When it comes to islet autoantibodies, if you only think of type 1 diabetes, you're wrong!

According to case reports in Japan [1], a 73-year-old female patient received two doses of the Moderna COVID-19 vaccine, her glycemic control began to deteriorate 4 weeks after the second dose, and 8 weeks after the second dose, the patient was diagnosed with new-onset type 1 diabetes with strong positive islet
autoantibodies.

In fact, foreign cases of new-onset type 1 diabetes have been reported
after vaccination.
It is speculated that this may be due to the fact that polyethylene glycol (PEG) lipid conjugates of stable vaccine nanoparticles can act as adjuvants and induce autoimmune reactions, not just the anaphylactic reactions
already described.
In addition, mRNAs may have adjuvant properties that activate strong and durable adaptive immune responses through tumor necrosis factor-α (TNF-α), interferon-α (IFN-α), and other cytokines secreted by immune cells[2].

Regarding the link between vaccines and type 1 diabetes, let's talk about islet autoantibodies
that are closely related to type 1 diabetes.
:left_arrow:

Understanding islet autoantibodies

Common islet autoantibodies mainly include glutamate decarboxylase antibody (GADA), islet cell antibody (ICA), tyrosine phosphatase antibody (IA-2A), insulin autoantibody (IAA), zinc transporter 8 antibody (ZnT8A), and it is also the most widely used, recognized and strongly related diabetes-related autoimmune antibody
.

Islet autoantibodies were first proposed in 1974 and are markers of immune destruction of islet β cells, which is also the main pathogenesis of autoimmune diabetes, so positive antibodies are the key indicators
for diagnosing autoimmune type 1 diabetes.
In addition, islet autoantibodies can be detected before the clinical signs of autoimmune diabetes appear, and studies have shown that more than 90% of children with type 1 diabetes before puberty are detectable positive for islet autoantibodies by age 5 years [3].

When it comes to islet autoantibody testing, if you only think of type 1 diabetes, you're wrong! Correct understanding of islet autoantibodies can not only diagnose type 1 diabetes, but also have so many application values!

Key indicators for the diagnosis of type 1 diabetes

According to the WHO (1999) classification system of diabetes etiology, diabetes can be divided into four types: type 1 diabetes mellitus (T1DM), type 2 diabetes mellitus (T2DM), gestational diabetes, and special types of diabetes
.

Among them, type 1 diabetes is divided into autoimmune and fulminant types
.
According to the Chinese Guidelines for the Diagnosis and Treatment of Type 1 Diabetes (2012 Edition), patients with clinically diagnosed T1DM should be further tested for islet autoantibodies to determine the cause
.

Diagnostic typing process for T1DM

In patients with initial onset of autoimmune diabetes, one or more islet autoantibodies are often tested positive [4].

Therefore, clinically, the above five islet autoantibodies are often detected at the same time, and there is evidence that the detection rate of T1DM can be increased to more than 90% by combining 3 or more antibody tests [5], greatly reducing the missed detection rate
.

Predict the onset of type 1 diabetes in advance

At present, the recognized pathogenesis of T1DM goes through three stages, the first stage is mainly for patients induced autoimmune abnormalities by precipitating factors, but at this time, the blood glucose is normal and no clinical symptoms appear; In the second stage, autoimmune abnormalities are experienced, but blood glucose is abnormal and clinical symptoms have not yet appeared; In the third stage, in addition to autoimmune abnormalities and blood glucose abnormalities, obvious clinical symptoms began to appear [6].

It can be seen that in the first stage, before the abnormalities of blood glucose and clinical symptoms, the presence of islet autoantibodies can be used to predict the occurrence
of T1DM.

According to the meta-analysis, the research analysis of the emergence of various antibodies affecting the autoimmune progress and T1DM development of islet cells is as follows [7]:

T1DM has a genetic predisposition, and the relatives of T1DM patients belong to high-risk groups, and it is recommended to screen for islet autoantibodies as soon as possible to prevent the risk
of disease in advance.

The best differential diagnostic indicator between type 1 diabetes and type 2 diabetes

T1DM refers to diabetes with a tendency to ketosis due to absolute insulin deficiency due to the destruction of islet β cells, and patients need to rely on insulin for life
.

Although the core of the pathological mechanism of T1DM is the autoimmune attack on islet β cells, resulting in severe insulin deficiency, relying on insulin or C-peptide may not be able to distinguish between T1DM and T2DM, especially in the early course of T1DM and later
in the course of type 2 diabetes.
The current diagnosis and treatment status is that patients with T1DM who are newly diagnosed are mainly diagnosed based on clinical symptoms and blood glucose levels, which will be prone to missed diagnosis and misdiagnosis
.

Even diabetic ketoacidosis, which is considered a typical feature of T1DM, occurs in T2DM, and adult occult autoimmune diabetes mellitus (LADA) is a type of disease that is easily misdiagnosed as T2DM, and according to several international large-scale epidemiological studies, LADA has been found to account for 2 to 12 percent of the newly diagnosed phenotype T2DM [8].

The clinical progress of LADA can be divided into non-insulin-dependent stage and insulin-dependent stage, and early accurate classification has an extremely important guiding role
in the treatment of patients.

LADA can actually be classified as a slow-progressing subtype of autoimmune T1DM, which necessitates a more reliable differential
diagnosis of T2DM.

Islet autoantibodies are the hallmark of type 1 diabetes, and the best laboratory indicator to distinguish between T1DM and T2DM is against islet autoantibodies such as glutamate decarboxylase, insulin, and zinc transporter 8 [9].

To reduce missed misdiagnosis, islet autoantibody screening
is recommended for all patients with newly diagnosed phenotype T2DM.

Ahuilong company has a perfect five islet autoantibodies: GADA, IAA, IA-2A, ICA, ZnT8A, detection methodology in addition to western blotting, and advanced acridine ester direct chemiluminescence, of which ZnT8A detection kit won the first chemiluminescence registration certificate in China, supporting iFlash series chemiluminescence analyzer, stand-alone detection speed up to 600 tests per hour, automatic operation, greatly optimizing the inspection efficiency
.