Islet Cell Cytoplasm Research Articles

253-OR: Microvascular Complications in Latent Autoimmune Diabetes of Adults: Results from the UKPDS

Background: Latent Autoimmune Diabetes of Adults (LADA) is a mild form of autoimmune diabetes which can be identified in 3-12% of adults who have a clinical diagnosis of T2D. LADA differs in genetic and clinical features with T2D, but whether this translates into a different risk for complications remains controversial. Aim: We examined the long-term risk of microvascular complications in the large population with a clinical diagnosis of new-onset T2D enrolled into the United Kingdom Prospective Diabetes Study (UKPDS), according to their LADA status. Methods: Islet-cell cytoplasm, glutamic acid decarboxylase and islet antigen-2 autoantibodies (AAb) were measured in 5028 UKPDS participants at, or soon after, T2D diagnosis. Those with ≥1 detectable AAb were defined as LADA and their incidence of a composite microvascular outcome (first occurrence of renal failure, renal death or diabetic retinopathy [blindness, vitreous haemorrhage or photocoagulation]), was compared with T2D participants. Results: There were 564 (11.2%) of participants with LADA. Compared with T2D, they were younger, with higher mean HbA1c and HDL-cholesterol, but lower body mass index (BMI), total cholesterol and systolic blood pressure (SBP) (all p<0.01). The microvascular outcome occurred in 1041 (51.3%) of UKPDS participants during median 17.3 (range: 0.1-29.9) years follow-up. A time-varying cox-model showed a lower risk of microvascular events in LADA participants during the first nine years of follow-up (HR 0.52, 95% CI 0.35-0.78, p<0.01), but a higher risk beyond nine years (HR 1.47, 95% CI 1.20-1.81, p<0.01). These HRs were unchanged after adjustment for age, HbA1c, lipids, SBP, BMI, estimated glomerular filtration rate, smoking and UKPDS treatment arm. Conclusions: The risk of microvascular complications in LADA patients differs over time, being lower in the earlier years after diagnosis but higher in later years compared with T2D, potentially impacting on their diabetic management. Disclosure E. Maddaloni: Speaker's Bureau; Self; Merck & Co., Inc., Pikdare. R.L. Coleman: None. R.R. Holman: Advisory Panel; Self; Bayer AG, Novartis AG, Novo Nordisk A/S. Research Support; Self; AstraZeneca, Bayer AG, Merck Sharp & Dohme Corp. Other Relationship; Self; AstraZeneca, Bayer AG, GlaxoSmithKline plc., Janssen Pharmaceuticals, Inc. Funding European Foundation for the Study of Diabetes

Plasmonic chip tackles type 1 diabetes diagnosis.

Diabetes mellitus is a group of metabolic disorders of carbohydrate metabolism in which patients develop hyperglycemia. Type 1 diabetes results from cellular-mediated autoimmune destruction of the insulin-producing pancreatic β-cells 1. Patients with type 1 diabetes frequently present with acute symptoms, including life-threatening ketoacidosis, and all patients require lifelong insulin therapy. Type 2 diabetes, which accounts for approximately 90% of all diabetes, has an insidious onset due to combined insulin resistance and insufficient insulin production. In many patients, type 2 diabetes can be controlled with diet, exercise, and oral agents. The worldwide incidence of diabetes has been increasing dramatically. Although most of the rise has been for type 2 diabetes, type 1 has climbed by 2.8% to 4.0% per annum, rising 21% in US youth between 2001 and 2009. At disease onset, most type 1 diabetes patients have autoantibodies to 1 or more of the following: islet cell cytoplasm, insulin [insulin autoantibodies (IAAs)],3 the 65-kDa isoform of glutamic acid decarboxylase (GAD65), insulinoma-associated antigen 2 (IA-2), and zinc transporter 8 (ZnT8) (these are collectively termed islet autoantibodies). Moreover, the presence of islet autoantibodies predicts the development of type 1 diabetes. A recent prospective study measured IAA, GAD65, and IA-2 in 13uu377 children who were at high risk for type 1 diabetes and followed them for 15 years 2. Virtually all the children who had multiple islet autoantibodies developed type 1 diabetes, whereas approximately 15% with a single islet autoantibody progressed to type 1 diabetes. Quantification of islet autoantibodies has proved difficult. Islet cell antibodies were the first autoantibodies identified in type 1 diabetes and are measured on frozen sections of human pancreas by indirect immunofluorescence. The method is technically demanding, labor intensive, difficult to standardize, and currently performed by few laboratories. The other antibodies are most frequently measured by …

