The islet autoantibody titres: their clinical relevance in latent autoimmune diabetes in adults (LADA) and the classification of diabetes mellitus

Atypical Diabetes: What Have We Learned and What Does the Future Hold?

As our understanding of the pathophysiology of diabetes evolves, we increasingly recognize that many patients may have a form of diabetes that does not neatly fit with a diagnosis of either type 1 or type 2 diabetes. The discovery and description of these forms of "atypical diabetes" have led to major contributions to our collective understanding of the basic biology that drives insulin secretion, insulin resistance, and islet autoimmunity. These discoveries now pave the way to a better classification of diabetes based on distinct endotypes. In this review, we highlight the key biological and clinical insights that can be gained from studying known forms of atypical diabetes. Additionally, we provide a framework for identification of patients with atypical diabetes based on their clinical, metabolic, and molecular features. Helpful clinical and genetic resources for evaluating patients suspected of having atypical diabetes are provided. Therefore, appreciating the various endotypes associated with atypical diabetes will enhance diagnostic accuracy and facilitate targeted treatment decisions.

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.

Efficacy of Regimens in the Treatment of Latent Autoimmune Diabetes in Adults: A Network Meta-analysis

INTRODUCTION

Latent autoimmune diabetes in adults (LADA) is a highly heterogeneous autoimmune condition with clinical and genetic characteristics that fall between those of type 1 diabetes mellitus and type 2 diabetes mellitus; therefore, there are no uniform criteria for the selection of therapeutic agents. We conducted a network meta-analysis to evaluate the efficacy of various therapeutic agents for LADA by comparing their effects on various indicators used to reflect LADA.

METHODS

We searched the PubMed, Cochrane Library, Embase and Web of Science databases from their inception to March 2023 and collected data from 14 randomized controlled trials on glucose-lowering drugs for LADA, including 23 studies and 15 treatment regimens. The effectiveness of drugs was ranked and evaluated by combining surface under the cumulative ranking (SUCRA) plots and forest plots. Factors that may influence study heterogeneity were also searched and analyzed by combining subgroup analysis, publication bias, funnel plots and sensitivity analysis.

RESULTS

The results of the network meta-analysis showed that insulin had the most significant effect on the control of change from baseline in glycosylated hemoglobin, type A1 (ΔHbA1c). Insulin combined with dipeptidyl peptidase-4 (DPP-4) inhibitors performed the best in reducing fasting blood glucose and body mass index. Treatment regimens involving thiazolidinediones were the most advantageous in HbA1c, fasting C-peptide and postprandial C-peptide control. Longer dosing may be more beneficial in maintaining islet β-cell function in the LADA population.

CONCLUSION

LADA is an immune condition with high heterogeneity, and treatment should be administered according to the C-peptide level of the LADA population. For this population with LADA with a certain level of β-cell function, combinations of insulin with DPP-4 inhibitors or thiazolidinediones probably can be more effective treatment options to maintain islet function and normal blood glucose.

TRIAL REGISTRATION

PROSPERO CRD42023410795.

Prevalence and factors associated with latent autoimmune diabetes in adults (LADA): a cross-sectional study

BACKGROUND

The Latent Autoimmune Diabetes in Adults (LADA) is a slowly progressive Type 1 diabetes subgroup with onset during middle age. Studies report that about 10% of adults initially diagnosed with clinical Type 2 diabetes (T2D) have LADA. Inappropriate diagnosis and mismanagement of the LADA can increase the risk of diabetic complications, which affect the quality of life and is the cause of increased mortality. In low-income countries setting, data regarding the magnitude of LADA is limited. We carried out this study to estimate the burden of misdiagnosed LADA among T2D patients in selected health facilities in Dar es Salaam and to bring awareness to the use of Glutamic Acid Decarboxylase (GAD) autoantibody in screening for LADA.

METHODOLOGY

We enrolled 186 phenotypically T2D patients in this cross-sectional study, through a standardized data collection tool we obtained participants' demographic and clinical information. For testing GAD levels, we used a double-antibody Enzyme-Linked Immunosorbent Assay (ELISA). The Fisher's Exact and student t-tests were used to test the significance of the statistical associations of the glycaemic control and diabetes complications between T2D and LADA.

RESULTS

Out of 186 patients, 156 gave conclusive GAD Ab ELISA reading with LADA accounting for 5.1% (95% CI: 2.5 - 10.0). The mean age of subjects was 54.3 years (Range: 33-85 years). The parameters such as mean age, family history of diabetes mellitus status, Fasting Blood Glucose, clinical characteristics, and complications did not show significant statistical differences between patients with LADA and Type 2 diabetes. However, all LADA- Human Immunodeficiency Virus (HIV) comorbid patients had retinopathy, which was statistically insignificant in 20 (87%) T2D-HIV comorbid patients (p = 0.669). Neither neuropathy, nephropathy, nor Diabetic Mellitus (D.M.) foot syndrome was observed among LADA-HIV comorbid patients. Nevertheless, 22 (95.7%), 3 (13%), and 2 (8.7%) of T2D-HIV comorbidity had neuropathy, nephropathy, or D.M. foot syndrome, respectively.

CONCLUSIONS

The study established a LADA prevalence of 5.1% among T2D patients and has shown the role of GAD autoantibody in the screening for LADA. The study calls for a well- designed larger longitudinal study to generate strong evidence on the association of risk factors and complications associated with the LADA. This will develop robust evidence on the association of risk factors and complications associated with the LADA and T2D.

Latent autoimmune diabetes in adults: a focus on β-cell protection and therapy

Latent autoimmune diabetes in adults (LADA) is a heterogeneous disease sharing some phenotypic, genetic, and immunological features with both type 1 and 2 diabetes. Patients with LADA have a relatively slow autoimmune process and more residual islet β-cell function at onset, allowing a time window to protect residual islet β cells and delay or inhibit disease progression. It is crucial to discover various heterogeneous factors affecting islet β-cell function for precise LADA therapy. In this review, we first describe the natural history of LADA. Thereafter, we summarize β-cell function-related heterogeneous factors in LADA, including the age of onset, body mass index, genetic background, and immune, lifestyle, and environmental factors. In parallel, we evaluate the impact of current hypoglycemic agents and immune intervention therapies for islet β-cell protection. Finally, we discuss the opportunities and challenges of LADA treatment from the perspective of islet β-cell function protection.

Toward an Improved Classification of Type 2 Diabetes: Lessons From Research into the Heterogeneity of a Complex Disease

CONTEXT

Accumulating evidence indicates that type 2 diabetes (T2D) is phenotypically heterogeneous. Defining and classifying variant forms of T2D are priorities to better understand its pathophysiology and usher clinical practice into an era of "precision diabetes."

EVIDENCE ACQUISITION AND METHODS

We reviewed literature related to heterogeneity of T2D over the past 5 decades and identified a range of phenotypic variants of T2D. Their descriptions expose inadequacies in current classification systems. We attempt to link phenotypically diverse forms to pathophysiology, explore investigative methods that have characterized "atypical" forms of T2D on an etiological basis, and review conceptual frameworks for an improved taxonomy. Finally, we propose future directions to achieve the goal of an etiological classification of T2D.

