SEPT. 8, 1956
ENZYME TESTS FOR GLUCOSE
tape have provided a colour scale and claim that accurate
quantitation is possible.This colour chart varies from batch
tobatch, and the present results show that reasonable
accuracy is possible in onily about half the urines examined;
moreover, the distinction between the colours given by con-
centrations of glucose above 0.5 g. per 100 ml. is difficult
and above 2 g. per 100 ml. impossible.
In the control of diabetic treatment the presence of small
amounts of glucose in the urine is of little importance. A
test of practical use must distinguish accurately between low
and high concentrations of glucose.
and the relative difficulty in distinguishing with certainty
between 0.5 g. per 100 ml. and concentrations around 5 g.
per 100 ml. render these tests unsuitable for use by diabetic
A test which does not readily dis-
tinguish between a glucose concentration corresponding to a
loss of 5 g. of glucose a day from a glucose concentration
corresponding to a loss perhaps of 100 g. or more a day is
likely to mislead gravely both the patient and his clinician.
The existing tests may be little better for the quantitative
determination of low concentrations of glucose, but the
bright orange colour of complete reduction in Benedict's
test or the clinitest is striking enough and indicative of a
significant Jevel of glycosuria.
A comparison has been made between two new
enzyme tests for the detection of glucose and existing
Both tests are equally good in this respect.
They are highly specific for glucose and may be of great
value either to supplement existing tests or perhaps to
take their place.
The claim that one of these tests
permits accurate estimation of glucose is not confirmed.
Thanks are due to Ames Company (London) Ltd. and Eli Lilly
and Co. Ltd. for supplies of clinistix and tes-tape respectively.
We also thank the former for seconding one of us (D. E. T.) to
the Department of Clinical Pathology at King's College Hospital
Medical School during the whole period of this study. We thank
Mrs. B. Rigby and Miss M. T. Pickett for assistance with the
estimation of large numbers of true urine glucose.
Neither test can do this,
Froesch, E. R., and Renold, A. E. (1956).
Gray, C. H., and Millar. H. R. (1953).
Harrison, G. A. (1947).
Quilley, E. (1955).
British Medical Journal, 1, 1361.
Chemical Methods Its Clinical Medicine.
J. Lab. med. Tech., 13, 158.
Enzyme Test for Glycosuria
Recently an enzymatic test has been developed which
specific for detecting glucose in urine. "Tes-tape" contains
such an enzyme system, and also incorporated in the paper
is a yellow dye.
When the paper tape is dipped in urine
containing glucose the paper changes colour from light green
to dark green and finally to blue, depending upon the amount
of glucose in the urine.A colour chart is supplied with
each batch of tes-tape, and yellow, greenish yellow, light
green, dark green, and dark blue are claimed to correspond
respectively to 0, 0.1, 0.25, 0.5, and 2 g. of glucose per
100 ml. of urine.
Such an easy quantitative test for glycosuria would be
a tremendous saving of time in a busy diabetic clinic and
a boon to diabetic patients. The findings from tes-tape were
therefore compared with the results from routine testing of
samples of urine obtained from 110 patients attending the
Diabetic Clinic, Leeds.Each sample of urine was tested by
one of us (D. C.) in a routine way by means of " clinitest ";
the same numbered sample was tested by an independent
worker with tes-tape.
The results are shown in Tables I
Table I shows very close agreement between the two tests
when no sugar or only 0.1 g. per 100 ml. is present.
TABLE I.-Comparison of Results from Tes-tape and Clinitest
Glucose (G./100 ml.)
TABLE II.-Percentage of Non-matching Results
Clinitest (2 g.) ..
Tes-tape (O-1-0 5S.)
Tesltape (2 g.)..
Clinitest (1 g.)..9
Tes-tape (Nil-OS g.)
Tes-tape (0-5-2 g.)
0.1 g. per 100 ml. results have been placed with the no sugar
group, since the significance of such trace amounts of sugar
is not known at the moment.
in increasing concentrations
show such close agreement, although a similar percentage
is recorded by both tests for 2 g. or more glucose per
Table II, however, shows that percentages for a 2% result
in Table I are misleading, as 24% of the tes-tape results did
not match with the clinitest results. The 0.25 g. per 100 ml.
differences between two tests were ignored in this analysis.
For example, 7% of the tests showing 2 g. per 100 ml. by
the clinitest revealed only 0.1 to 0.5 g. per 100 ml. by the
Conversely, 4% were negative for glucose by the
clinitest, but 0.5 to 2 g. per 100 ml. was recorded by the
From these results and previous work with "clinistix"
(unpublished) it would appear that the enzyme tests may be
useful in deciding whether glucose is present or not in a
sample of urine.
Such a test may be useful in a maternity
out-patient department or casualty department of a general
These results show that the new enzyme test from urinary
glucose is most unreliable when regarded as a quantitative
blue reactions indicate a strongly positive result-are likely
to be misinterpreted in view of previous experience with
other methods. Diabetic patients have long been accustomed
with Fehling's Benedict's, and more recently with clinitest,
to interpret the blue reaction as a sign of absence of sugar,
and confusion would therefore be inevitable.
the new tests can be of no use to the physician in the
management of diabetic patients when 11% of the tests
cannot distinguish the presence of no sugar or over 2 g. per
R. E. TUNBRIDGE, M.D., M.Sc., F.R.C.P.
RONALD G. PALEY, M.D., Ph.D.
Department of Medicine,
University of Leeds.
Comparison of the two tests
of urinary sugar does not
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