Similar genetic features and different islet cell autoantibody pattern of latent autoimmune diabetes in adults (LADA) compared with adult-onset type 1 diabetes with rapid progression

Practical Clinical Applications of Islet Autoantibody Testing in Type 1 Diabetes

BACKGROUND

The distinction between type 1 diabetes (T1D) and type 2 diabetes (T2D) is extremely important for the choice of therapy, body weight and dietary management, screening for coexistent autoimmune diseases and comorbidities, anticipated prognosis, and risk assessment in relatives. Not uncommonly, the presentation of the patient may not allow an unambiguous discrimination between T1D and T2D. To help resolve this challenge, the detection of islet autoantibodies can support the diagnosis of T1D.

CONTENT

The presence of islet autoantibodies in a person with diabetes indicates an autoimmune etiology therefore establishing the diagnosis of T1D. Presently 5 islet autoantibodies are available for routine clinical use: islet cell cytoplasmic autoantibodies (ICA), insulin autoantibodies (IAA), glutamic acid decarboxylase autoantibodies (GADA), insulinoma associated-2 autoantibodies (IA-2A), and zinc transporter-8 autoantibodies (ZnT8A). There are caveats to the selection of which islet autoantibodies should be measured. Islet autoantibodies can also predict the development of T1D. Therefore, once safe and effective therapies are available to prevent T1D, islet autoantibody testing is expected to become a routine part of medical practice. A very rare cause of autoimmune diabetes is the type B insulin resistance syndrome resulting from antagonistic autoantibodies to the insulin receptor. Rarely hypoglycemia can result from agonistic insulin receptor autoantibodies, or high-titer IAA causing the autoimmune insulin syndrome (i.e., Hirata disease).

SUMMARY

In summary, autoimmune causes of dysglycemia are increasing in clinical importance requiring the scrutiny of laboratorians. The determination of islet autoantibodies can greatly aid in the diagnosis and the prediction of T1D.

Comparing the bone mineral density among male patients with latent autoimmune diabetes and classical type 1 and type 2 diabetes, and exploring risk factors for osteoporosis

AIMS

This study aimed to compare the bone mineral densities (BMDs) among male patients with latent autoimmune diabetes in adults (LADA), classical type 1 diabetes (T1DM), and type 2 diabetes (T2DM), and to examine the risk factors for developing low BMD in these patients.

PATIENTS AND METHODS

Between January 2017 and October 2020, a total of 57, 67, and 223 male patients with LADA, classical T1DM, and T2DM, respectively, were recruited from the endocrinology department of Shanghai Tenth People's Hospital. Hormonal markers of bone metabolism, lipid profiles, uric acid, glycosylated hemoglobin A1c (HbA1c), and beta-cell function were measured using blood samples. BMD was measured at the lumbar spine, femoral neck, and right hip by dual-energy X-ray absorptiometry.

RESULTS

The mean BMD values from all three skeletal sites in male patients with LADA were comparable to those with classical T1DM but were much lower than those with T2DM. After adjusting for confounding factors, multiple linear regression analysis demonstrated that in all male patients with diabetes, body mass index (BMI), uric acid, and fasting C-peptide showed significant positive associations with BMD at all three skeletal sites; however, osteocalcin showed a negative association at all three sites.

CONCLUSIONS

Compared with male patients with T2DM, lower BMDs were observed in patients with LADA and T1DM. Low BMI, uric acid, C-peptide levels, and high osteocalcin levels are risk factors for developing low BMD in male patients with diabetes.

Critical Amino Acid Variants in HLA-DRB1 and -DQB1 Allotypes in the Development of Classical Type 1 Diabetes and Latent Autoimmune Diabetes in Adults in the Japanese Population

The effects of amino acid variants encoded by the human leukocyte antigen (HLA) class II on the development of classical type 1 diabetes (T1D) and latent autoimmune diabetes in adults (LADA) have not been fully elucidated. We retrospectively investigated the HLA-DRB1 and -DQB1 genes of 72 patients with classical T1D and 102 patients with LADA in the Japanese population and compared the frequencies of HLA-DRB1 and -DQB1 alleles between these patients and the Japanese populations previously reported by another institution. We also performed a blind association analysis with all amino acid positions in classical T1D and LADA, and compared the associations of HLA-DRB1 and -DQB1 amino acid positions in classical T1D and LADA. The frequency of DRß-Phe-13 was significantly higher and those of DRß-Arg-13 and DQß-Gly-70 were significantly lower in patients with classical T1D and LADA than in controls. The frequencies of DRß-His-13 and DQß-Glu-70 were significantly higher in classical T1D patients than in controls. The frequency of DRß-Ser-13 was significantly lower and that of DQß-Arg-70 was significantly higher in LADA patients than in controls. HLA-DRß1 position 13 and HLA-DQß1 position 70 could be critical amino acid positions in the development of classical T1D and LADA.

The association of human leukocyte antigen class II (HLA II) haplotypes with the risk of Latent autoimmune diabetes of adults (LADA): Evidence based on available data

AIMS

Latent autoimmune diabetes in adult (LADA), classified as between type 1 and type 2 diabetes mellitus, has received widespread attention. A number of studies have investigated the association between HLA DQA-DQB, DRB-DQB haplotypes and the onset of LADA. However, the conclusions remained inconsistent. Therefore, this study aims to clarify the impact of these HLA haplotypes on the pathogenesis of LADA.

METHODS

Systematic searches were carried out on the Medline, PubMed, Embase and Wan Fang respectively to investigate the association of LADA with HLA DQA-DQB, DRB-DQB up to June 05, 2020. We performed this retrospective research using meta-analysis.

RESULTS

The pooled results demonstrated that in Chinese, DQA1*05-DQB1*0201, DQA1*03-DQB1*0401, and DQA1*03-DQB1*0303 were statistically significantly associated with increasing the risk of LADA (P < 0.001), while DQA1*0102-DQB1*0602 was statistically significantly correlated with decreasing the susceptibility to the disease (P = 0.003). However, there was no obvious association found between DQA1*0201-DQB1*0201 (P = 0.984), DQA1*03-DQB1*0302 (P = 0.110), DQA1*0601-DQB1*0301 (P = 0.398) and LADA. In Japanese, DRB1*0802-DQB1*0302 (P = 0.003) and DRB1*0901-DQB1*0303 (P = 0.001), but not DRB1*0405-DQB1*0401 (P = 0.136), were found to be a risk factor for LADA. As for Caucasian, both DRB1*03-DQB1*0201 and DRB1*04-DQB1*0302 were predisposed to the development of LADA with a statistical significance (P < 0.001).

CONCLUSION

In all, HLA DQA-DQB, HLA DRB-DQB haplotypes might play a role in the risk of LADA, which could provide an improved understanding of LADA pathogenesis and the detection of susceptible HLA haplotypes in the diagnosis and therapy of this disease.

Past, present and future of latent autoimmune diabetes in adults

Latent autoimmune diabetes in adults (LADA) is the most common form of autoimmune diabetes diagnosed in adults. Similar to type 1 diabetes, the prevalence of LADA is impacted by ethnicity and geography. LADA is characterized by β cell loss due to autoimmunity and insulin resistance and has highly heterogeneous clinical features, autoimmunity, and genetics in a glutamic acid decarboxylase antibody (GADA) titre-dependent manner, suggesting LADA is part of a continuum spectrum between type 1 and type 2 diabetes. Although LADA is the most frequent form of autoimmune diabetes diagnosed in adults, clinical trials involving LADA are scarce. Here we review the recent advancements in LADA epidemiology, clinical features, pathogenesis, and interventions. We also highlight the environmental factors that are thought to play an important role in addition to genetics in the pathogenesis of LADA. In the future, high-throughput molecular profiles might shed light on the nature of LADA among the wide spectrum of diabetes and offer new opportunities to identify novel LADA-specific biomarkers.

Setting the Stage for Islet Autoimmunity in Type 2 Diabetes: Obesity-Associated Chronic Systemic Inflammation and Endoplasmic Reticulum (ER) Stress

Islet autoimmunity has been identified as a component of both type 1 (T1D) and type 2 (T2D) diabetes, but the pathway through which islet autoimmunity develops in T1D and T2D may be different. Acknowledging the presence of islet autoimmunity in the pathophysiology of T2D, a historically nonautoimmune metabolic disease, would pave the way for important changes in classifications of and therapeutic options for T2D. In order to fully appreciate the importance of islet autoimmunity in T2D, the underlying mechanisms for immune system activation need to be explored. In this review, we focus on the potential origin of immune system activation (innate and adaptive) leading to the development of islet autoimmunity in T2D.