EVIDENCE SYNTHESIS

Differences among ethnic and racial groups were early observations of phenotypic heterogeneity. Investigations that uncover complex interactions of pathophysiologic pathways leading to T2D are supported by epidemiological and clinical differences between the sexes and between adult and youth-onset T2D. Approaches to an etiological classification are illustrated by investigations of atypical forms of T2D, such as monogenic diabetes and syndromes of ketosis-prone diabetes. Conceptual frameworks that accommodate heterogeneity in T2D include an overlap between known diabetes types, a "palette" model integrated with a "threshold hypothesis," and a spectrum model of atypical diabetes.

CONCLUSION

The heterogeneity of T2D demands an improved, etiological classification scheme. Excellent phenotypic descriptions of emerging syndromes in different populations, continued clinical and molecular investigations of atypical forms of diabetes, and useful conceptual models can be utilized to achieve this important goal.

Low C-peptide together with a high glutamic acid decarboxylase autoantibody level predicts progression to insulin dependence in latent autoimmune diabetes in adults: The HUNT study

AIM

To search for risk factors that could predict progression in latent autoimmune diabetes in adults (LADA) and compare them with those for type 2 diabetes.

MATERIALS AND METHODS

This study included 175 participants with LADA (autoantibody positive, without insulin treatment ≥1 year after diagnosis) and 2331 participants with type 2 diabetes (autoantibody negative, without insulin treatment ≥1 year after diagnosis) from the HUNT2 and HUNT3 surveys. We used Cox regression models and receiver operating characteristic curve analysis to identify predictive factors for progression to insulin dependency within 10 years.

RESULTS

Low C-peptide levels (<0.3 nmol/L) predicted progression to insulin dependency within 10 years in both LADA (hazard ratio [HR] 6.40 [95% CI, 2.02-20.3]) and type 2 diabetes (HR 5.01 [95% CI, 3.53-7.10]). In addition, a high glutamic acid decarboxylase autoantibody (GADA) level (HR 5.37 [95% CI, 1.17-24.6]) predicted progression in LADA. Together, these two factors had a discriminatory power between non-progressors and progressors of area under the curve (AUC) of 0.86 (95% CI, 0.80-0.93). In type 2 diabetes, younger age at diagnosis (<50 years: HR 2.83 [95% CI, 1.56-5.15]; 50-69 years: HR 2.11 [95% CI, 1.19-3.74]), high HbA1c levels (≥53 mmol/mol, HR 2.44 [95% CI, 1.72-3.46]), central obesity (HR 1.65 [95% CI, 1.06-2.55]) and a body mass index of more than 30 kg/m² (HR 1.73 [95% CI, 1.23-2.41]) were independent predictors. Together with C-peptide they reached an AUC of 0.79 (95% CI, 0.76-0.82).

CONCLUSION

Factors predicting progression to insulin dependence are partly similar and partly dissimilar between LADA and type 2 diabetes. A constellation of low C-peptide and high GADA levels identifies LADA patients who are probable to progress to insulin dependence.

Low rate of latent autoimmune diabetes in adults (LADA) in patients followed for type 2 diabetes: A single center's experience in Turkey

Objective

In this study, we aimed to determine the frequency of and the clinical and metabolic features of patients with latent autoimmune diabetes in adults (LADA) at a single center in Turkey.

Methods

Patients over 30 years of age diagnosed with type 2 diabetes who did not require insulin for a minimum of 6 months following diagnosis were included. Data from 324 patients (163 women; 161 men), with a mean age of 54.97 ± 7.53 years, were analyzed in the study. Levels of antibodies to glutamate decarboxylase (anti-GAD) were measured in all patients, and LADA was diagnosed in patients testing positive for anti-GAD antibodies.

Results

Anti-GAD positivity was identified in 5 patients (1.5%). Family history of diabetes, body mass index (BMI), age, sex distribution, insulin resistance, serum triglycerides, high-density lipoprotein, and low-density lipoprotein were similar in the LADA and type 2 diabetes patients. Median HbA1c was significantly higher (10.8% vs. 7.38%, p = 0.002) and fasting C-peptide was lower (0.75 ng/mL vs. 2.82 ng/mL, p = 0.009) in patients with LADA compared to in those with type 2 diabetes. Among the 5 patients with LADA, 4 were positive for antithyroid peroxidase antibodies. The median disease duration was relatively shorter among patients with LADA (4 years vs. 7 years, p = 0.105).

Conclusion

We observed a LADA frequency of 1.5% among Turkish patients followed for type 2 diabetes. The presence of obesity and metabolic syndrome did not exclude LADA, and patients with LADA had worse glycemic control than patients with type 2 diabetes did.

Defining and Classifying New Subgroups of Diabetes

An etiologically based classification of diabetes is needed to account for the heterogeneity of type 1 and type 2 diabetes (T1D and T2D) and emerging forms of diabetes worldwide. It may be productive for both classification and clinical discovery to consider variant forms of diabetes as a spectrum. Maturity onset diabetes of youth and neonatal diabetes serve as models for etiologically defined, rare forms of diabetes in the spectrum. Ketosis-prone diabetes is a model for more complex forms, amenable to phenotypic dissection. Bioinformatic approaches such as clustering analyses of large datasets and multi-omics investigations of rare and atypical phenotypes are promising avenues to explore and define new subgroups of diabetes.

Therapeutic approaches for latent autoimmune diabetes in adults: One size does not fit all

Recent advances in the understanding of latent autoimmune diabetes in adults (LADA) pathophysiology make it increasingly evident that people with LADA comprise a heterogenous group of patients. This makes the establishment of a standard treatment algorithm challenging. On top of its glucose-lowering action, insulin may exert anti-inflammatory effects, rendering it an attractive therapeutic choice for a type of diabetes in which autoinflammation and beta cell insufficiency play major pathogenetic roles. However, there is growing evidence that other antidiabetic drugs, such as metformin, dipeptidyl peptidase-4 inhibitors, glucagon-like peptide-1 receptor agonists, and thiazolidinediones, might have a role in optimizing glycemic control and preserving beta cell function in individuals with LADA, either alone or in combination with insulin. Although most of these drugs have been routinely used in the daily clinical setting for years, large prospective randomized trials are needed to assess whether they are capable of delaying progression to insulin dependence as well as their effects on diabetic complications. The aim of the present review is to discuss the current state and future perspectives of LADA therapy, emphasizing the need for individualized and patient-centered therapeutic approaches.

Downregulation of T-Cell Transcription Factors in Adult Latent Autoimmune Diabetes with High-Titer Glutamic Acid Decaroxylase Antibody

INTRODUCTION

Latent autoimmune diabetes in adults (LADA) shows a heterogeneous clinical profile that is dependent on the glutamic acid decaroxylase antibody (GADA) titer. We speculated that LADA patients with a high or low GADA titer may have distinct T-lymphocyte subset profiles and distinct expression patterns of transcription factors involved in T-cell immunomodulation.

METHODS

Patients with LADA (n = 40) and type 2 diabetes (T2DM; n = 14) were recruited to the study, and peripheral blood mononuclear cells were isolated. The proportions of T-lymphocyte subsets (Th1 [T helper type 1], Th2 [T helper type 2], Treg [regulatory T], and Th17 [T helper type 17] cells) were determined by flow cytometry. Real-time polymerase chain reaction (PCR) was performed to estimate mRNA expression levels of the T-cell subtype-enriched transcription factors T-bet (Th1), GATA3 (Th2), transcription factor forkhead box protein 3 (FOXP3) (Treg), and RORC (Th17).

