Only multiple autoantibodies to islet cells (ICA), insulin, GAD65, IA-2 and IA-2beta predict immune-mediated (Type 1) diabetes in relatives.

We report here our prospective study of 15,224 non-diabetic, first-degree relatives of probands with immune-mediated (type 1) diabetes (IMD), of which 135 were found to eventually develop diabetes. We determined islet cell, insulin, GAD65, insulinoma-associated antigen-2 and 2beta autoantibodies (ICA, IAA, GAD65A, IA-2A and IA-2betaA), on the first available serum samples. The latter three autoantibodies were however assayed on subsets of the relatives with and without ICA, IAA and/or GAD65A, plus most of the relatives who developed diabetes. Of the relatives who progressed to diabetes, 94% had at least one of these autoantibodies on the first screening, while ICA proved to be the most sensitive single marker (sensitivity 74%). Risk of diabetes was however negligible when ICA was found in the absence of the others (5-year risk=5.3%), but increased dramatically whenever two or more autoantibodies were present (5-year risk=28.2% and 66.2%, respectively). The most predictive combination of markers was ICA plus IA-2A and/or IA-2beta A. Loss of first phase insulin release to IVGTT also occurred only in those ICA-positive relatives who had one or more of the other autoantibodies. The data suggests that significant beta-cell damage is seen only when the underlying autoimmunity has spread to multiple antigenic islet cell determinants. Combinations of the autoantibodies occurred most often in relatives with the highest risk HLA-DR/DQ phenotypes. These data document that only relatives positive for at least two or more of these five autoantibodies are at significant risk of diabetes themselves. Intervention trials for the prevention of type 1 diabetes could be designed based on testing for these autoantibodies alone, without the need for HLA typing and IVGTT testing.     

Only Multiple Autoantibodies to Islet Cells (ICA), Insulin, GAD65, IA-2 and IA-2β Predict Immune-Mediated (Type 1) Diabetes in Relatives

We report here our prospective study of 15,224 non-diabetic, first-degree relatives of probands with immune-mediated (type 1) diabetes (IMD), of which 135 were found to eventually develop diabetes. We determined islet cell, insulin, GAD65, insulinoma-associated antigen-2 and 2βautoantibodies (ICA, IAA, GAD65A, IA-2A and IA-2βA), on the first available serum samples. The latter three autoantibodies were however assayed on subsets of the relatives with and without ICA, IAA and/or GAD65A, plus most of the relatives who developed diabetes. Of the relatives who progressed to diabetes, 94% had at least one of these autoantibodies on the first screening, while ICA proved to be the most sensitive single marker (sensitivity 74%). Risk of diabetes was however negligible when ICA was found in the absence of the others (5-year RISK=5.3%), but increased dramatically whenever two or more autoantibodies were present (5-year RISK=28.2% and 66.2%, respectively). The most predictive combination of markers was ICA plus IA-2A and/or IA-2β A. Loss of first phase insulin release to IVGTT also occurred only in those ICA-positive relatives who had one or more of the other autoantibodies. The data suggests that significant β-cell damage is seen only when the underlying autoimmunity has spread to multiple antigenic islet cell determinants. Combinations of the autoantibodies occurred most often in relatives with the highest risk HLA-DR/DQ phenotypes. These data document that only relatives positive for at least two or more of these five autoantibodies are at significant risk of diabetes themselves. Intervention trials for the prevention of type 1 diabetes could be designed based on testing for these autoantibodies alone, without the need for HLA typing and IVGTT testing.     

Islet autoantibodies in cord blood from patients who developed type 1 diabetes mellitus at 15-30 years of age

Islet cell autoantibodies are early markers for type 1 diabetes. The aim of this study was to determine whether islet autoantibodies were present at birth in young adults who developed type 1 diabetes at 15-30 years of age. Cord blood sera from 30 patients who developed type 1 diabetes between 15 and 25 years of age and sera from 320 randomly selected control children were tested for islet cell antibodies (ICA) by indirect immunofluorescence and autoantibodies against the 65 kD isoform of glutamic acid decarboxylase (GADA), islet cell antigen-2 (IA-2A) and insulin (IAA) by radiobinding assays. The young adults who developed type 1 diabetes did not differ from controls in the cord blood prevalence of any of the four islet autoantibodies. This is in contrast to our previous findings that children who developed type 1 diabetes below 15 years of age had an increased prevalence of cord blood islet autoantibodies. Our present data suggest that, in contrast to children, pre- and perinatal risk factors are less likely to be involved in the development of type 1 diabetes in young adults.     