HLA-DQB1 and HLA-DRB1 Variants Confer Susceptibility to Latent Autoimmune Diabetes in Adults: Relative Predispositional Effects among Allele Groups

Latent autoimmune diabetes in adults (LADA) was recently demonstrated to be the most frequent form of adult-onset autoimmune diabetes mellitus. Case–control studies have investigated the relationship between human leukocyte antigen (HLA)-DQB1 and HLA-DRB1 polymorphisms and LADA risk, but their conclusions are inconsistent. This study aimed to more precisely explore the correlation between these HLA gene variants and LADA development. Eight databases, including PubMed, Embase, and Medline, were systematically searched for relevant studies up to September 15, 2018. We performed this retrospective study using meta-analysis and relative predispositional effect (RPE) methods. The meta-analysis results indicated that DQB1*02 (odds ratio (OR) = 1.685, p_c < 0.005) and DQB1*06 (OR = 0.604, p_c = 0.010) have opposite effects on susceptibility to LADA, while a significant decrease in LADA risk caused by DQB1*05 (OR = 0.764, p_c = 0.100) disappeared upon Bonferroni correction. The RPE method confirmed the roles of DQB1*02 (χ² = 46.475, p < 0.001) and DQB1*06 (χ² = 17.883, p < 0.001) and further suggested protective effects of DQB1*05 (χ² = 16.496, p < 0.001). Additionally, the meta-analysis results showed that DRB1*03 (OR = 2.685, p_c < 0.013), DRB1*04 (OR = 1.954, p_c < 0.013), and DRB1*09 (OR = 1.346, p_c < 0.013) are associated with increased LADA risk, while DRB1*12 (OR = 0.600, p_c < 0.013) and DRB1*13 (OR = 0.583, p_c < 0.013) carriers have a decreased risk of developing LADA. Furthermore, the RPE method revealed that DRB1*03 (χ² = 98.754, p < 0.001), DRB1*04 (χ² = 94.685, p < 0.001), DRB1*09 (χ² = 40.489, p < 0.001), DRB1*01 (χ² = 12.181, p < 0.001), DRB1*07 (χ² = 10.882, p = 0.001), and DRB1*08 (χ² = 5.000, p = 0.025) play protective roles against LADA. LADA showed a close relationship with genetic polymorphisms of HLA-DQB1 and WHLA-DRB1, which could contribute to a better understanding of disease pathogenesis and the identification of predisposing loci in the diagnosis and treatment of LADA.

Etiology and Pathogenesis of Latent Autoimmune Diabetes in Adults (LADA) Compared to Type 2 Diabetes

As the heterogeneity of diabetes is becoming increasingly clear, opportunities arise for more accurate assessment of factors influencing disease onset, which may lead to more efficient primary prevention. LADA - latent autoimmune diabetes in adults - is a common, hybrid form of diabetes with features of both type 1 and type 2 diabetes. This review aims to summarize current knowledge on the pathophysiological and etiological overlap and differences between LADA and type 2 diabetes, discuss similarities between LADA and type 1 diabetes and point at future research needs. Studies conducted to date show a clear genetic overlap between LADA and type 1 diabetes with a high risk conferred by variants in the human leukocyte antigen (HLA) region. In contrast, data from the limited number of studies on lifestyle factors available indicate that LADA may share several environmental risk factors with type 2 diabetes including overweight, physical inactivity, alcohol consumption (protective) and smoking. These factors are known to influence insulin sensitivity, suggesting that insulin resistance, in addition to insulin deficiency due to autoimmune destruction of the beta cells, may play a key role in the pathogenesis of LADA. Moreover, this implies that onset of LADA, similar to type 2 diabetes, to some extent could be prevented or postponed by lifestyle modification such as weight reduction and increased physical activity. The preventive potential of LADA is an important topic to elucidate in future studies, preferably intervention studies.

Identification of a distinct phenotype of elderly latent autoimmune diabetes in adults: LADA China Study 8

BACKGROUND

Latent autoimmune diabetes in adults (LADA) exhibits significant clinical heterogeneity, but the underlying causes remain unclear. The aim of this study was to investigate whether age of onset of LADA contributes to the observed clinical heterogeneity by comparing the clinical, metabolic, and immunogenetic characteristics between elderly and young LADA patients.

METHODS

The cross-sectional study included a total of 579 patients with LADA which was further divided into elderly LADA (E-LADA) group (n = 135, age of onset ≥60 years) and young LADA (Y-LADA) group (n = 444, age of onset <60 years). Age-matched subjects with type 2 diabetes were served as control (E-T2D group, n = 622). Clinical characteristics, serum autoantibodies, and HLA-DQ haplotypes were compared among these groups.

RESULTS

Compared with patients with Y-LADA, patients with E-LADA have better residual beta-cell function and higher level of insulin resistance (both P < .01), more metabolic syndrome characteristics, similar proportion of islet autoantibody positivity, and strikingly different HLA-DQ genetic background. In comparison with E-T2D patients, E-LADA patients tend to have similar metabolic syndrome prevalence, comparable C-peptide levels, and insulin resistance levels and share similar HLA-DQ genetic characteristics.

CONCLUSIONS

Elderly LADA differs phenotypically and genetically from Y-LADA but has a clinical and genetic profile more similar to that of E-T2D. These distinct phenotypes could potentially help physicians better manage patients with E-LADA.

First Genome-Wide Association Study of Latent Autoimmune Diabetes in Adults Reveals Novel Insights Linking Immune and Metabolic Diabetes

OBJECTIVE

Latent autoimmune diabetes in adults (LADA) shares clinical features with both type 1 and type 2 diabetes; however, there is ongoing debate regarding the precise definition of LADA. Understanding its genetic basis is one potential strategy to gain insight into appropriate classification of this diabetes subtype.

RESEARCH DESIGN AND METHODS

We performed the first genome-wide association study of LADA in case subjects of European ancestry versus population control subjects (n = 2,634 vs. 5,947) and compared against both case subjects with type 1 diabetes (n = 2,454 vs. 968) and type 2 diabetes (n = 2,779 vs. 10,396).

RESULTS

The leading genetic signals were principally shared with type 1 diabetes, although we observed positive genetic correlations genome-wide with both type 1 and type 2 diabetes. Additionally, we observed a novel independent signal at the known type 1 diabetes locus harboring PFKFB3, encoding a regulator of glycolysis and insulin signaling in type 2 diabetes and inflammation and autophagy in autoimmune disease, as well as an attenuation of key type 1-associated HLA haplotype frequencies in LADA, suggesting that these are factors that distinguish childhood-onset type 1 diabetes from adult autoimmune diabetes.

CONCLUSIONS

Our results support the need for further investigations of the genetic factors that distinguish forms of autoimmune diabetes as well as more precise classification strategies.

The Relationship between insulin variable number of tandem repeats (INS-VNTR) -23 A/T and cytotoxic Tlymphocyte associated protein-4 (CTLA-4) +49 A/G polymorphisms with islet autoantibodies in persons with diabetes

Background: Both genetic and environmental factors are important in pathogenesis of diabetes. Non HLA (Human Leukocyte Antigen) genes such as INS-VNTR and CTLA-4 in addition of HLA genes have influence on genetic susceptibility for diabetes mellitus. In this study the association of +49 A/G CTLA-4 and -23 A/T INS-VNTR polymorphisms with diabetes and their association with islet autoantibodies were investigated. Methods: Thirty four autoantibody positive adult persons with diabetes mellitus and 39 persons with Type 1diabetes mellitus (T1DM), 40 autoantibody negative Type 2 diabetes mellitus (T2DM) patients and 40 healthy controls were studied using Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) technique. Results: The frequencies of -23 A/T INS-VNTR genotypes were not significantly different among study groups. It was shown that the distribution of the +49A/G CTLA-4 allele and genotype frequencies did not differ between T1DM patients, autoantibody positive adult patients and controls. With increasing CTLA-4 G allele and GG/AG genotypes, the frequency of Glutamic Acid Decarboxylase Autoantibody (GADA), Islet Cell Autoantibody (ICA) and Islet Antigen 2 Antibody (IA2A) positive patients were increased. Conclusion: Our results suggest that susceptibility allele A of -23A/T INS-VNTR does not have any role in the pathogenesis of diabetes in our patients and susceptibility allele G of +49 A/G CTLA-4 if not, has a small role in pathogenesis of diabetes in T1DM and autoantibody positive adult patients and in spite of significant increase in autoantibody negative T2DM group it does not have any role in disease pathogenesis.

