The low prevalence of immunogenetic markers in Korean adult-onset IDDM patients

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.

Recent information on test utilization and intraindividual change in anti-glutamic acid decarboxylase antibody in Korea: a retrospective study

INTRODUCTION

This study aimed to evaluate the test utilization and intraindividual changes of anti-glutamic acid decarboxylase antibody (GADA), a biomarker for autoimmune diabetes in Korean adults.

RESEARCH DESIGN AND METHODS

We retrospectively investigated longitudinally measured GADA test results to assess test utilization and intraindividual changes through a laboratory information system.

RESULTS

During the 3-year study period, 11 668 GADA tests were performed in 11 184 Korean adults. The overall rate of GADA positivity at initial measurement was 7.8%. Among the 11 668 test results, 871 GADA test results from 401 Korean patients (228 men and 173 women) requested by 54 hospitals were analyzed for intraindividual changes. Among these 401 patients, 80 (20.0%) had positive (≥2.0 U/mL) and 35 (8.7%) had gray zone GADA (1.0-1.9 U/mL) level at initial measurement. The prevalence of GADA-positive patients based on initial measurement was significantly different by type of medical institution. Among 80 patients with initial positive results, 5 (6.3%) experienced qualitative GADA changes during follow-up. Among the 321 patients with initially negative or gray zone GADA, 9 (2.8%) changed to GADA positive at least once during follow-up.

CONCLUSIONS

Although most patients had stable GADA results, some exhibited qualitative changes during follow-up. This study can help to understand the variation in GADA positivity in the monitored patients.

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.

Clinical heterogeneity of type 1 diabetes (T1D) found in Asia

Diabetes mellitus among young patients in Asia is caused by a complex set of factors. Although type 1 diabetes (T1D) remains the most common form of diabetes in children, the recent unabated increase in obesity has resulted in the emergence of type 2 diabetes (T2D) as a new type of diabetes among adolescents and young adults. In addition to the typical autoimmune type 1 diabetes (T1aD) and T2D patients, there is a variable incidence of cases of non-autoimmune types of T1D associated with insulin deficiency (T1bD). Additional forms have been described, including fulminant T1D (FT1D). Although most diagnoses of T1D are classified as T1aD, fulminant T1D exists as a hyper-acute subtype of T1D that affects older children, without associated autoimmunity. Patient with this rare aetiology of diabetes showed a complete loss of β-cell secretory capacity without evidence of recovery, necessitating long-term treatment with insulin. In addition, latent autoimmune diabetes in adults is a form of autoimmune-mediated diabetes, usually diagnosed during the insulin-dependent stage that follows a non-insulin requiring phase, which can be diagnosed earlier based on anti-islet autoantibody positivity. Some reports discuss T1bD. Others are elaborating on the presence of "atypical T1b diabetes," such as Flatbush diabetes. The prevalence of diabetes mellitus in young adults continues to rise in Asian populations as T2D increases. With improved characterization of patients with diabetes, the range of diabetic subgroups will become even more diverse in the future. Distinguishing T1D, T2D, and other forms of diabetes in young patients is challenging in Asian populations, as the correct diagnosis is clinically important and has implications for prognosis and management. Despite aetiological heterogeneity in the usual clinical setting, early diagnosis and classification of patients with diabetes relying on clinical grounds as well as measuring islet autoantibodies and fasting plasma C-peptide could provide a possible viable method to minimize complications.

The effect of glargine versus glimepiride on pancreatic β-cell function in patients with type 2 diabetes uncontrolled on metformin monotherapy: open-label, randomized, controlled study

The aim of present study is to assess whether if basal insulin, glargine, could improve insulin secretory function of β-cells compared with glimepiride when metformin alone was failed. This was an open-label and multi-center study for 52 weeks in Korean patients with uncontrolled type 2 diabetes by metformin monotherapy. Subjects were randomized to glargine or glimepiride groups (n = 38 vs. 36, respectively). The primary endpoint was to compare changes in c-peptide via glucagon test after 48 weeks. Glycemic efficacy and safety endpoints (glycated hemoglobin (HbA1c), HOMA-B, fasting plasma glucose (FPG), lipid profiles, and hypoglycemic events) were also checked. The mean disease duration of all subjects was 88.2 months. Changes in C-peptide was no significant different between groups (P = 0.73), even though insulin secretion was not worsened in both groups at the endpoint. Glargine was not superior to glimepiride in other β-cell function indexes such as HOMA-B (P = 0.28). HbA1c and FPG reduced significantly in each groups but not different between two groups. Although, severe hypoglycemia did not occur, symptomatic hypoglycemia was more frequent in glimepiride group (P = 0.01). Insulin glargine was as effective as glimepiride in controlling hyperglycemia and maintaining β-cell function in Korean patients with type 2 diabetes during 48 weeks study period, after failure of metformin monotherapy. Hypoglycemic profile was favorable in the insulin glargine group and less weight gain was observed in the glimepiride group. Our results suggest that glargine and glimepiride can be considered after failure of metformin monotherapy.