C-Peptide Levels in Latent Autoimmune Diabetes in Adults Treated With Linagliptin Versus Glimepiride: Exploratory Results From a 2-Year Double-Blind, Randomized, Controlled Study

Latent autoimmune diabetes in adults (LADA) is a slowly progressing form of immune-mediated diabetes often misdiagnosed as type 2 diabetes because of its typical clinical presentation, i.e., an adult without weight loss or ketoacidosis not initially requiring insulin (1). Prior to insulin dependence, pharmacological options for reducing hyperglycemia comprise the oral glucose-lowering drugs used in type 2 diabetes; however, none has been established as the drug of choice in LADA because of the scarcity of evidence for or against the various agents (2). This study was a prespecified, exploratory analysis of a large ( n = 1,519) trial in which patients diagnosed with type 2 diabetes and HbA1c of 6.5–10.0% (48–86 mmol/mol) on metformin were randomized to additional once-daily linagliptin 5 mg or glimepiride 1−4 mg for 2 years (NCT00622284) (3). Fasting plasma samples taken during the study were tested for autoantibodies against GAD 65-kDa isoform (GAD65), islet cell cytoplasm, tyrosine phosphatase IA-2 (IA-2A), or insulin (IAA), and patients were classified as having LADA if positive for …

Clinical characteristics and autoantibody pattern in newly diagnosed adult‑onset autoimmune diabetes

Autoimmune diabetes in adults comprises a broad spectrum of clinical phenotypes. The aim of the study was to investigate clinical and biochemical features and anti-islet autoantibody pattern in adult patients with newly diagnosed autoimmune diabetes with regard to age and the number of autoantibodies detected at diagnosis. We retrospectively evaluated 344 patients (aged ≥18 years) with newly diagnosed diabetes and a positive anti-islet antibody titer. Patients were divided based on age (<35 and ≥35 years of age) or the number of detected autoantibodies (1, 2, or 3). The studied age groups did not differ with respect to the majority of clinical and laboratory features (e.g., clinical presentation, metabolic status, or degree of insulin deficiency). Autoantibodies to islet cell cytoplasm and to glutamic acid decarboxylase 65 occurred more frequently in younger patients, while the prevalence of autoantibodies to intracytoplasmatic domain of the tyrosine phosphatase-like protein (IA-2A) was similar in both age groups. Single autoantibody positivity was observed more often in older patients. The most common isolated autoantibody in this group was IA-2A. The presence of multiple autoantibodies was associated with younger age, lower fasting and stimulated C-peptide levels, and shorter duration of symptoms. The patient's age at diabetes onset does not determine clinical and biochemical characteristics at diagnosis but is associated with different autoantibody status. IA-2A antibodies may be useful in diagnosing autoimmune diabetes in adult patients. The assessment of the immune profile at diagnosis may help identify patients at a higher risk of significant insulin deficiency.

The three ZNT8 autoantibody variants together improve the diagnostic sensitivity of childhood and adolescent type 1 diabetes

