Wenn Sie Deutsch
klicken Sie bitte
______________________________________________________________________ How accurate must
noninvasive blood glucose meters measure to get a sales approval?
For further information read :
Comment on the
meeting of the FDA Committee
on invasive and non-invasive blood glucose meters, for the analysis
done for home blood glucose self-monitoring -March 20. and 21. 1997-
kindly reported to me by Mr.
Bob Rosenthal Futrex Company.
On March 20 and 21 in 1997, the devices in the fields of Clinical
Chemistry and Clinical Toxicology (science of poisons) competent
committee of the FDA met for a two-day meeting.
The purpose of this meeting was to speak about aspects which affect
blood glucose meters for blood glucose self-monitoring.
The said committee was composed also of experts who do not work for the
FDA. For example, there were 7 doctors of medicine, of which the most
directly related to various aspects of diabetic care and treatment of
There also took part 3 experts for Clinical Chemistry in the meeting,
which are responsible for laboratory analysis in the
hospital. There responsibility includes the analysis of blood glucose.
In addition, also a representative of the industry and a
representative of the consuming part .attended the meeting.
At the beginning of the meeting a number of targets have been set by
the FDA. It was hoped the committee would be able to identify ways that
would lead to these objectives.
It was discussed as follows:
* Should the current FDA - Method for the authorization of systems for
blood glucose self-monitoring be changed?
* Why is obtained a
much poorer accuracy of blood glucose
self-monitoring, then when the accuracy is tested by independent
outsiders, than that which is delivered by the manufacturers in
their 510 (K)
approval requests (request that a company must provide to be able to
sell medical device).
* The devices for blood glucose self-monitoring in principle are used
in 3 different occasions, for example at home, in the doctor's office,
and in the clinic. This raises the question of whether the FDA should
establish different admission policies, depending on what conditions
the device is used later.
*Should the FDA establish very specific guidelines for the admission of
glucose meters for blood glucose self-monitoring, and if so, how should
these guidelines look like?
* Should for noninvasive blood glucose monitoring devices be provided
the same requirements to the accuracy, and used the same admission
policies as they are used for blood glucose meters with blood
Unfortunately, the number and difficulty of the
questions was almost overwhelming, and therefore did not bring about a
final determination of the issues at stake in the situation. But there
were visible during the presentation of manufacturers of blood glucose
meters a lot of interesting details.
This protocol provides a summary of the information, with particular
emphasis was placed on how individual statements impact in terms of
non-invasive blood glucose meters, respectively.
The current generation of blood glucose meters with blood from the
fingertip for blood glucose self-monitoring.
One can distinguish two types of patients in which blood glucose meters
for blood sugar control are used.
* Metabolic Stable patients - These are mainly patients at home
or in the primary care setting, thay are not in an
emergency or exceptional situation.
* Metabolic Unstable patients - These are patients who are in a
hospital emergency room or in the intensive care unit.
It was expressed that the current blood glucose monitoring devices
could possibly not provide accurate measurements in metabolically
labile patients. There were two reasons mentioned.
* Low hematocrit level. The instruments currently used do not provide
accurate readings when the hematocrit level is low. In metabolically
stable patients the hematocrit level is typically between 40 and 45%.
In metabolically labile patients however the hematocrit level may be
deeper. This low hematocrit values in blood glucose meters with blood
from the fingertip lead to erroneous results which are of importance
metabolic control of the patient.
* Deep, systolic blood pressure. The blood glucose meters currently
used measure may not be correct if the systolic blood pressure is below
mm Hg. In this blood pressure region the blood is substantially in the
central part of the human body and only a limited amount reaches the
capillaries. This causes measurement errors.
In addition to the above, a limitation of the accuracy of
the measuring instruments currently in use may also still be found
* At high altitude (reduced oxygen content of the air)
* If the humidity is high.
* In newborns.
How accurate need blood glucose meters for blood glucose
self-monitoring to be?
