Clinical phenotype and beta-cell autoimmunity in Italian patients with adult-onset diabetes

The worldwide prevalence of latent autoimmune diabetes of adults among adult-onset diabetic individuals: a systematic review and meta-analysis

PURPOSE

The actual global burden of Latent Autoimmune Diabetes of Adults (LADA) remains unknown even though its prevalence is almost equal to the type 1 form of diabetes. Hence the present systematic review and meta-analysis were performed to estimate the prevalence of LADA among diabetic individuals using the studies published at global levels.

METHODS

A comprehensive literature revival was performed to identify articles on the prevalence of LADA published till 2023. The prevalence estimates were calculated using DerSimonian and Laird random-effects models with a heterogeneity measure by Cochrane Q and I2 statistics. Publication bias was assessed by the Doi plot and Luis Furuya-Kanamori asymmetry index (LFKindex). P < 0.05 was considered statistically significant.

RESULTS

The overall pooled prevalence of LADA obtained from a total of 51,725 diabetic individuals was found to be 8.9% (95%CI 7.5-10.4, P < 0.001) with a prevalence range of 2.3% in to 18.9% in United Arab Emirates and Bahrain respectively. Subgroup analysis of LADA in the context of the IDF geographic regions showed a higher prevalence in North America (13.5%), 9.5% in Middle East and North Africa, 9.4% in Africa, 9.2% in South East Asia, 8.3% in Western Pacific and the lowest prevalence of 7.0% in Europe.

CONCLUSION

The Meta-analysis revealed a worldwide prevalence of LADA as 8.9%, with the highest prevalence in Bahrain and the lowest in United Arab Emirates. Further, the higher prevalence in some IDF regions and the inconsistent association between socioeconomic status and LADA recommend more research in the future.

Relationship between β-Cell Autoantibodies and Their Combination with Anthropometric and Metabolic Components and Microvascular Complications in Latent Autoimmune Diabetes in Adults

AIMS

Our study aimed to investigate the relationship between three autoantibodies and their combination with anthropometric and metabolic components and microvascular complications in patients with latent autoimmune diabetes in adults (LADA).

METHODS

Our study included 189 LADA patients divided into four subgroups according to the autoantibodies present: glutamic acid decarboxylase autoantibodies (GADA) only; zinc transporter-8 autoantibodies (ZnT8A)+GADA; insulinoma-associated-2 autoantibodies (IA-2)+GADA; and ZnT8+IA-2+GADA.

RESULTS

Compared to GADA positivity only, patients with ZnT8+GADA positivity and ZnT8+IA-2+GADA positivity had a shorter diabetes duration and lower body mass index (BMI); patients with ZnT8+GADA positivity were younger and showed an increase in glomerular filtration rate, while those with ZnT8+IA-2+GADA positivity had lower C-peptide and lower insulin resistance measured with HOMA2-IR. In a multiple regression analysis, ZnT8 positivity was associated with lower BMI (p = 0.0024), female sex (p = 0.0005), and shorter duration of disease (p = 0.0034), while IA-2 positivity was associated with lower C-peptide levels (p = 0.0034) and shorter diabetes duration (p = 0.02). No association between antibody positivity and microvascular complications of diabetes, including retinopathy, neuropathy, and microalbuminuria, as well as with variables of glucose control and β-cell function were found.

CONCLUSION

The results of our study suggest that ZnT8 and IA-2 autoantibodies are present in a significant number of LADA patients and associated with clinical and metabolic characteristics resembling classic type 1 diabetes. Due to increased LADA prevalence, earlier identification of patients requiring frequent monitoring with the earlier intensification of insulin therapy might be of special clinical interest.

Adult-onset autoimmune diabetes

Adult-onset autoimmune (AOA) diabetes pathophysiology starts with immune changes, followed by dysglycaemia and overt disease. AOA diabetes can occur as classic type 1 diabetes when associated with severe loss of insulin secretion. More frequently, it is diagnosed as latent autoimmune diabetes in adults, a slowly progressing form with late onset, a long period not requiring insulin, and it is often misdiagnosed as type 2 diabetes. As its clinical presentation varies remarkably and immune markers often lack specificity, it is challenging to classify each case ad hoc, especially when insulin treatment is not required at diagnosis. Proper care of AOA diabetes aims to prevent complications and to improve quality of life and life expectancy. To achieve these goals, attention should be paid to lifestyle factors, with the aid of pharmacological therapies properly tailored to each individual clinical setting. Given the heterogeneity of the disease, choosing the right therapy for AOA diabetes is challenging. Most of the trials testing disease-modifying therapies for autoimmune diabetes are conducted in people with childhood onset, whereas non-insulin diabetes therapies have mostly been studied in the larger population with type 2 diabetes. More randomized controlled trials of therapeutic agents in AOA diabetes are needed.

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.

Latent Autoimmune Diabetes of Adults (LADA) Is Likely to Represent a Mixed Population of Autoimmune (Type 1) and Nonautoimmune (Type 2) Diabetes