Prevalence of beta-cell and thyroid autoantibody positivity in schoolchildren during three-year follow-up

The prevalence of autoantibodies against the 65 kD isoform of glutamic acid decarboxylase (GAD65Ab), insulin (IAA), islet cells (ICA), thyroid peroxidase (TPOAb) and thyroglobulin (TgAb), in relation to HLA-DR types, was assessed in 310 (HLA in 280) twelve-year-old children during three-year follow-up. Altogether, 26.8% (83/310) of the children were found to carry at least one autoantibody. The HLA-DR3/DR4 genotype was significantly more prevalent in the subgroup of children GAD65Ab-positive on at least one occasion than among GAD65Ab-negative children [33% (2/6) vs. 5% (12/274); p = 0.031, as was the HLA-DR4/x genotype among children seropositive for at least one thyroid autoantibody, compared to the corresponding seronegative subgroup 152% (34/65) vs. 34% (74/215); p=0.01]. The proportion of children seropositive in at least one of the three tests was 1.9% (6/310) for GAD65Ab, 2.6% (8/310) for IAA, 5.2% (16/310) for ICA, 11.3% (35/310) for TPOAb and 19.4% (60/310) for TgAb. All autoantibodies except GAD65Ab tended to disappear during follow-up, and at the three-year follow-up IAA had disappeared in 50% (2/4) of cases, ICA in 67% (6/9), TPOAb in 30% (6/20) and TgAb in 38% (18/47) of cases. The turnover of seropositive subjects and the large proportion of children seropositive for at least one islet or thyroid autoantibody during a three-year follow-up suggest transient autoantibodies to be more common than is discernible in cross-sectional investigations.     

Islet Autoantibodies in Cord Blood from Patients who developed Type 1 Diabetes Mellitus at 15–30 Years of Age

Islet cell autoantibodies are early markers for type 1 diabetes. The aim of this study was to determine whether islet autoantibodies were present at birth in young adults who developed type 1 diabetes at 15–30 years of age. Cord blood sera from 30 patients who developed type 1 diabetes between 15 and 25 years of age and sera from 320 randomly selected control children were tested for islet cell antibodies (ICA) by indirect immunofluorescence and autoantibodies against the 65?kD isoform of glutamic acid decarboxylase (GADA), islet cell antigen-2 (IA-2A) and insulin (IAA) by radiobinding assays. The young adults who developed type 1 diabetes did not differ from controls in the cord blood prevalence of any of the four islet autoantibodies. This is in contrast to our previous findings that children who developed type 1 diabetes below 15 years of age had an increased prevalence of cord blood islet autoantibodies. Our present data suggest that, in contrast to children, pre- and perinatal risk factors are less likely to be involved in the development of type 1 diabetes in young adults.     

Humoral beta-cell autoimmunity in relation to HLA-defined disease susceptibility in preclinical and clinical type 1 diabetes

We have studied the relationship between diabetes-associated autoantibodies and various HLA genotypes and alleles in patients with newly diagnosed type 1 diabetes, in non-diabetic siblings and in children representing the general population to test the hypothesis that specific HLA genes regulate the humoral immune response to various autoantigens. Among the newly diagnosed patients we observed that those carrying the DR4-DQB1*0302 haplotype had increased levels of insulin autoantibodies (IAA) and IA-2 antibodies (IA-2A), but low levels of GAD antibodies (GADA). In contrast, those with the DR3-DQB1*02 haplotype had increased GADA titers but low IAA and IA-2 levels. DQB1*02-homozygous patients had a conspicuously low frequency and low levels of IA-2A. Among the siblings there was an apparent association between genetic risk and the prevalence of islet cell antibodies (ICA), IAA, GADA, IA-2A and multiple autoantibodies, the latter being detectable at a frequency of 24.1% in high risk siblings and at a frequency of only 0.9% in those with genotypes conferring disease protection. Among 7-16-year-old Finnish schoolchildren there was an association between GADA and the DQB1*02/*0302 genotype and the DQB1*0302 allele. Among young children identified from the general population based on high (DQB1*02/0302 heterozygosity) or moderate (DQB1*0302/x; x not equal *02, *0301, *0602, *0603) genetic risk for type 1 diabetes the high risk children seroconverted more often to positivity for ICA, GADA and IA-2A over their first 2 years of life. Among older sibs of these children we observed an obvious relationship between the degree of genetic risk and the frequency of ICA, IAA, GADA, IA-2A, and multiple antibodies. Taken together these observations suggest that HLA genes have a strong impact on the appearance of diabetes-associated autoantibodies both in first-degree relatives of affected children and in the general population. In patients with newly diagnosed disease IA-2A may be a more specific marker of beta-cell damage, whereas GADA might reflect a propensity to autoimmunity in general.     