Aims: We tested whether autoantibodies to all three ZnT8RWQ variants, GAD65, insulinoma-associated protein 2 (IA-2), insulin and autoantibodies to islet cell cytoplasm (ICA) in combination with human leukocyte antigen (HLA) would improve the diagnostic sensitivity of childhood type 1 diabetes by detecting the children who otherwise would have been autoantibody-negative.Methods: A total of 686 patients diagnosed in 1996–2005 in Skåne were analyzed for all the seven autoantibodies [arginin 325 zinc transporter 8 autoantibody (ZnT8RA), tryptophan 325 zinc transporter 8 autoantibody (ZnT8WA), glutamine 325 Zinc transporter 8 autoantibody (ZnT8QA), autoantibodies to glutamic acid decarboxylase (GADA), Autoantibodies to islet-antigen-2 (IA-2A), insulin autoantibodies (IAA) and ICA] in addition to HLA-DQ genotypes.Results: Zinc transporter 8 autoantibody to either one or all three amino acid variants at position 325 (ZnT8RWQA) was found in 65% (449/686) of the patients. The frequency was independent of age at diagnosis. The ZnT8RWQA reduced the frequency of autoantibody-negative patients from 7.5 to 5.4%—a reduction by 28%. Only 2 of 108 (2%) patients who are below 5 years of age had no autoantibody at diagnosis. Diagnosis without any islet autoantibody increased with increasing age at onset. DQA1-B1*X-0604 was associated with both ZnT8RA (p = 0.002) and ZnT8WA (p = 0.01) but not with ZnT8QA (p = 0.07). Kappa agreement analysis showed moderate (>0.40) to fair (>0.20) agreement between pairs of autoantibodies for all combinations of GADA, IA-2A, ZnT8RWQA and ICA but only slight ( < 0.19) agreement for any combination with IAA.Conclusions: This study revealed that (1) the ZnT8RWQA was common, independent of age; (2) multiple autoantibodies were common among the young; (3) DQA1-B1*X-0604 increased the risk for ZnT8RA and ZnT8WA; (4) agreement between autoantibody pairs was common for all combinations except IAA. These results suggest that ZnT8RWQA is a necessary complement to the classification and prediction of childhood type 1 diabetes as well as to randomize the subjects in the prevention and intervention of clinical trials.

Diabetes-Related Autoantibodies and Gestational Diabetes

Gestational diabetes mellitus (GDM) has long been recognized as a heterogeneous disorder (1,2), with autoimmunity against the β-cell contributing in a small subset of patients (3). Autoimmune diabetes is caused by the destruction of β-cells of pancreatic islets by an immune-mediated process, promoted by the interaction of genetic and environmental factors (4). Autoantibodies (AAs) against pancreatic β-cell antigens precede the clinical onset of type 1 diabetes (4). Circulating islet cell antibodies, originally described by indirect immunofluorescence in 1974 (5), have been demonstrated in the great majority of individuals with type 1 diabetes, both at the preclinical state and at the onset of clinically overt diabetes, and they persist in the circulation for a long time. Islet cell AAs include autoantibodies to islet cell cytoplasm (islet cell autoantibodies [ICAs]), to native insulin (insulin autoantibodies [IAAs]), to GAD (GADA) (6–8), and to tyrosine phosphatases (insulinoma-associated antigens IA-2A and IA-2β) (9,10). Age not only modifies the risk of autoimmune diabetes, but also the presence of AAs, the intensity of β-cell destruction, the rate of progression to overt diabetes, and the degree of residual insulin secretion. Approximately 30% of subjects with classic autoimmune diabetes (type 1A diabetes) present after age 35 years (11). Childhood autoimmune diabetes is associated with an increased prevalence of alleles DR3, DQB1*0201 and DR4, and DQB1*0302, with the proportion of heterozygotes declining with age at diagnosis (12). Children with the allele HLA DR2, DQB1*0602, almost never develop diabetes, whereas this allele confers a much lower protection for adult-onset autoimmune diabetes (13). Since the discovery of AAs against islet cell antigens, it has been recognized that a fraction of adults considered to have type 2 diabetes probably have autoimmune diabetes and that the presence of GADAs indicates a strong possibility of requiring …

Combined positivity for HLA DQ2/DQ8 and IA-2 antibodies defines population at high risk of developing type 1 diabetes

