44 +/- 17 days) the data were
>presented to the patient, and alerts were set at 3.1, 5.6,
>and 11.1 mmol/l. Patients spent a median of 47% less time
>below 3.1 mmol/l (P<0.05) and 25% less time above
>13.3 mmol/l (P<0.05) during the nonblinded study period
> compared with the blinded control period. CONCLUSIONS:
> The availability of real-time continuous glucose values
> may help patients reduce their hyperglycemic excursions
> and lower the risk of hypoglycemia.
Thanks Charly. Steph
"Charly Coughran" <ccoughran@REMOVE-TO-DELETE-UCSD.EDU>
wrote in message
news:Xns950F7DEAD2040ccoughranucsdedu@132.239.1.221...
>
> As some of the old timers will recall, I was in the first
> batch of humans implanted with a continuous glucose sensor
> with a radio link to a belt receiver. Few, if any, of the
> first batch were successful due to what were, in
> retrospect, silly mistakes in implant procedure. That is
> why you have to actually do the tests. I heard that the
> results in the second batch were very good. Posted below
> is the abstract of a paper which I believe to be based on
> that second batch.
>
> Before you read it and get too excited, here are the
> results of a poll take at a Diabetes Technology Meeting
> where they had been presented with the results of the
> trial. Nobody should be holding their breath for quick
> implementation of a closed loop system, the eventual goal.
> http://www.diabetes123.com/d_0j_129.htm
>
> __________ Quote start___________ In the final session of
> the conference, participants were asked to vote, using a
> hand-held electronic voting device, on several questions
> related to diabetes and technology. When asked when an
> artificial pancreas would be available for widespread
> clinical use, the results of the voting was:
>
>
> 2 years - 1% 4 years - 12% 6 years - 25% 10 years - 45%
> Never - 17%
>
> Panel members overseeing the voting session felt more
> optimistic, generally feeling that some sort of continuous
> sensor control of a pump was about six years away from
> clinical availability. _______________Quote
> End__________________
>
> Diabetes Care. 2004 Mar;27(3):734-8.
>
> Improved glucose excursions using an implantable real-time
> continuous glucose sensor in adults with type 1 diabetes.
>
> Garg SK, Schwartz S, Edelman SV.
>
> Department of Medicine and Pediatrics, Barbara Davis
> Center for Childhood Diabetes, University of Colorado
> Health Sciences Center, Denver, Colorado 80262, USA.
> satish.garg@uchsc.edu
>
> OBJECTIVE: The capability of emerging glucose sensor
> technology to continuously monitor glucose levels may
> provide ways to achieve glycemic targets while reducing
> hypoglycemia. RESEARCH DESIGN AND METHODS: A first-
> generation, long-term continuous glucose sensor (DexCom,
> San Diego, CA) was implanted subcutaneously in 15 patients
> with type 1 diabetes. Safety, efficacy, and potential
> benefits were evaluated during a blinded control period
> and in a study period during which patients had real-time
> access to the glucose data. RESULTS: The bias differences
> between self-monitored blood glucose (SMBG) and sensor
> data were <15% at 2.8, 4.4, 5.6, 8.3, and 11.1 mmol/l. No
> procedure or device-related adverse events were observed.
> Of 15 patients, 13 (87%) had functional sensors during the
> 12-h simulated home use study with 96% of points in the A
> and B regions of the Clarke error grid, an R value of
> 0.88, and a mean absolute relative difference of 16% when
> retrospectively compared with SMBG. In actual home use,
> during the blinded control period (50 +/- 16 days) data
> were not displayed to the patient, whereas during the
> unblinded study period (44 +/- 17 days) the data were
> presented to the patient, and alerts were set at 3.1, 5.6,
> and 11.1 mmol/l. Patients spent a median of 47% less time
> below 3.1 mmol/l (P<0.05) and 25% less time above
> 13.3 mmol/l (P<0.05) during the nonblinded study period
> compared with the blinded control period. CONCLUSIONS:
> The availability of real-time continuous glucose values
> may help patients reduce their hyperglycemic excursions
> and lower the risk of hypoglycemia.
>
>
>
> --
> -------
> Charly Coughran ccoughran@DELETE-TO-RESPOND-UCSD.EDU
The first observatin is that if you had formatted this as
Objective: ....
Next Topic: ,,,,
I can't help but wonder if you can't include some sort of
transmitter and send the data to a computer. Usefull for
both type I's and type II's.
