A prospective study of the development of diabetes in relatives of patients with insulin-dependent diabetes

Pancreatic islet reserve in type 1 diabetes

Type 1 diabetes (T1D) is a chronic autoimmune disease characterized by pancreatic islet β cell loss and dysfunction resulting in insulin deficiency and hyperglycemia. During a presymptomatic phase of established β cell autoimmunity, β cell loss may first be evident through assessment of β cell secretory capacity, a measure of functional β cell mass. Reduction in pancreatic islet β cell reserve eventually manifests as impaired first-phase insulin response to glucose and abnormal glucose tolerance, which progresses until the functional capacity for β cell secretion can no longer meet the demand for insulin to control glycemia. A functional β cell mass of ∼25% of normal may be required to avoid symptomatic T1D but is already associated with dysregulated glucagon secretion. With symptomatic T1D, stimulated C-peptide levels >0.60 ng/mL (0.200 pmol/mL) indicate the presence of clinically meaningful residual β cell function for contributing to glycemic control, although even higher residual C-peptide appears necessary for evidencing glucose-dependent islet β and α cell function that may contribute to maintaining (near)normal glycemia. β cell replacement by islet transplantation can restore a physiologic reserve capacity for insulin secretion, confirming thresholds for functional β cell mass required for independence from insulin therapy.

Perinatal risk factors for type 1 diabetes revisited: a population-based register study

AIMS/HYPOTHESIS

Single-centre studies and meta-analyses have found diverging results as to which early life factors affect the risk of type 1 diabetes during childhood. We wanted to use a large, nationwide, prospective database to further clarify and analyse the associations between perinatal factors and the subsequent risk for childhood-onset type 1 diabetes using a case-control design.

METHODS

The Swedish Childhood Diabetes Register was linked to the Swedish Medical Birth Register and National Patient Register, and 14,949 cases with type 1 diabetes onset at ages 0-14 years were compared with 55,712 matched controls born from the start of the Medical Birth Register in 1973 to 2013. After excluding confounders (i.e. children multiple births, those whose mother had maternal diabetes and those with a non-Nordic mother), we used conditional logistic regression analyses to determine risk factors for childhood-onset type 1 diabetes. We used WHO ICD codes for child and maternal diagnoses.

RESULTS

In multivariate analysis, there were small but statistically significant associations between higher birthweight z score (OR 1.08, 95% CI 1.06, 1.10), delivery by Caesarean section (OR 1.08, 95% CI 1.02, 1.15), premature rupture of membranes (OR 1.08, 95% CI 1.01, 1.16) and maternal urinary tract infection during pregnancy (OR 1.39, 95% CI 1.04, 1.86) and the subsequent risk of childhood-onset type 1 diabetes. Birth before 32 weeks of gestation was associated with a lower risk of childhood-onset type 1 diabetes compared with full-term infants (OR 0.54, 95% CI 0.38, 0.76), whereas birth between 32 and 36 weeks' gestation was associated with a higher risk (OR 1.24, 95% CI 1.14, 1.35). In subgroup analyses (birth years 1992-2013), maternal obesity was independently associated with subsequent type 1 diabetes in the children (OR 1.27, 95% CI 1.15, 1.41) and rendered the association with Caesarean section non-significant. In contrast to previous studies, we found no association of childhood-onset type 1 diabetes with maternal-child blood-group incompatibility, maternal pre-eclampsia, perinatal infections or treatment of the newborn with phototherapy for neonatal jaundice. The proportion of children with neonatal jaundice was significantly higher in the 1973-1982 birth cohort compared with later cohorts.

CONCLUSIONS/INTERPRETATION

Perinatal factors make small but statistically significant contributions to the overall risk of childhood-onset type 1 diabetes. Some of these risk factors, such as maternal obesity, may be amendable with improved antenatal care. Better perinatal practices may have affected some previously noted risk factors over time.

Characterisation of rapid progressors to type 1 diabetes among children with HLA-conferred disease susceptibility

AIMS/HYPOTHESIS

In this study, we aimed to characterise rapid progressors to type 1 diabetes among children recruited from the general population, on the basis of HLA-conferred disease susceptibility.