Latent autoimmune diabetes of adults (LADA) is typically defined as a new diabetes diagnosis after 35 years of age, presenting with clinical features of type 2 diabetes, in whom a type 1 diabetes-associated islet autoantibody is detected. Identifying autoimmune diabetes is important since the prognosis and optimal therapy differ. However, the existing LADA definition identifies a group with clinical and genetic features intermediate between typical type 1 and type 2 diabetes. It is unclear whether this is due to 1) true autoimmune diabetes with a milder phenotype at older onset ages that initially appears similar to type 2 diabetes but later requires insulin, 2) a disease syndrome where the pathophysiologies of type 1 and type 2 diabetes are both present in each patient, or 3) a heterogeneous group resulting from difficulties in classification. Herein, we suggest that difficulties in classification are a major component resulting from defining LADA using a diagnostic test-islet autoantibody measurement-with imperfect specificity applied in low-prevalence populations. This yields a heterogeneous group of true positives (autoimmune type 1 diabetes) and false positives (nonautoimmune type 2 diabetes). For clinicians, this means that islet autoantibody testing should not be undertaken in patients who do not have clinical features suggestive of autoimmune diabetes: in an adult without clinical features of type 1 diabetes, it is likely that a single positive antibody will represent a false-positive result. This is in contrast to patients with features suggestive of type 1 diabetes, where false-positive results will be rare. For researchers, this means that current definitions of LADA are not appropriate for the study of autoimmune diabetes in later life. Approaches that increase test specificity, or prior likelihood of autoimmune diabetes, are needed to avoid inclusion of participants who have nonautoimmune (type 2) diabetes. Improved classification will allow improved assignment of prognosis and therapy as well as an improved cohort in which to analyze and better understand the detailed pathophysiological components acting at onset and during disease progression in late-onset autoimmune diabetes.

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.

Relationships between Islet-Specific Autoantibody Titers and the Clinical Characteristics of Patients with Diabetes Mellitus

BACKGROUND

Dysimmunity plays a key role in diabetes, especially type 1 diabetes mellitus. Islet-specific autoantibodies (ISAs) have been used as diagnostic markers for different phenotypic classifications of diabetes. This study was aimed to explore the relationships between ISA titers and the clinical characteristics of diabetic patients.

METHODS

A total of 509 diabetic patients admitted to Department of Endocrinology and Metabolism at the Affiliated Hospital of Nantong University were recruited. Anthropometric parameters, serum biochemical index, glycosylated hemoglobin, urinary microalbumin/creatinine ratio, ISAs, fat mass, and islet β-cell function were measured. Multiple linear regression analysis was performed to identify relationships between ISA titers and clinical characteristics.

RESULTS

Compared with autoantibody negative group, blood pressure, weight, total cholesterol (TC), low density lipoprotein cholesterol (LDL-C), visceral fat mass, fasting C-peptide (FCP), 120 minutes C-peptide (120minCP) and area under C-peptide curve (AUCCP) of patients in either autoantibody positive or glutamate decarboxylase antibody (GADA) positive group were lower. Body mass index (BMI), waist circumference, triglycerides (TGs), body fat mass of patients in either autoantibody positive group were lower than autoantibody negative group. GADA titer negatively correlated with TC, LDL-C, FCP, 120minCP, and AUCCP. The islet cell antibody and insulin autoantibody titers both negatively correlated with body weight, BMI, TC, TG, and LDL-C. After adjusting confounders, multiple linear regression analysis showed that LDL-C and FCP negatively correlated with GADA titer.

CONCLUSION

Diabetic patients with a high ISA titer, especially GADA titer, have worse islet β-cell function, but less abdominal obesity and fewer features of the metabolic syndrome.

Population segmentation of type 2 diabetes mellitus patients and its clinical applications - a scoping review

Background

Population segmentation permits the division of a heterogeneous population into relatively homogenous subgroups. This scoping review aims to summarize the clinical applications of data driven and expert driven population segmentation among Type 2 diabetes mellitus (T2DM) patients.

Methods

The literature search was conducted in Medline®, Embase®, Scopus® and PsycInfo®. Articles which utilized expert-based or data-driven population segmentation methodologies for evaluation of outcomes among T2DM patients were included. Population segmentation variables were grouped into five domains (socio-demographic, diabetes related, non-diabetes medical related, psychiatric / psychological and health system related variables). A framework for PopulAtion Segmentation Study design for T2DM patients (PASS-T2DM) was proposed.

Results

Of 155,124 articles screened, 148 articles were included. Expert driven population segmentation approach was most commonly used, of which judgemental splitting was the main strategy employed (n = 111, 75.0%). Cluster based analyses (n = 37, 25.0%) was the main data driven population segmentation strategies utilized. Socio-demographic (n = 66, 44.6%), diabetes related (n = 54, 36.5%) and non-diabetes medical related (n = 18, 12.2%) were the most used domains. Specifically, patients’ race, age, Hba1c related parameters and depression / anxiety related variables were most frequently used. Health grouping/profiling (n = 71, 48%), assessment of diabetes related complications (n = 57, 38.5%) and non-diabetes metabolic derangements (n = 42, 28.4%) were the most frequent population segmentation objectives of the studies.

Conclusions

Population segmentation has a wide range of clinical applications for evaluating clinical outcomes among T2DM patients. More studies are required to identify the optimal set of population segmentation framework for T2DM patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12874-021-01209-w.

Prevalence of positive islet autoantibody in type 2 diabetes patients: a cross-sectional study in a Chinese community

BACKGROUND

Islet autoantibodies occur in type 2 diabetes. Our study aimed to investigate the prevalence of positive islet autoimmunity in community patients with type 2 diabetes.

METHODS

A total of 495 community patients with type 2 diabetes were recruited using the method of cluster sampling in this cross-sectional study. Three islet autoantibodies including glutamic acid decarboxylase antibody (GADA), insulin autoantibody (IAA) and islet cell antibody (ICA) were measured, and clinical characteristics involved in those individuals were evaluated.

RESULTS

The positive rate of islet autoantibodies was 28.5% in total, while combinations of different autoantibodies were rarely seen. Compared with GADA-negative group, positive counterparts significantly tended to have lower levels of body mass index (BMI), waist-hip ratio (WHR), and urinary microalbumin (mALB) (P < 0.05). Adjusted for confounding factors, WHR, triglycerides (TG), and mALB seemed to be negative independent predictors of GADA (OR < 1, P < 0.05). Patients with positive IAA tended to receive insulin treatment (P < 0.0001). Besides, fasting blood glucose (FBG), serum levels of high-density lipoprotein cholesterol (HDL-CH), aspartate transaminase (AST), and γ-glutamyltransferase (GGT) were more likely to be higher in IAA positive subgroup in comparison with the negative counterparts. While after AST was adjusted by unconditional logistic regression analysis, history of insulin treatment, FBG, HDL-CH, and GGT were confirmed as positive predictors of IAA. Furthermore, in patients who were IAA positive, those treated with exogenous insulin tended to have longer duration of diabetes than non-insulin treatment counterparts (P < 0.0001). With regard to ICA, however, there were no significant differences between the two subgroups, except that serum level of AST/ALT seemed to be slightly different (P = 0.064).