Tyrosine Phosphatase-like Protein (IA-2) and Glutamic Acid Decarboxylase (GAD65) Autoantibodies: A Study of Chinese Patients with Diabetes Mellitus

Type 1 diabetes in most Asian populations may not have a salient autoimmune basis when assessed with single determinations of the major markers, islet cell antibodies (ICAs) and glutamic acid decarboxylase antibodies (GAD65ab). With the inclusion of antibodies to tyrosine phosphatase-like protein IA-2 (IA-2ab) as an additional major marker, we re-examined autoimmune diabetes in a group of Chinese patients. We studied 272 subjects at various stages of disease with blood samples procured for biochemical analysis. ICAs were measured by immunofluorescence, GAD65ab and IA-2ab by radioimmunoassay. Sixty-seven patients fulfilled clinical diagnosis of type 1 diabetes and the remaining 205 patients were type 2. Prevalence of single autoantibody type in recent-onset type 1 diabetes (<1 year duration; n =47 ) showed 10.6% with ICAs, 44.7% GAD65ab and 36.2% IA-2ab. GAD65ab account for more than two-thirds of the markers found in type 1 diabetes. Combined analysis further showed that 51.1% had at least one antibody type, 31.9% with two or more antibodies and 8.5% with all three antibodies. Islet autoimmunity presence in childhood-onset type 1 diabetes improved with the addition of IA-2ab, though less impact was seen in the adult-onset. Similarly, combined analysis for type 2 patients with recent diabetes showed a modest increase to 13% with islet autoimmunity compared to 8% when assessed by GAD65ab alone. Combining IA-2ab and GAD65ab assays results detected slightly more immune-mediated diabetes, compared to using a single GAD65ab determination. Non-autoimmune causes need to be considered in the pathogenesis of type 1 diabetes in Chinese, particularly in adults.     

Tyrosine phosphatase-like protein (IA-2) and glutamic acid decarboxylase (GAD65) autoantibodies: a study of Chinese patients with diabetes mellitus

Type 1 diabetes in most Asian populations may not have a salient autoimmune basis when assessed with single determinations of the major markers, islet cell antibodies (ICAs) and glutamic acid decarboxylase antibodies (GAD65ab). With the inclusion of antibodies to tyrosine phosphatase-like protein IA-2 (IA-2ab) as an additional major marker, we re-examined autoimmune diabetes in a group of Chinese patients. We studied 272 subjects at various stages of disease with blood samples procured for biochemical analysis. ICAs were measured by immunofluorescence, GAD65ab and IA-2ab by radioimmunoassay. Sixty-seven patients fulfilled clinical diagnosis of type 1 diabetes and the remaining 205 patients were type 2. Prevalence of single autoantibody type in recent-onset type 1 diabetes ( < 1 year duration; n = 47) showed 10.6% with ICAs, 44.7% GAD65ab and 36.2% IA-2ab. GAD65ab account for more than two-thirds of the markers found in type 1 diabetes. Combined analysis further showed that 51.1% had at least one antibody type, 31.9% with two or more antibodies and 8.5% with all three antibodies. Islet autoimmunity presence in childhood-onset type 1 diabetes improved with the addition of IA-2ab, though less impact was seen in the adult-onset. Similarly, combined analysis for type 2 patients with recent diabetes showed a modest increase to 13% with islet autoimmunity compared to 8% when assessed by GAD65ab alone. Combining IA-2ab and GAD65ab assays results detected slightly more immune-mediated diabetes, compared to using a single GAD65ab determination. Non-autoimmune causes need to be considered in the pathogenesis of type 1 diabetes in Chinese, particularly in adults.     