What are the characteristics of phenotypic type 2 diabetic patients with low-titer GAD65 antibodies?

Type 2 diabetes results from combined insulin resistance and β-cell deficiency. Type 1 diabetes results from β-cell destruction associated with islet autoantibodies, including those directed against glutamate decarboxylase (GAD65 antibodies [GADA]). Clinical impact of low GADA positivity (<60 U/ml) in type 2 diabetes is debated, being rarely performed in routine care. The aim of our study was to determine the prevalence and cardiometabolic/autoimmune phenotype of GADA[+] patients. 524 type 2 diabetes consecutive outpatients were assessed for glucose homeostasis using homeostasis model assessment (HOMA): insulin sensitivity (HOMA S); β-cell function (HOMA B) and annualized loss in [BXS]. GADA prevalence was 6% (n = 30). There were no differences between groups for age, diabetes duration and family history of diabetes. There were proportionately more women (33 vs. 53%) in GADA[+]. There were no differences in body mass index, waist circumference or visceral fat. HOMA S was lower than normal, with no difference between groups, as was HOMA B. Annualized rate of [BXS] loss was 1.26%/year (GADA[+]) versus 1.34%/year (GADA[-]; NS). HbA1c was 7.8% (GADA[+]) versus 7.6% (GADA[-]; NS). Among all patients, prevalence of autoimmune thyroid disease was 10%. In GADA[+], this prevalence was significantly increased and equally affected both sexes: 29% (men) versus 25% (women), while for GADA[-] the prevalence was 5% (men) versus 18% (women; p < 0.0001). Low-titer GADA autoimmunity among type 2 diabetes patients was not associated with accelerated β-cell function, nor with any distinctive cardiometabolic phenotype, but for a markedly increased prevalence of autoimmune thyroid disease, especially among men.

The prevalence and characteristics of latent autoimmune diabetes in adults (LADA) and its relation with chronic complications in a clinical department of a university hospital in Korea

Few studies were performed to evaluate the prevalence of latent autoimmune diabetes in adults (LADA) and the difference of chronic complications between LADA, T1DM, and T2DM in Korean. The aim of this study is to establish the prevalence of LADA in a diabetic clinic of Soonchunhyang University hospital and to compare the phenotypic characteristics according to DM classification based on positivity of glutamic acid decarboxylase antibodies (GADA). Also, another important point concerns the occurrence of diabetes chronic microvascular complications in LADA. 323 patients who were checked GADA among diabetic patients admitted at Soonchunhyang University hospital were recruited. Twenty-eight patients (8.7%) were identified as positive for GADA. 11.5% (n = 37) were diagnosed with T1DM and 5.3% (n = 17) were diagnosed with LADA. GADA titer showed significant negative correlation with age of onset, total cholesterol (TC), triglyceride (TG), fasting C-peptide, stimulated C-peptide, BMI, and positive correlation with HbA1C and HDL-C. Compared with those that tested negative for GADA, patients with GADA positive had lower values of onset age, BMI, TC, TG, LDL-C, fasting, and stimulated C-peptide levels and higher values of HbA1C. A significant gradual increase of values was observed for the onset age, BMI, SBP, DBP, fasting, and stimulated C-peptide across the T1DM, LADA, and T2DM subgroups. Concerning the chronic complications there was no difference in prevalence of retinopathy, neuropathy and nephropathy between three groups. Of LADA patients, 12 patients were receiving insulin treatment and mean time to insulin initiation was about 37 months. In conclusion, because our study suggests LADA subgroups in Korea appear to have a faster decline in C-peptide levels, it is worth detecting the patients with LADA early and effort to preserve beta cell function. Furthermore, our results showed that the prevalence of microvascular complication was comparable between the subgroups.