CONCLUSION

These data suggested that type 2 diabetic community patients with positive GADA tended to be lean and were able to maintain normal lipid metabolism, while patients with positivity of IAA were frequently accompanied with insulin treatment and more closely associated with diabetic liver damage.

Immunological and clinical characteristics of latent autoimmune diabetes in the elderly

BACKGROUND

Latent autoimmune diabetes in adults (LADA) is determined by both a noninsulin-dependent clinical presentation and an autoimmune pathogenic process. Glutamic acid decarboxylase antibody (GADA) constitutes the most important marker, although IA-2A and ZnT8A also define LADA presentation. Type 2 diabetes mellitus (T2DM) is the most prevalent type particularly over 65 years old. Studies about autoimmunity in this age group are scarce.

OBJECTIVE

The aim of this work was to determine whether three autoantibodies for diabetes autoimmunity were present in elderly T2DM patients, and to assess the distinctive clinical features of autoantibody-positive patients.

RESEARCH DESIGN AND METHODS

We recruited 153 patients with diabetes with onset of diabetes after 65 years of age and a BMI under 30 kg/m² .

RESULTS

The prevalence of at least one of the autoantibodies was 15.68% (24/153). The most prevalent autoantibody was GADA with 8.49% (13/153), followed by ZnT8A with 6.50% (10/153) and IA2A with 1.96% (3/153). The autoimmunity-positive group presented higher HbA1c (7.01 ± 1.98 vs 6.35 ± 1.01; P = 0.007) and more prevalent insulin therapy (25% vs 10.85%; P = 0.047). GADA-positive patients with diabetes presented higher FPG (7.79 ± 3.79 mmol/L vs 6.43 ± 1.6 mmol/L; P = 0.014) and insulin therapy more frequently (46% vs 10.71%; p = 0.015). GADA titre levels in the individuals with BMI under 27 kg/m² were higher (35.00 ± 4.20) than those in the group with BMI over 27 kg/m² (8.83 ± 3.041; P = 0.0005).

CONCLUSION

Autoantibodies GADA and Znt8A may be useful markers in identifying a subgroup of older patients with a clinical presentation of diabetes which could be characterized as latent autoimmune diabetes in the elderly.

Slowly Progressive Type 1 Diabetes Mellitus: Current Knowledge And Future Perspectives

Slowly progressive type 1 insulin-dependent diabetes mellitus (SPIDDM), sometimes referred to as latent autoimmune diabetes in adults (LADA), is a heterogeneous disease that is often confused with type 1 and type 2 diabetes. As a result, there were few diagnostic criteria for this disorder until 2012, when the Japan Diabetes Society established criteria that could be used in clinical practice. A primary question is whether pathologic markers for type 1 or type 2 diabetes are present in the pancreas of patients with SPIDDM, because the phenotype of SPIDDM is similar to both type 1 and type 2 diabetes. Recent studies clarified pathologic findings in the pancreas of patients with SPIDDM, which included T-cell-mediated insulitis, a marker of type 1 diabetes; pseudoatrophic islets (islets specifically devoid of beta cells), another hallmark of type 1 diabetes; and a lack of amylin (ie, islet amyloid polypeptide) deposition to the islet cells, a pathologic marker of type 2 diabetes. In terms of preventing the loss of beta-cell function in patients with SPIDDM, several studies have shown that some drugs, including dipeptidyl peptidase-4 inhibitors, are effective. There is an increased need for early diagnosis of SPIDDM to preserve beta-cell function. This review presents updated findings on the pathogenesis and immunologic findings of the affected pancreas, diagnostic markers, risk factors for progression of beta-cell dysfunction, epidemiology, clinical features, diagnostic strategies, prevention strategies, and clinical options for patients with SPIDDM.

Latent Autoimmune Diabetes in Adults: A Review on Clinical Implications and Management

Latent autoimmune diabetes in adults (LADA) is a heterogeneous disease characterized by a less intensive autoimmune process and a broad clinical phenotype compared to classical type 1 diabetes mellitus (T1DM), sharing features with both type 2 diabetes mellitus (T2DM) and T1DM. Since patients affected by LADA are initially insulin independent and recognizable only by testing for islet-cell autoantibodies, it could be difficult to identify LADA in clinical setting and a high misdiagnosis rate still remains among patients with T2DM. Ideally, islet-cell autoantibodies screening should be performed in subjects with newly diagnosed T2DM, ensuring a closer monitoring of those resulted positive and avoiding treatment of hyperglycaemia which might increase the rate of β-cells loss. Thus, since the autoimmune process in LADA seems to be slower than in classical T1DM, there is a wider window for new therapeutic interventions that may slow down β-cell failure. This review summarizes the current understanding of LADA, by evaluating data from most recent studies, the actual gaps in diagnosis and management. Finally, we critically highlight and discuss novel findings and future perspectives on the therapeutic approach in LADA.

A Global Perspective of Latent Autoimmune Diabetes in Adults

Latent autoimmune diabetes in adults (LADA) is characterized by the presence of islet autoantibodies and initial insulin independence, which can lead to misdiagnosis of type 2 diabetes (T2D). As such, understanding the genetic etiology of LADA could aid in more accurate diagnosis. However, there is ongoing debate regarding the exact definition of LADA, so understanding its impact in different populations when contrasted with type 1 diabetes (T1D) and T2D is one potential strategy to gain insight into its etiology. Unfortunately, the lack of consistent and thorough autoantibody screening around the world has hampered well-powered genetic studies of LADA. This review highlights recent genetic and epidemiological studies of LADA in diverse populations as well as the importance of autoantibody screening in facilitating future research.