RESULTS

The frequency of Th1 (as a percentage of total CD4⁺T cells) was greater in the LADA patients with high-titer GADA than in the LADA patients with low-titer GADA (11.06 ± 1.62 vs. 7.05 ± 0.86, P = 0.030). Compared to the T2DM group, in the low-titer GADA group the frequency of Th1 was significantly reduced (7.05 ± 0.86 vs. 16.75 ± 3.73, P = 0.017) and the frequency of Th17 frequency was signficantly increased (1.11 ± 0.09 vs. 0.74 ± 0.16, P = 0.017). Compared to T2DM patients, in the high-titer GADA group there was a significantly reduced expression of FOXP3 (0.35 ± 0.13 vs. 1.75 ± 0.54, P = 0.002), RORC (0.53 ± 0.19 vs. 2.00 ± 0.77, P = 0.046), and GATA3 (0.74 ± 0.17 vs. 2.31 ± 0.91, P = 0.046). Similarly, the high-titer GADA group expressed reduced levels of FOXP3 and RORC compared to the low-titer GADA group (0.35 ± 0.13 vs. 1.50 ± 0.41, P = 0.027; 0.53 ± 0.19 vs. 1.35 ± 0.21, P  = 0.027, respectively). There was a negative correlation between FOXP3 expression level and GADA titer for the entire cohort (r = - 0.0433, P = 0.015) and a stronger negative correlation in LADA patients (r = - 0.606, P = 0.008).

CONCLUSION

LADA patients with high-titer GADA express lower levels of T-cell transcription factors, including the Treg transcription factor FOXP3, which may contribute to differences in the clinical profile compared to LADA patients with low-titer GADA.

TRIAL REGISTRATION

ClinicalTrials.gov identifier, NCT01159847.

Stiff Person Syndrome and Type 1 Diabetes Mellitus: a Case of the Chicken or the Egg?

Anti-glutamic acid decarboxylase (anti-GAD) antibodies are linked with both autoimmune diabetes and the rare neurological disorder stiff person syndrome (SPS). SPS is an uncommon autoimmune-mediated condition characterized by painful episodic spasms and progressive muscle rigidity. We present the case of a 23-year-old non-diabetic, insulin-naïve woman with known SPS who was hospitalized for SPS-related symptomatology. The patient quickly developed type 1 diabetes mellitus (T1DM) with unexpectedly large insulin requirements. To our knowledge, there are no other reports describing rapid T1DM development during an acute hospitalization for SPS and fewer than 5 case reports describing the association of SPS with extreme insulin resistance. Our case highlights the key clinical features, pathology, and pathogenesis of both SPS and T1DM and explores the relationship between the two disease processes.

Islet autoantibody positivity in overweight and obese adults with type 2 diabetes

Islet autoantibodies are typically associated with type 1 diabetes, but have been found in patients diagnosed with type 2 diabetes in whom they are associated with lower adiposity. The significance of autoantibody positivity in overweight and obese patients is not well understood. The aim of this study was to determine the prevalence and clinical significance of islet autoantibodies in overweight/obese adults diagnosed with type 2 diabetes. This study includes 204 participants at one site of the multicenter Look AHEAD (Action for Health in Diabetes) trial (ClinicalTrials.gov identifier: NCT00017953) which randomized overweight/obese adults diagnosed with type 2 diabetes to an intensive lifestyle intervention or diabetes support and education. We measured antibodies to glutamic acid decarboxylase, insulinoma antigen-2, and zinc transporter 8. Participants with and without autoantibodies were compared with respect to baseline clinical features, and longitudinal changes in weight, hemoglobin A1c, and antihyperglycemic medications. We found that 13 participants (6.4%) were autoantibody positive, including six of 47 participants (12.8%) with BMI ≥40 kg/m². At baseline, autoantibody positive participants had higher HDL cholesterol (1.27 vs. 1.09 mmol/L, p = .034) and lower fasting C-peptide (0.32 vs. 0.57 nmol/L, p = .049). Over four years, autoantibody positive participants lost 5.1 kg more weight than autoantibody negative participants (p = .056). Longitudinal changes in hemoglobin A1c did not differ by autoantibody status, though autoantibody positive participants were more likely to increase the number of antihyperglycemic medications or initiate insulin (p = .011). In conclusion, islet autoantibodies were present in 6.4% of overweight/obese adults with type 2 diabetes including those with severe obesity, and were associated with distinct clinical features. The effect of autoantibody positivity on weight loss interventions requires further study.

Type 1 Diabetes-related Autoantibodies in Different Forms of Diabetes

Autoantibodies against Glutamic Acid Decarboxylase (GADA), insulinoma antigen-2 (IA- 2A), insulin (IAA) and the most recently Zinc Transporter 8 (ZnT8A) are one of the most reliable biomarkers for autoimmune diabetes in both children and adults. They are today the only biomarkers that can distinguish Latent Autoimmune Diabetes in Adults (LADA) from phenotypically type 2 diabetes. As the frequency of autoantibodies at diagnosis in childhood type 1 diabetes depends on age, GADA is by far the most common in adult onset autoimmune diabetes, especially LADA. Being multiple autoantibody positive have also shown to be more common in childhood diabetes compared to adult onset diabetes, and multiple autoantibody positivity have a high predictive value of childhood type 1 diabetes. Autoantibodies have shown inconsistent results to predict diabetes in adults. Levels of autoantibodies are reported to cause heterogeneity in LADA. Reports indicate that individuals with high levels of autoantibodies have a more type 1 diabetes like phenotype and individuals with low levels of autoantibody positivity have a more type 2 diabetes like phenotype. It is also well known that autoantibody levels can fluctuate and transient autoantibody positivity in adult onset autoimmune diabetes have been reported to affect the phenotype.

Glutamic Acid Decarboxylase Autoantibody-negative Slowly Progressive Type 1 Diabetes Mellitus: A Case Report and Literature Review

A 59-year-old non-obese Japanese woman developed diabetes mellitus with a negative glutamic acid decarboxylase autoantibody (GADA) test result. Her hyperglycemia was initially well controlled by oral hypoglycemic agents; however, despite continued treatment the hyperglycemia gradually worsened. As she had endogenous insulin deficiency and tested positive for insulin autoantibody (IAA), insulin therapy was initiated. Few studies have investigated GADA-negative patients with slowly progressive type 1 diabetes mellitus (SPT1D). Our IAA-positive SPT1D patient progressed from the clinical onset of diabetes mellitus to starting insulin therapy relatively quickly (1.5 years), similarly to other previously reported non-obese patients with GADA-positive SPT1D.

Zinc transporter 8 autoantibodies (ZnT8-ab) are associated with higher prevalence of multiple diabetes-related autoantibodies in adults with type 1 diabetes

AIM

The study aimed to assess the prevalence of zinc transporter 8 autoantibodies (ZnT8-ab), other diabetes-related autoantibodies and clinical manifestation of type 1 diabetes in adults, depending on age of the onset of disease.

METHODS

119 patients with type 1 diabetes, 66 at age <35 years (T1DM < 35) and 53 T1DM at age ≥35 years (T1DM ≥ 35). We assessed clinical features, GAD-ab, IA2-ab, ICA, ZnT8-ab and thyroid peroxidase antibodies (ATPO).