METHODS

We monitored 7410 HLA-predisposed children participating in the Finnish Type 1 Diabetes Prediction and Prevention (DIPP) study for the development of beta cell autoimmunity and type 1 diabetes from birth over a median follow-up time of 16.2 years (range 0.9-21.1 years). Islet cell antibodies (ICA) and autoantibodies to insulin (IAA), GAD (GADA) and islet antigen 2 (IA-2A) were assessed as markers of beta cell autoimmunity. Rapid progression was defined as progression to clinical type 1 diabetes within 1.5 years of autoantibody seroconversion. We analysed the association between rapid progression and demographic and autoantibody characteristics as well as genetic markers, including 25 non-HLA SNPs predisposing to type 1 diabetes.

RESULTS

Altogether, 1550 children (21%) tested positive for at least one diabetes-associated autoantibody in at least two samples, and 248 (16%) of seroconverters progressed to type 1 diabetes by the end of 2015. The median time from seroconversion to diagnosis was 0.51 years in rapid progressors (n = 42, 17%) and 5.4 years in slower progressors. Rapid progression was observed both among young (<5 years) and early pubertal children (>7 years), resulting in a double-peak distribution of seroconversion age. Compared with slower progressors, rapid progressors had a higher frequency of positivity for multiple (≥2) autoantibodies and had higher titres of ICA, IAA and IA-2A at seroconversion, and there was a higher prevalence of the secretor genotype in the FUT2 gene among those carrying the high-risk HLA genotype. Compared with autoantibody-positive non-progressors, rapid progressors were younger, were more likely to carry the high-risk HLA genotype and a predisposing SNP in the PTPN22 gene, had higher frequency of ICA, IAA, GADA and IA-2A positivity and multipositivity, and had higher titres of all four autoantibodies at seroconversion.

CONCLUSIONS/INTERPRETATION

At seroconversion, individuals with rapid progression to type 1 diabetes were characterised by a younger age, higher autoantibody titres, positivity for multiple autoantibodies and higher prevalence of a FUT2 SNP. The double-peak profile for seroconversion age among the rapid progressors demonstrates for the first time that rapid progression may take place not only in young children but also in children in early puberty. Rapid progressors might benefit from careful clinical follow-up and early preventive measures.

Re-exposure to beta cell autoantigens in pancreatic allograft recipients with preexisting beta cell autoantibodies

Re-exposure to beta cell autoantigens and its relevance in the presence of donor-specific antibodies (DSA) in pancreatic allograft recipients is not well known. Thirty-three patients requiring a pancreas transplant were enrolled in an IRB approved study. They underwent prospective monitoring for DSA and beta cell autoantibody (BCAA) levels to GAD65, insulinoma-associated antigen 2 (IA-2), insulin (micro-IAA [mIAA]), and islet-specific zinc transporter isoform-8 (ZnT8). Twenty-five (75.7%) had pre-transplant BCAA. Twenty had a single antibody (mIAA n = 15, GAD65 n = 5); five had two or more BCAA (GAD65 + mIAA n = 2, GAD65 + mIAA+IA-2 n = 2, GA65 + mIAA+IA-2 + ZnT8 = 1). No changes in GAD65 (p > 0.29), IA-2 (>0.16), and ZnT8 (p > 0.07) were observed between pre-transplant and post-transplant at 6 or 12 months. A decrease in mIAA from pre- to post-6 months (p < 0.0001), 12 months (p < 0.0001), and from post-6 to post-12 months (p = 0.0002) was seen. No new BCAA was observed at one yr. Seven (21.0%) developed de novo DSA. The incidence of DSA was 24% in patients with BCAA vs. 25% in patients without BCAA (p = 0.69). Pancreatic allograft function of patients with vs. without BCAA, and with and without BCAA + DSA was comparable until last follow-up (three yr). Re-exposure to beta cell autoantigens by pancreas transplant may not lead to increased levels or development of new BCAA or pancreatic allograft dysfunction.

Autoimmune responses in T1DM: quantitative methods to understand onset, progression, and prevention of disease

