Is It Time to Screen the General Population for Type 1 Diabetes?

GAD65Abs Are Not Associated With Beta-Cell Dysfunction in Patients With T2D in the GRADE Study

Context

Autoantibodies directed against the 65-kilodalton isoform of glutamic acid decarboxylase (GAD65Abs) are markers of autoimmune type 1 diabetes (T1D) but are also present in patients with Latent Autoimmune Diabetes of Adults and autoimmune neuromuscular diseases, and also in healthy individuals. Phenotypic differences between these conditions are reflected in epitope-specific GAD65Abs and anti-idiotypic antibodies (anti-Id) against GAD65Abs. We previously reported that 7.8% of T2D patients in the GRADE study have GAD65Abs but found that GAD65Ab positivity was not correlated with beta-cell function, glycated hemoglobin (HbA1c), or fasting glucose levels.

Context

In this study, we aimed to better characterize islet autoantibodies in this T2D cohort. This is an ancillary study to NCT01794143.

Methods

We stringently defined GAD65Ab positivity with a competition assay, analyzed GAD65Ab-specific epitopes, and measured GAD65Ab-specific anti-Id in serum.

Results

Competition assays confirmed that 5.9% of the patients were GAD65Ab positive, but beta-cell function was not associated with GAD65Ab positivity, GAD65Ab epitope specificity or GAD65Ab-specific anti-Id. GAD65-related autoantibody responses in GRADE T2D patients resemble profiles in healthy individuals (low GAD65Ab titers, presence of a single autoantibody, lack of a distinct epitope pattern, and presence of anti-Id to diabetes-associated GAD65Ab). In this T2D cohort, GAD65Ab positivity is likely unrelated to the pathogenesis of beta-cell dysfunction.

Conclusion

Evidence for islet autoimmunity in the pathophysiology of T2D beta-cell dysfunction is growing, but T1D-associated autoantibodies may not accurately reflect the nature of their autoimmune process.

IgG subclass and Fc glycosylation shifts are linked to the transition from pre- to inflammatory autoimmune conditions

A crucial factor for the development of inflammatory autoimmune diseases is the occurrence of antibodies directed against self-tissues and structures, which leads to damage and inflammation. While little is known about the cause of the development of mis-directed, disease-specific T and B cells and resulting IgG autoantibody responses, there is increasing evidence that their induction can occur years before disease symptoms appear. However, a certain proportion of healthy individuals express specific IgG autoantibodies without disease symptoms and not all subjects who generate autoantibodies may develop disease symptoms. Thus, the development of inflammatory autoimmune diseases seems to involve two steps. Increasing evidence suggests that harmless self-directed T and B cell and resulting IgG autoantibody responses in the pre-autoimmune disease stage might switch to more inflammatory T and B cell and IgG autoantibody responses that trigger the inflammatory autoimmune disease stage. Here, we summarize findings on the transition from the pre-disease to the disease stage and vice versa, e.g. by pregnancy and treatment, with a focus on low-/anti-inflammatory versus pro-inflammatory IgG autoantibody responses, including IgG subclass and Fc glycosylation features. Characterization of biomarkers that identify the transition from the pre-disease to the disease stage might facilitate recognition of the ideal time point of treatment initiation and the development of therapeutic strategies for re-directing inflammatory autoimmune conditions.

Immune Intervention and Preservation of Pancreatic Beta Cell Function in Type 1 Diabetes

Type 1 diabetes (T1D) results from the immune-mediated destruction of insulin-producing β cells located within the pancreatic islets of Langerhans. The autoimmune process leads to a deficiency in insulin production and resultant hyperglycemia requiring lifelong treatment with insulin administration. T1D continues to dramatically increase in incidence, especially in young children. Substantial knowledge surrounding human disease pathogenesis exists, such that T1D is now predictable with the measurement of antibodies in the peripheral blood directed against insulin and other β cell proteins. With the ability to predict, it naturally follows that T1D should be preventable. As such, over the last two decades, numerous well-controlled clinical trials have been completed attempting to prevent diabetes onset or maintain residual β cell function after clinical onset, all providing relatively disappointing results. Here, we review the T1D prevention efforts, the current landscape of clinical therapies, and end with a discussion regarding the future outlook for preventing T1D.

Screening for T1D risk to reduce DKA is not economically viable

BACKGROUND

Children at high risk for developing type 1 diabetes (T1D) can be identified on the basis of human leukocyte antigen (HLA) genotype and the subsequent development of islet cell autoantibodies. Several studies have documented reduced incidence of diabetic ketoacidosis (DKA) in new-onset T1D when high-risk children are identified at an early age. Many have questioned whether general population screening for T1D risk should be standard of practice. We sought to perform a purely economic, cost-benefit analysis to determine if a screening program to reduce the incidence of DKA at diagnosis in children less than 5 yr is cost effective.

METHODS

We compared the cost of population screening with the benefit of preventing DKA. The cost of screening included one-time HLA typing on the entire population followed by islet cell autoantibody testing in high-risk children every 6 months until age 5 yr. The potential benefits of screening included reductions in parental lost income, medical expenses, morbidity, and mortality.

RESULTS

Screening for T1D risk for the sole purpose of reducing the cost of DKA at onset of T1D was not economically viable unless HLA testing and autoantibody testing could be performed for less than $1 and $0.03, respectively.

CONCLUSIONS

Current screening costs far outweigh the economic benefits of preventing new-onset DKA in children under 5 yr of age.