Disease-associated autoantibodies during pregnancy and at birth in families affected by type 1 diabetes.

We studied the pattern of type 1 diabetes-associated autoantibodies during pregnancy and the transplacental transfer of these autoantibodies to the fetal circulation and searched for possible signs of prenatal induction of beta-cell autoimmunity in newborn infants. The population comprised 208 mothers and their newborn infants. Seventy-four of the mothers (36%) had type 1 diabetes and 134 (64%) of the infants had an affected father or sibling. Blood samples were obtained from the mother at the end of the first trimester and at delivery, and from the cord blood of the newborn infant. Close to 40% of the mothers with type 1 diabetes had antibodies to islet cells (ICA), 55% to glutamic acid decarboxylase (GADA) and 54% to the IA-2 protein (IA-2A) in early pregnancy, whereas the corresponding frequencies in the nonaffected mothers were 5.2%, 5.2% and 3.0%. No significant changes could be seen in autoantibody levels during pregnancy, and there was a close correlation between the two maternal samples. One third of the infants of mothers with type 1 diabetes tested positive for ICA, 50% for GADA and 51% for IA-2A. Six percent of the infants of nondiabetic mothers had ICA, 2.2% GADA and none had IA-2A. None of the infants of the antibody negative mothers had antibodies in their cord blood. These observations indicate that the immunomodulatory effect of pregnancy on signs of beta-cell autoimmunity is weak, but if diabetes-associated autoantibodies are present in the mother, most of them are transferred to the fetal circulation. Our data do not provide any support for fetal induction of beta-cell autoimmunity.     

Expression of beta-cell autoimmunity does not differ between potential dizygotic twins and siblings of patients with type 1 diabetes

Twin studies help to elucidate the contribution of genes and environment to type 1 diabetes (T1DM). The Diabetes Prevention Trial-1 (DPT-1) tested for anti-islet autoantibodies: 34,765 non-diabetic non-twin siblings of patients with T1DM, and 896 non-diabetic potential twins of patients with T1DM. Zygosity (being monozygotic [MZ] or dizygotic [DZ]) was unknown except for 357 non-diabetic subjects with opposite gender to their diabetic twin, who must be DZ. Expression of cytoplasmic islet cell (ICA), GAD65, ICA512 and insulin autoantibodies in 357 different-sex (DZ) potential non-diabetic twins of T1DM patients was, respectively, 4.5%, 4.7%, 3.0% and 2.4%, which was lower than in 539 same-sex potential non-diabetic twins (including MZ and DZ) of T1DM patients for ICA (7.8%, p < 0.05), GAD65 (13.4%, p < 0.0001) and ICA512 (6.5%, p < 0.03). In contrast, expression of ICA, GAD65, ICA512 and insulin autoantibodies was not significantly different in different-sex (DZ) potential twins versus all siblings (respectively, 4.2%, 4.8%, 2.2%, 2.5%), different-sex siblings (3.9%, 4.9%, 2.2%, 2.5%) or same-sex siblings (4.4%, 4.7%, 2.2%, 2.5%) of T1DM patients. In conclusion, anti-islet autoimmunity is not increased in non-diabetic DZ twins of T1DM patients compared to non-diabetic siblings of T1DM patients, suggesting that the greater environmental sharing by twins does not increase risk of anti-islet autoimmunity.     

IA-2 autoantibodies in incident type I diabetes patients are associated with a polyadenylation signal polymorphism in GIMAP5