RESULTS

In T1DM < 35 lower initial serum C-peptide concentration was observed and diabetes ketoacidosis (DKA) was more common. ATPO positivity was more prevalent in T1DM ≥ 35 (35.8 vs 21.2%, p = 0.04). The prevalence of GAD-ab, IA2-ab and ZnT8-ab was similar in both groups, the titres of IA2-ab and ICA were higher in T1DM < 35 but titre of ZnT8-ab was higher in T1DM ≥ 35. The majority of T1DM < 35 patients were positive for three autoantibodies (40.9%), while T1DM ≥ 35 subjects most often presented with only one (30.2%) antibody, most commonly GAD-ab (81.2%). 45% T1DM < 35 and 34% T1DM ≥ 35 subjects were positive for ZnT8-ab. ZnT8-ab positive patients had higher titre and more frequent occurrence of multiple diabetes-related autoantibodies than ZnT8-ab negative patients.

CONCLUSIONS

Adults with T1DM < 35 and T1DM ≥ 35 differ in the severity of autoimmune response at diagnosis. ZnT8-ab positivity is related to higher titre and more frequent occurrence of multiple diabetes-related autoantibodies.

Latent autoimmune diabetes in adults (LADA) in Asian and European populations

Diabetes mellitus is a chronic disorder caused by relative or absolute insulin deficiency and characterized by chronic hyperglycaemia. It is expected that by year 2025, 80% of all type 2 diabetic patients will be living in developing or low- and middle-income countries. Among Asians, there has been an overall increase in abdominal obesity; however, the risk of diabetes in these populations starts at much lower body mass index as compared to Caucasians. A significant proportion of diabetic patients with adult-onset, initially nonrequiring insulin treatment, have diabetes-associated autoantibodies in their sera. A new subclass of diabetes with the designation of latent autoimmune diabetes of adult-onset (LADA) has been proposed for this category of subjects. Studies have demonstrated that patients with autoimmune diabetes, characterized by the presence of glutamic decarboxylase autoantibodies display a different clinical phenotype from classical type 2 diabetes without glutamic decarboxylase autoantibodies. This subset of phenotypic type 2 diabetes subjects with islet autoantibodies tend to have sulphonylurea failure and need insulin treatment earlier in the disease process. Diagnosing LADA at an initial stage will be important so that insulin can be initiated earlier, facilitating improved glycemic control sooner as well as the preservation of residual beta-cell function in adult-onset autoimmune diabetes. Because of differences in dietary habits, environmental factors, and phenotypic characteristics between European and Asian populations, there may be heterogeneity in the prevalence and other characteristics of LADA in these two populations.

Prevalence of Positive Diabetes-Associated Autoantibodies among Type 2 Diabetes and Related Metabolic and Inflammatory Differences in a Sample of the Bulgarian Population

BACKGROUND

The study aimed to estimate the prevalence of unrecognized cases with positive autoantibodies among type 2 diabetes (T2D) in a sample of the Bulgarian population and to compare some metabolic and inflammatory markers to those of patients having negative autoantibodies and subjects with latent autoimmune diabetes (LADA).

METHODS

Patients with T2D, patients with LADA, and control participants were enrolled. Antiglutamic acid decarboxylase, anti-insulinoma-associated 2, and antizinc transporter 8 autoantibodies were assayed through ELISA. C-reactive protein and interleukin 6 (IL-6) and tumor necrosis factor alpha were assessed.

RESULTS

Ten percent of patients with T2D had positive autoantibodies. They had lower body mass index (p = 0.014), worse glycemic control (HbA1c, p = 0.033), and better HDL cholesterol (p = 0.026) than those in negative autoantibodies cases. Compared to LADA, glycemia and anthropometric data did not differ significantly but metabolic syndrome was more prevalent among newly found cases with positive autoantibodies (p = 0.046). Their level of inflammatory markers was similar to that of patients having negative autoantibodies (p > 0.05), but IL-6 was higher when compared to LADA (p = 0.002).

CONCLUSION

Prevalence of patients having positive autoantibodies within T2D in the analyzed sample of the Bulgarian population was 10%. They shared common metabolic features with subjects with LADA, but inflammatory phenotype was closer to that of T2D.

Islet autoantibody status in a multi-ethnic UK clinic cohort of children presenting with diabetes

OBJECTIVE

We prospectively determined islet autoantibody status in children presenting with diabetes to a single UK region in relation to ethnicity.

DESIGN

316 (68.0% non-white) children presenting with diabetes between 2006 and 2013 were tested centrally for islet cell autoantibodies (ICA) and glutamic acid decarboxylase autoantibodies (GAD-65) at diagnosis, and if negative for both, tested for insulin autoantibodies (IAA). The assay used to measure GAD-65 autoantibodies changed from an in-house to a standardised ELISA method during the study.

RESULTS

Even with use of the standardised ELISA method, 25.8% of children assigned a diagnosis of type 1 diabetes still tested negative for all three autoantibodies. 30% of children assigned a diagnosis of type 2 diabetes were autoantibody positive, and these had the highest glycated haemoglobin (HbA1c) levels at 12 months follow-up compared with other groups (p value for analysis of variance <0.001), although the sample size was small. Autoantibody positivity was similar between non-white and white children regardless of assay used (60.0% (n=129) vs 56.4% (n=57), χ(2)=0.9, p=0.35), as was mean GAD-65 autoantibody levels, but fewer non-white children had two or more autoantibodies detectable (13% (n=28) vs 27.7% (n=28), χ(2)=12.1, p=0.001).

CONCLUSIONS

Islet autoantibody positivity was associated with a more severe phenotype, as demonstrated by poorer glycaemic control, regardless of assigned diabetes subtype. Positivity did not differ by ethnic group.

The prevalence of latent autoimmune diabetes in adults and its correlates in patients with type 2 diabetes in Kerman, Iran [2011]

INTRODUCTION

Latent autoimmune diabetes in adults [LADA] is a type of autoimmune diabetes in adults that is usually identified by positive GAD-antibody [glutamic acid decarboxylase]. Epidemiological studies show that this disease has no identified prevalence and incidence in Asia due to the various criteria in diagnosing the disease.

METHODS

500 patients with type 2 diabetes based on American Diabetes Association [ADA] criteria and age of diabetes onset above 35 years old who needed no insulin until at least 6 months after the diagnosis of diabetes were selected from KERCADR Study and their anti-GAD serum level was determined.

RESULTS

From 500 patients, 429 ones [85%] were negative and 71 ones [14.2%] were positive for GAD antibody. The prevalence of latent autoimmune diabetes was higher in the age group of 50-59 years compared to the other age groups. There was no significant correlation between LADA and hypertension, family history of diabetes, cigarette smoking and tobacco use.

CONCLUSION

The prevalence rate of latent autoimmune diabetes in adults in patients with type 2 diabetes was 14.2% and we could not find any relationship.