Prevention trials in first-degree relatives of type 1 diabetic patients are hampered by large interindividual differences in progression rate to diabetes. We investigated whether specific combinations of immune and genetic markers can identify subgroups with more homogeneous progression to clinical onset. Antibodies against islet cell cytoplasm (ICA), insulin (IAA), glutamate decarboxylase (GADA) and IA-2 protein (IA-2A) were measured in 790 non-diabetic control subjects and 4,589 first-degree relatives under age 40. On first sampling, 11.1% of the siblings presented at least one antibody type (p<0.001 vs other relatives). During follow-up (median 52 months) 43 subjects developed type 1 diabetes (31 siblings, ten offspring of a diabetic father, two offspring of a diabetic mother). Using Kaplan-Meier survival analysis and Cox regression, IA-2A conferred the highest 5-year diabetes risk (>50%) irrespective of the number of antibodies present. In initially IA-2A-positive relatives (n=58) progression to hyperglycaemia depended more on HLA DQ status than on type of kinship (84% progression in the presence of DQ2/DQ8 vs 32% in its absence; p<0.003). In IA-2A-negative relatives (n=4,531) 5-year progression to diabetes increased with the number of other antibodies (ICA, GADA and/or IAA) (p<0.001) but overall did not exceed 10% even for two or more antibodies. Among relatives initially positive for one or more antibody type other than IA-2A (n=315), there was significantly more progression to diabetes (overall still <10%) in carriers of DQ2 (p<0.001 vs no DQ2), regardless of DQ8 status. These observations suggest that the HLA-DQ-inferred risk of diabetes can proceed through two distinct pathways distinguished by IA-2A status. Combined positivity for DQ2/DQ8 and IA-2A defines a more homogeneous high-risk population for prevention trials than those used so far.

Islet autoantibodies in clinically diagnosed type 2 diabetes: prevalence and relationship with metabolic control (UKPDS 70)

We examined the prevalence of islet autoantibodies and their relationship to glycaemic control over 10 years in patients diagnosed clinically with new-onset type 2 diabetes. Patient clinical characteristics and autoantibody status were determined at entry to the UK Prospective Diabetes Study (UKPDS) before randomisation to different glucose control policies. Patients were followed for 10 years. Data available on 4,545 of the 5,102 UKPDS patients showed that 11.6% had antibodies to at least one of three antigens: islet cell cytoplasm, glutamic acid decarboxylase and islet autoantibody 2A (IA-2A). Autoantibody-positive patients were younger, more often Caucasian and leaner, with lower beta cell function and higher insulin sensitivity than autoantibody-negative patients. They also had higher HbA1c, and HDL-cholesterol levels, and lower blood pressure, total cholesterol and plasma triglyceride levels. Despite relative hyperglycaemia, autoantibody-positive patients were less likely to have the metabolic syndrome (as defined by the National Cholesterol Education Program Adult Treatment Program III), reflecting a more beneficial overall risk factor profile. Of 3,867 patients with post-dietary run-in fasting plasma glucose (FPG) values between 6.0 and 14.9 mmol/l and no hyperglycaemic symptoms, 9.4% were autoantibody-positive, compared with 25.1% of 678 patients with FPG values of 15.0 mmol/l or higher, or hyperglycaemic symptoms. In both groups, no differences were seen between those with and without autoantibodies in changes to HbA1c over time, but autoantibody-positive patients required insulin treatment earlier, irrespective of the allocated therapy (p<0.0001). Autoantibody-positive patients can be treated initially with sulphonylurea, but are likely to require insulin earlier than autoantibody-negative patients.

CTLA-4 gene polymorphism confers susceptibility to insulin-dependent diabetes mellitus (IDDM) independently from age and from other genetic or immune disease markers