In a large case-control study of Swedish incident type I diabetes patients and controls, 0-34 years of age, we tested the hypothesis that the GIMAP5 gene, a key genetic factor for lymphopenia in spontaneous BioBreeding rat diabetes, is associated with type I diabetes; with islet autoantibodies in incident type I diabetes patients or with age at clinical onset in incident type I diabetes patients. Initial scans of allelic association were followed by more detailed logistic regression modeling that adjusted for known type I diabetes risk factors and potential confounding variables. The single nucleotide polymorphism (SNP) rs6598, located in a polyadenylation signal of GIMAP5, was associated with the presence of significant levels of IA-2 autoantibodies in the type I diabetes patients. Patients with the minor allele A of rs6598 had an increased prevalence of IA-2 autoantibody levels compared to patients without the minor allele (OR=2.2; Bonferroni-corrected P=0.003), after adjusting for age at clinical onset (P=8.0 x 10(-13)) and the numbers of HLA-DQ A1*0501-B1*0201 haplotypes (P=2.4 x 10(-5)) and DQ A1*0301-B1*0302 haplotypes (P=0.002). GIMAP5 polymorphism was not associated with type I diabetes or with GAD65 or insulin autoantibodies, ICA, or age at clinical onset in patients. These data suggest that the GIMAP5 gene is associated with islet autoimmunity in type I diabetes and add to recent findings implicating the same SNP in another autoimmune disease.     

Characterization of antibody responses to endogenous and exogenous antigen in the nonobese diabetic mouse

It is suggested that a T-helper cell 2 (Th2) shift and Th2 spreading of autoimmunity following immunization with beta-cell antigen causes diabetes protection. To address this, antibody titer and subclass to insulin, glutamic acid decarboxylase (GAD)65, IA-2, and IA-2beta proteins were measured by radiobinding assays in untreated or immunized female nonobese diabetic mice. Untreated nonobese diabetic mice developed autoantibodies to insulin (IAA), but not GAD or IA-2/IA-2beta, and IAA-positive mice had increased diabetes risk (P < 0.001). IAA were IgG1 and IgG2b. In immunized mice, IgG1 and lesser IgG2b insulin antibodies were promoted by subcutaneous injection of insulin plus incomplete Freund's adjuvant, insulin plus Montanide ISA 720, and glucagon plus incomplete Freund's adjuvant, but not by incomplete Freund's adjuvant plus GAD65, IA-2beta, or phenylethanolamine N-methyltransferase, or adjuvant alone. Diabetes incidence was significantly reduced in immunized groups with elevated insulin antibody (IA) responses. Spreading of antibody responses to GAD or IA-2/IA-2beta following immunization was rare, and antibody epitope spreading was only detected in IA-2beta immunized mice. Humoral autoimmunity in nonobese diabetic mice is, therefore, limited to IAA with Th2 subclass phenotype and is associated with increased diabetes risk. This contrasts the diabetes protection provided by immunization protocols that promote this response and suggests that Th2 immunity may not be the principal regulator of beta-cell destruction in autoimmune diabetes.     

Disease-associated autoantibodies and HLA-DQB1 genotypes in children with newly diagnosed insulin-dependent diabetes mellitus (IDDM). The Childhood Diabetes in Finland Study Group

The possible relation between HLA-DQ genotypes and both frequencies and levels of autoantibodies associated with IDDM was assessed by examining HLA-DQB1 alleles and antibodies to islet cells (ICA), insulin (IAA), glutamic acid decarboxylase (GADA) and the protein tyrosine phosphatase-related IA-2 molecule (IA-2A) in 631 newly diagnosed diabetic children under the age of 15 years. ICA were found in 530 children (84.0%), while close to half of the subjects (n = 307; 48.7%) tested positive for IAA. GADA were detected in 461 index cases (73.1%), with a higher frequency in those older than 10 years (78.9% versus 69.2% in the younger ones; P = 0.006). More than 85% of the children (n = 541; 85.7%) tested positive for IA-2A. Altogether there were only 11 children (1.7%) who had no detectable autoantibodies at diagnosis. There were no differences in the prevalence of ICA or GADA between four groups formed according to their HLA-DQB1 genotype (DQB1*0302/02, *0302/X (X = other than *02), *02/Y (Y = other than *0302) and other DQB1 genotypes). The children with the *0302/X genotype had a higher frequency of IA-2A and IAA than those carrying the *02/Y genotype (93.8% versus 67.3%, P < 0.001; and 49.0% versus 33.6%, P = 0.002, respectively). The children with the *02/Y genotype had the highest GADA levels (median 36.2 relative units (RU) versus 14.9 RU in those with *0302/X; P = 0.005). Serum levels of IA-2A and IAA were increased among subjects carrying the *0302/X genotype (median 76.1 RU versus 1.6 RU, P = 0.001; and 50 nU/ml versus 36 nU/ml, P = 0.004) compared with those positive for *02/Y. Only three out of 11 subjects homozygous for *02 (27.3%) tested positive for IA-2A, and they had particularly low IA-2A (median 0.23 RU versus 47.6 RU in the other subjects; P < 0.001). The distribution of HLA-DQB1 genotypes among autoantibody-negative children was similar to that in the other patients. These results show that DQB1*0302, the most important single IDDM susceptibility allele, is associated with a strong antibody response to IA-2 and insulin, while GAD-specific humoral autoimmunity is linked to the *02 allele, in common with a series of other autoimmune diseases as well as IDDM. We suggest that IA-2A may represent beta cell-specific autoimmunity, while GADA may represent a propensity to general autoimmunity.     