Relationship between autoantibodies combination, metabolic syndrome components and diabetic complications in autoimmune diabetes in adults

The aim of our study was to establish the possible association between double or triple antibody positivity and latent autoimmune diabetes (LADA) phenotype in the context of metabolic syndrome (MS) prevalence and its individual components. This cross-sectional study population comprised 69 islet cell antibody-positive patients coming for their comprehensive annual review. They were divided into three groups according to antibody positivity. Twenty-five (36.2 %) were male, mean age of 51 years with disease duration of 8 years. Twenty-eight (40.58 %) were positive only for GAD Abs, 26 (37.68 %) were positive for ICA and GAD Abs and 15 (21.74 %) were positive for GAD, ICA, and IA2 Abs. The lowest value of waist circumference, MS, and artherial hypertension prevalence was found in the group positive for all three antibodies. In the multinomial multivariate logistic regression model, MS was negatively associated with triple Abs positivity compared to single Ab positivity and double Abs positivity. Our results highlight the importance of inverse association between simultaneous Abs positivity for ICA, GAD, and IA2 with the MS and its components present in LADA patients. This inverse relationship might implicate that LADA patients are phenotypically closer to T1DM. The contribution of IA2 Ab positivity merits is to be considered in the determination of LADA phenotypes, while its diagnostic value needs to be clarified in future follow-up studies.

Exponential increase of glutamic acid decarboxylase (GAD) antibody titer after initiating and stopping insulin in a patient with slowly progressive type 1 diabetes

Few articles have described fluctuations in glutamic acid decarboxylase antibody (GADAb) levels after a diagnosis of slowly progressive type 1 diabetes (SPIDDM). Here, we present a case in which GADAb levels exponentially increased after initiating and stopping insulin. A 64-year-old female patient newly diagnosed with SPIDDM was admitted and started multiple daily insulin injections. The patient's GADAb titer was 6.9 U/mL (normal: <1.4 U/mL) and the patient had a type 1 diabetes susceptible HLA class II haplotype known in the Japanese population as: DRB1*04:05-DQB1*04:01. When the patient's "honeymoon period" set in, hypoglycemia was observed and the dose of insulin was reduced. Two months after the diagnosis, 1 unit of insulin glargine/day was being injected and the patient demonstrated good glycemic control. Subsequently, the patient's home doctor recommended that insulin injections be stopped. Three months after the diagnosis, the patient's GADAb titer suddenly increased to 1600 U/mL. The patient's GADAb titer decreased but was still positive (40 U/mL) 36 months after diagnosis. HbA1c levels were maintained below 7%, and oral glucose tolerance tests at 10, 26, and 36 months after diagnosis suggested that the patient had preserved insulin secretion. To the best of our knowledge, this is the first report that describes exponential increases in GADAb after initiating and stopping insulin in a patient with SPIDDM.

Impact of islet autoimmunity on the progressive β-cell functional decline in type 2 diabetes

OBJECTIVE

Cross-sectional studies have suggested that islet autoimmunity may be more prevalent in type 2 diabetes (T2D) than previously appreciated and may contribute to the progressive decline in β-cell function. In this study, we longitudinally evaluated the effect of islet autoimmune development on the progressive β-cell dysfunction in T2D patients.

RESEARCH DESIGN AND METHODS

Twenty-three T2D patients negative for islet autoantibodies (GAD antibody and insulinoma-associated protein 2) and islet-specific T cells were evaluated prospectively for up to 36 months. We investigated the percentage of patients who developed islet autoantibodies (Ab+) and/or islet-reactive T cells (T+) and the effect of the islet autoimmunity on fasting and glucagon-stimulated C-peptide responses. We defined positive islet autoimmunity as Ab+ and/or T+ for at least two study visits.

RESULTS

Of the 23 patients, 6 (26%) remained negative for islet autoimmunity (Ab-T-), 14 (61%) developed Ab+ and/or T+, and 3 (13%) were unclassifiable because they developed islet autoimmunity at only one study visit. Islet Ab+ was observed to be less stable than islet-specific T-cell responses. Development of islet autoimmunity was significantly associated with a more rapid decline in fasting (P < 0.0001) and glucagon-stimulated (P < 0.05) C-peptide responses.

CONCLUSIONS

These pilot data suggest that the development of islet autoimmunity in T2D is associated with a significantly more rapid β-cell functional decline.

Type 2 diabetes susceptibility gene variants predispose to adult-onset autoimmune diabetes

AIMS/HYPOTHESIS

Latent autoimmune diabetes in adults (LADA) is phenotypically a hybrid of type 1 and type 2 diabetes. Genetically LADA is poorly characterised but does share genetic predisposition with type 1 diabetes. We aimed to improve the genetic characterisation of LADA and hypothesised that type 2 diabetes-associated gene variants also predispose to LADA, and that the associations would be strongest in LADA patients with low levels of GAD autoantibodies (GADA).

METHODS

We assessed 41 type 2 diabetes-associated gene variants in Finnish (phase I) and Swedish (phase II) patients with LADA (n = 911) or type 1 diabetes (n = 406), all diagnosed after the age of 35 years, as well as in non-diabetic control individuals 40 years or older (n = 4,002).

RESULTS

Variants in the ZMIZ1 (rs12571751, p = 4.1 × 10(-5)) and TCF7L2 (rs7903146, p = 5.8 × 10(-4)) loci were strongly associated with LADA. Variants in the KCNQ1 (rs2237895, p = 0.0012), HHEX (rs1111875, p = 0.0024 in Finns) and MTNR1B (rs10830963, p = 0.0039) loci showed the strongest association in patients with low GADA, supporting the hypothesis that the disease in these patients is more like type 2 diabetes. In contrast, variants in the KLHDC5 (rs10842994, p = 9.5 × 10(-4) in Finns), TP53INP1 (rs896854, p = 0.005), CDKAL1 (rs7756992, p = 7.0 × 10(-4); rs7754840, p = 8.8 × 10(-4)) and PROX1 (rs340874, p = 0.003) loci showed the strongest association in patients with high GADA. For type 1 diabetes, a strong association was seen for MTNR1B (rs10830963, p = 3.2 × 10(-6)) and HNF1A (rs2650000, p = 0.0012).

CONCLUSIONS/INTERPRETATION

LADA and adult-onset type 1 diabetes share genetic risk variants with type 2 diabetes, supporting the idea of a hybrid form of diabetes and distinguishing them from patients with classical young-onset type 1 diabetes.

Association between calcaneus quantitative ultrasound (QUS) parameters and thyroid status in middle-aged and elderly Chinese men with euthyroidism: a population-based cross-sectional study

Although it is generally accepted that thyroid hormones affect bone metabolism, there is little data on the association of thyroid antibodies with bone status. We aimed to investigate the association between thyroid hormones or antibodies and quantitative ultrasound (QUS) parameters. This was a cross-sectional, population-based study conducted in Nanjing, China. A total of 1,001 Chinese men over 40 years were enrolled. We measured free triiodothyronine, free thyroxin (fT4), thyroid-stimulating hormone, anti-thyroid peroxidase (anti-TPO), anti-thyroglobulin, 25-hydroxyvitamin D, and QUS parameters. After adjusting for potential confounders, QUS values decreased from the lowest to highest tertiles of fT4 in euthyroid men [quantitative ultrasound index (QUI) p = 0.002, broadband ultrasound attenuation (BUA) p = 0.000, speed of sound (SOS) p = 0.009, respectively]. Men with high anti-TPO levels (≥200 IU/ml) were found to have lower QUI (p = 0.030), BUA (p = 0.034), and SOS (p = 0.041) values than controls (<200 IU/ml). The prevalence of vitamin D deficiency was significantly higher in individuals with high anti-TPO than those in lower levels (87.5 vs. 59.5 %, p = 0.001). Our results suggest that high fT4 or anti-TPO values are associated with lower QUS parameters. Prospective studies are needed to confirm the precise relationship between thyroid status and osteoporosis.