SUMMARY Apart from genes in the HLA complex (IDDM1) and the variable number of tandem repeats in the 5′ region of the insulin gene (INS VNTR, IDDM2), several other loci have been proposed to contribute to IDDM susceptibility. Recently, linkage and association have been shown between the cytotoxic T lymphocyte-associated protein 4 (CTLA-4) gene on chromosome 2q and IDDM. In a registry-based group of 525 recent-onset IDDM patients &amp;lt; 40 years old we investigated the possible interactions of a CTLA-4 gene A-to-G transition polymorphism with age at clinical disease onset and with the presence or absence of established genetic (HLA-DQ, INS VNTR) and immune disease markers (autoantibodies against islet cell cytoplasm (ICA); insulin (IAA); glutamate decarboxylase (GAD65-Ab); IA-2 protein tyrosine phosphatase (IA-2-Ab)) determined within the first week of insulin treatment. In new-onset IDDM patients, G-allele-containing CTLA-4 genotypes (relative risk (RR) = 1.5; 95% confidence interval (CI) = 1.2–2.0; P &amp;lt; 0.005) were not preferentially associated with age at clinical presentation or with the presence of other genetic (HLA-DR3 or DR4 alleles; HLA-DQA1*0301-DQB1*0302 and/or DQA1*0501-DQB1*0201 risk haplotypes; INS VNTR I/I risk genotype) or immune (ICA, IAA, IA-2-Ab, GAD65-Ab) markers of diabetes. For 151 patients, thyrogastric autoantibodies (anti-thyroid peroxidase, anti-thyroid-stimulating hormone (TSH) receptor, anti-parietal cell, anti-intrinsic factor) were determined, but association between CTLA-4 risk genotypes and markers of polyendocrine autoimmunity could not be demonstrated before or after stratification for HLA- or INS-linked risk. In conclusion, the presence of a G-containing CTLA-4 genotype confers a moderate but significant RR for IDDM that is independent of age and genetic or immune disease markers.

IA-2 autoantibodies predict impending type I diabetes in siblings of patients.

Multiple islet autoantibody positivity is currently believed to best predict progression to Type I (insulin-dependent) diabetes mellitus. We compared its predictive value with that of positivity for a particular type of islet autoantibody, directed against the IA-2 antigen. Autoantibodies against islet cell cytoplasm (ICA), insulin (IAA), GAD (GADA) and IA-2 (IA-2A) were measured at initial sampling in 1724 non-diabetic siblings (median age [range]:16 [0-39] years) of Type I diabetic patients with a median follow-up of 50 months. On initial sampling 11% of siblings were positive for one antibody type or more and 2.1% for three of more types. During follow-up, 27 antibody-positive siblings developed diabetes. Using survival analysis, the risk for clinical onset within 5 years was 34% in subjects positive for three or more types compared with 13% in those with one type or more. Progression to diabetes amounted to 12% within 5 years among siblings positive for IAA, 20% for ICA, 19% for GADA but 59% for IA-2A (p<0.001 vs absence of the respective antibody). IA-2A were detected in 1.7% of all siblings and in 56% of the prediabetic subjects on first sampling. Initial positivity for two or three antibody markers was associated with a higher progression rate in IA-2A positive as compared to IA-2A negative siblings (p=0.001). In absence of IA-2A initial positivity for another antibody (IAA, ICA or GADA) conferred a low (<10% within 5 years) risk of diabetes compared to subjects lacking this antibody. In siblings of Type I diabetic patients, IA-2A positivity is a more direct predictor of impending clinical onset than multiple antibody positivity per se. Assessment of IA-2A status allows us to select subjects with homogeneously high risk of diabetes for participation in prevention trials.

Antibodies to SOX13 (ICA12) are Associated with Type 1 Diabetes

SOX 13 is an islet cell autoantigen (ICA12), identified by antibody screening of an islet cDNA library, using sera from patients with Type 1 diabetes. We ascertained the frequency of antibody reactivity to SOX 13 and compared it with other Type 1 diabetes autoantibody reactivities. Antibodies were measured by radioimmunoprecipitation (RIP) using 35S labelled SOX 13 expressed in rabbit reticulocyte lysate. Sera from 109 subjects with Type 1 diabetes, 29 with Type 2 diabetes, 144 with other autoimmune diseases and from 201 controls were tested for anti-SOX13, and results were compared with the frequency of antibodies to glutamic acid decarboxylase (anti-GAD), islet cell antigen 512 (anti-ICA512) and islet cell cytoplasm (ICA). Anti-SOX13 were detected in 20 (18.3%) of 109 subjects with Type 1 diabetes, and more frequently in adults than in children (29% vs 10%). Anti-SOXI3 usually occurred with anti-GAD but rarely with anti-ICA512. Seven sera positive for anti-SOX13 did not react with either GAD, ICA512 or islet cell cytoplasm indicating that anti-SOX13 represented a distinct population of antibodies. Reactivity to SOX 13 represents a further autoantibody response in adults with Type 1 diabetes and may provide a useful disease marker in subjects in whom other autoantibody tests are negative.