Metabolic risk profiles in diabetes stratified according to age at onset, islet autoimmunity and fasting C-peptide

OBJECTIVE

Islet autoimmunity, age at onset and time to insulin treatment are often used to define subgroups of diabetes. However, the latter criterion is not clinical useful. Here, we examined whether an unbiased stratification of diabetes according to age at onset, fasting C-peptide and GAD autoantibodies (GADab) defines groups with differences in glycaemic control and markers of cardiometabolic risk.

DESIGN AND METHODS

A cohort of 4374 adults with relatively newly diagnosed diabetes referred to a Danish hospital during 1997-2012 was stratified according to age at onset above or below 30 years, fasting C-peptide above or below 300 pmol/l (CPEP_high or CPEP_low), and presence or absence of GADab (GAD_pos or GAD_neg). HbA_1c, BMI, blood pressure (BP), lipid profile, alanine aminotransferase (ALT) and creatinine were evaluated.

RESULTS

GADab were present in 13% of the cohort. Age at onset was not associated with major differences between groups. Patients with insulin deficient diabetes (CPEP_low; n = 503) had higher HbA_1c but otherwise lower cardiometabolic risk (lower BMI, BP, LDL, triacylglycerol, and ALT, and higher HDL) than both patients with latent autoimmune diabetes of adults (LADA defined as GAD_posCPEP_high; n = 327) and patients with type 2 diabetes (GAD_negCPEP_high; n = 3544). Patients with LADA defined an intermediate group with higher HbA_1c but otherwise lower cardiometabolic risk than patients with type 2 diabetes.

CONCLUSIONS

Our results demonstrate that fasting C-peptide and GADab status, but not age at onset, define groups of patients with diabetes with clinically relevant differences in glycaemic control and cardiometabolic risk.

Clinical features of childhood diabetes mellitus focusing on latent autoimmune diabetes

PURPOSE

This study was designed to evaluate the clinical characteristics of childhood diabetes mellitus (DM) according to its classification as well as the clinical course of latent autoimmune diabetes (LAD) that initially showed noninsulin dependence despite autoantibody positivity.

METHODS

A total of 91 subjects diagnosed between 2001 and 2015 were enrolled in the study. They were classified into 3 groups: type 1 DM, LAD, and type 2 DM. Clinical features and laboratory findings were compared among groups.

RESULTS

Among 91 subjects, type 1 DM, LAD, and type 2 DM were 51 (56.0%), 7 (7.7%), and 33 (36.3%), respectively. In LAD, age at diagnosis and BMI Z-scores were higher, as compared with those in type 1 DM. Initial serum c-peptide levels were higher in LAD than those in type 1 DM, but lower than those in type 2 DM. In LAD, the mean follow-up duration was 4.56 years, and 43% of the patients ultimately required intensive insulin treatment with dosage of > 0.5 U/kg/day. HbA1C and serum c-peptide levels at the time of intensive insulin treatment were 9.43±0.93% and 1.37±1.36 ng/mL, respectively. Recent serum c-peptide/glucose ratio was lower in the group requiring intensive insulin treatment than the group without intensive insulin treatment, with P-value of 0.057 (0.003±0.005 vs. 0.071±0.086).

CONCLUSION

Initial autoantibody evaluation is useful for classification and management. Close monitoring of the patients with LAD is important due to the expected need for intensive insulin treatment within several years.

HLA Genetic Discrepancy Between Latent Autoimmune Diabetes in Adults and Type 1 Diabetes: LADA China Study No. 6

CONTEXT

The discrepancies in terms of human leukocyte antigen (HLA)-DRB1-DQA1-DQB1 conferred risks between latent autoimmune diabetes in adults (LADA) and type 1 diabetes (T1D) patients remained almost completely unknown. The goal of the current study is to determine and compare HLA-conferred risks between LADA and T1D.

DESIGN

A case-control study was conducted in a representative Chinese data set containing 520 T1D patients, 562 LADA patients, and 1065 controls. The frequencies and odds ratios for HLA susceptible haplotypes and genotypes and for arginine at residue 52 in the DQ-α chain or aspartic acid at residue 57 in the DQ-β chain were analyzed.

RESULTS

DRB1*0405-DQA1*03-DQB1*0401 and DRB1*0901-DQA1*03-DQB1*0303 are the major LADA susceptible haplotypes, which also confer comparable risks for T1D (odds ratio 2.02 vs 2.20 and 1.61 vs 2.30, respectively). The strongly associated T1D haplotype DRB1*0301-DQA1*05-DQB1*0201 is also associated with LADA but confers only half of the T1D risk (odds ratio 2.65 vs 4.84). Interestingly, the most susceptible T1D haplotypes, DRB1*0901-DQA1*05-DQB1*0201, DRB1*0301-DQA1*03-DQB1*0201, and DRB1*0301-DQA1*03-DQB1*0303, are not associated with LADA. Genotypes for DR3/DR3, DR3/DR9, and DR9/DR9 are highly associated with T1D susceptibility, whereas only DR9/DR9 confers risk for LADA. DR3/DR3 is the high-risk genotype in Chinese T1D patients, which manifests similar risk as the DR3/DR4 genotype in Caucasians but with a lower frequency. DR9/DR9 is the high risk LADA genotype in Chinese. Alleles with DQ-α arginine at residue 52-positive, DQ-β aspartic acid at residue 57-negative, and their combination formed in cis or trans confer susceptibility to T1D but not to LADA.

CONCLUSION

Our results suggest that LADA risk conferred by HLA-DRB1-DQA1-DQB1 loci in Chinese differs significantly from that of T1D risk. This information would be useful for classifying Asian LADA patients, which should provides novel insight into the understanding of its pathoetiology as well.

Insulin secretion in patients with latent autoimmune diabetes (LADA): half way between type 1 and type 2 diabetes: action LADA 9

BACKGROUND

The study of endogenous insulin secretion may provide relevant insight into the comparison of the natural history of adult onset latent autoimmune diabetes (LADA) with types 1 and 2 diabetes mellitus. The aim of this study was to compare the results of the C-peptide response to mixed-meal stimulation in LADA patients with different disease durations and subjects with type 2 and adult-onset type 1 diabetes.

METHODS

Stimulated C-peptide secretion was assessed using the mixed-meal tolerance test in patients with LADA (n = 32), type 1 diabetes mellitus (n = 33) and type 2 diabetes mellitus (n = 30). All patients were 30 to 70 years old at disease onset. The duration of diabetes in all groups ranged from 6 months to 10 years. The recruitment strategy was predefined to include at least 10 subjects in the following 3 disease onset categories for each group: 6 to 18 months, 19 months to 5 years and 5 to 10 years.

RESULTS

At all time-points of the mixed-meal tolerance test, patients with LADA had a lower stimulated C-peptide response than the type 2 diabetes group and a higher response than the type 1 diabetes group. The same results were found when the peak or area under the C-peptide curve was measured. When the results were stratified by time since disease onset, a similar pattern of residual insulin secretory capacity was observed.

CONCLUSIONS

The present study shows that the magnitude of stimulated insulin secretion in LADA is intermediate between that of type 1 and type 2 diabetes mellitus.

LADA and CARDS: a prospective study of clinical outcome in established adult-onset autoimmune diabetes

OBJECTIVE

Diabetes-associated autoantibodies can be detected in adult-onset diabetes, even when initially non-insulin requiring, i.e., with latent autoimmune diabetes. We aimed to identify adult-onset autoimmune diabetes in patients with established "type 2 diabetes" participating in the Collaborative Atorvastatin Diabetes Study (CARDS) to characterize their phenotype and clinical outcome.

RESEARCH DESIGN AND METHODS

We prospectively studied 2,425 European patients with presumed type 2 diabetes (mean age 62 years, diabetes duration 7.9 years) for outcomes at 3.9 years after randomization to either atorvastatin or placebo. Subjects were screened for autoantibodies to GAD (GADA), insulinoma-associated antigen-2 (IA-2A), and zinc-transporter 8 (ZnT8A).