Clinical heterogeneity of adult Japanese diabetes depending on titers of glutamic acid decarboxylase autoantibodies

Aims/Introduction:  We examined whether levels of glutamic acid decarboxylase autoantibodies (GADAb) might show the clinical heterogeneity of adult Japanese diabetes.

MATERIALS AND METHODS

  In this cross-sectional study, the serum levels of GADAb were measured in a total of 1857 consecutive adult diabetic patients aged 20 years or older. The patients with positive GADAb, arbitrarily defined as ≥1.5 U/mL, were divided into quartiles according to the number of patients. The age- and sex-matched diabetic patients without GADAb were selected as a control group.

RESULTS

  A total of 103 (5.5%) of the diabetic patients had GADAb, and showed higher HbA1c and serum high-density lipoprotein (HDL) cholesterol levels, lower body mass index (BMI), urinary C-peptide immunoreactivity (CPR), serum triglycerides (TG) and uric acid (UA) levels, and lower prevalence of metabolic syndrome than the control group (P < 0.05). Quartiles 3 and 4 (i.e. GADAb ≥4.6 U/mL) showed a higher HbA1c level, lower BMI, urinary CPR, serum TG and UA levels, quartile 2 (2.5 ≤ GADAb < 4.6 U/mL) showed a lower BMI level than the control group (P < 0.05). Among the clinical parameters, we observed significant upward trends for both HbA1c and serum HDL cholesterol levels, and significant downward trends for BMI, serum TG and UA, urinary CPR levels, and prevalence of metabolic syndrome across GADAb quartiles (P < 0.05 for trend).

CONCLUSIONS

  These results show that the clinical phenotype of adult Japanese diabetes correlates with GADAb levels, and that patients with GADAb (≥2.5 U/mL) show different characteristics from those without GADAb, although further longitudinal studies are required. (J Diabetes Invest, doi: 10.1111/j.2040-1124.2011.00190.x, 2011).

Positivity for islet cell autoantibodies in patients with monogenic diabetes is associated with later diabetes onset and higher HbA1c level

AIMS

Islet cell autoantibodies are associated with autoimmune insulitis and belong to the diagnostic criteria of type 1 diabetes mellitus. However, growing evidence suggests that autoantibodies are present in other types of diabetes. Here, we focus on the autoantibody incidence in Czech patients with maturity-onset diabetes of the young and analyse their functional relevance in terms of diabetes onset and control.

METHODS

Autoantibodies against glutamic acid decarboxylase (GAD) 65 and protein tyrosine phosphatase islet antigen 2 (IA-2) were measured in a cohort of 28 Czech patients with maturity-onset diabetes of the young, all confirmed by genetic testing. Selected clinical data were correlated to the status and kinetics of autoantibodies.

RESULTS

One quarter of patients with maturity-onset diabetes of the young examined (7/28; 25%) was positive for GAD or IA-2 autoantibodies. GAD autoantibodies were more prevalent (7/7) than IA-2 autoantibodies (1/7). The incidence of autoantibodies did not correlate with human leukocyte antigen status. The patients who were positive for the autoantibodies developed diabetes later than those who were autoantibody-negative, but had worse glycaemic control (increased HbA1c ). Expression of autoantibodies decreased with any improvement of diabetes compensation. Only one patient did not correspond to the above and displayed signs of combined signs of maturity-onset diabetes of the young and Type 1 diabetes.

CONCLUSIONS

The data suggest transient but highly prevalent islet cell autoantibody expression in Czech patients with maturity-onset diabetes of the young. The autoantibodies were found in patients with delayed diabetes onset, and in times of insufficient diabetes control. As improvement of glycaemic control was associated with a decrease in levels of autoantibodies, their presence may reflect the kinetics of β-cell destruction induced by causes other than autoimmune ones.

Variation of C peptide decay rate in diabetic patients with positive glutamic acid decarboxylase antibody: better discrimination with initial fasting C peptide

BACKGROUND

Diabetic patients with positive glutamic acid decarboxylase antibody (GAD-Ab) could be classified as autoimmune diabetes, which is discriminated into acute-onset classical type 1 diabetes (T1DM) and latent autoimmune diabetes in adults (LADA). However, whether the decay rate of beta cell function is relevant with the mode of onset (acute or latent-onset) is unclear. We aimed to investigate whether initial C peptide levels could help differentiate variation of C peptide decay rate.

METHODS

Five hundred and twenty-seven newly diagnosed GAD-Ab positive diabetic patients were followed up to assess the natural course of beta cell function. Beta cell function failure was defined as fasting C peptide and postprandial C peptide levels less than 100 pmol/L and 150 pmol/L respectively.

RESULTS

All these diabetic patients were discriminated according to initial fasting C peptide of 300 pmol/L, that is B+ (larger than 300 pmol/L) and B- (less than 300 pmol/L) group. The proportion of developing beta cell function failure was 13.1% in B+ group and 90.5% in B- group, which suggested that fasting C peptide levels made a good distinction of the heterogeneity in autoimmune diabetes. Receiver operator characteristic (ROC) analysis suggested that the fasting C peptide level of 300 pmol/L was optimal for determining beta cell function failure with sensitivity of 90.5% and specificity of 86.9%.

CONCLUSIONS

Initial level of fasting C peptide is a good indicator for predicting beta cell function failure in GAD-Ab positive diabetic patients.

Frequency, immunogenetics, and clinical characteristics of latent autoimmune diabetes in China (LADA China study): a nationwide, multicenter, clinic-based cross-sectional study

Adult non-insulin requiring diabetes includes latent autoimmune diabetes of adults (LADA), distinguished from type 2 diabetes by the presence of islet autoantibodies. LADA China determined the characteristics of Chinese LADA. This nationwide, multicenter, clinic-based cross-sectional study was conducted in 46 university-affiliated hospitals in 25 Chinese cities. All 4,880 ketosis-free diabetic patients (<1 year postdiagnosis, without insulin therapy for >6 months, aged ≥30 years) had GAD antibody (GADA) and HLA-DQ genotype measured centrally with clinical data collected locally. GADA-positive subjects were classified as LADA. Of the patients, 5.9% were GADA positive with LADA. LADA showed a north-south gradient. Compared with GADA-negative type 2 diabetes, LADA patients were leaner, with lower fasting C-peptide and less metabolic syndrome. Patients with high GADA titers are phenotypically different from those with low GADA titers, while only a higher HDL distinguished the latter from those with type 2 diabetes. HLA diabetes-susceptible haplotypes were more frequent in LADA, even in those with low-titer GADA. HLA diabetes-protective haplotypes were less frequent in LADA. Our study implicates universal immunogenetic effects, with some ethnic differences, in adult-onset autoimmune diabetes. Autoantibody positivity and titer could be important for LADA risk stratification and accurate therapeutic choice in clinical practice.

GADA titer-related risk for organ-specific autoimmunity in LADA subjects subdivided according to gender (NIRAD study 6)

CONTEXT

Latent autoimmune diabetes in adults (LADA) includes a heterogeneous population wherein, based on glutamic acid decarboxylase antibody (GADA) titer, different subgroups of subjects can be identified.

OBJECTIVE

The aim of the present study was to evaluate GADA titer-related risk for β-cell and other organ-specific autoimmunity in LADA subjects.