Type 2 diabetes in East Asians: similarities and differences with populations in Europe and the United States

There is an epidemic of diabetes in Asia. Type 2 diabetes develops in East Asian patients at a lower mean body mass index (BMI) compared with those of European descent. At any given BMI, East Asians have a greater amount of body fat and a tendency to visceral adiposity. In Asian patients, diabetes develops at a younger age and is characterized by early β cell dysfunction in the setting of insulin resistance, with many requiring early insulin treatment. The increasing proportion of young-onset and childhood type 2 diabetes is posing a particular threat, with these patients being at increased risk of developing diabetic complications. East Asian patients with type 2 diabetes have a higher risk of developing renal complications than Europeans and, with regard to cardiovascular complications, a predisposition for developing strokes. In addition to cardiovascular-renal disease, cancer is emerging as the other main cause of mortality. While more research is needed to explain these interethnic differences, urgent and concerted actions are needed to raise awareness, facilitate early diagnosis, and encourage preventive strategies to combat these growing disease burdens.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

LADA prevalence estimation and insulin dependency during follow-up

BACKGROUND

Latent autoimmune diabetes in adults (LADA) is a form of autoimmune-mediated diabetes in adults, usually defined by GAD autoantibody positivity. Few epidemiological surveys on LADA in Asians did not come to a conclusive answer regarding prevalence and incidence, because of different criteria used in patient ascertainment.

METHODS

We estimated LADA prevalence in a recent type 2 diabetes cohort by the positivity of circulating autoantibodies to pancreatic islet cell antigens (GAD, IA-2 and zinc transporter 8 (ZnT8)) applying a comparable Caucasian criteria. We then observed the development of insulin dependency prospectively for 36 months.

RESULTS

Applying the European NIRAD LADA group criteria, we found a high prevalence of LADA (4.4%) in Korean patients with phenotypic type 2 diabetes. This high prevalence of LADA in Korea is noteworthy since the previous population-based LADA prevalence survey reported low prevalence (1.7%). When we consider the low-titre GAD antibodies and the low prevalence of multiple autoantibodies, however, increased LADA prevalence does not necessarily mean increase in future insulin dependency. After 36 months of follow-up, only 3 of 39 patients who were initially classified as LADA have become insulin-dependent. Those three were all positive for multiple autoantibodies (GAD, IA-2 and zinc transporter 8 antibody). Other features of insulin secretion or insulin resistance did not determine future insulin necessity.

CONCLUSIONS

Although the LADA prevalence estimated by anti-GAD positivity appeared to increase, the true insulin dependency evidenced by multiple antibody positivity did not increase in Korea.

Autoantibodies against aminoacyl-tRNA synthetase: novel diagnostic marker for type 1 diabetes mellitus

OBJECTIVES

To investigate whether or not antiaminoacyl-tRNA synthetase (aaRS) autoantibodies could be detected in patients with type 1 diabetes mellitus (DM) and be used as a diagnostic marker for type 1 DM, autoantibodies against aaRSs were measured in the plasma of normal subjects, patients with type 1 DM and patients with type 2 DM.

METHODS

An enzyme-linked immunosorbent assay was performed to detect anti-aaRS autoantibodies in the plasma of normal subjects, and patients with type 1 DM, and patients with type 2 DM.

RESULTS

From the 65 (normal), 58 (type 1 DM) and 57 (type 2 DM) subjects, anti-aaRS autoantibodies were found in 37.9% of patients with type 1 DM compared with 1.54% of the non-diabetic controls, and 5.26% of the patients with type 2 DM (p <0.0001). In addition, anti-aaRS autoantibodies were identified in 30% of patients with type 1 DM without classical type 1 DM autoantibodies.

CONCLUSION

Anti-aaRS autoantibodies were identified in 37.9% of patients with type 1 DM. The results of this study demonstrate for the first time that autoantibodies against aaRSs are specifically associated with type 1 DM.