Pathophysiology-based phenotyping in type 2 diabetes: A clinical classification tool

BACKGROUND

Type 2 diabetes may be a more heterogeneous disease than previously thought. Better understanding of pathophysiological subphenotypes could lead to more individualized diabetes treatment. We examined the characteristics of different phenotypes among 5813 Danish patients with new clinically diagnosed type 2 diabetes.

METHODS

We first identified all patients with rare subtypes of diabetes, latent autoimmune diabetes of adults (LADA), secondary diabetes, or glucocorticoid-associated diabetes. We then used the homeostatic assessment model to subphenotype all remaining patients into insulinopenic (high insulin sensitivity and low beta cell function), classical (low insulin sensitivity and low beta cell function), or hyperinsulinemic (low insulin sensitivity and high beta cell function) type 2 diabetes.

RESULTS

Among 5813 patients diagnosed with incident type 2 diabetes in the community clinical setting, 0.4% had rare subtypes of diabetes, 2.8% had LADA, 0.7% had secondary diabetes, 2.4% had glucocorticoid-associated diabetes, and 93.7% had WHO-defined type 2 diabetes. In the latter group, 9.7% had insulinopenic, 63.1% had classical, and 27.2% had hyperinsulinemic type 2 diabetes. Classical patients were obese (median waist 105 cm), and 20.5% had cardiovascular disease (CVD) at diagnosis, while insulinopenic patients were fairly lean (waist 92 cm) and 17.5% had CVD (P = 0.14 vs classical diabetes). Hyperinsulinemic patients were severely obese (waist 112 cm), and 25.5% had CVD (P < 0.0001 vs classical diabetes).

CONCLUSIONS

Patients clinically diagnosed with type 2 diabetes are a heterogeneous group. In the future, targeted treatment based on pathophysiological characteristics rather than the current "one size fits all" approach may improve patient prognosis.

Latent Autoimmune Diabetes in Adults: Current Status and New Horizons

Autoimmune diabetes is a heterogeneous disease which can arise at any age. Subjects with adult-onset autoimmune diabetes who do not necessitate insulin-therapy for at least 6 months after diagnosis are demarcated as having latent autoimmune diabetes in adults (LADA). This condition is more heterogeneous than young-onset autoimmune diabetes and shares clinical and metabolic characteristics with both type 2 and type 1 diabetes. Patients with LADA are considered by having highly variable β-cell destruction, different degrees of insulin resistance and heterogeneous titre and pattern of islet autoantibody, suggesting different pathophysiological pathways partially explaining the heterogeneous phenotypes of LADA. To date the heterogeneity of LADA does not allow to establish a priori treatment algorithm and no specific guidelines for LADA therapy are available. These subjects are mostly treated as affected by type 2 diabetes, a factor that might lead to the progression to insulin-dependency quickly. A personalised medicine approach is necessary to attain optimal metabolic control and preserve β-cell function to decrease the risk of long-term diabetes complications. Recent data concerning the use of oral antidiabetic agents as dipeptidyl peptidase 4 inhibitors and glucagon-like peptide 1 receptor agonists indicate up-and-coming results in term of protect C-peptide levels and improving glycaemic control. This review summarises current knowledge on LADA, emphasising controversies regarding its pathophysiology and clinical features. Moreover, we discuss data available about novel therapeutic approaches that can be considered for prevention of β-cell loss in LADA.

Adult-onset autoimmune diabetes: current knowledge and implications for management

Adult-onset autoimmune diabetes is a heterogeneous disease that is characterized by a reduced genetic load, a less intensive autoimmune process and a mild metabolic decompensation at onset compared with young-onset type 1 diabetes mellitus (T1DM). The majority of patients with adult-onset autoimmune diabetes do not require insulin treatment for at least 6 months after diagnosis. Such patients are defined as having latent autoimmune diabetes in adults (LADA), which is distinct from classic adult-onset T1DM. The extensive heterogeneity of adult-onset autoimmune diabetes is apparent beyond the distinction between classic adult-onset T1DM and LADA. LADA is characterized by genetic, phenotypic and humoral heterogeneity, encompassing different degrees of insulin resistance and autoimmunity; this heterogeneity is probably a result of different pathological mechanisms, which have implications for treatment. The existence of heterogeneous phenotypes in LADA makes it difficult to establish an a priori treatment algorithm, and therefore, a personalized medicine approach is required. In this Review, we discuss the current understanding and gaps in knowledge regarding the pathophysiology and clinical features of adult-onset autoimmune diabetes and highlight the similarities and differences with classic T1DM and type 2 diabetes mellitus.

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.

Latent Autoimmune Diabetes in Adults in the United Arab Emirates: Clinical Features and Factors Related to Insulin-Requirement

AIMS

To describe and to characterize clinical features of latent autoimmune diabetes in adults (LADA) compared to type 1 and type 2 diabetes in the UAE.

METHODS

In this cross-sectional study a dataset including 18,101 subjects with adult-onset (>30 years) diabetes was accessed. 17,072 subjects fulfilled the inclusion/exclusion criteria. Data about anthropometrics, demographics, autoantibodies to Glutamic Acid Decarboxylase (GADA) and to Islet Antigen 2 (anti-IA2), HbA1c, cholesterol and blood pressure were extracted. LADA was diagnosed according to GADA and/or anti-IA2 positivity and time to insulin therapy.