RESULTS

A total of 173 patients (7.1%) had GADA, of whom 11 (0.5%) and 5 (0.2%) were also positive for IA-2A and ZnT8A, respectively. At baseline, 44% of GADA-positive patients were not on insulin. Fewer autoantibody-positive than autoantibody-negative patients had metabolic syndrome (64 vs. 80%), and more were on insulin (56 vs. 17%) (P < 0.0001 for each) without lower HbA1c (69 mmol/mol [8.5%] vs. 62 mmol/mol [7.8%]). The frequency of microvascular and macrovascular events was similar in both cohorts, independent of atorvastatin.

CONCLUSIONS

Adult-onset autoimmune diabetes was prevalent, even in patients with established diabetes presumed to have type 2 diabetes. After 11.8 years' diabetes duration, nearly half the patients with autoimmune diabetes were not on insulin treatment and almost two-thirds had metabolic syndrome. The type of diabetes, whether autoimmune diabetes or type 2 diabetes, did not impact the risk of microvascular disease.

Overlap of genetic susceptibility to type 1 diabetes, type 2 diabetes, and latent autoimmune diabetes in adults

Despite the notion that there is a degree of commonality to the biological etiology of type 1 diabetes (T1D) and type 2 diabetes (T2D), the lack of overlap in the genetic factors underpinning each of them suggests very distinct mechanisms. A disorder considered to be at the "intersection" of these two diseases is "latent autoimmune diabetes in adults" (LADA). Interestingly, genetic signals from both T1D and T2D are also seen in LADA, including the key HLA and transcription factor 7-like 2 (TCF7L2) loci, but the magnitudes of these effects are more complex than just pointing to LADA as being a simple admixture of T1D and T2D. We review the current status of the understanding of the genetics of LADA and place it in the context of what is known about the genetics of its better-studied "cousins," T1D and T2D, especially with respect to the myriad of discoveries made over the last decade through genome-wide association studies.

Glycemic control and insulin requirements in type 1 diabetic patients depending on the clinical characteristics at diabetes onset

INTRODUCTION

The long-term prognosis of type 1 diabetes (T1DM) was evaluated in relation to the clinical characteristics at the time of diabetes onset.

PATIENTS AND METHODS

We examined retrospectively the clinical and laboratory characteristics present at the time of diagnosis in 301 adult patients (187 men) consecutively admitted to hospital with T1DM onset and evaluated the clinical outcome of T1DM during 6 ± 4.8 years following diagnosis.

RESULTS

Women needed a greater insulin dose per kg of body weight over the first 2 years following diagnosis. Younger patients at diagnosis had greater insulin requirements during follow-up. Patients with at least one positive pancreatic antibody needed a greater insulin dose 2 years after diagnosis and developed poorer glycemic control during follow-up than patients with no detectable pancreatic antibodies at onset. Diabetic ketoacidosis at onset was associated with greater insulin requirements over the first 2 years of follow-up and with poorer glycemic control during the course of the illness. C-peptide levels at diagnosis correlated with insulin requirements during the first 2 years of follow-up. Patients with higher HbA1c levels at diagnosis had greater insulin requirements in the first year of follow-up. A correlation was found between the HbA1c levels at the consecutive years of follow-up.

CONCLUSIONS

Female sex, younger age, humoral pancreatic autoimmunity, diabetic ketoacidosis, lower pancreatic reserve and higher HbA1c levels at onset could predict a poor long-term clinical outcome of T1DM in terms of insulin requirements and glycemic control.

Latent autoimmune diabetes in adults is perched between type 1 and type 2: evidence from adults in one region of Spain

BACKGROUND

The aim of this study was to characterize the clinical characteristics and insulin secretion in adults with latent autoimmune diabetes in adults (LADA). We also compared these characteristics in subjects with antibody-negative type 2 diabetes (T2DM) or adult-onset type 1 diabetes (T1DM) to subjects with LADA.

METHODS

In this cross-sectional study, 82 patients with LADA, 78 with T1DM and 485 with T2DM were studied. Clinical and metabolic data, in particular those that related to metabolic syndrome, fasting C-peptide and islet-cell autoantibodies [glutamic acid decarboxylase (GADAb) and IA2 (IA2Ab)] were measured.

RESULTS

The frequency of metabolic syndrome in patients with LADA (37.3%) was higher than in those with T1DM (15.5%; p = 0.005) and lower than in patients with T2DM (67.2%; p < 0.001). During the first 36 months of the disease, the C-peptide concentration in LADA patients was higher than in subjects with T1DM but was lower than in T2DM patients (p < 0.01 for comparisons). Glycemic control in LADA patients (HbA1c 8.1%) was worse than in patients with T2DM (HbA1c 7.6%; p =0.007). An inverse association between GADAb titers and C-peptide concentrations was found in subjects with LADA (p < 0.001). Finally, LADA patients rapidly progressed to insulin treatment.

CONCLUSIONS

As in other European populations, patients with LADA in Spain have a distinct metabolic profile compared with patients with T1DM or T2DM. LADA is also associated with higher impairment of beta-cell function and has worse glycemic control than in T2DM. Beta cell function is related to GADAb titers in patients with LADA.

Adult-onset autoimmune diabetes in Europe is prevalent with a broad clinical phenotype: Action LADA 7

OBJECTIVE

Specific autoantibodies characterize type 1 diabetes in childhood but are also found in adult-onset diabetes, even when initially non-insulin requiring, e.g., with latent autoimmune diabetes (LADA). We aimed to characterize adult-onset autoimmune diabetes.

RESEARCH DESIGN AND METHODS

We consecutively studied 6,156 European diabetic patients attending clinics within 5 years of diagnosis (age range, 30-70 years) examined cross-sectionally clinically and for GAD antibodies (GADA) and antibodies to insulinoma-associated antigen-2 (IA-2A) and zinc-transporter 8 (ZnT8A).

RESULTS

Of 6,156 patients, 541 (8.8%) had GADA and only 57 (0.9%) IA-2A or ZnT8A alone. More autoantibody-positive than autoantibody-negative patients were younger, leaner, on insulin (49.5 vs. 13.2%), and female (P < 0.0001 for each), though LADA patients (9.7% of total) did not show categorically distinct clinical features from autoantibody-negative type 2 diabetes. Similarly, more GADA patients with high (>200 World Health Organization IU) (n = 403) compared with low (n = 138) titer were female, lean, and insulin treated (54.6 vs. 39.7%) (P < 0.02 for each). Autoantibody-positive patients usually had GADA (541 of 598; 90.5%) and had LADA more often than type 1 autoimmune diabetes (odds ratio 3.3).

CONCLUSIONS

Adult-onset autoimmune diabetes emerges as a prevalent form of autoimmune diabetes. Our results indicate that adult-onset autoimmune diabetes in Europe encompasses type 1 diabetes and LADA in the same broad clinical and autoantibody-positive spectrum. At diagnosis, patients with adult-onset autoimmune diabetes are usually non-insulin requiring and clinically indistinguishable from patients with type 2 diabetes, though they tend to be younger and leaner. Only with screening for autoantibodies, especially GADA, can they be identified with certainty.

Responders to insulin therapy at 18 months in adults with newly diagnosed diabetes: which insulin regimen?

OBJECTIVES

To describe baseline characteristics of responders to insulin therapy (HbA(1c) targets < 58 mmol/mol, 7.5%) at 18 months among adults with newly diagnosed diabetes.

METHODS

A retrospective UK study derived from 479 general practices electronic dataset. We included all adults (age > 18 years) with newly diagnosed diabetes who required insulin therapy within 6 months of diagnosis. The data comprised insulin regimen (long-acting only; premixed insulin only; basal bolus insulin regimen), gender, Townsend quintile, baseline and an 18-month measurement of clinical and biochemical variables. Multiple imputations were undertaken and logistic regression used to assess the effect of covariates.