* In 1986, the American Diabetic Association published guidelines for
the admission of blood glucose meters for blood glucose
Thereafter, the deviation from the laboratory value within the
measurement range of 1,7
mmol/l. to 22,2
mmol/l. (30 to 400 mg / dL) should not be more
* In 1993, the ADA introduced new requirements for accuracy. These
apply to all instruments that are to be brought onto the market.
Thereafter, the maximum deviation from the laboratory value may be as
low as 5%.
However, one admitted that the presently already on the market old
instruments should continue to be sold at the old accuracy requirements
of 1986 .
In 1987 Clarke, Cox and other developed the unique "Error Grid
(Diabetes Care 1987 10: 622-628) This "Error Grid analysis" showed the
presence of so-called fault zones within which a possible error would
not have an impact to the quality of treatment of diabetic patients.
(For example at a blood glucose level of 3,9
mmol/l.(70 mg / dl) or
greater a accuracy, with a maximum deviation of 20% deviation from the
laboratory for glucose would be quite acceptable.
The "Error Grid Analysis" also defined ranges within which a
measurement error can not be accepted because this error would be
detrimental in this area on the quality of care of diabetic patients.
* A recent study carried out the most glucometers for blood glucose
self-monitoring showed that 20% of all measurements were not lying
within a maximum deviation of plus or minus 15% of the laboratory value.
The most important point in this context, however, was called by Dr.
Gutmann by the FDA and Dr. Ratner, who represents the Juvenile Diabetes
Federation (association of juvenile diabetes).
They both showed that it was found in screening for diabetes treatment
(DCCT) that intensive blood glucose self-monitoring and a matched
diabetes treatment could prevent serious diabetes complications such as
blindness, loss of kidney function or other serious complications by up
to 70%. These studies were performed over a period of 10 years as a
long-term study. The most important in this context statement that was
made by two speakers was the following:
In the long-term study (DCCT) blood glucose meters were used, which
were older than one or even two generations as blood glucose meters
currently used with blood from the fingertip. It was in these
instruments, for example, still needed to wipe the blood just after 90
seconds from the test strip. These old instruments reached a lower
accuracy than the devices currently available.
Despite these limitations, revealed in the course of the
(DCCT), improvements in the health of
diabetics were clearly visible, when the blood
glucose value was measured often.
The above notes by Dr. Gutman and Dr. Ratner clearly show that in
reality it just is not necessary to achieve the accuracycurrently
by the ADA of 5% in order to avoid the serious complications
Use by patients
compared to laboratory application.
A detailed discussion on the topic: use of blood glucose
monitoring, blood glucose self-monitoring, use of blood glucose
hospitals and doctors' offices. For the vast majority of diabetics
this diskusson is likely to be of minor importance.
It is of course necessary that a device that is used in the laboratory
measures as accurately as possible. The laboratory use, however,
in comparison to
self-monitoring is rather the exception. It is estimated that over 95%
even 99% of all blood glucose meters may
be used for blood glucose
self-monitoring in the household. We call this type of application,
diabetic monitors its blood sugar itself a clinical application
meter, in contrast to the laboratory application.
The only reason to demand unfounded high accuracy in laboratory blood
glucose monitoring for diabetes self-control because these devices are
also used by a few in the laboratory of a hospital, would cause serious
economic problems and unnecessarily provoke further problems.
Non-invasive blood glucose meters.
The Biocontrol Company explained how high in their opinion should be,
the performance requirements to non-invasive blood glucose meters.
It has been demonstrated that it is unrealistic to assume that the
first generation of injury-free blood glucose meters should achieve the
same level of accuracy as the current blood glucose meters with blood
or the even more stringent accuracy requirements recommended by the ADA
in 1995 .
It was made clear that if such stringent accuracy requirements would be
required by the FDA, the non-invasive measurement of blood glucsoe
could not bea realized. At least not in the foreseeable future. It was
argued, that for the community of diabetics this would be cause great
Source: Comments on FDA Panel Meeting on Invasive and Non-Invasive
Glucose Meters Home. http://www.futrex.com