RESULTS

437 (2.6%) patients were identified as LADA and 34 (0.2%) as classical type 1 diabetes in adults. Mean age at diagnosis, BMI, waist circumference, systolic blood pressure and HbA1c significantly differed between, LADA, type 2 and type 1 diabetes, LADA showing halfway features between type 2 and type 1 diabetes. A decreasing trend for age at diagnosis and waist circumference was found among LADA subjects when subdivided by positivity for anti-IA2, GADA or for both antibodies (p=0.013 and p=0.011 for trend, respectively). There was a gradual downward trend in autoantibody titre in LADA subjects requiring insulin within the first year from diagnosis to subjects not requiring insulin after 10 years of follow-up (p<0.001).

CONCLUSIONS

This is the first study describing the clinical features of LADA in the UAE, which appear to be different from both type 1 and type 2 diabetes. Furthermore, we showed that the clinical phenotype of LADA is dependent on different patterns of antibody positivity, influencing the time to insulin requirement.

Low prevalence of latent autoimmune diabetes in adults in northern India

AIM

To study the frequency of islet antibodies in a large cohort of clinic- and community-based patients with Type 2 diabetes in northern India.

METHODS

We measured glutamic acid decarboxylase (GAD) antibodies in 618 adults with Type 2 diabetes (378 patients with diabetes attending a hospital clinic, 240 patients diagnosed in a community survey) and in 192 healthy subjects residing in north India. Islet antigen 2 (IA2) antibodies were also studied in a proportion of the patients with diabetes (n = 492) and in a control population (n = 191). GAD and IA2 antibodies were measured by immunoprecipitation of the respective (35) S-labelled recombinant antigen.

RESULTS

We found that GAD antibodies were present in nine (1.5%) patients with diabetes (clinic population: 0.8%, community study: 2.5%), a prevalence similar to that among the subjects without diabetes (n = 2; 1%). IA2 antibodies were detected in seven patients with Type 2 diabetes (1.4%) and in two healthy control subjects (1.0%). The frequency of either GAD or IA2 antibodies was similar in people with and without diabetes (3.2 vs 2.1%). No subject was found to have both antibodies. Insulin requirement was higher among antibody-positive than among antibody-negative patients (GAD antibody: 33 vs 6.3%; P = 0.001; GAD or IA2 antibody: 23.1 vs 6.4%; P = 0.02); however, other clinical features were similar in the two groups.

CONCLUSIONS

In the present north-Indian population with Type 2 diabetes, the overall prevalence of GAD antibodies and the prevalence of either GAD or IA2 antibodies were considerably lower than those reported in white European populations.

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.

High GADA titer increases the risk of insulin requirement in LADA patients: a 7-year follow-up (NIRAD study 7)

OBJECTIVE

The aim of this study was to determine whether glutamic acid decarboxylase antibody (GADA) titer and other clinical parameters could define the risk of progression to insulin therapy in latent autoimmune diabetes in adults (LADA) patients during a 7-year follow-up.

METHODS

This study involved 220 LADA and 430 type 2 diabetes subjects followed up for 7 years from the time of GADA screening to evaluate their progression toward insulin therapy. Kaplan-Meier curves and multivariate logistic regression analysis were performed to identify the markers capable of influencing this progression.

RESULTS

During the follow-up, the drop out was 4% in both groups. A total of 119 (56.1%) out of 212 LADA patients required insulin during the 7 years of follow-up. The Kaplan-Meier plots showed that 74/104 (71.1%) of high GADA titer required insulin compared with 45/108 (41.6%) of low GADA titer and with 86/412 (20.9%) of type 2 diabetes (P<0.0001 for both). A BMI of ≤25 kg/m2 and IA-2IC and zinc transporter 8 (ZnT8) positivity were also shown as the markers of faster progression (P<0.0001 for both). The proportion of LADA patients requiring insulin was significantly higher in the group of subjects treated also with sulfonylurea in the first year from diagnosis compared with those treated with diet and/or insulin sensitizers (P<0.001). The multivariate analysis confirmed that the presence of high GADA titer was a significant predictor of insulin requirement (P<0.0001, OR=6.95).

CONCLUSIONS

High GADA titer, BMI ≤ 25, ZnT8 and IA-2IC positivity and sulfonylurea treatment, in the first year from diagnosis, significantly increase the progression toward insulin requirement in LADA patients.

Autoimmune aspects of type 2 diabetes mellitus - a mini-review

Autoimmunity is a well-known pathogenic component in type 1 diabetes (T1DM). The assumption that the pathogenesis of type 2 diabetes (T2DM) also encompasses autoimmune aspects is recognized increasingly, based on the presence of circulating autoantibodies against β cells, self-reactive T cells, but also on the glucose-lowering efficacy of some immunomodulatory therapies in T2DM. The identification of these autoantibodies in elderly patients with slowly progressive manifestation of diabetes led to the introduction of a distinct clinical entity termed latent autoimmune diabetes of the adult (LADA), which combines features of both T1DM and T2DM. The autoantibody cluster differs in patients with LADA from patients with T1DM, but their presence indicates steady progression towards β-cell death and subsequent need for initiation of insulin treatment in a shorter period of time compared to autoantibody-negative T2DM patients. Autoimmune aspects in T2DM are not solely restricted to autoantibodies and thus LADA. They include the self-reactive T cells or defects in regulatory T cells (Tregs), which have been detected in autoantibody-negative T2DM patients as well. One contributor to the autoimmune activation in T2DM seems to be the chronic inflammatory state, characteristic of this disease. Upon inflammation-induced tissue destruction, cryptic 'self' antigens can trigger an autoimmune response, which in turn accelerates β-cell death. Both innate and adaptive immune system components, specifically macrophages and self-reactive T cells, contribute to an increased secretion of inflammatory cytokines involved in inflammatory and autoimmune processes. However, the extent to which inflammation overlaps with autoimmunity is not known. Our review focuses on autoimmune involvement in T2DM, with an emphasis on LADA and the humoral immune response, on the involvement of chronic inflammation in autoimmunity, and specifically the role of B and T cells as links between inflammatory and autoimmune reactions. We will further stress the consequences of autoimmune activation for T2DM patients and present novel therapeutic approaches for T2DM management that rely on immune modulation.