Understanding the physiological processes that underlie autoimmune disorders and identifying biomarkers to predict their onset are two pressing issues that need to be thoroughly sorted out by careful thought when analyzing these diseases. Type 1 diabetes (T1D) is a typical example of such diseases. It is mediated by autoreactive cytotoxic CD4⁺ and CD8⁺ T-cells that infiltrate the pancreatic islets of Langerhans and destroy insulin-secreting β-cells, leading to abnormal levels of glucose in affected individuals. The disease is also associated with a series of islet-specific autoantibodies that appear in high-risk subjects (HRS) several years prior to the onset of diabetes-related symptoms. It has been suggested that T1D is relapsing-remitting in nature and that islet-specific autoantibodies released by lymphocytic B-cells are detectable at different stages of the disease, depending on their binding affinity (the higher, the earlier they appear). The multifaceted nature of this disease and its intrinsic complexity make this disease very difficult to analyze experimentally as a whole. The use of quantitative methods, in the form of mathematical models and computational tools, to examine the disease has been a very powerful tool in providing predictions and insights about the underlying mechanism(s) regulating its onset and development. Furthermore, the models developed may have prognostic implications by aiding in the enrollment of HRS into trials for T1D prevention. In this review, we summarize recent advances made in determining T- and B-cell involvement in T1D using these quantitative approaches and delineate areas where mathematical modeling can make further contributions in unraveling certain aspect of this disease.

Autoantibody and human leukocyte antigen profiles in children with autoimmune liver disease and their first-degree relatives

OBJECTIVE

Familial clustering of juvenile autoimmune liver disease (AILD), including autoimmune hepatitis and autoimmune sclerosing cholangitis (ASC), is rare, despite a high prevalence of autoimmune disorders in AILD families.

METHODS

To investigate this discrepancy, we measured autoantibodies diagnostic for AILD, anti-nuclear, anti-smooth muscle, anti-liver kidney microsomal type 1, anti-liver cytosol type 1, and anti-soluble liver antigen antibodies, and human leukocyte antigen profiles in 31 patients and 65 of their first-degree relatives (FDR). The autoantibody profile was compared with that of 42 healthy subjects (HS).

RESULTS

Autoantibodies were detected in 71% (22/31) patients. Anti-nuclear antibody or anti-smooth muscle antibody were present in 4/65 FDR (6.2%). HS were negative for all autoantibodies. The frequencies of homozygous HLA DRB1*0301 (DR3) genes and haplotype A1-B8-DR3 were higher in the patients (25% and 43%) than in FDR (9% and 27%) and HS (0% and 16%). The frequencies of disease-protective genes DR4 and/or DR15 were lower in the patients (25%) than in FDR (42%) and HS (42%). Only 1 family contained 2 patients with AILD, 1 with ASC and 1 with primary sclerosing cholangitis. Both patients possessed A1-B8-DR3 genes, the ASC being homozygous and the primary sclerosing cholangitis heterozygous. Six FDR had nonhepatic autoimmune disorders, none being autoantibody positive.

CONCLUSIONS

Homozygosity for DR3 plays a major role in the predisposition to juvenile AILD. Diagnostic autoantibodies for AILD are rare among patients' FDR and not linked to clinical manifestation of AILD.

Type 1 diabetes: translating mechanistic observations into effective clinical outcomes

Type 1 diabetes (T1D) remains an important health problem, particularly in western countries, where the incidence has been increasing in younger children. In 1986, Eisenbarth described T1D as a chronic autoimmune disease. Work over the past three-and-a-half decades has identified many of the genetic, immunological and environmental factors that are involved in the disease and have led to hypotheses concerning its pathogenesis. Clinical trials have been conducted to test these hypotheses but have had mixed results. Here, we discuss the findings that have led to our current concepts of the disease mechanisms involved in T1D and the clinical studies promoted by these studies. The findings from preclinical and clinical studies support the original proposed model for how T1D develops but have also suggested that this disease is more complex than was originally thought and will require broader treatment approaches.

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.

Islet autoantibody seroconversion in the DPT-1 study: justification for repeat screening throughout childhood

OBJECTIVE

Although type 1 diabetes autoimmunity frequently begins in childhood, little is known about the relationship between age and autoimmunity development. Our aim was to determine the timing of seroconversion to diabetes-associated autoantibody (DAA) positivity and risk in first- and second-degree relatives of patients with type 1 diabetes.

RESEARCH DESIGN AND METHODS

Study subjects were identified through the Diabetes Prevention Trial-Type 1 (DPT-1). Children 3-18 years of age (n = 42,447) were screened for DAAs; 1,454 were ICA positive (≥ 10 JDF units), 1,758 were GAD65 positive, and 899 were ICA512 positive at the time of initial screening. Subjects who were initially antibody negative (n = 39,212) were recalled for rescreening, and 11,813 returned for rescreening.