METHODS

Adult-onset autoimmune diabetes subjects (n=236) and type 2 diabetes (T2DM) subjects (n=450) were characterized for protein tyrosine phosphatase (IA-2IC and IA-2(256-760)), zinc transporter 8 (ZnT8), thyroid peroxidase, (TPO), steroid 21-hydroxylase (21-OH), tissue transglutaminase (tTG), and antiparietal cell (APC) antibodies.

RESULTS

High GADA titer compared to low GADA titer showed a significantly higher prevalence of IA-2IC, IA-2(256-760), ZnT8, TPO, and APC antibodies (P≤0.04 for all comparison). 21-OH antibodies were detected in 3.4% of high GADA titer. A significant decreasing trend was observed from high GADA to low GADA and to T2DM subjects for IA-2(256-760), ZnT8, TPO, tTG, and APC antibodies (P for trend≤0.001). TPO was the only antibody showing a different prevalence between gender; low GADA titer and T2DM female patients had a higher frequency of TPO antibody compared to males (P=0.0004 and P=0.0006, respectively), where the presence of high GADA titer conferred an odds ratio of 8.6 for TPO compared to low GADA titer. After subdividing high and low GADA titer subjects according to the number of antibodies, we observed that 73.3% of high GADA titer subjects were positive for at least one or more antibodies, compared to 38.3% of low GADA titer (P<0.0001).

CONCLUSIONS

In LADA subjects, high GADA titer was associated with a profile of more severe autoimmunity and, in male gender, specifically predisposed to thyroid autoimmunity. A regular screening for other antibodies is recommended in LADA patients according to GADA titer and gender.

Diagnostic criteria of latent autoimmune diabetes in adults (LADA): a review and reflection

Diabetes has become a major public health problem in China nowadays. There are almost 97 million diabetic patients nationwide. Latent autoimmune diabetes in adults (LADA) is a subtype of autoimmune diabetes. Although it has been reported for about 20 years, the diagnostic criteria of this disease remain controversial. The discussion mainly focused on serum autoantibodies, period of insulin need and age of diagnosis. Besides, β cell function, metabolic parameters, genetic factors and cell immunity may also contribute to the formulation of the criteria. Here, we aim to review and discuss the diagnostic criteria of latent autoimmune diabetes in adults.

Latent autoimmune diabetes in adults in a population-based cohort of Polish patients with newly diagnosed diabetes mellitus

INTRODUCTION

Latent autoimmune diabetes in adults (LADA) is a slowly developing form of autoimmune diabetes characterized by the presence of type 1 diabetes-associated autoantibody. The aim of this study was to determine the incidence and characteristics of LADA in a population-based cohort of Polish patients with newly-diagnosed diabetes.

MATERIAL AND METHODS

The study cohort was taken from the resident population of the city Białystok, Poland, during the period 1 January to 31 December 2003, aged 20-64 years. During this period we identified 231 cases of diabetes. We measured glutamic acid decarboxylase (GADA) and insulin antibody (IAA), insulin, C peptide and glycated hemoglobin (HbA(1c)). Diagnosis of LADA was made according to Immunology Diabetes Society and Action LADA criteria.

RESULTS

The incidence of LADA was 10 per year per 100 000 people. The proportion of patients with LADA was 8.9% among newly diagnosed cases with diabetes. Patients with LADA were younger at diagnosis (48.5 ±9.4 years vs. 54.8 ±10.6 years, p < 0.01), had lower body mass index (26.9 ±9.3 kg/m(2) vs. 29.5 ±5.2 kg/m(2), p < 0.05), C peptide (126 ±127 pmol/l vs. 446 ±592 pmol/l, p < 0.001), and were less insulin resistant (HOMA IR 0.94 ±0.85 vs. 3.6±4.4, p < 0.001) compared to patients with type 2 diabetes. Glycated hemoglobin and fasting glucose were similar in patients with LADA and type 2 diabetes.

CONCLUSIONS

In addition to GAD, anti-insulin antibodies are useful for diagnosing autoimmune diabetes in adults. Patients with LADA have similar glucose control parameters (HbA(1c)) compared to patients with type 2 diabetes, although they are usually younger and have a lower body mass index. Patients with LADA make up a significant proportion of newly diagnosed people with diabetes mellitus in a Polish population.

Association of major histocompatibility complex class 1 chain-related gene a dimorphism with type 1 diabetes and latent autoimmune diabetes in adults in the Algerian population

Major histocompatibility complex class I chain-related gene A (MICA-129) dimorphism was investigated in 73 autoimmune diabetes patients (type 1 diabetes and latent autoimmune diabetes in adults) and 75 controls from Algeria. Only MICA-129 Val allele and MICA-129 Val/Val genotype frequencies were higher among patients than in the control group. Statistical analysis of the estimated extended HLA-DR-DQ-MICA haplotypes shown that individual effects of MICA alleles on HLA-DQ2-DR3-MICA-129 Val/Val and HLA-DQ8-DR4-MICA-129 Val/Val haplotypes were significantly higher in patients than in the control groups. These preliminary data might suggest a relevant role of MICA-129 Val/Val single nucleotide polymorphism (weak/weak binders of NKG2D receptor) in the pathogenesis of T1D and LADA.

Cellular interferon-γ and interleukin-13 immune reactivity in type 1, type 2 and latent autoimmune diabetes: action LADA 6

OBJECTIVE

Type 1 diabetes and latent autoimmune diabetes in adults (LADA) are thought to result from immune-mediated β-cell destruction. It remains unclear why LADA is clinically less severe compared to type 1 diabetes. This study aimed to compare the pro-inflammatory (interferon-γ, IFN-γ) and anti-inflammatory (interleukin-13, IL-13) T-cell responses in humans with LADA and type 1 diabetes.

RESEARCH DESIGN AND METHODS

IFN-γ and IL-13 T-cell responses to a panel of 16 (auto)-antigens were tested using an enzyme linked immune-spot technique and peripheral T-cells from 35 patients with type 1 diabetes, 59 patients with type 2 diabetes, 23 LADA patients, and 42 control subjects.

RESULTS

LADA and type 1 diabetes patients did not display any statistically significant differences in the frequency of IFN-γ or IL-13 responses to auto-antigenic stimuli, positive control or mitogen. Overall very low T cell reactivity to autoantigens was detected in all groups. IL-13 responses but not IFN-γ responses to recall antigen tetanus toxoid were higher in healthy control subjects compared to patients with type 1 or type 2 diabetes or LADA (P<0.05). Diabetes, independent of type, was associated with weaker response to recall antigen tetanus toxoid.

CONCLUSIONS

LADA patients are indistinguishable from type 1 diabetes patients for cellular IFN-γ and IL-13 responses upon mitogen and recall antigen stimulation. These results extend previous findings showing that systemic cytokine/chemokine and humoral responses in type 1 diabetes and LADA are similar.

Interventions for latent autoimmune diabetes (LADA) in adults

BACKGROUND

Latent autoimmune diabetes in adults (LADA) is a slowly developing type 1 diabetes.

OBJECTIVES

To compare interventions used for LADA.

SEARCH STRATEGY

Studies were obtained from searches of electronic databases, supplemented by handsearches, conference proceedings and consultation with experts. Date of last search was December 2010.

SELECTION CRITERIA

Randomised controlled trials (RCT) and controlled clinical trials (CCT) evaluating interventions for LADA or type 2 diabetes with antibodies were included.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data and assessed risk of bias. Studies were summarised using meta-analysis or descriptive methods.