Appearance of islet cell autoantibodies after clinical diagnosis of diabetes mellitus

Islet cell antibodies (ICA) and glutamic acid decarboxylase antibodies (GAD65Ab) are often present at diagnosis of insulin dependent diabetes mellitus (type I diabetes) and are supposed to decline in level and frequency during the first years of disease. We have analysed ICA and GAD65Ab at onset and after one year in 395 population based randomly selected 15-34 year old patients newly diagnosed with diabetes mellitus, to study how these autoantibodies persist, disappear and appear and their relation to C-peptide levels. Of the 395 samples 212 (54%) were positive for ICA, 250 (63%) were positive for GAD65Ab and 170 (43%) were positive for both. At follow up after one year, 27/183 (15%) of the ICA negative patients and 25/145 (17%) of the GAD65Ab negative patients had converted to positivity. Among the 103 patients negative for both ICA and GAD65Ab, 16 turned positive for one or both antibodies after one year. Patients converting to positivity for one or the other antibody after one year, had lower C-peptide levels after one year than patients who initially were and remained negative, supporting the hypothesis that these patients have a genuine type I diabetes. In conclusion, newly diagnosed patients may be negative for autoantibodies at diagnosis but develop these antibodies later on during the disease.     

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.     

Accelerated progression from islet autoimmunity to diabetes is causing the escalating incidence of type 1 diabetes in young children

The incidence of type 1 diabetes is rising worldwide, particularly in young children. Since type 1 diabetes is preceded by autoimmunity to islet antigens, there must be a consequent increase in the incidence of islet autoimmunity in young children or a more rapid rate of progression to diabetes once islet autoimmunity initiates. This study was to determine whether the incidence of islet autoimmunity or the rate of progression from autoimmunity to diabetes onset has changed over a 20-year period in children genetically predisposed to type 1 diabetes. Between 1989 and 2010, children who were first-degree relatives of patients with type 1 diabetes and who were born in Germany were prospectively followed from birth without intervention. A total of 324 children (BABYDIAB study) born between 1989 and 2000 and 216 children (TEDDY study) born between 2004 and 2010 with matched HLA genotypes were recruited before age 3 months and included for analysis. Children were followed for the development of autoantibodies to insulin, GAD, and IA-2, and for progression to diabetes. The cumulative frequency of diabetes by age 4 years was 2.5% (95% CI 0.8-4.2%) in BABYDIAB children and 6.2% (95% CI 2.3-10.1%) in TEDDY children (p = 0.03). The cumulative frequency of islet autoantibodies by age 4 years was similar in the children from both studies (11.3% vs 13.9%). Progression to diabetes from the development of islet autoantibodies was markedly increased in autoantibody-positive children from the more recently recruited TEDDY cohort (50% progression within 85.2 months for BABYDIAB children vs 9.6 months for TEDDY children; p = 0.009), also if children were further selected on the basis of high-risk HLA genotypes or the development of autoantibodies to multiple islet antigens (p = 0.01). The findings suggest that recent increasing incidence of type 1 diabetes in young children could be due to weakening of mechanisms that normally regulate autoimmune destruction of islet beta cells.     

T cell responses to enterovirus antigens and to beta-cell autoantigens in unaffected children positive for IDDM-associated autoantibodies.

