الفهرس 
DIAGNOSIS OF DIABETES MELLITUSOnly 14 pages are availabe for public view
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Abstract
Type 1 diabetes mellitus is the most severe type of diabetes, leading to life-long dependency on
daily insulin injections, and long-term serious complications. The early detection of populations
at risk of developing type 1 diabetes mellitus is mandatory in order to develop effective programms
for preventing or delaying the onset of the disease.
Islet cell antibodies (ICA) have long been used as the classical serological marker of
autoimmunity in type 1 diabetes mellitus. However, as ICA assay is qualitative and difficult to
standardize, alternative assays are needed. Accordingly, the aim of the present study was to
evaluate the prevalence of two newly introduced autoantibodies to biochemically-defined cell
antigens, namely the anti-GAD6s antibodies and anti-IA-2 antibodies in newly diagnosed type
1diabetic patients and relatives; and to assess their clinical utility as screening markers for
type 1DM when used individually or in combination in a trial to elucidate whether these
autoantibodies can replace the formerly used histochemical ICA test.
The study was conducted on 21 newly diagnosed type 1 diabetic children (aged 8.45±3.96), 14
healthy first degree relatives (FDRs) of diabetic patients (aged 9.7+ 2.13) and 10 healthy age-matched
control subjects. All individuals involved in the study were subjected to laboratory assessment of
random serum glucose on Synchron CX-5 autoanalyzer, anti-GAD65 and anti-IA-2 antibodies and
anti-IA-2 antibodies (by direct radioligand assay using a kit product of Medipan Diangostica) in
addition to anti-islet cell antibodies (measured by indirect immunofluorescence using a kit product
ofiNOVA Diagnostic Inc.).
The results of this ·study revealed that anti GAD65 antibody was the most prevalent autoantibody in
both patients (81%) and FDRs (29%), followed by ICA (62% and 14%, respectively). Anti-IA2 was the
least prevalent antibody, being detected in 29% of patients and 7% of FDRs. None of the three
autoantibodies was detected in any of the healthy control subjects, yielding a diagnostic
specificity of 100%, respectively.
There was no statistically significant association between the anti-GAD65 antibody status and ICA
or anti-IA-2 antibody status (P>0.05 respectively). However, a statistically significant
association was recorded between the anti-IA-2 antibody status and ICA status in both
patients and relatives (P<0.05
respectively). Our study also revealed that both anti GAD6s antibodies and anti-IA-2 antibodies
were not related to the gender or age of patients or first degree relatives (P>0.05,
respectively).
Assessment of the diagnostic performance of each of the studied autoantibodies when used
individually revealed that the anti-GAD6s antibodies had the best diagnostic performance (D. Sens.
81%, Spec 100%, PV+ 100%, py- 71% & DE 87%) as compared to ICA (D. Sens 62%, D. Spec. 100%, PV+
100%, py- 56 & DE 74%)
and anti-IA-2 antibodies (D. Sens 29%, D. Spec. 100%, PV+ 100%, py- 40%, DE 52%).
The combined use of anti-GAD6s antibodies and anti-IA-2 antibodies considering simultaneous
positivity for both antibodies as the diagnostic criterion offered no advantage over the use of
anti-IA-2 antibody testing alone (DE 52%, Sens 29%), this still being inferior to the performance
of ICA. Meanwhile, on considering positivity of one ofthe two autoantibodies as the diagnostic
criterion, the diagnostic performance was the same as that of anti-GAD6s antibodies testing alone
(DE 87%, Sens 81%) and was superior to the performance of iCA.