RESULTS

A total of 1492 patients (aged 19-93 years) were analysed. Means (SD) baseline HbA(1c) and BMI were 10.3% (2.6%) and 29.6 (7.0%), respectively. Following multiple imputation for missing data, logistic regression analysis indicated important covariates to achieve HbA(1c) targets were baseline HbA(1c), lipid lowering therapy, gender and age. Including all covariates, those treated with premixed insulin were 47% more likely to achieve target HbA(1c) at 18 months than those treated with a basal-bolus regimes (adjusted OR 1.47; 95% CI 1.12-1.92, P = 0.006)) and 32% more likely than those treated with long-acting insulin was (adjusted OR 1.32; 95% CI 1.01-1.74, P = 0.044). Those with a higher baseline HbA(1c) level, on lipid-lowering therapy, women and younger patients had a lower response rate. Mean weight gain (SD) was 2.4 kg (8.5 kg) and was not influenced by treatment regimen.

CONCLUSION

The use of premixed insulin regimen among newly diagnosed patients with diabetes appears to be most effective in reaching HbA(1c) target values, independent of other confounders. The appropriate choice of insulin regimen at initiation should therefore take into account various metabolic and psychosocial factors.

Latent Autoimmune Diabetes Mellitus in Adults (LADA) and it's characteristics in a subset of Nigerians initially managed for type 2 diabetes

INTRODUCTION

Latent autoimmune diabetes in adults (LADA) is an entity characterized by the presence of GAD autoantibodies. LADA is largely understudied and underreported amongst Nigerians with Diabetes Mellitus (DM). We undertook to document the Prevalence, clinical and biochemical characteristics of LADA in a subset of Nigerians who hitherto had been treated for type 2 DM.

METHODS

This is a cross-sectional study conducted on 235 patients being managed for type 2 DM. The diagnosis of LADA was made in the presence of Glutamic Acid Decarboxylase autoantibody (GADA) positivity in the study subjects. Thereafter persons with LADA were compared with those without LADA. Clinical parameters such as demographic data, history of diabetes mellitus (DM) and its complications were obtained, biochemical parameters including Fasting blood glucose (FBG), C-peptide, glycated haemoglobin (HbA1c) and lipid parameters were compared in both groups of Study subject. Test statistics used were Student t- test and χ 2. SPSS was used for data analysis.

RESULTS

Thirty three out of 235 of the Study subjects were GADA positive, giving a prevalence of 14%. The mean age (SD) of the subjects with LADA is 53.24(7.22) with an age range of 30-63 years. Majority (48%) of LADA subjects were in the 50-59 age category. There was no significant difference in the proportion of males and females with LADA (p = 0.3). 37% of patients with LADA were on insulin for glycaemic control. Three (3) LADA subjects had history/clinical evidence of autoimmune thyroid disease. 66% of LADA were in the overweight/obese category. LADA subjects had significant poor long term glycaemic control compared with anti-GAD negative subjects (p = 0.026). About half of LADA subjects were insulinopaenic. LADA subjects had lower levels of total cholesterol than GADA-ve subjects (p = 0.03). A higher proportion of LADA had evidence of microvascular complications of DM compared with antiGAD negative individuals.

CONCLUSION

The diagnosis of LADA should be entertained in overweight/obese persons from the fourth decade of life presenting with DM. Pharmacotherapy with insulin is a potential means of managing hyperglycaemia in this group of patients especially since a significant proportion are insulinopaenic. The Prevalence of LADA in our patients is comparable to what obtains in Ghanaian and Caucasian populations.

Prevalence and clinical characteristics of recently diagnosed type 2 diabetes patients with positive anti-glutamic Acid decarboxylase antibody

BACKGROUND

Latent autoimmune diabetes in adults (LADA) refers to a specific type of diabetes characterized by adult onset, presence of islet auto-antibodies, insulin independence at the time of diagnosis, and rapid decline in β-cell function. The prevalence of LADA among patients with type 2 diabetes varies from 2% to 20% according to the study population. Since most studies on the prevalence of LADA performed in Korea were conducted in patients who had been tested for anti-glutamic acid decarboxylase antibody (GADAb), a selection bias could not be excluded. In this study, we examined the prevalence and clinical characteristics of LADA among adult patients recently diagnosed with type 2 diabetes.

METHODS

We included 462 patients who were diagnosed with type 2 diabetes within 5 years from the time this study was performed. We measured GADAb, fasting insulin level, fasting C-peptide level, fasting plasma glucose level, HbA1c, and serum lipid profiles and collected data on clinical characteristics.

RESULTS

The prevalence of LADA was 4.3% (20/462) among adult patients with newly diagnosed type 2 diabetes. Compared with the GADAb-negative patients, the GADAb-positive patients had lower fasting C-peptide levels (1.2±0.8 ng/mL vs. 2.0±1.2 ng/mL, P=0.004). Other metabolic features were not significantly different between the two groups.

CONCLUSION

The prevalence of LADA is 4.3% among Korean adult patients with recently diagnosed type 2 diabetes. The Korean LADA patients exhibited decreased insulin secretory capacity as reflected by lower C-peptide levels.

The type 2 diabetes-associated variant in TCF7L2 is associated with latent autoimmune diabetes in adult Europeans and the gene effect is modified by obesity: a meta-analysis and an individual study

AIMS/HYPOTHESIS

The variants of transcription factor 7-like 2 (TCF7L2) gene have been proposed to be associated with latent autoimmune diabetes in adults (LADA). We sought to confirm the possible association in Europeans and to examine the interaction between one gene variant and clinical data.

METHODS

The TCF7L2 rs7903146 C-to-T polymorphism was genotyped in 211 LADA, 1,297 type 2 diabetic, 545 type 1 diabetic and 1,497 control individuals from Hungary. A meta-analysis of our and previously published studies was performed to evaluate the size and the heterogeneity of the gene effect.

RESULTS

The meta-analysis yielded a significant effect of TCF7L2 T allele (OR 1.28; p < 0.0001) on LADA risk without heterogeneity among Europeans. The T allele conferred equally strong susceptibility to LADA and type 2 diabetes. In the Hungarian dataset, the T allele was associated with LADA and type 2 diabetes, but not with type 1 diabetes. T allele carriers had significantly lower BMI than patients with the CC genotype in the LADA and type 2 diabetes groups (p = 0.0021 and p = 0.0013, respectively). In both diseases, the diabetes risk was significantly higher in the non-overweight than in the overweight BMI category (p = 0.0013 and p < 0.0001, respectively); susceptibility to LADA was increased by 2.84-fold in non-overweight individuals compared with overweight ones.

CONCLUSIONS/INTERPRETATION

The meta-analysis demonstrates that TCF7L2 rs7903146 polymorphism is a population-independent susceptibility locus for LADA in Europeans. The effect size is similar for LADA and type 2 diabetes. The gene effect on diabetes risk may be modulated by BMI, such that the lower the BMI, the higher the gene effect.

Latent autoimmune diabetes of adults is phenotypically similar to type 1 diabetes in a minority population

CONTEXT

Latent autoimmune diabetes of adults (LADA) is a form of autoimmune diabetes that has been classified as part of type 1 diabetes or as a distinct clinical entity. Its precise place as a disease category is therefore controversial.

OBJECTIVE

The objective of this study was to further examine this issue by comparing the phenotypes of LADA and type 1 diabetes in a predominately minority population.

PATIENTS AND METHODS

We studied 126 subjects who were anti-glutamic acid decarboxylase antibody-positive in two separate studies--63 subjects in an outpatient study (study 1), and 63 inpatients after resolution of ketoacidosis (study 2). Clinical and biochemical phenotyping was performed in all patients in each group.

RESULTS

Few significant differences were found in the clinical or biochemical phenotypes in patients classified as LADA when compared with type 1 diabetes. Adiposity, body mass index, waist/hip ratio, fasting plasma C-peptide, serum high-density lipoprotein cholesterol, and triglycerides were all similar. The only distinguishing feature was a history of hypertension (study 1) or systolic blood pressure (study 2). Also, a history of ketoacidosis did not influence the phenotype of LADA in the outpatients in any discernable way.

CONCLUSIONS

We conclude that LADA and type 1 diabetes are phenotypically indistinguishable in this predominantly minority population with a mean duration of glutamic acid decarboxylase antibody-positive diabetes of about 8 yr.

Immunology in the Clinic Review Series; focus on metabolic diseases: development of islet autoimmune disease in type 2 diabetes patients: potential sequelae of chronic inflammation

Historically, the development of type 2 diabetes has been considered not to have an autoimmune component, in contrast to the autoimmune pathogenesis of type 1 diabetes. In this review we will discuss the accumulating data supporting the concept that islet autoreactivity and inflammation is present in type 2 diabetes pathogenesis, and the islet autoimmunity appears to be one of the factors associated with the progressive nature of the type 2 diabetes disease process.