The clinical and immunogenetic characteristics of adult-onset type 1 diabetes mellitus in Korea

Although the HLA class II alleles and immunological abnormalities are associated with type 1 diabetes mellitus (T1DM) in all racial groups, there are considerable variations in the genotypes and the prevalence of autoantibodies. In order to investigate the characteristics of the immunogenetic patterns and to use these as an early diagnostic tool and guideline for a therapeutic plan, we examined the clinical characteristics and the patterns of anti-GAD antibody (GADA), IA-2 antibody (IA-2A), HLA-DR and HLA-DQ in Korean adult-onset T1DM patients. Adult-onset patients had higher serum C-peptide levels than child-onset patients. In adult-onset patients, the prevalence of GADA and IA-2A were 59.5% and 15.3% respectively, and increased frequencies of HLADR4 and-DR9 were found. The frequencies of HLADQA1,-DQB1 and-DQ heterodimers were similar to those of the control, but child-onset patients had high frequencies of the HLA-DR3,-DR4,-DR9, DQA1*0301, DQA1*0501 and DQB1*0201 genotypes. In conclusion, Korean adult-onset T1DM patients had a lower prevalence of GADA, which was comparable to that found in Caucasian patients. The detection of GADA might help to predict the insulin dependency of adult-onset diabetes. Difference in the frequencies of diabetes associated with HLA type suggests that there might be a heterogeneity in the pathogenesis of diabetes according to the age of onset.

Antigenic determinants to GAD autoantibodies in patients with type 1 diabetes with and without autoimmune thyroid disease

Type 1 diabetes (T1D) is frequently associated with other autoimmune diseases. Most T1D patients' sera contain two distinct glutamic acid decarboxylase (GAD) antibody specificities, of which one targets an epitope region in the middle-third of GAD65 (amino acids 221-359) and the other targets the carboxy-third of GAD65 (amino acids 453-569). Using five chimeric GAD65/GAD67 proteins to maintain conformation-dependent epitopes of GAD65, we compared the humoral repertoire of antibodies from 127 T1D patients with and without autoimmune thyroid diseases (ATD). Thirty-one patients with T1D (24%) expressed antithyroid autoantibodies ATA and 22 patients (17%) had ATD in comparison to 6% of age-matched controls having ATA. GAD65-antibody-positive patients much more often (28% versus 5%, P < 0.0004) had ATD. Of 66 GAD65-autoantibody-positive T1D patients, 34 had autoantibodies reacting with both middle and carboxy epitopes. Autoantibodies of the other 32 reacted with middle, carboxy, or other epitopes but not with both middle- and carboxy-third. Those with GAD65 autoantibodies reacting with both middle- and carboxy-third had less ATD. Of 22 (23%) patients with ATD, 5 compared to 29 of 47 (62%) T1D patients without ATD had GAD65 autoantibodies reacting with both middle- and carboxy-third (relative risk = 0.2, P < 0.01). These results indicate that there are both similarities and differences in the humoral response to GAD65 in ATD and T1D, and expression of antibodies to middle- and carboxy-third at the same time is a feature specific to T1D.

Clinical and biochemical characteristics of nonobese type 2 diabetic patients with glutamic acid decarboxylase antibody in Korea

We evaluated the prevalence of glutamic acid decarboxylase autoantibody (GADA) in nonobese patients with type 2 diabetes mellitus in Korea and investigated the characteristics of GADA-positive and GADA-negative patients. Two years later, we assessed the progression of beta-cell function in these patients. Of the 647 nonobese patients with type 2 diabetes mellitus enrolled in the study, 10.1% was positive for GADA. Glutamic acid decarboxylase antibody-positive patients had lower fasting and stimulated C-peptide levels compared with GADA-negative patients (1.70 +/- 0.72 vs 1.24 +/- 0.59 microg/L, P < .001; 2.59 +/- 1.51 vs 1.99 +/- 0.82 microg/L, P < .001). Patients treated with insulin had lower fasting and stimulated C-peptide levels than those not treated (1.13 +/- 0.52 vs 1.66 +/- 0.73 microg/L, P = .002; 1.85 +/- 0.69 vs 2.49 +/- 0.91 microg/L, P = .004) and had higher titers of GADA (30.5 +/- 7.3 vs 6.0 +/- 4.8 U/mL, P < .001). In terms of progression of beta-cell function, fasting and stimulated C-peptide levels were significantly lower in GADA-positive patients after 2 years (from 1.24 +/- 0.59 to 0.95 +/- 0.54 microg/L, P = .004; from 1.99 +/- 0.82 to 1.61 +/- 0.77 microg/L, P = .007), whereas no such difference was observed in the GADA-negative patients. We demonstrate that a significant proportion of Korean patients may be positive for GADA; this is consistent with studies of white subjects, although disagrees with previous reports on Korean subjects. By assessing the presence of GADA in Korean type 2 diabetic patients, we are able to predict their course of beta-cell function and identify in advance those who are likely to require insulin treatment.

