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[IP] Medline explanation of "Type Wierd"
I found this explanation of "TYPE WIERD" on the website Medline. Thought
that my fellow IP'ers might find it enlightening for some of the antibody
How can I differentiate a slowly developing type 1 diabetes from true type 2
diabetes without resorting to the fancy antibody tests?
Faisal Masud, MD
from Desmond A. Schatz, MD, 08/31/00
This is a problem being encountered more and more frequently. Type 1
diabetes is recognized as an autoimmune disease characterized by the
presence of autoantibodies directed against islet autoantigens (islet-cells
[ICA], glutamic acid decarboxylase [GADA], ICA512A/IA-2A, and insulin
In classical childhood-onset newly diagnosed type 1 diabetes, ICA and/or
GADA are found in 60% to 80% of patients and at least 1 autoantibody is
present in 80% to 90% of cases.
It is well recognized now that more than 25% of all patients with type 1
diabetes develop the disease after 20 years of age, constituting 10% to 20%
of all adult patients with diabetes. Unlike the process in very young
patients with type 1 diabetes, the autoimmune destructive process is much
slower, making it sometimes difficult to distinguish clinically. Therefore,
this syndrome has been termed LADA, for latent autoimmune diabetes mellitus
This has clinical significance because data clearly exists (from studies of
younger patients with classical type 1 diabetes) demonstrating that early
and intensive insulin therapy is associated with beta cell preservation and
the prevention of complications. Furthermore, initiation of insulin therapy
may prevent further weight loss and ketoacidosis. In addition, the incidence
of thyrogastric autoimmunity is significantly higher in patients with islet
autoantibodies and therefore should be assessed.
Therefore, the clinician should strongly suspect type 1 diabetes,
particularly in younger adult patients who are not overweight and who are
failing a trial of diet/exercise or oral hypoglycemic agents (typically
within 2-3 years of diagnosis). C-peptide levels (fasting and stimulated)
are also significantly lower. Although not as high as in younger patients,
there is a higher frequency of HLA DR3 and/or DR4 alleles. About 85% of ICA-
or GADA-positive patients diagnosed with type 2 diabetes subsequently
Approximately 70% to 80% of LADA patients have GADA. Whereas screening for
LADA by testing for the combination of ICA, IAA, and ICA 512/IA-2A will
identify more than 90% of affected patients under 20 years of age, they are
present in about 65% of patients over 20 years. Consequently, GADA is the
best screening antibody in patients over 20 years of age.
Screening for islet-related antibodies should no longer be considered
"fancy" testing but should become routine when a diagnosis of type 1 is
suspected. Several commercial laboratories and academic centers perform
these assays routinely. The Immunology of Diabetes Society will be
conducting a workshop in the next couple of months aimed at standardizing
the autoantibody assays.
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