Autoantibodies to Multiple Islet Autoantigens in Patients with Abrupt Onset Type 1 Diabetes and Diabetes Diagnosed with Urinary Glucose Screening

It has been reported that there is a heterogeneity in the clinical course of Japanese patients with type 1 diabetes. To elucidate the associations of expression of autoantibodies to multiple islet antigens with age of onset and mode of diagnosis of diabetes in Japanese patients with type 1 diabetes, autoantibodies against the protein tyrosine phosphatase-like molecules ICA512 (IA-2) and phogrin (IA-2β) (ICA512/phogrin-A), GAD (GADA), insulin (IAA), and islet cell cytoplasm (ICA) were determined in sera from 73 Japanese patients with type 1 diabetes obtained within 14 days of diagnosis. Patients were divided into groups based on the age of onset (≤10 years, n=24 and >10 years, n=49) or the mode of onset (abrupt onset, n=59 and urinary screening identified, n=14). Of 73 new-onset patients with type 1 diabetes, 43 (59%) and 32 (44%) had ICA512A and phogrin-A levels exceeding the 99th percentile of 184 normal control subjects, respectively. Forty-five patients (62%) were positive for either ICA512A or phogrin-A. The frequencies for other autoantibodies were 71% for GADA, 48% for IAA, and 62% for ICA. The frequency of ICA512/phogrin-A was significantly higher in patients with an age of onset less than 10 years (83%) than in patients aged >10 years (51%, P<0.01). The positivity of ICA512/phogrin-A was less in patients whose diabetes was diagnosed by the urine glucose screening test (21%, P<0.001) than in abrupt onset patients (71%). Combined analysis (≥1 antibody) of GADA, IAA, and ICA512/phogrin-A detected 88% of abrupt onset and 93% of screening-positive patientsvs . 70% and 29%, respectively, for ICA (P<0.0005). These results indicate that the expression of ICA512/phogrin-A and cytoplasmic ICA is less in patients identified by urinary glucose testing but indicate that with combined autoantibody testing 90% of patients can be identified independent of the mode of diagnosis.

UKPDS 25: autoantibodies to islet-cell cytoplasm and glutamic acid decarboxylase for prediction of insulin requirement in type 2 diabetes

Autoantibodies to islet-cell cytoplasm (ICA) and glutamic acid decarboxylase (GADA) can occur in apparently typical, non-insulin dependent diabetes mellitus (type 2). We investigated whether the presence of either or both antibodies characterises a subtype of diabetes and provides better prediction of requirement for insulin therapy by 6 years' follow-up than clinical variables. We measured ICA and GADA at diagnosis of diabetes in a representative population of 3672 white patients with type 2 diabetes, aged between 25 and 65 years. The phenotype was assessed by age of onset, body-mass index, percentage haemoglobin A1c (HbA1c), and islet beta-cell function. We investigated the need for insulin therapy among 1538 patients not assigned insulin and followed up for 6 years from diagnosis. The proportion of patients with ICA and GADA decreased with increasing age at diagnosis (from 33 [21%] of 157 patients aged 25-34 [corrected] to 66 [4%] of 1769 aged 55-65 for ICA; from 53 [34%] to 122 [7%] for GADA). Among patients younger than 35 at diagnosis, those with ICA or GADA had lower body-mass index than those without (mean 24.9 [SD 6.0] vs 31.7 [7.3] kg/m2; p < 0.0001 and had higher percentage of HbA1c (9.7 vs 8.7%, p < 0.05). 94% of patients with ICA and 84% of those with GADA required insulin therapy by 6 years, compared with 14% of those without the antibodies (p < 0.0001). Among patients older than 55 at diagnosis, the difference between those with and without antibodies in body-mass index was smaller (27.2 [5.4] vs 28.6 [4.8] kg/m2, p < 0.001); 44% of those with ICA, 34% of those with GADA, and 5% with neither antibody required insulin therapy by 6 years (p < 0.0001). Among patients older than 45 years, body-mass index and HbA1c provided little predictive information for insulin requirement, whereas the positive predictive values of GADA (> or = 60 U/L) alone, or both GADA (> or = 20 U/L) and ICA (> 5 U/L), for insulin therapy were 52% and 68%. Among young adults with type 2 diabetes, the phenotype of those with ICA or GADA antibodies was similar to that of classic juvenile-onset insulin-dependent diabetes, and either phenotype or antibodies predicted insulin requirement. In older adults, the phenotype was closer to that of patients without antibodies and only the presence of antibodies predicted an increased likelihood of insulin requirement.