Low prevalence of autoimmune diabetes markers in a mixed ethnic population of Singaporean diabetics

BACKGROUND

Circulating antibodies to glutamic acid decarboxylase (GADab) and tyrosine phosphatase-like molecule IA-2 (IA-2ab) are major indicators for auto-immune destruction of pancreatic islet cells. They identify a majority of Caucasians with type 1 diabetes and approximately 50% of Asians, providing evidence of an idiopathic aetiology in the latter. The present study investigated these autoantibodies in a mixed ethnic group.

METHODS

Hospital clinic patients with clinically defined type 1 (n = 93) and type 2 (n = 300) diabetes and representing Singapore's major ethnic groups--Chinese, Indians and Malays--were studied. GADab and IA-2ab frequencies, and association of autoimmunity status with clinical and biochemical profiles were analysed.

RESULTS

Radio-immunoprecipitation assays detected either or both antibodies (seropositivity) in 41.9% of subjects with type 1 diabetes. GADab was detected in 36.6% and IA-2ab in 23.7% of type 1 diabetics. Prevalence of IA-2ab showed a reduction in frequency with disease duration (P = 0.026). In clinical type 2 diabetics, seropositivity was 10.0% with higher frequency in Malays (17.5%) than Chinese (9.7%) and Indians (4.5%). Multivariate analysis revealed that low fasting C-peptide was associated with seropositivity (odds ratio (OR) = 0.15; 95% confidence interval (CI) = 0.04-0.58). A significant relationship (OR = 13.5; 95% CI = 5.0-36.7) between insulin requirement and duration (>5 years) was also revealed. In patients with type 2 diabetes there was a trend of gradual progression to insulin dependency. However, there was considerable variation in body mass index between ethnic subgroups of type 2 diabetics, particularly for Chinese (mean (SD) = 26.0 (4.7)) and Malays (mean (SD) = 29.2 (5.9); P < 0.001).

CONCLUSIONS

Presence of both antibodies in our mixed ethnic group of type 1 diabetes patients was much lower than in Caucasians. Significant numbers of patients were seronegative for antibodies. Influences due to ethnicity and adiposity would require further investigations.

SOX13 autoantibodies are likely to be a supplementary marker for type 1 diabetes in Korea

The SOX13, one of the family of transcription factors that play key roles in organ development, is reported to be a diabetes autoantigen, islet cell antigen 12 (ICA12). Recently, a study of antibodies to SOX13 was conducted in patients with type 1 diabetes mellitus (T1DM) indicating that these antibodies potentially identified patients without antibodies to the major T1DM-associated autoantigens, insulin, GAD, or IA-2. We know that the prevalence of islet-specific autoantibodies (GAD, IA-2) in Korean patients is much lower than that in white patients. It may be possible that other autoantibodies that could be directed to as yet unknown antigen may play a role in Korean T1DM patients. To investigate this, we measured SOX13 autoantibodies applying a radioligand binding assay using in vitro transcribed and translated antigen in 188 T1DM patients (mean duration, 4.2 years) and 64 T2DM patients and compared the results with those of 101 healthy control subjects. SOX13 autoantibodies occurred at a significantly higher frequency among T1DM patients (55/188, 29.3%) than among T2DM patients (4/64, 6.2%) or healthy adult controls (1/101, 1%). The 55 patients with positive SOX13 antibodies had significantly shorter duration of diabetes than SOX13 antibody-negative patients (3.6 +/- 2.8 vs. 4.5 +/- 3.9 years; p < 0.05). We could detect a prevalence similar to control in patients with Hashimoto's thyroiditis (4.9%, n = 101) and rheumatoid arthritis (6.7%, n = 89). As a whole, 44 of the 55 patients with SOX13 antibodies had at least one or more other autoantibodies to the major T1DM-associated autoantigens. However, SOX13 antibodies were the only antibodies detected as positive in 1 of the 11 new-onset patients. We conclude, therefore, that these antibodies are likely to be one of several epitope-spreading responses to islet- or nonislet-specific autoantigens seen in the development of T1DM, and they may be used as a supplementary marker for investigating T1DM in Korea.