Thad O <not_that_o_but_olczyk@interaccess.com> wrote in
news:aemgd096qnfhusg7a08bv7f9putcnbk66r@4ax.com:
> I can't help but wonder if you can't include some sort of
> transmitter and send the data to a computer. Usefull for
> both type I's and type II's.
>
I don't know the extent of their plans, the belt receiver I
had was clearly a first generation device. It up loaded
stored data to a computer via a cable, serial I believe but
it might have been USB. The Dexon rep who was helping the
study nurses up load data was a software guy with no
knowledge of the electronics in the receiver or the sensor
so it was hard to get much information. Power consumption at
the sensor, especially transmit power, was a big issue so I
don't think they were using anything standard like Blue
Tooth. Sensor transmit range was only 3'. That would mean to
communicate with both the sensor and a computer via wireless
link, the receiver would have to have two transmitters.
It would be useful for both type 1s and 2s, but I can't see
many 2s undergoing surgery for the extra data. It is out
patient surgery, but not doctor's office surgery. Not to
mention, its not going to be cheap.
--
-------
Charly Coughran ccoughran@DELETE-TO-RESPOND-UCSD.EDU
Thanks Charly for you excellent posts. I first heard about a
closed loop system before 1970. I was working on small
electronic systems. A fellow from Colorado was in the blood
glucose working area and wanted info on our work.
I had no interest in diabetes at that time. but it seemed a
device was near. I also remember his comments on the use of
money collected for diabetes. Very negative comments.
So when I found out I had diabetes in 1976 I expected some
real progress in a few years.
Here we are about 30 years later and still all promises.
I do not want a system that uses home computer technology.
An unique system would be much safer. Common readout would
not serve a purpose. Suppose someone did not like me and
hacked my system. :-) Guy
Guy <gswil@intertex.net> wrote on Tue, 22 Jun 2004 12:46:11 -0500:
> Thanks Charly for you excellent posts. I first heard about
> a closed loop system before 1970. I was working on small
> electronic systems. A fellow from Colorado was in the
> blood glucose working area and wanted info on our work.
> I had no interest in diabetes at that time. but it seemed
> a device was near. I also remember his comments on the use
> of money collected for diabetes. Very negative comments.
Yes. But the vague idea in 1970 has now become a device
under test in 2004. It might not work very well, but at
least it's there.
> So when I found out I had diabetes in 1976 I expected some
> real progress in a few years.
When I found out I had diabetes in 1965 (and I mean "found
out" in the literal sense - nobody actually told me), I kept
hearing "but a cure's just round the corner, isn't it?"
> Here we are about 30 years later and still all promises.
If it's any consolation, Guy, I don't expect to see a cure
for DM (of whichever type) in my lifetime either.
> I do not want a system that uses home computer technology.
> An unique system would be much safer. Common readout would
> not serve a purpose. Suppose someone did not like me and
> hacked my system. :-)
That was also my first thought. If there's going to be a spy
implanted in my body, then nobody else should be able to
control it. That means, at the very least, strong
cryptographic authentification between the implanted device
and the transmitter.
Guy
--
Alan Mackenzie (Munich, Germany) Email: aacm@muuc.dee; to
decode, wherever there is a repeated letter (like "aa"),
remove half of them (leaving, say, "a").
Guy wrote:
> I do not want a system that uses home computer technology.
> An unique system would be much safer. Common readout would
> not serve a purpose. Suppose someone did not like me and
> hacked my system. :-)
Hi Guy,
Just want to say that I've never had an external hacker
crash my HP-48 open-loop feedback control of my insulin
doses. All my problems were self-inflicted by making a fast
change and not testing the code, (simple change, what could
possibly go wrong?). Then the system crashes a week later
when you're in a hurry. The HP-48 did have viruses in some
free code off the internet a few years ago. But I never
loaded unknown code on my medical HP-48. So I was never
infected on this primary system.
There is a new version of the HP-48 that uses the ARM
microprocessor with a 48 MHz clock (the old was 4 MHz and HP
proprietary Saturn processor). My concern is the batteries
will not last as long and I don't need the speed yet. But I
do need a keyboard and that's why I don't like most of the
PDAs. I've had the calculator batteries last 9-10 months on
my current 48s. But the new 48GII says 2 months for the
battery life. So it's probably 1 month in reality. My HP
iPAQ PDA lasts 5 hours before recharging is required. So 1
month is not bad relative to the power-hogging backlit
displays on PDAs.