RESULTS

DAA seroconversion occurred in 469 (4%) children; 258 seroconverted to ICA, 234 to GAD65, and 99 to ICA512. The median time to seroconversion was 2 years. The 2-year risk for DAAs was highest in early childhood. For each 1-year increase in age in this cohort, the risk of any autoantibody seroconversion (HR 0.95, 95% CI 0.92-0.97) decreased by 5%, and for any two autoantibodies risk decreased by 13% (0.87, 0.82-0.93).

CONCLUSIONS

Risk of autoantibody seroconversion among children followed in DPT-1 is age dependent. Younger children have the highest risk for DAAs, with the majority of children seroconverting by 13 years of age (75%). This suggests that annual screenings should be started in early childhood and continued through early adolescence to identify the majority of subjects at risk for type 1 diabetes and eligible for prevention trials.

Prognostic performance of metabolic indexes in predicting onset of type 1 diabetes

OBJECTIVE

In this investigation we evaluated nine metabolic indexes from intravenous glucose tolerance tests (IVGTTs) and oral glucose tolerance tests (OGTTs) in an effort to determine their prognostic performance in predicting the development of type 1 diabetes in those with moderate risk, as defined by familial relation to a type 1 diabetic individual, a positive test for islet cell antibodies and insulin autoantibody, but normal glucose tolerance.

RESEARCH DESIGN AND METHODS

Subjects (n = 186) who had a projected risk of 25-50% for developing type 1 diabetes within 5 years were followed until clinical diabetes onset or the end of the study as part of the Diabetes Prevention Trial-Type 1. Prognostic performance of the metabolic indexes was determined using receiver operating characteristic (ROC) curve and survival analyses.

RESULTS

Two-hour glucose from an OGTT most accurately predicted progression to disease compared with all other metabolic indicators with an area under the ROC curve of 0.67 (95% CI 0.59-0.76), closely followed by the ratio of first-phase insulin response (FPIR) to homeostasis model assessment of insulin resistance (HOMA-IR) with an area under the curve value of 0.66. The optimal cutoff value for 2-h glucose (114 mg/dl) maintained sensitivity and specificity values >0.60. The hazard ratio for those with 2-h glucose ≥ 114 mg/dl compared with those with 2-h glucose <114 mg/dl was 2.96 (1.67-5.22).

CONCLUSIONS

The ratio of FPIR to HOMA-IR from an IVGTT provided accuracy in predicting the development of type 1 diabetes similar to that of 2-h glucose from an OGTT, which, because of its lower cost, is preferred. The optimal cutoff value determined for 2-h glucose provides additional guidance for clinicians to identify subjects for potential prevention treatments before the onset of impaired glucose tolerance.

Progression to diabetes in relatives of type 1 diabetic patients: mechanisms and mode of onset

OBJECTIVE

Relatives of type 1 diabetic patients are at enhanced risk of developing diabetes. We investigated the mode of onset of hyperglycemia and how insulin sensitivity and beta-cell function contribute to the progression to the disease.

RESEARCH DESIGN AND METHODS

In 328 islet cell autoantibody-positive, nondiabetic relatives from the observational arms of the Diabetes Prevention Trial-1 Study (median age 11 years [interquartile range 8], sequential OGTTs (2,143 in total) were performed at baseline, every 6 months, and 2.7 years [2.7] later, when 115 subjects became diabetic. Beta-cell glucose sensitivity (slope of the insulin-secretion/plasma glucose dose-response function) and insulin sensitivity were obtained by mathematical modeling of the OGTT glucose/C-peptide responses.

RESULTS

In progressors, baseline insulin sensitivity, fasting insulin secretion, and total postglucose insulin output were similar to those of nonprogressors, whereas beta-cell glucose sensitivity was impaired (median 48 pmol/min per m2 per mmol/l [interquartile range 36] vs. 87 pmol/min per m2 per mmol/l [67]; P < 0.0001) and predicted incident diabetes (P < 0.0001) independently of sex, age, BMI, and clinical risk. In progressors, 2-h glucose levels changed little until 0.78 years before diagnosis, when they started to rise rapidly (approximately 13 mmol x l(-1) x year(-1)); glucose sensitivity began to decline significantly (P < 0.0001) earlier (1.45 years before diagnosis) than the plasma glucose surge. During this anticipation phase, both insulin secretion and insulin sensitivity were essentially stable.

CONCLUSIONS

In high-risk relatives, beta-cell glucose sensitivity is impaired and is a strong predictor of diabetes progression. The time trajectories of plasma glucose are frequently biphasic, with a slow linear increase followed by a rapid surge, and are anticipated by a further deterioration of beta-cell glucose sensitivity.