Current knowledge of Japanese type 1 diabetic syndrome

The Japanese have one of the lowest incidence of childhood type 1 diabetes in the world, but the incidence of this disease is clearly increasing within the Japanese population, as reported in several European countries. Latent autoimmune diabetes mellitus in adult (LADA) patients are also likely to have a lower incidence compared to Caucasians. Among the non-autoimmune (type 1B) diabetes in Japanese adults, there exists a novel subtype of type 1 diabetes characterized by extremely rapid onset and pancreatic exocrine inflammation. HLA and non-HLA gene associations to type 1 diabetes may vary depending on ethnic origin. Highly susceptible HLA haplotypes of type 1 diabetes observed in Caucasian patients are not found in Japanese patients, while protective HLA haplotypes are similar. Association studies of non-HLA genes have identified several candidate genes that influence the heterogeneity of disease phenotypes as well as disease susceptibility to type 1 diabetes. The INS-VNTR gene or polymorphisms of MICA gene are associated with susceptibility, whereas a certain allele of MICA gene and IL-10 gene polymorphism are associated with clinical heterogeneity of the disease. An expression of multiple autoantibodies to a biochemically determined autoantigen confers a high risk for progression to type 1 diabetes. The combined evaluation of multiple autoantibodies is more sensitive than is ICA testing for the diagnosis of type 1 diabetes. A high titer of GAD autoantibody has the predictive value of future insulin deficiency in patients with LADA. For accurate predictive strategies of future insulin deficiency, combinational multiple autoantibodies analysis or genetic determination should be considered for effective immune intervention.

GAD65 antibody prevalence and association with thyroid antibodies, HLA-DR in Chinese children with type 1 diabetes mellitus

Persistent humoral autoimmunity to the enzyme glutamic acid decarboxylase (GAD) has been described in a substantial proportion of patients with type 1 diabetes mellitus. Higher prevalence of GAD antibody in diabetes patients using a new radioligand-binding assay with recombinant human GAD65 antibodies (GAD65Ab) has been seen in several studies. Using this method, we have reassessed the prevalence of GAD65Ab and investigated the association of GAD65Ab with HbA1C values, C-peptide values, HLA-DR typing and thyroid autoimmune antibody in 70 Chinese children with type 1 diabetes mellitus (mean age of onset 8.21+/-3.84 years, mean duration 3.39+/-2.54 years). Our result revealed that GAD65 antibodies were present in 54.3% (38/70) of diabetes children. There was no significant difference in gender, diabetes onset and duration, HbA1c, C-peptide concentration and frequencies of HLA DR3, DR4, DR9, DR3/DR4, DR3/DR9 and DR4/DR9 genotypes between GAD65Ab+ and GAD65Ab- groups. There was no negative correlation between GAD65Ab values and duration of diabetes in those with GAD65Ab positivity (r=-0.239, P>0.05). The frequencies of antimicrosomal and anti-thyroglobulin antibodies in GAD65Ab+ (13.5,8.1%, respectively) were not different from GAD65- patients (9.4,12.5%, respectively).

HLA typing and immunological characterization of young-onset diabetes mellitus in a Hong Kong Chinese population

AIMS

A study of the Hong Kong Chinese showed that the majority of subjects with young-onset diabetes (age of diagnosis < 35 years) present with a phenotype suggestive of Type 2 diabetes mellitus, although up to 50% subsequently need insulin treatment. The aim of this study was to use a combination of clinical, genetic and immunological markers to characterize the disease phenotype further in such individuals and to determine whether the requirement for insulin is the result of autoimmune disease.

METHODS

One hundred and thirty-seven Hong Kong Chinese with young-onset diabetes were studied, irrespective of their mode of presentation. The subjects were typed for alleles of the HLA-DR and -DQ genes and investigated for the presence of autoantibodies to glutamic acid decarboxylase (GAD). Plasma C-peptide concentration and requirement for insulin were also determined.

RESULTS

One hundred and three subjects presented with a syndrome resembling Type 2 diabetes, while 34 presented with Type 1 diabetes. Of the former group, 35 patients (34.0%) were insulin-deficient, 16 (15.5%) were insulin-treated and seven (6.9%) were positive for GAD autoantibodies. Among the GAD-positive subjects presenting with Type 2 diabetes, the HLA-DRB1*03 allele may be a marker of early progression to insulin therapy.

CONCLUSIONS

Seven subjects with Type 2 diabetes at presentation had autoantibodies to GAD. Causes other than GAD autoimmunity, however, must be sought to explain the high prevalence of insulin deficiency observed in the Chinese patients. This study highlights the heterogeneity of the pathogenic processes leading to the diabetic phenotype.