Enterovirus infections have been implicated in the pathogenesis of IDDM in a number of studies. The aim of the present study was to evaluate whether the cellular immune response to enterovirus antigens is abnormal in children who test positive for IDDM-associated autoantibodies. Lymphocyte proliferation responses were analysed to enterovirus antigens and to a panel of beta-cell autoantigen preparations in 31 non-diabetic ICA and/or GAD65 antibody-positive children and in 19 ICA/GAD65-negative control children. The responses to highly purified enteroviruses did not differ between autoantibody (AA)-positive and -negative subjects. However, proliferation responses to coxsackievirus-infected cell lysate, which also included non-structural proteins of the virus, were higher in AA-positive than in AA-negative subjects (P<0.05). This difference was most marked in children carrying the HLA-DQB1*02 allele (P=0.01). AA-positive subjects also had higher responses to one of the three GAD65 antigen preparations compared to AA-negative subjects (P<0.05). Proliferation responses to the adenovirus hexon protein did not differ between the groups. These results show that the increased responses to virus infected cell lysates are associated with early phases of beta-cell autoimmunity.     

Association between insulin resistance and GAD65-autoantibody levels--a pilot study in an adult non-diabetic population

The aim of this pilot study was to investigate any association between insulin resistance (IR) and serum levels of autoantibodies against the glutamic acid decarboxylase (GAD65Ab) among adult non-diabetic subjects. Based on calculations of IR using the IR homeostasis model in a Swedish adult non-diabetic population (n = 756) participating in the WHO MONICA-study, an insulin sensitive group (n = 54, M/F:27/27) and an insulin resistant group (n = 46 M/F:24/22) were identified. Serum from the subjects were analysed for the presence of GAD65Ab. There was no significant difference in GAD65Ab levels between the groups. However, there was a correlation between IR and serum GAD65Ab within the insulin sensitive group (Spearman rho 0.4, p < 0.01). Our observation could indicate that IR could serve as an initiator or a progression factor in the autoimmune process in subjects predisposed to autoimmunity. This finding will be further investigated in a larger study including subjects with a continuum of IR.     

Pancreatic autoantibodies in Tunisian children with newly diagnosed type 1 diabetes

We analyzed 86 children with newly diagnosed type 1 diabetes for antibodies to islet cells (ICA), glutamic acid decarboxylase (GADA), second-islet antigen (IA-2A), and insulin (IAA) in order to evaluate the prevalence of immune-mediated type 1 diabetes, as well as to recognize which autoantibody combination is more frequently associated with the disease. A positive result for one or more diabetes-related antibodies evaluated was found in 78 children (90.7%). With regard to single autoantibody testing, ICA were found to be positive in 49 patients (57%), GADA in 56 (65.1%), IA-2A in 37 (43%), and IAA in 43 (50%) patients. Combining the determination of at least two autoantibodies, GADA and/or IAA were better detectable than other antibody combination, being positive in 70 patients (81.4%). GADA and IA-2A represent also a useful screening combination; being positive in 65 patients (75.6%). Our data indicate that the vast majority of cases of type 1 diabetes in children may be considered as immune-mediated and that multiple autoantibody analysis improves identification of the disease.     

Prevalence of autoantibodies in children newly diagnosed with type 1 diabetes mellitus

Type 1 diabetes mellitus (T1DM) is an increasingly encountered chronic illness in Saudi Arabia. It is known to have an immune-mediated pathogenesis, which results in the loss of insulin-secreting beta-cells responsible for maintaining normal blood glucose levels. The three main autoantibodies identified to play a role in the pathogenesis are islet cell antibodies (ICA), insulin autoantibodies (IAA) and glutamic acid decarboxylase antibodies (GAD). This study aims to determine at what age during childhood the autoantibodies ICA, IAA and GAD are most prevalent, and identify any correlation between their presence and the severity of the initial clinical presentation. Medical records of children diagnosed with T1DM in Riyadh in 2000-2007 were reviewed, and a total of 98 patients were included in the study (age range: 1-12 years, mean: 6.6 years, equal numbers by gender), of which 49% presented with diabetic ketoacidosis (DKA). Results showed that 67% were positive for ICA, 36% for IAA and 84.4% for GAD. The presence of ICA was predominant in children aged under six years. The presence of ICA and GAD in the absence of IAA was associated with more severe clinical presentation.