Diabetes and beta cell function: from mechanisms to evaluation and clinical implications

Diabetes is a complex, heterogeneous condition that has beta cell dysfunction at its core. Many factors (e.g. hyperglycemia/glucotoxicity, lipotoxicity, autoimmunity, inflammation, adipokines, islet amyloid, incretins and insulin resistance) influence the function of pancreatic beta cells. Chronic hyperglycaemia may result in detrimental effects on insulin synthesis/secretion, cell survival and insulin sensitivity through multiple mechanisms: gradual loss of insulin gene expression and other beta-cell specific genes; chronic endoplasmic reticulum stress and oxidative stress; changes in mitochondrial number, morphology and function; disruption in calcium homeostasis. In the presence of hyperglycaemia, prolonged exposure to increased free fatty acids result in accumulation of toxic metabolites in the cells (“lipotoxicity”), finally causing decreased insulin gene expression and impairment of insulin secretion. The rest of the factors/mechanisms which impact on the course of the disease are also discusses in detail.

The correct assessment of beta cell function requires a concomitant quantification of insulin secretion and insulin sensitivity, because the two variables are closely interrelated. In order to better understand the fundamental pathogenetic mechanisms that contribute to disease development in a certain individual with diabetes, additional markers could be used, apart from those that evaluate beta cell function.

The aim of the paper was to overview the relevant mechanisms/factors that influence beta cell function and to discuss the available methods of its assessment. In addition, clinical considerations are made regarding the therapeutical options that have potential protective effects on beta cell function/mass by targeting various underlying factors and mechanisms with a role in disease progression.

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.

Heterogeneity among patients with latent autoimmune diabetes in adults

BACKGROUND

Some type 1 diabetic patients do not require insulin at diagnosis of diabetes, and they progress to insulin dependence only after several years (latent autoimmune diabetes in adults). However, not all patients with latent autoimmune diabetes in adults progress to insulin dependence. We compared the characteristics of patients with high glutamic acid decarboxylase antibodies (GADA) titres (≥10 U/mL) to those of patients with low titres and examined other factors possibly associated with the progression to insulin dependence.

METHODS

We began registering diabetic patients in 1993 and have since followed them prospectively. Among these patients, we analysed clinical characteristics and progression to insulin dependence in those followed for more than 5 years.

RESULTS

Patients with high GADA titres were younger and had lower body mass index, shorter disease durations and lower serum C-peptide (s-CPR) levels than the patients with low GADA titre and GADA negative type 2 diabetes. Frequencies of other islet-related autoantibodies were significantly higher in patients with high GADA titre than in those with low GADA titres. Disease protective HLA class II genotypes were less frequent in patients with high titre. The positive predictive value of being GADA positive was only 42.7%. The positive predictive value increased to 78.6% when the cut-off was set at the relatively high level of 10 U/mL. Combining GADA with other islet-related autoantibodies or HLA class II genotype increased positive predictive value but decreased sensitivity.

CONCLUSIONS

Our results suggest that latent autoimmune diabetes in adults constitutes a heterogeneous group and that the majority of patients with high GADA titres (≥10 U/mL) will ultimately develop type 1 diabetes while those with low titres include patients with type 1 and type 2 diabetes.

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.

Diabetes related autoimmunity in gestational diabetes mellitus: is it important?

Some GDM women show autoantibody positivity during and after pregnancy and pancreatic autoantibodies can appear for the first time in some patients after delivery. Autoantibody positivity is often accompanied by a high frequency of DR3 and DR4 alleles, which are classically related to the development of type 1 diabetes and, although not all studies agree on this point, by an immunological imbalance expressed by the behaviour of the lymphocyte subpopulation, which can be seen as diabetic anomalies overlapping with the immunological changes that occur during pregnancy. It is worth emphasizing that such patients may develop classical type 1 diabetes during and/or after their pregnancy or they may evolve, often some years after their pregnancy, into cases of latent autoimmune diabetes of adulthood (LADA). Autoimmune GDM accounts for a relatively small number of cases (about 10% of all GDM) but the risk of these women developing type 1 diabetes or LADA is very high, so these patients must be identified in order to prevent the severe maternal and fetal complications of type 1 diabetes developing in pregnancy, or its acute onset afterwards. Since women with autoimmune GDM must be considered at high risk of developing type 1 diabetes in any of its clinical forms, these women should be regarded as future candidates for the immunomodulatory strategies used in type 1 diabetes.

Heterogeneity of patients with latent autoimmune diabetes in adults: linkage to autoimmunity is apparent only in those with perceived need for insulin treatment: results from the Nord-Trøndelag Health (HUNT) study

OBJECTIVE

Subjects with the diagnosis of latent autoimmune diabetes in adults (LADA) are more prone to need insulin treatment than those with type 2 diabetes. However, not all patients with LADA develop the need for insulin treatment, indicating the heterogeneity of LADA. We investigated this heterogeneity by comparing phenotypes of LADA with and without perceived need for insulin treatment (data obtained at times when diagnosis of LADA was not investigated) and also compared LADA and type 2 diabetes phenotypes.

RESEARCH DESIGN AND METHODS

We used data from the all population-based Nord-Trøndelag Health study (n = 64,931), performed in 1995-1997. Data were assembled for individuals with LADA (n = 106) and type 2 diabetes (n = 943).