Beyond the hormone: insulin as an autoimmune target in type 1 diabetes

Insulin is not only the hormone produced by pancreatic β-cells but also a key target antigen of the autoimmune islet destruction leading to type 1 diabetes. Despite cultural biases between the fields of endocrinology and immunology, these two facets should not be regarded separately, but rather harmonized in a unifying picture of diabetes pathogenesis. There is increasing evidence suggesting that metabolic factors (β-cell dysfunction, insulin resistance) and immunological components (inflammation and β-cell-directed adaptive immune responses) may synergize toward islet destruction, with insulin standing at the crossroad of these pathways. This concept further calls for a revision of the classical dichotomy between type 1 and type 2 diabetes because metabolic and immune mechanisms may both contribute to different extents to the development of different forms of diabetes. After providing a background on the mechanisms of β-cell autoimmunity, we will explain the role of insulin and its precursors as target antigens expressed not only by β-cells but also in the thymus. Available knowledge on the autoimmune antibody and T-cell responses against insulin will be summarized. A unifying scheme will be proposed to show how different aspects of insulin biology may lead to β-cell destruction and may be therapeutically exploited. We will argue about possible reasons why insulin remains the mainstay of metabolic control in type 1 diabetes but has so far failed to prevent or halt β-cell autoimmunity as an immune modulatory reagent.

Pro- and anti-inflammatory cytokines in latent autoimmune diabetes in adults, type 1 and type 2 diabetes patients: Action LADA 4

AIMS/HYPOTHESIS

Systemic pro- and anti-inflammatory cytokines are associated with both type 1 and type 2 diabetes, while their role in latent autoimmune diabetes in adults (LADA) is unclear. Therefore, we compared cytokine concentrations in patients with LADA, type 1 or type 2 diabetes and healthy individuals to test the hypothesis that differences of cytokine concentrations between all groups are attributable to diabetes type and BMI.

METHODS

The pro-inflammatory cytokines IL-6 and TNF-α, and the anti-inflammatory cytokines IL-1 receptor antagonist (IL-1RA) and IL-10 were measured in 90 participants with type 1 diabetes, 61 with LADA, 465 with type 2 diabetes and 41 control participants using multiple regression models adjusted for BMI, sex, age, blood pressure and diabetes duration.

RESULTS

Patients with type 2 diabetes had higher concentrations of systemic IL-1RA, IL-6 and TNF-α cytokines than patients with either LADA or type 1 diabetes (p < 0.0001 for all differences). Cytokine concentrations in controls were lower than those in all diabetes types (p < 0.04). Increased BMI was positively associated with higher systemic cytokine concentrations in all diabetes types (p < 0.0001). Despite the association of cytokines with anthropometric data, differences between diabetes forms persisted also after adjusting analysis for the confounders BMI, age, sex, disease duration and blood pressure (p < 0.04).

CONCLUSIONS/INTERPRETATION

Although body mass associates positively with pro- and anti-inflammatory cytokine levels, patients with type 2 diabetes have higher cytokine levels independent of the prevailing BMI. LADA and type 1 diabetes could not be distinguished by systemic cytokines.

Frequency of the anti-glutamic acid decarboxylase immunological marker in patients with diabetes duration longer than three years in southern Brazil

CONTEXT AND OBJECTIVE

The anti-GAD (glutamic acid decarboxylase) antibody is considered to be an important marker for type 1 diabetes mellitus (DM1), with frequency that varies depending on the population studied and the duration of the disease. Therefore, the aim of this study was to determine the frequency of this autoantibody in a group of patients in southern Brazil with DM1 that had been diagnosed more than three years previously.

DESIGN AND SETTING

Analytical cross-sectional study with a control group conducted at the Biomedicine Laboratory of Universidade Feevale.

METHODS

This study was conducted between June 2007 and December 2008, and 109 individuals were enrolled during this period. Fifty-eight were DM1 patients and 51 were individuals free from DM1 and without any history of diabetes, who constituted the control group.

RESULTS

In the DM1 group, the mean age was 27 ± 1.7 years and 50% were men. The mean fasting blood glucose in the DM1 group was 208 ± 15 mg/dl and mean HbA1c (glycosylated hemoglobin) was 8.7 ± 0.25%. In the control group, the mean fasting blood glucose and HbA1c were 82 mg/dl and 5.0% respectively. Thirty-seven individuals with DM1 (63.8%) were positive for anti-GAD, and this proportion was significantly larger than in the control group.

CONCLUSIONS

These results show the high prevalence of anti-GAD in the population of diabetic patients in southern Brazil, thus indicating that the antibody was still present a long time after the disease had been diagnosed.

"I am pregnant and my husband has diabetes. Is there a risk for my child?" A qualitative study of questions asked by email about the role of genetic susceptibility to diabetes

Background

Diabetes Mellitus is a global health problem. Scientific knowledge on the genetics of diabetes is expanding and is more and more utilised in clinical practice and primary prevention strategies. Health consumers have become increasingly interested in genetic information. In the Netherlands, the National Genetic Research and Information Center provides online information about the genetics of diabetes and thereby offers website visitors the opportunity to ask a question per email. The current study aims at exploring people's need of (additional) information about the role of inheritance in diabetes. Results may help to tailor existing clinical and public (online) genetic information to the needs of an increasing population at risk for diabetes.

Methods

A data base with emailed questions about diabetes and inheritance (n = 172) is used in a secondary content analysis. Questions are posted in 2005-2009 via a website providing information about more than 600 inheritable disorders, including all diabetes subtypes. Queries submitted were classified by contents as well as persons' demographic profiles.

Results

Questions were received by diabetes patients (49%), relatives (30%), and partners (21%). Questioners were relatively young (54.8% ≤ 30 years) and predominantly female (83%). Most queries related to type 1 diabetes and concerned topics related to (future) pregnancy and family planning. Questioners mainly asked for risk estimation, but also clarifying information (about genetics of diabetes in general) and advice (mostly related to family planning) was requested. Preventive advice to reduce own diabetes risk was hardly sought.

Conclusions

Genetic information on diabetes provided by professionals or public health initiatives should address patients, as well as relatives and partners. In particular women are receptive to genetic information; they worry about the diabetes related health of (future) offspring. It seems important that information on the contribution of genetics to type 1 diabetes is more readily available. Considering the high prevalence of type 2 diabetes with strong evidence for a genetic predisposition, more effort seems needed to promote awareness around familial clustering and primary prevention.

Is diabetes mellitus a continuous spectrum?

BACKGROUND

Diabetes mellitus has been historically divided into type 1 and type 2 diabetes, with type 1 being an autoimmune disease and type 2 being primarily a metabolic disease.

CONTENT

The current diabetes classification scheme needs to be reevaluated because of the accumulating evidence of immune system involvement in the pathophysiology of type 2 diabetes.

SUMMARY

There are similarities and differences between type 1 and type 2 diabetes with regard to pathogenesis, pathophysiology, and genetics. We propose a resolution to the dilemma of the current classification scheme.

Number of autoantibodies and HLA genotype, more than high titers of glutamic acid decarboxylase autoantibodies, predict insulin dependence in latent autoimmune diabetes of adults

OBJECTIVE

In latent autoimmune diabetes of adults (LADA), the progression into insulin-dependent diabetes is usually faster than in type 2 diabetes (T2D) but the factors influencing this progression are not completely known. In this study, we searched for sensitive markers associated with early development of insulin dependence.

DESIGN

The screening of 5568 T2D patients for glutamic acid decarboxylase autoantibodies (GAD65Ab) identified 276 LADA patients (M=131; F=145) and in 251 of them, tyrosine phosphatase-2 (IA-2Ab) and thyroperoxidase autoantibodies (TPOAbs), some clinical features and genotype variation of the main type 1 diabetes (T1D) disease susceptibility loci (HLA-DRB1 and HLA-DQB1) were analyzed.

RESULTS

Four years after the diagnosis of diabetes, high GAD65Ab titer was not significantly associated with faster progression toward insulin deficiency (P=0.104). Patients with GAD65Ab and TPOAb or IA-2Ab or triple positivity for both islet and TPOAbs (GAD65Ab/IA-2Ab/TPOAb) showed a significantly faster disease progression (P=0.002). Among 104 TPOAb-positive LADA patients, 10 received replacement therapy (l-thyroxine), 43 showed high TSH levels (62.7% developed insulin dependence), and 3 had hyperthyroidism treated with methimazole. Multivariate analysis revealed a significant effect on disease progression only for TPOAb (P=0.022), female gender (P=0.036), low body mass index (BMI; P=0.001), and T1D high/intermediate risk HLA-DRB1/DQB1 genotypes grouped (P=0.020).

