GAD65 Antibody Epitopes and Genetic Background in Latent Autoimmune Diabetes in Youth (LADY)

Type 1 diabetes: A new vision of the disease based on endotypes

Diagnosis and management of type 1 diabetes (T1D) have remained largely unchanged for the last several years. The management of the disease remains primarily focused on its phenotypical presentation and less on endotypes, namely the specific biological mechanisms behind the development of the disease. Furthermore, the treatment of T1D is essentially universal and indiscriminate-with patients administering insulin at varying dosages and frequencies to maintain adequate glycaemic control. However, it is now well understood that T1D is a heterogeneous disease with many different biological mechanisms (i.e. endotypes) behind its complex pathophysiology. A range of factors, including age of onset, immune system regulation, rate of β-cell destruction, autoantibodies, body weight, genetics and the exposome are recognised to play a role in the development of the condition. Patients can be classified into distinct diabetic subtypes based on these factors, which can be used to categorise patients into specific endotypes. The classification of patients into endotypes allows for a greater understanding of the natural progression of the disease, giving rise to more accurate and patient-centred therapies and follow-up monitoring, specifically for other autoimmune diseases. This review proposes 6 unique endotypes of T1D based on the current literature. The recognition of these endotypes could then be used to direct therapeutic modalities based on patients' individual pathophysiology.

Clinical and HLA genotype analysis of immune checkpoint inhibitor-associated diabetes mellitus: a single-center case series from China

Objective

To investigate the clinical characteristics and HLA genotypes of patients with immune checkpoint inhibitor-associated diabetes mellitus (ICI-DM) in China.

Methods

We enrolled 23 patients with ICI-DM and 51 patients with type 1 diabetes (T1D). Clinical characteristics of the patients were collected. HLA-DRB1, HLA-DQA1, and HLA-DQB1 genotyping was conducted via next-generation sequencing.

Results

The ICI-DM patients had a male predominance (70.6%), a mean body mass index (BMI) of 21.2 ± 3.5 kg/m², and a mean onset of ICI-DM in 5 (IQR, 3-9) cycles after ICI therapy. Most (78.3%) ICI-DM patients were treated with anti-PD-1, 78.3% presented with diabetic ketoacidosis, and all had low C-peptide levels and received multiple insulin injections. Compared to T1D patients, ICI-DM patients were significantly older (57.2 ± 12.4 vs 34.1 ± 15.7 years) and had higher blood glucose but lower HbA1c levels (P<0.05). Only two (8.7%) ICI-DM patients were positive for islet autoantibodies, which was lower than that in T1D patients (66.7%, P<0.001). A total of 59.1% (13/22) of ICI-DM patients were heterozygous for an HLA T1D risk haplotype, and DRB1*0901-DQA1*03-DQB1*0303 (DR9) and DRB1*0405-DQA1*03-DQB1*0401 were the major susceptible haplotypes. Compared to T1D, the susceptible DR3-DQA1*0501-DQB1*0201 (DR3) and DR9 haplotypes were less frequent (17.7% vs 2.3%; P=0.011 and 34.4% vs 15.9%; P=0.025), whereas the protective haplotypes (DRB1*1101-DQA1*05-DQB1*0301 and DRB1*1202-DQA1*0601-DQB1*0301) were more frequent in ICI-DM patients (2.1% vs 13.6%; P=0.006 and 4.2% vs 15.9%; P=0.017). None of the ICI-DM patients had T1D-associated high-risk genotypes DR3/DR3, DR3/DR9, and DR9/DR9. Among the 23 ICI-DM patients, 7 (30.4%) presented with ICI-associated fulminant type 1 diabetes (IFD), and 16 (69.6%) presented with ICI-associated type 1 diabetes (IT1D). Compared to IT1D patients, IFD patients exhibited marked hyperglycemia and low C-peptide and HbA1c levels (P<0.05). Up to 66.7% (4/6) of IFD patients were heterozygous for reported fulminant type 1 diabetes susceptibility HLA haplotypes (DRB1*0405-DQB1*0401 or DRB1*0901-DQB1*0303).

Conclusion

ICI-DM shares similar clinical features with T1D, such as acute onset, poor islet function and insulin dependence. However, the lack of islet autoantibodies, the low frequencies of T1D susceptibility and high frequencies of protective HLA haplotypes indicate that ICI-DM represents a new model distinct from classical T1D.

Determination of autoantibodies in type 2 diabetes: one simple way to improve classification

This letter aims to increase interest in better classification of type 2 diabetes. This can be done in a simple and cheap way via determination of autoantibodies. Autoantibody analysis can be used to detect the 7-12% of people with diabetes that is phenotypic of type 2 diabetes but is, in fact, latent autoimmune diabetes in adults (LADA), which may be regarded as a variant of type 1 diabetes. This may help to explain why some individuals with type 2 diabetes do not go into remission after reducing their weight, while others do, and why remission sometimes ends earlier than expected. Improved classification of diabetes may play an important role in determining adequate therapy.

Distribution of autoantibodies to insulinoma-associated antigen-2 and zinc transporter 8 in type 1 diabetes and latent autoimmune diabetes: A nationwide, multicentre, cross-sectional study

AIMS

This study investigated insulinoma-associated-2 autoantibody (IA-2A) and zinc transporter 8 autoantibody (ZnT8A) distribution in patients with type 1 diabetes (T1D) and latent autoimmune diabetes (LAD) and the autoantibodies' association with clinical characteristics and HLA-DR-DQ genes.

MATERIALS AND METHODS

This cross-sectional study recruited 17,536 patients with diabetes from 46 hospitals across China. A total of 189 patients with T1D and 58 patients with LAD with IA-2A positivity, 126 patients with T1D and 86 patients with LAD with ZnT8A positivity, and 231 patients with type 2 diabetes (T2D) were selected to evaluate islet autoantibodies, clinical phenotypes, and HLA-DR-DQ gene frequency.

RESULTS

IA-2A was bimodally distributed in patients with T1D and LAD. Patients with low IA-2A titre LAD had lower fasting C-peptide (FCP) (p < 0.01), lower postprandial C-peptide (PCP) (p < 0.001), and higher haemoglobin A1c (HbA1c) levels (p < 0.05) than patients with T2D. Patients with high IA-2A titre LAD were younger than patients with low IA-2A titre LAD (p < 0.05). Patients with low IA-2A titre T1D had lower FCP (p < 0.01), lower PCP (p < 0.01), and higher HbA1c levels (p < 0.05) than patients with high IA-2A titre LAD. HLA-DR-DQ genetic analysis demonstrated that the frequency of susceptible HLA haplotypes was higher in IA-2A-positive patients (p < 0.001) than in patients with T2D. Patients with high ZnT8A titre LAD had lower FCP (p = 0.045), lower PCP (p = 0.023), and higher HbA1c levels (p = 0.009) and a higher frequency of total susceptible haplotypes (p < 0.001) than patients with low ZnT8A titre LAD.

CONCLUSIONS

IA-2A in patients with T1D and LAD was bimodally distributed, and the presence of IA-2A could demonstrate partial LAD clinical characteristics. ZnT8A titre had a certain predictive value for islet functions in patients with LAD.