RESULTS

In the comparison of individuals with LADA both with and without the need for insulin, insulin-treated subjects had higher titers of GAD antibodies (P < 0.001) and lower fasting C-peptide levels (P < 0.001). GAD antibodies and C-peptide correlated negatively (r = -0.40; P = 0.009). In the comparison of individuals with LADA and type 2 diabetes, all without the need for insulin, markers of metabolic syndrome were equally prevalent and pronounced. Age, C-peptide, and glucose levels were also similar. In the comparison of insulin-treated individuals with LADA and type 2 diabetes, more patients with LADA received insulin (40 vs. 22%, P < 0.001) and C-peptide levels were lower (P < 0.001). Patients with LADA were leaner but were still overweight (mean BMI 28.7 vs. 30.9 kg/m2 in type 2 diabetes, P < 0.001). In the comparison of type 2 diabetic patients with and without insulin, insulin-treated subjects were more obese and had higher A1C and lower C-peptide levels (P < 0.001).

CONCLUSIONS

Our conclusions are that 1) the need for insulin treatment in LADA is linked to the degree of autoimmunity and beta-cell failure, 2) subjects with LADA and type 2 diabetes without the need for insulin treatment are phenotypically similar, and 3) insulin treatment in type 2 diabetic patients is associated with both insulin resistance and beta-cell insufficiency.

Easily obtainable clinical features increase the diagnostic accuracy for latent autoimmune diabetes in adults: an evidence-based report

BACKGROUND

Latent autoimmune diabetes in adults (LADA) represents a subgroup of diabetes mellitus. LADA is characterised by adult-onset diabetes and circulating autoimmune antibodies. LADA patients may need a different therapeutic approach than the usual type 2 diabetes mellitus. When LADA is inadequately diagnosed as type 2 diabetes mellitus, LADA patients will mistakenly be exposed to a high dose of oral glucose lowering drugs and their possible side effects.

AIM

To assess which clinical features predict the presence or absence of LADA in patients older than 25 years presenting with hyperglycemia.

METHODS

A structured Medline and Embase search was conducted. Titles and abstracts were screened using predetermined selection criteria. Critical appraisal was based on standardized validity criteria for diagnostic research.

RESULTS

One-hundred and eighty-four papers were retrieved of which after assessment of relevance and validity 2 studies remained for further analysis. One study reported a probability of LADA of 0.99 with one or two out of the following five clinical features: age at onset <50 years; acute symptoms; BMI<25 kg/m(2); a history of autoimmune disease; a family history positive for diabetes mellitus. The other study reported a probability of LADA of zero with none of the following clinical features and of 0.32 with one out of three: fasting blood glucose> or =15 mmol/l and/or HbA(1c)> or =10%; 10% reduction in body weight in the previous 3 months; BMI<25 kg/m(2).

CONCLUSION

Further testing for LADA by measurement of autoimmune antibodies appears to be unnecessary in the absence of a specific set of clinical features. Before initiating therapy applying the above criteria may help to separate LADA from usual type 2 diabetes.

Incidence of type 1 and type 2 diabetes in adults and children in Kronoberg, Sweden

All newly diagnosed diabetes in Kronoberg during 3 years was registered, with blood samples from 1630/1666 (97.8%) adults. Those positive for GADab and/or ICA and/or C-peptide<0.25nmol/L (0.7%) were classified as type 1 diabetes, the remaining as type 2. Incidence of type 1 in 0-19-year-olds was 37.8(36.1-39.6, 95%CI) and in 20-100 year-olds 27.1(25.6-27.4) per 100 000 and year, it was bimodal with equal peaks in 0-9 year-olds and in 50-80-year-olds. Adults had type 2 incidence 378 (375-380), children 3.1 (2.6-3.6). Among adults 6.9% had type 1 and 93.1% type 2. Among antibodypositive adults (n=101), GADab were present in 90%, ICA in 71%, both GADab and ICA in 61%. Ophthalmology contact as second source was confirmed for 98%. There were no gender differences in type 1 in any age group, small ones in pediatric subgroups. In type 2 men predominated in ages above 40 years. Incidences of type 1 diabetes in both children and adults were very high and as high above age 50 years as in children. Incidence of type 2 was the highest reported from Sweden, to which new diagnostic criteria, a high degree of case-finding, and many elders, may have contributed, but results may also reflect a true increase in incidence of both types of diabetes.

In vivo and in vitro studies of GAD-antibody positive subjects with Type 2 diabetes: A distinct sub-phenotype

The purpose of this study was to determine if immune mechanisms in GAD positive patients' contribute to the pathogenesis of a specific sub-type of Type 2 diabetes. GAD positive (n=8) and GAD negative (n=8) subjects diagnosed with Type 2 diabetes were matched for age, gender, body mass index, duration of diabetes and glycaemic control. All subjects underwent an insulin-modified frequently sampled intravenous glucose tolerance test to measure insulin sensitivity and insulin secretory function with minimal model analysis. In addition, BRIN-BD11 clonal beta-cells were supplemented with patients' sera to determine basal and alanine-stimulated insulin secretion and terminal complement complex (TCC) formation. Both groups were severely insulin resistant (0.56+/-0.17 vs. 0.99+/-0.3310(-4)min(-1)/(microUml(-1)) for GADneg and GADpos, respectively) but the GAD negative subjects had a higher basal (87+/-11 vs. 58+/-14pmoll(-1), p<0.05) and glucose-stimulated insulin secretion (DeltaAUCins 0.96+/-0.12 vs. 0.60+/-0.12pmol/(l(-1)min), p<0.05). In vivo measures of insulin secretion were negatively correlated with TCC formation, independent of antibody status. In conclusion, GAD positive subjects initially diagnosed with Type 2 diabetes are unable to compensate for insulin resistance due to more pronounced beta-cell impairment. TCC formation may be partly responsible for the insulin secretory dysfunction associated with this specific sub-type of Type 2 diabetes.