CONCLUSIONS

High GAD65Ab titers per se are not a major risk factor for disease progression in LADA, while the number of positive autoantibodies and HLA DRB1-DQB1 genotypes at high risk for T1D are significant predictors. Moreover, clinical characteristics such as low BMI and female gender are more likely to identify patients who will require insulin therapy within 4 years of diagnosis.

Latent autoimmune diabetes in adults: A distinct but heterogeneous clinical entity

Latent autoimmune diabetes in adults (LADA) accounts for 2%-12% of all cases of diabetes. Patients are typically diagnosed after 35 years of age and are often misdiagnosed as type II Diabetes Mellitus (DM). Glycemic control is initially achieved with sulfonylureas but patients eventually become insulin dependent more rapidly than with type II DM patients. Although they have a type II DM phenotype, patients have circulating beta (β) cell autoantibodies, a hallmark of type I DM. Alternative terms that have been used to describe this condition include type 1.5 diabetes, latent type I diabetes, slowly progressive Insulin Dependent Diabetes Mellitus, or youth onset diabetes of maturity. With regards to its autoimmune basis and rapid requirement for insulin, it has been suggested that LADA is a slowly progressive form of type I DM. However, recent work has revealed genetic and immunological differences between LADA and type I DM. The heterogeneity of LADA has also led to the proposal of criteria for its diagnosis by the Immunology of Diabetes Society. Although many workers have advocated a clinically oriented approach for screening of LADA, there are no universally accepted criteria for autoantibody testing in adult onset diabetes. Following recent advances in immunomodulatory therapies in type I DM, the same strategy is being explored in LADA. This review deals with the contribution of the genetic, immunological and metabolic components involved in the pathophysiology of LADA and recent approaches in screening of this distinct but heterogeneous clinical entity.

Latent autoimmune diabetes in adults differs genetically from classical type 1 diabetes diagnosed after the age of 35 years

OBJECTIVE

We studied differences between patients with latent autoimmune diabetes in adults (LADA), type 2 diabetes, and classical type 1 diabetes diagnosed after age 35 years.

RESEARCH DESIGN AND METHODS

Polymorphisms in HLA-DQB1, INS, PTPN22, and CTLA4 were genotyped in patients with LADA (n = 213), type 1 diabetes diagnosed at >35 years of age (T1D(>35y); n = 257) or <20 years of age (T1D(<20y); n = 158), and type 2 diabetes.

RESULTS

Although patients with LADA had an increased frequency of HLA-DQB1 and PTPN22 risk genotypes and alleles compared with type 2 diabetic subjects, the frequency was significantly lower compared with T1D(>35y) patients. Genotype frequencies, measures of insulin secretion, and metabolic traits within LADA differed according to GAD antibody (GADA) quartiles, but even the highest quartile differed from type 1 diabetes. Having two or more risk genotypes was associated with lower C-peptide concentrations in LADA.

CONCLUSIONS

LADA patients differed genetically and phenotypically from both T1D(>35y) and type 2 diabetic patients in a manner dependent on GADA levels.

Effect of human leukocyte antigen class II genes on acute-onset and slow-onset type 1 diabetes in the Japanese population

The contribution of the human leukocyte antigen (HLA) subtype to slow-onset type 1 diabetes (T1D), which includes latent autoimmune diabetes in adults (LADA), remains unclear in the Japanese population. We compared the frequencies of HLA DR-DQ haplotypes and genotypes of 72 acute-onset T1D patients, 100 slow-onset T1D patients, and 292 control subjects. The frequencies of DRB1*0405-DQB1*0401 (DR4) and DRB1*1302-DQB1*0604 (DR13) haplotypes were significantly higher in acute-onset patients, whereas that of the DRB1*1502-DQB1*0601 haplotype was significantly lower than those in slow-onset diabetes patients and controls. In contrast, DRB1*0802-DQB1*0302 (DR8) and DRB1*0901-DQB1*0303 (DR9) haplotypes were significantly more frequent, and the DRB1*1501-DQB1*0602 haplotype was extremely rare, in acute-onset patients and slow-onset diabetes patients. Genotype analysis revealed that DR4/9, DR4/13, and DR9/13 in acute-onset patients indicated high odds ratios (6.81, 12.0, and 15.6, respectively), whereas DR4/8 was significantly more frequent in slow-onset diabetes patients, but not in acute-onset patients. Our study demonstrated for the first time that the DR8 haplotype confers susceptibility to slow-onset T1D in the Japanese population. Moreover, there potentially are hierarchies for predisposing haplotypes, namely, DR13 > DR4 > DR9 > DR8 and for protective haplotypes, namely, DRB1*1501-DQB1*0602 > DRB1*1502-DQB1*0601.

Can the genetics of type 1 and type 2 diabetes shed light on the genetics of latent autoimmune diabetes in adults?

The pathophysiology of latent autoimmune diabetes in adults (LADA) is considered less understood than its much better characterized counterparts of type 1 and type 2 diabetes (T1D and T2D), where its clinical presentation exhibits some features of each of these two main diseases, earning it a reputation as being "type 1.5 diabetes". The etiology of LADA remains unknown, but a genetic component has been implicated from recent reports of T1D and T2D genes playing a role in its pathogenesis. One way to shed much needed light on the classification of LADA is to determine the discrete genetic factors conferring risk to the pathogenesis of this specific phenotype and to determine to what extent LADA shares genetic similarities with T1D and T2D. For instance, no conclusive support for a role of the T1D-associated INS gene has been reported in T2D; conversely, but similarly, no evidence has been found for the role of the T2D-associated genes IDE/HHEX, SLC30A8, CDKAL1, CDKN2A/B, IGF2BP2, FTO, and TCF7L2 in T1D. However, and somewhat at odds with current thinking, TCF7L2, the most strongly associated gene with T2D to date, is strongly associated with LADA, a disorder considered by the World Health Organization to be a slowly progressing form of T1D. In this review, we address recent advances in the genetics of T1D and T2D and how such discoveries have in turn shed some light on the genetics of LADA as being potentially at the "genetic intersection" of these two major diseases.

Latent autoimmune diabetes in adults

CONTEXT

Autoantibodies that are reactive to islet antigens are present at the time of diagnosis in most patients with type 1 diabetes. Additionally, approximately 10% of phenotypic type 2 diabetic patients are positive for at least one of the islet autoantibodies, and this group is often referred to as "latent autoimmune diabetes in adults (LADA)." These patients share many genetic and immunological similarities with type 1 diabetes, suggesting that LADA, like type 1 diabetes, is an autoimmune disease. However, there are differences in autoantibody clustering, T cell reactivity, and genetic susceptibility and protection between type 1 diabetes and LADA, implying important differences in the underlying disease processes.

EVIDENCE ACQUISITION AND SYNTHESIS

In this clinical review, we will summarize the current understanding of LADA based on the MEDLINE search of all peer-reviewed publications (original articles and reviews) on this topic between 1974 and 2009.

CONCLUSIONS

In LADA, diabetes occurs earlier in the beta-cell-destructive process because of the greater insulin resistance. Complexities arise also because of variable definitions of LADA and type 1 diabetes in adults. As immunomodulatory therapies that slow or halt the type 1 diabetes disease process are discovered, testing these therapies in LADA will be essential.