In any case, I've been pleased with my independent-from-PCs
HP-48 dosing program for 12-14 years now. I backup to memory
cards, on autopilot every Tuesday morning at 4 am (keeping 1
month of backups), that are independent of the PC. But a
backup can also be sent to the PC. However, the current
method is completely self-contained and requires no support
from the PC. This has been a successful strategy for my high
availability medical use.
If the electricity dies, I keep dosing with a flashlight.
No big deal,
--
Jim Dumas T1 4/86, background retinopathy, rarely
hypoglycemic: <1/mo. lispro+R+U+NPH daily, moderate
exercise, typically <6% HbA1c
Charly Coughran wrote:
> Nobody should be holding their breath for quick
> implementation of a closed loop system, the eventual goal.
> http://www.diabetes123.com/d_0j_129.htm
>
Today I was reading an article in the local newspaper about
a glucose sensor that involves implantation. Craig Grimes, a
engineering professor at Pennsylvania State University, was
the lead author of an article published online last month.
The article will be published by the Analytical Chemistry
journal on July 15.
"The passive sensors require no internal power supply and
no connection outside the body, Grimes explained.
'Whenever a reading is needed, aperson can wave their hand
or arm in front of a reader that will automatically detect
the sensor.'
The glucose sensor is coated with a substance that respondes
to changes in acidity, ant then is given a second coat of
the chemical glucose oxidase. This reacts with blood glucose
to produce an acid, which causes the undercoating to swell
and changes the frequency of the sensor as the reader is
held close. The reader interprets the changes in frequency
against a scale of blood glucose levels.
The team is also working toward developing sensors that can
detect multiple chemicals at the same time. This involves a
tree-like array of sensors of varying lengths and
frequencies attached to a central frame. Each would be
coated with a different reactive chemical resulting in a
harp-like plataform about one quarter inch high for a 10-
chemical test."
A similar article to the newspaper article that is online:
Measuring blood sugar with a wave of the arm http://www.eurekalert.org/pub_releases/2004-06/acs-
bs062804.php
SENSOR LETTERS http://www.aspbs.com/sensorlett/
http://www.ee.psu.edu/grimes/sensors/
http://www.ee.psu.edu/grimes/materials/ E-mail:
cgrimes@engr.psu.edu
Frank
Alan Mackenzie wrote:
> Guy <gswil@intertex.net> wrote on Tue, 22 Jun 2004
> 12:46:11 -0500:
>
>> Thanks Charly for you excellent posts. I first heard
>> about a closed loop system before 1970. I was working
>> on small electronic systems. A fellow from Colorado was
>> in the blood glucose working area and wanted info on
>> our work.
>
>> I had no interest in diabetes at that time. but it seemed
>> a device was near. I also remember his comments on the
>> use of money collected for diabetes. Very negative
>> comments.
>
> Yes. But the vague idea in 1970 has now become a device
> under test in 2004. It might not work very well, but at
> least it's there.
And it was a device in 1972, 1973, 1974, 1976, twice in
1980, etc., etc., etc. There have been at least 5 major
announcements of devices "just around the corner" in the
last 5 years, and none of them have worked well enough.
The continuing advance of science and knowledge still hasn't
addressed the basic signal/noise problems in measuring blood
glucose. Glucometers handle it by using chemicals which are
consumed, but are not suitable for constant monitoring.
>> So when I found out I had diabetes in 1976 I expected
>> some real progress in a few years.
>
> When I found out I had diabetes in 1965 (and I mean
> "found out" in the literal sense - nobody actually told
> me), I kept hearing "but a cure's just round the corner,
> isn't it?"
>
>> Here we are about 30 years later and still all promises.
>
> If it's any consolation, Guy, I don't expect to see a cure
> for DM (of whichever type) in my lifetime either.
Actually, I still hold out some hope for the immune-system
work for Type 1's. But human medical technology experiences
breakthroughs, and those are hard to predict.
>> I do not want a system that uses home computer
>> technology. An unique system would be much safer. Common
>> readout would not serve a purpose. Suppose someone did
>> not like me and hacked my system. :-)
>
> That was also my first thought. If there's going to be a
> spy implanted in my body, then nobody else should be able
> to control it. That means, at the very least, strong
> cryptographic authentification between the implanted
> device and the transmitter.
Heh. Fortunately, this is a fairly well-solved problem in
the pacemaker world.
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