Evaluation of ICA512As in Combination With Other Islet Cell Autoantibodies at the Onset of IDDM

The ICA512 pancreatic islet autoantigen is a putative tyrosine phosphatase that is co-identified with the earlier described 40-kDa autoantigen. We report the frequency of autoantibodies to islet cell antigen 512 (ICA512As) in recent-onset IDDM and compare this with other islet cell autoantibodies, including those to GAD (GADAs), insulin (IAAs), and islet cell cytoplasm (ICAs) identified by immunofluorescence. Sera from 232 children aged between 9 months and 14.9 years collected within 14 days of diagnosis were tested for ICA512As by a radioimmunoprecipitation assay. The results were compared with previously reported data for GADAs (n = 232), IAAs (n = 167), and ICAs (n = 230). The frequency of a positive result for ICA512As in children with newly diagnosed IDDM was 60%. The frequency was greater for children with an age of onset between 5 and 10 years (69%) than for children aged < 5 years (49%) and aged between 10 and 15 years (56%). The frequencies for other autoantibody reactivities were 69% for GADAs, 65% for IAAs, and 70% for ICAs. A combination of positive results for ICA512As, GADAs, and IAAs gave a sensitivity for the diagnosis of childhood IDDM of 95%, which was not significantly increased by a positive result for ICAs (96%). Our results further establish that positivity in a combination of tests is more valuable for the prediction of IDDM than a result for any single autoantibody and that the age of the patient should be considered when selecting the combination of tests to use.

CTLA-4 gene polymorphism confers susceptibility to insulin-dependent diabetes mellitus (IDDM) independently from age and from other genetic or immune disease markers. The Belgian Diabetes Registry.

Apart from genes in the HLA complex (IDDM1) and the variable number of tandem repeats in the 5' region of the insulin gene (INS VNTR, IDDM2), several other loci have been proposed to contribute to IDDM susceptibility. Recently, linkage and association have been shown between the cytotoxic T lymphocyte-associated protein 4 (CTLA-4) gene on chromosome 2q and IDDM. In a registry-based group of 525 recent-onset IDDM patients <40 years old we investigated the possible interactions of a CTLA-4 gene A-to-G transition polymorphism with age at clinical disease onset and with the presence or absence of established genetic (HLA-DQ, INS VNTR) and immune disease markers (autoantibodies against islet cell cytoplasm (ICA); insulin (IAA); glutamate decarboxylase (GAD65-Ab); IA-2 protein tyrosine phosphatase (IA-2-Ab)) determined within the first week of insulin treatment. In new-onset IDDM patients. G-allele-containing CTLA-4 genotypes (relative risk (RR)= 1.5; 95% confidence interval (CI) = 1.2-2.0; P < 0.005) were not preferentially associated with age at clinical presentation or with the presence of other genetic (HLA-DR3 or DR4 alleles; HLA-DQA1*0301-DQB1*0302 and/or DQA1*0501-DQB1*0201 risk haplotypes; INS VNTR I/I risk genotype) or immune (ICA, IAA, IA-2-Ab, GAD65-Ab) markers of diabetes. For 151 patients, thyrogastric autoantibodies (anti-thyroid peroxidase, anti-thyroid-stimulating hormone (TSH) receptor, anti-parietal cell, anti-intrinsic factor) were determined, but association between CTLA-4 risk genotypes and markers of polyendocrine autoimmunity could not be demonstrated before or after stratification for HLA- or INS-linked risk. In conclusion, the presence of a G-containing CTLA-4 genotype confers a moderate but significant RR for IDDM that is independent of age and genetic or immune disease markers.