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

Latent autoimmune diabetes in the adult (LADA) is a slowly progressive form of autoimmune diabetes, characterized by diabetes-associated autoantibody positivity. A recent hypothesis proposes that LADA consists of a heterogeneous population, wherein several subgroups can be identified based on their autoimmune status. A systematic review of the literature was carried out to appraise whether the clinical characteristics of LADA patients correlate with the titre and numbers of diabetes-associated autoantibodies. We found that the simultaneous presence of multiple autoantibodies and/or a high-titre anti-glutamic acid decarboxylase (GAD)--compared with single and low-titre autoantibody--is associated with an early age of onset, low fasting C-peptide values as a marker of reduced pancreatic B-cell function, a high predictive value for future insulin requirement, the presence of other autoimmune disorders, a low prevalence of markers of the metabolic syndrome including high body mass index, hypertension and dyslipidaemia, and a high prevalence of the genotype known to increase the risk of Type 1 diabetes. We propose a more continuous classification of diabetes mellitus, based on the finding that the clinical characteristics gradually change from classic Type 1 diabetes to LADA and finally to Type 2 diabetes. Future studies should focus on determining optimal cut-off points of anti-GAD for differentiating clinically relevant diabetes mellitus subgroups.

High titer of autoantibodies to GAD identifies a specific phenotype of adult-onset autoimmune diabetes

OBJECTIVE

The aim of the present study was to define heterogeneity of adult-onset autoimmune diabetes based on characterization of GAD antibodies (GADAs).

RESEARCH DESIGN AND METHODS

Patients enrolled in a nationwide survey, the Non Insulin Requiring Autoimmune Diabetes (NIRAD) Study, have been screened for GADAs and IA-2 antibodies (IA-2As) and further characterized for GADA titer, antibodies to thyroid peroxidase (TPO), and HLA DRB1-DQB1 polymorphisms.

RESULTS

Of 4,250 consecutive type 2 diabetic patients, 4.5% had either GADAs and/or IA-2As. Patients with autoimmune diabetes showed a clinical phenotype significantly different from that of type 2 diabetes, including higher fasting glucose and A1C, lower BMI and uric acid, lower prevalence of metabolic syndrome and its components, and higher frequency of TPO antibodies. More interestingly, analysis of GADA titers showed a bimodal distribution that identified two subgroups of patients with high (>32 GADA arbitrary units) and low (< or =32 GADA arbitrary units) GADA titers. Compared with those with low GADA titers, patients with high GADA titers had more prominent traits of insulin deficiency and a profile of more severe autoimmunity resulting in higher A1C, lower BMI, a lower prevalence of metabolic syndrome and its components (P < 0.02 for all), a higher prevalence of IA-2As, TPO antibodies (P < 0.003 for both), and DRB1*03-DQB1*0201 (50 vs. 26.8%, P = 0.001), and a decreasing frequency of DQB1*0602 and DRB1*0403 (from type 2 to low and to high GADA titer autoimmune diabetes; P < 0.001 for trend for both comparisons).

CONCLUSIONS

GADA titers identify two subgroups of patients with adult-onset autoimmune diabetes having distinct clinical, autoimmune, and genetic features.

New insights into the pathophysiology of gestational diabetes mellitus: possible role of human leukocyte antigen-G

Diabetes can develop in up to 10% of pregnant women who have not previously had the condition. This condition which usually begins in the second half of the pregnancy is called gestational diabetes mellitus (GDM). In most cases, all diabetic symptoms disappear following delivery. However, women with GDM have an increased risk of developing type 2 diabetes mellitus (DM) later in life, especially if they were overweight before the pregnancy. The cause of GDM is unknown. Although hormones present in the pregnancy, especially human placental lactogen, are thought to be responsible for the development of this condition, many questions remain to be answered. It is still not known why GDM develops in a subgroup of pregnant women. It may be possible that events leading to the development of GDM are triggered by an antigenic load which is the fetus itself. Human leukocyte antigen-G (HLA-G) expression that functions to protect the fetus from immune attack by down-regulating cytotoxic T cell responses to fetal trophoblast antigens is postulated to protect the islet cells of the pancreatic tissue also. HLA-G and nuclear factor-kappaB (NF-kappaB) interaction is suggested to be central in the events leading to GDM development. An analogy between the development of DM in some transplant patients and GDM development in a proportion of pregnancies is postulated, so that an antigenic load triggers the diabetogenic process. Further support of this hypothesis with new studies may lead to the possibility that recombinant HLA-G can be used for the prevention of diabetes in high risk patients.

Islet antibodies associated with pancreatic B-cell dysfunction at and 3 years after diagnosis of diabetes in subjects aged 35-64 years old: degree of impairment less severe than in those aged 0-34 years old

AIMS

To determine differences in pancreatic B-cell function in relation to islet antibodies at diagnosis of diabetes and 3 years later in subjects aged 35-64 years old compared with those aged 0-34 years.

METHODS

From a population-based diabetes register, 46 (0-34 years old) and 323 (35-64 years old) incident diabetic patients were investigated at diagnosis and 3 years later. Islet cell antibodies (ICA, GADA and IA-2A) and fasting plasma C-peptide were measured.

RESULTS

Islet antibodies were found in 80% of the subjects aged 0-34 years and in 11% of those aged 35-64 years at diagnosis. ICA and GADA was the only combination of two islet antibodies detected in those aged 35-64 years and was, with or without IA-2A, associated with significantly lower median fasting C-peptide values than in those without or with only one antibody [0.35 nmol/l, interquartile range (IQR) 0.63 vs. 0.85 nmol/l, IQR 0.49; P = 0.0004]. However, fasting C-peptide in subjects aged 35-64 years old with multiple islet antibodies was higher than in those aged 0-34 years with islet antibodies (median 0 nmol/l, IQR 0.16, P = 0.0019). After 3 years' follow-up, fasting C-peptide was even lower in subjects aged 35-64 years old with three islet antibodies (median 0.14 nmol/l, IQR 0.27; P = 0.05).

CONCLUSIONS

Islet antibodies were common in adults at diagnosis of diabetes. The combination of ICA and GADA indicates impaired B-cell function at diagnosis of diabetes in those aged 35-64 years old.