MAIN RESULTS

Searches identified 13,306 citations. Fifteen publications (ten studies) were included, involving 1019 participants who were followed between three months to 10 years (1060 randomised). All studies had a high risk of bias. Sulphonylurea (SU) with insulin did not improve metabolic control significantly more than insulin alone at three months (one study, n = 15) and at 12 months (one study, n = 14) of treatment and follow-up. SU (with or without metformin) gave poorer metabolic control compared to insulin alone (mean difference in glycosylated haemoglobin A1c (HbA1c) from baseline to end of study, for insulin compared to oral therapy: -1.3% (95% confidence interval (CI) -2.4 to -0.1; P = 0.03, 160 participants, four studies, follow-up/duration of therapy: 12, 30, 36 and 60 months; however, heterogeneity was considerable). In addition, there was evidence that SU caused earlier insulin dependence (proportion requiring insulin at two years was 30% in the SU group compared to 5% in conventional care group (P < 0.001); patients classified as insulin dependent was 64% (SU group) and 12.5% (insulin group, P = 0.007). No intervention influenced fasting C-peptide, but insulin maintained stimulated C-peptide better than SU (one study, mean difference 7.7 ng/ml (95% CI 2.9 to 12.5)). In a five year follow-up of GAD65 (glutamic acid decarboxylase formulated with aluminium hydroxide), improvements in fasting and stimulated C-peptide levels (20 μg group) were maintained after five years. Short term (three months) follow-up in one study (n = 74) using Chinese remedies did not demonstrate a significant difference in improving fasting C-peptide levels compared to insulin alone (0.07 µg/L (95% CI -0.05 to 0.19). One study using vitamin D with insulin showed steady fasting C-peptide levels in the vitamin D group but declining fasting C-peptide levels (368 to 179 pmol/L, P = 0.006) in the insulin alone group at 12 months follow-up. Comparing studies was difficult as there was a great deal of heterogeneity in the studies and in their selection criteria. There was no information regarding health-related quality of life, complications of diabetes, cost or health service utilisation, mortality and limited evidence on adverse events (studies on oral agents or insulin reported no adverse events in terms of severe hypoglycaemic episodes).

AUTHORS' CONCLUSIONS

Two studies show SU leading to earlier insulin dependence and a meta-analysis of four studies with considerable heterogeneity showed poorer metabolic control if SU is prescribed for patients with LADA compared to insulin. One study showed that vitamin D with insulin may protect pancreatic beta cells in LADA. Novel treatments such as GAD65 in certain doses (20 μg) have been suggested to maintain fasting and stimulated C-peptide levels. However, there is no significant evidence for or against other lines of treatment of LADA.

Prevalence and correlates of latent autoimmune diabetes in adults in Tianjin, China: a population-based cross-sectional study

OBJECTIVE

Data on latent autoimmune diabetes in adults (LADA) from population-based studies are sparse. We sought to investigate the prevalence and correlates of LADA.

RESEARCH DESIGN AND METHODS

A total of 8,109 participants, who were aged ≥15 years and living in Tianjin, China, were assessed to identify individuals with type 2 diabetes (American Diabetes Association Criteria, 1997) and further to detect patients with LADA. LADA was ascertained by 1) the presence of type 2 diabetes and age ≥35 years, 2) the lack of a requirement for insulin at least 6 months after the diagnosis of type 2 diabetes, and 3) serum GAD antibody positivity. Data were analyzed using multinomial logistic regression with adjustment for potential confounders.

RESULTS

Of all participants, 498 (6.1%) were patients with type 2 diabetes. Of them, 46 (9.2%) were found to have LADA. The prevalence of LADA was 0.6% (46 of 8,109), and tended to increase with age up to 50-59 years in all participants. The odds ratios (95% CI) of LADA related to hypertension, family history of diabetes, waist-to-hip ratio ≥0.85, and major stressful events were 1.93 (1.02-3.65), 17.59 (9.08-34.06), 5.37 (2.31-12.49), and 4.09 (1.75-9.52), respectively.

CONCLUSIONS

The prevalence of LADA is ∼9% in patients with type 2 diabetes. Hypertension, family history of diabetes, central obesity, and major stressful events may be associated with the occurrence of LADA.

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.

Reevaluation of a case of type 1 diabetes mellitus diagnosed before 6 months of age

BACKGROUND

A 17-year-old female was referred for the reassessment of her type 1 diabetes mellitus, with which she had been diagnosed at the age of 15 weeks owing to symptoms of ketoacidosis. The patient had mild learning difficulties, which resulted in her requiring additional support at school. There was no family history of diabetes.

INVESTIGATIONS

Measurements of plasma C-peptide and glutamate decarboxylase autoantibodies. Molecular genetic testing was performed.

DIAGNOSIS

Intermediate developmental delay, epilepsy and neonatal diabetes mellitus (DEND) syndrome as a result of a 59V>M Kir6.2 mutation.

MANAGEMENT

Treatment with high-dose oral glibenclamide replaced insulin treatment. Good glycemic control was achieved with levels of HbA(1c) consistently below 6.5% and no hypoglycemia.

Association of TCF7L2 gene variants with low GAD autoantibody titre in LADA subjects (NIRAD Study 5)

AIMS

We previously demonstrated the presence of two different populations among adult-onset autoimmune diabetes (latent autoimmume diabetes of adults; LADA) having high or low titre of antibodies to glutamic acid decarboxylase (GADA). The transcription factor 7-like 2 (TCF7L2) gene has been recognized as the major gene associated with Type 2 diabetes. The aim of the present study was to evaluate whether the phenotypic heterogeneity of LADA based on GADA titre is associated with TCF7L2 polymorphisms.

METHODS

Two hundred and fifty patients identified as LADA, divided into two subgroups with low (< or = 32 arbitrary units) or high (> 32 units) GADA titre, 620 subjects with Type 2 diabetes [from the Non-Insulin Requiring Autoimmune Diabetes (NIRAD) study cohort of 5330 subjects] in addition to 551 consecutive cases of Type 1 diabetes and 545 normoglycaemic subjects were analysed for the rs12255372 and rs7903146 polymorphisms of the TCF7L2 gene using Taqman.

RESULTS

The genotype and allele distributions of the two polymorphisms revealed similar frequencies in subjects with low GADA titre and Type 2 diabetes. High GADA titre, Type 1 diabetes and controls also showed comparable frequencies. A significant increase of GT/TT genotypes of the rs12255372 single-nucleotide polymorphism (SNP) and CT/TT genotypes of the rs7903146 SNP was observed in low GADA titre and Type 2 diabetes compared with high GADA titre, Type 1 diabetes and controls (P < or = 0.04 for both comparisons). The risk alleles of both variants were increased in low GADA titre and Type 2 diabetes compared with high GADA titre, Type 1 diabetes and control subjects (P < 0.02 for all comparisons).

CONCLUSIONS

TCF7L2 common genetic variants of susceptibility are associated only with low GADA antibody titre in LADA patients.

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.

GADA testing: the current state of knowledge

This review considers the current knowledge and practice of GADA testing people with diabetes in Europe and the UK. Important issues are raised, including interpretation of the results and the clinical relevance of the GADA titre. Recommendations are made towards standardising GADA testing, using World Health Organization units.