HLA-DR, DQ and anti-GAD antibodies in first degree relatives of type I diabetes mellitus

The differential antibody response to glutamic acid decarboxylase (anti-GAD) and to islet cell cytoplasm (ICA) according to HLA-DR and DQ genotypes were examined in 28 Spanish patients with Type I diabetes mellitus (11.1 ± 10.4 year diabetes duration) and their 41 first degree non-diabetic relative. Anti-GAD was detected by radioimmunoprecipitation and ICA by indirect immunofluorescence and HLA-DR/DQ alleles were assigned by PCR and sequence specific oligonucleotide probes. The frequency in patients of positivity for ICA was 7.1% and of anti-GAD − 64.3%, and in relatives, the frequency of ICA − was 4.9%, and anti-GAD + 9.8%. Concurrent positivity for ICA and anti-GAD existed in only one patient, and in none of the relatives. We confirm for a Spanish population the high frequency of risk genotypes for Type I, involving DR3, DR4 and DQB1*0302 (DQ8), which were present in 26 of 28 (93%) patients and 32 of 41 (78%) relatives. The most frequent genotypes were DR3/DQB1*0201/DQA1*0501-DR4/DQB1*0302/DQA1*0301(9 patients, 32%; 6 relatives, 15%) DR3/DQB1*0201/ DQA1*0501-DR3/DQB1*0201/DQA1*0501 (5 patients, 18% 7 relatives, 17% and DR3/DQB1*0201/DQA1*0501-DR1/DQB1*0501/DQA1*0101 (5 patients, 18%; 1 relative, 2%). Positivity for anti-GAD or for ICA did not correlate with gender, or age at onset or duration of DM. The distribution of high risk HLA genotypes were similar regardless the anti-GAD or anti-ICA status either in patients or in their relatives.

Antibodies to Glutamic Acid Decarboxylase Reveal Latent Autoimmune Diabetes Mellitus in Adults With a Non—Insulin-Dependent Onset of Disease

The classification of adults with diabetes mellitus can be invalidated by patients who initially present as NIDDM but who later become frankly insulin dependent. In some of these, the pathogenesis could be similar to that in IDDM, namely autoimmune destruction of the pancreatic beta-cells. We studied 102 patients > 35 yr of age at diabetes onset who had initially been nonketotic and non-insulin-dependent for > or = 6 mo. They were classified according to glucagon-stimulated C-peptide levels into an insulin-deficient group (n = 33) and a non-insulin-deficient group (n = 69). We measured antibodies to GAD, islet cell cytoplasm, thyroid antigens, and gastric parietal cells in both groups. Anti-GAD was significantly higher in the insulin deficient group, 76% (25 of 33), than in the non-insulin deficient group, 12% (8 of 69), and this difference was substantially greater than that shown for ICAs. Thus, in a proportion of adults who present with NIDDM, a slowly evolving autoimmune insulitis can be revealed by testing for anti-GAD. This could have important connotations not only for early intervention, but also for the correct classification of diabetes.

Immunoelectron microscopic localization of antigens which react with islet cell cytoplasmic antibodies within human pancreatic beta cells.

The presence of circulating autoantibody to islet cell cytoplasm is considered to be an important marker of Type 1 (insulin-dependent) diabetes mellitus. In the present study using islet cell cytoplasmic antibody positive patient sera as the first antibody, we studied the intracellular distribution of its antigen at the electron microscopic level using the pre-embedding immunoperoxidase method. Specific immunoreactivity was found in the membranes of beta cell-secretory granules and cytoplasmic membranes. This result is compatible with the interpretation that the antigen(s) on the membranes of beta cell secretory granules is (are) the target of islet cell cytoplasmic antibody.