MICA polymorphism is associated with type 1 diabetes in the Korean population

OBJECTIVE

Recent studies have demonstrated that MICA (major histocompatibility complex class I chain-related genes) on the short arm of the chromosome 6 are associated with susceptibility to various autoimmune diseases in Caucasians. The aim of our study was to investigate the role of MICA in type 1 diabetes susceptibility independent of the HLA DR-DQ polymorphism in genetically distinct Koreans.

RESEARCH DESIGN AND METHODS

A total of 119 patients selected from Korean Seoul type 1 diabetes registry and 134 nondiabetic unrelated control subjects were typed for exon 5 polymorphism of MICA in addition to HLA DR-DQ typing. A total of 52 simplex families of type 1 diabetes were also studied.

RESULTS

The MICA microsatellite allele consisting of six repetitions of GCT/AGC (A6) was present at a significantly lower frequency in the diabetic patient group (Pc < 0.01; Pc = P value after Bonferroni correction) than in the control population. The MICA microsatellite allele consisting of four repetitions (A4) was present at a higher frequency in diabetic patients (P < 0.05). This deviated distribution was not changed even after controlling for the HLA DRB1-DQB1 haplotype. Transmission/disequilibrium test revealed significant deviation of transmission for alleles at the A6 polymorphism within the MICA gene (P < 0.05).

CONCLUSIONS

We could assess that the MICA gene might be associated with type 1 diabetes transracially independent of the HLA gene.

Increased prevalence of autoimmune thyroid disease in patients with type 1 diabetes

BACKGROUND

Type 1 diabetes mellitus is frequently associated with other autoimmune diseases. The occurrence of common features of autoimmune diseases and the coassociation of multiple autoimmune diseases in the same individual or family supports the notion that there may be common genetic factors.

METHODS

To investigate potential clustering of autoimmune thyroid disease (ATD) among type 1 diabetes patients and the contribution of common susceptibility genes to this, HLA DR/DQ alleles as well as antithyroid autoantibodies were measured in 115 Korean patients with type 1 diabetes and their 96 first-degree family members.

RESULTS

Twenty-five percent of the patients had ATD, whereas 3 of 36 (8%) age-matched normal controls had ATD (RR = 3.7, p < 0.05). Twenty-six of ninty-six (27%) type 1 diabetes family members had ATD. No differences in the distribution of HLA alleles/haplotypes and genotypes between the patients with and without ATD were found.

CONCLUSION

From this finding, we could assess that individuals with type 1 diabetes and their relatives frequently develop ATD, perhaps due to common susceptibility genes that are shared among first degree relatives.

Autoantibodies to glutamic acid decarboxylase in diabetic patients from a multi-ethnic Australian community: the Fremantle Diabetes Study

AIMS

To investigate ethnic/racial differences in the prevalence of serum antibodies to glutamic acid decarboxylase (GADA) and ICA512/IA-2 in diabetic patients from a large, urban community.

METHODS

A cross-sectional sample of 1,381 diabetic patients aged 11-98 years, representing 61% of those identified in a postcode-defined population base of 120,097 people were studied. Diabetes was classified on clinical grounds. Serum GADA and anti-ICA512/IA-2 were measured by radioimmunoprecipitation assay.

RESULTS

Anglo-Celts formed 62% of the sample, southern Europeans 18%, other Europeans 8% and Asians 3%. GADA prevalence in Type 1 and Type 2 diabetes mellitus was 46.0% and 4.2%, respectively, amongst Anglo-Celts and 22.2% and 1.7% in southern Europeans. The prevalence of anti-ICA512/IA-2 in Type 1 diabetes was 17.4% and, in a sample of 233 patients with Type 2 diabetes, 0.8%. GADA-positive Type 2 patients had a lower body mass index and greater glycosylated haemoglobin, and were more likely to be taking insulin, than GADA-negative Type 2 diabetic subjects (P < 0.05), consistent with the phentoype of latent autoimmune diabetes of adults (LADA). In both Type 1 and Type 2 diabetes, there was a strong inverse association between GADA and serum triglycerides (P < 0.001).

CONCLUSIONS

The relatively low GADA prevalence in Anglo-Celt patients with Type 1 diabetes is a feature of this community-based study and suggests that GADA levels do fall with time, given the older age of the sample and a relatively long period between diagnosis and sampling. Southern Europeans had an even lower GADA prevalence, regardless of diabetes type. Variations in GADA frequency in diabetic patients of differing European ethnicity has implications for clinical management and healthcare planning.