The glutamic acid decarboxylase 65 immunoglobulin G subclass profile differs between adult-onset type 1 diabetes and latent autoimmune diabetes in adults (LADA) up to 3 years after clinical onset

Autoantibodies against glutamic acid decarboxylase 65 (GADA) are found frequently in patients with autoimmune diabetes. Immunoglobulin (Ig)G(1) is the most frequent subclass among the GADA IgG subclasses. IgG(4) is a more common subclass in latent autoimmune diabetes in adults (LADA) at clinical onset compared to type 1 diabetes. The aim of this work was to study the different GADA-IgG subclass profiles during a 3-year follow-up in these groups of autoimmune diabetes. Adult-onset subjects, classified as either type 1 (n = 40) or LADA (n = 43), were included in the study. New samples were collected every year from these patients. In addition to conventional GADA analyses, GADA-IgG subclasses were also analysed with a radioimmunoprecipitation assay using biotin-conjugated antibodies (directed against human IgG subclasses and IgM) and streptavidin Sepharose. During 3 years' follow-up, all the IgG subclass levels decreased in type 1 diabetes - IgG(1): P < 0.001; IgG(2): P < 0.001; IgG(3): P < 0.001; IgG(4): P < 0.05 (Friedman's' test) - while levels remained stable for all four subclasses in LADA. GADA IgM, however, decreased in both groups (P < 0.001). Patients with LADA have higher GADA IgG(3) and IgG(4) at clinical onset and seem to maintain the levels and profile of their IgG subclasses up to 3 years after clinical onset, while all the GADA IgG subclass levels decrease in type 1 diabetic patients. This indicates a persistent different immune response in LADA compared to type 1 diabetes and further indicates the difference in pathogenesis.

A detailed investigation of maternally inherited diabetes and deafness (MIDD) including clinical characteristics, C-peptide secretion, HLA-DR and -DQ status and autoantibody pattern

BACKGROUND

This article presents a clinically characterization of the mitochondrial DNA mutation (A3243G) associated with maternally inherited diabetes and deafness (MIDD) syndrome in two families.

METHODS

Six patients with MIDD and one mutation-positive relative with normal glucose tolerance (NGT) were examined. Fasting serum C-peptide was measured in all subjects and compared with controls having NGT (n = 14). C-peptide response to an intravenous glucose tolerance test (IVGTT) was investigated in the diabetic patients not treated with insulin (n = 3) and in the mutation-positive healthy individual and compared with the controls.

RESULTS

The A3243G heteroplasmy value varied between 5 and 30%. All A3243G carriers had HLA-DR1-DQ5 haplotype, and either the -DQ5 or the -DQ6 allele. The fasting and the serum C-peptide levels at 120 min during the IVGTT did not differ between the A3243G carriers and the controls. A missing first phase and a decreased total C-peptide response was detected in the mutation-positive diabetics compared with controls (p < 0.0001). The same abnormality was found in the A3243G carrier with NGT. Circulating islet cell antibody (ICA) was present in three patients with MIDD. Glutamic acid decarboxylase (GAD), tyrosine phosphatase-like protein IA-2 (IA-2) and mitochondrial antibodies were missing. The diagnosis of MIDD was delayed in each case.

CONCLUSIONS

A missing first phase and a decreased total C-peptide response during an IVGTT was characteristic for the A3243G mutation. The fasting C-peptide level of the carriers did not differ from the controls. Circulating ICA was present in some patients, but GAD, IA-2 and mitochondrial antibodies were absent. All subjects had HLA-DR1-DQ5 haplotype, and either -DQ5 or -DQ6 alleles.

Differences in prevalence of antibodies to GAD and IA-2 and their titers at diagnosis in children with slowly and rapidly progressive forms of type 1 diabetes

We compared the frequencies of antibodies to GAD (GADA) and IA-2 (IA-2A) and their titers at diagnosis in 48 Japanese children with slowly progressive form of type 1 diabetes (SPT1D) and 70 children with rapidly progressive form of type 1 diabetes (RPT1D). High prevalences of both GADA and IA-2A were found at diagnosis in both the patients with SPT1D (70.8% and 75.0%), and those with RPT1D (71.4% and 71.9%). Most patients, regardless of the form of type 1 diabetes, were positive for both antibodies, though 6 of the 9 patients less than 5 years of age were negative for both antibodies. GADA titers below 50 U/ml were significantly more frequent in the patients with SPT1D (79.4% vs. 38.0%, p=0.0002), and titers above 100 U/ml significantly more frequent in those with RPT1D (38.0% vs. 11.8%, p=0.0081). No significant association was noted between the titers of IA-2A and the clinical form of type 1 diabetes. These results suggest that low GADA titers may reflect mild autoimmune destruction of beta-cells with slow disease progression. Titers of IA-2A do not appear to reflect the degree of autoimmune damage of the beta-cells.

Metabolic syndrome and autoimmune diabetes: action LADA 3

OBJECTIVE

The purpose of this study was to estimate whether prevalence of metabolic syndrome in adult European diabetic patients is associated with type of diabetes.

RESEARCH DESIGN AND METHODS

A consecutive series of patients attending hospital-based diabetes clinics were assessed for the frequency of metabolic syndrome and compared with population-based control subjects as part of the Action LADA study. In total, 2,011 subjects (aged 30-70 years) were studied, including 1,247 patients with recent-onset type 2 diabetes without glutamic acid decarboxylase autoantibodies (GADAs), 117 non-insulin-requiring patients with GADAs who had not received insulin therapy for at least 6 months after diagnosis (designated latent autoimmune diabetes of adults [LADA]), 288 type 1 diabetic patients, and 359 normal subjects.

RESULTS

Frequency of metabolic syndrome was significantly different in patients with type 1 diabetes (31.9%) and LADA (41.9%) (P = 0.015) and in both conditions was less frequent than in type 2 diabetic patients (88.8%) (P < 0.0001 for each). Eliminating glucose as a variable, the prevalence of metabolic syndrome was similar in patients with autoimmune diabetes (type 1 diabetes and/or LADA) (17.3%) and control subjects (23.7%) but remained more common in type 2 diabetic patients (47.8%) (P = 0.001 for all groups). In both type 1 diabetic patients and those with LADA, individual components of metabolic syndrome were similar but less common than in type 2 diabetic patients (P < 0.0001 for each).

CONCLUSIONS

The prevalence of metabolic syndrome is significantly higher in type 2 diabetic patients than in patients with LADA or adults with type 1 diabetes. Excluding glucose as a variable, metabolic syndrome is not more prevalent in patients with autoimmune diabetes than in control subjects. Metabolic syndrome is not a characteristic of autoimmune diabetes.

Common variants in the TCF7L2 gene help to differentiate autoimmune from non-autoimmune diabetes in young (15-34 years) but not in middle-aged (40-59 years) diabetic patients

AIMS/HYPOTHESIS

Type 1 diabetes in children is characterised by autoimmune destruction of pancreatic beta cells and the presence of certain risk genotypes. In adults the same situation is often referred to as latent autoimmune diabetes in adults (LADA). We tested whether genetic markers associated with type 1 or type 2 diabetes could help to discriminate between autoimmune and non-autoimmune diabetes in young (15-34 years) and middle-aged (40-59 years) diabetic patients.

METHODS

In 1,642 young and 1,619 middle-aged patients we determined: (1) HLA-DQB1 genotypes; (2) PTPN22 and INS variable-number tandem repeat (VNTR) polymorphisms; (3) two single nucleotide polymorphisms (rs7903146 and rs10885406) in the TCF7L2 gene; (4) glutamic acid decarboxylase (GAD) and IA-2-protein tyrosine phosphatase-like protein (IA-2) antibodies; and (5) fasting plasma C-peptide.

RESULTS

Frequency of risk genotypes HLA-DQB1 (60% vs 25%, p = 9.4 x 10(-34); 45% vs 18%, p = 1.4 x 10(-16)), PTPN22 CT/TT (34% vs 26%, p = 0.0023; 31% vs 23%, p = 0.034), INS VNTR class I/I (69% vs 53%, p = 1.3 x 10(-8); 69% vs 51%, p = 8.5 x 10(-5)) and INS VNTR class IIIA/IIIA (75% vs 63%, p = 4.3 x 10(-6); 73% vs 60%, p = 0.008) was increased in young and middle-aged GAD antibodies (GADA)-positive compared with GADA-negative patients. The type 2 diabetes-associated genotypes of TCF7L2 CT/TT of rs7903146 were significantly more common in young GADA-negative than in GADA-positive patients (53% vs 43%; p = 0.0004). No such difference was seen in middle-aged patients, in whom the frequency of the CT/TT genotypes of TCF7L2 was similarly increased in GADA-negative and GADA-positive groups (55% vs 56%).

CONCLUSIONS/INTERPRETATION

Common variants in the TCF7L2 gene help to differentiate young but not middle-aged GADA-positive and GADA-negative diabetic patients, suggesting that young GADA-negative patients have type 2 diabetes and that middle-aged GADA-positive patients are different from their young GADA-positive counterparts and share genetic features with type 2 diabetes.