Predictive characteristics of diabetes-associated autoantibodies among children with HLA-conferred disease susceptibility in the general population

OBJECTIVE

As data on the predictive characteristics of diabetes-associated autoantibodies for type 1 diabetes in the general population are scarce, we assessed the predictive performance of islet cell autoantibodies (ICAs) in combination with autoantibodies against insulin (IAAs), autoantibodies against GAD, and/or islet antigen 2 for type 1 diabetes in children with HLA-defined disease predisposition recruited from the general population.

RESEARCH DESIGN AND METHODS

We observed 7,410 children from birth (median 9.2 years) for beta-cell autoimmunity and diabetes. If a child developed ICA positivity or diabetes, the three other antibodies were measured in all samples available from that individual. Persistent autoantibody positivity was defined as continued positivity in at least two sequential samples including the last available sample.

RESULTS

Pre-diabetic ICA positivity was observed in 1,173 subjects (15.8%), 155 of whom developed type 1 diabetes. With ICA screening, 86% of 180 progressors (median age at diagnosis 5.0 years) were identified. Positivity for four antibodies was associated with the highest disease sensitivity (54.4%) and negative predictive values (98.3%) and the lowest negative likelihood ratio (0.5). The combination of persistent ICA and IAA positivity resulted in the highest positive predictive value (91.7%), positive likelihood ratio (441.8), cumulative disease risk (100%), and specificity (100%). Young age at seroconversion, high ICA level, multipositivity, and persistent positivity for IAA were significant risk markers for type 1 diabetes.

CONCLUSIONS

Within the general population, the combination of HLA and autoantibody screening resulted in disease risks that are likely to be as high as those reported among autoantibody-positive siblings of children with type 1 diabetes.

A risk score for type 1 diabetes derived from autoantibody-positive participants in the diabetes prevention trial-type 1

OBJECTIVE

The accurate prediction of type 1 diabetes is essential for appropriately identifying prevention trial participants. Thus, we have developed a risk score for the prediction of type 1 diabetes.

RESEARCH DESIGN AND METHODS

Diabetes Prevention Trial-Type 1 (DPT-1) participants, islet cell autoantibody (ICA)-positive relatives of type 1 diabetic patients (n = 670), were randomly divided into development and validation samples. Risk score values were calculated for the validation sample from development sample model coefficients obtained through forward stepwise proportional hazards regression.

RESULTS

A risk score based on a model including log-BMI, age, log-fasting C-peptide, and postchallenge glucose and C-peptide sums from 2-h oral glucose tolerance tests (OGTTs) was derived from the development sample. The baseline risk score strongly predicted type 1 diabetes in the validation sample (chi(2) = 82.3, P < 0.001). Its strength of prediction was almost the same (chi(2) = 83.3) as a risk score additionally dependent on a decreased first-phase insulin response variable from intravenous glucose tolerance tests (IVGTTs). Biochemical autoantibodies did not contribute significantly to the risk score model. A final type 1 diabetes risk score was then derived from all participants with the same variables as those in the development sample model. The change in the type 1 diabetes risk score from baseline to 1 year was in itself also highly predictive of type 1 diabetes (P < 0.001).

CONCLUSIONS

A risk score based on age, BMI, and OGTT indexes, without dependence on IVGTTs or additional autoantibodies, appears to accurately predict type 1 diabetes in ICA-positive relatives.

Prediction and prevention of type 1 diabetes: progress, problems, and prospects

Type 1 diabetes mellitus (T1D) arises from selective immunologically mediated destruction of the insulin-producing beta-cells in the pancreatic islets of Langerhans with consequent insulin deficiency. This occurs in genetically susceptible individuals and is a cellular-mediated process, presumably a specific reaction to one or more beta-cell proteins (autoantigens), although probably initiated by some environmental factor(s). There is consequent progressive impairment of beta-cell function and decline in beta-cell mass. A secondary humoral immune response is characterized by the appearance of autoantibodies that serve as markers of the immune damage to beta-cells. This insidious T1D disease process evolves over a period of years. The decline in beta-cell function and mass is evidenced metabolically by loss of first-phase insulin response to an intravenous glucose challenge, and later by the appearance of impairment in glycemic regulation, manifested as dysglycemia--usually as impaired glucose tolerance, but occasionally as impaired fasting glucose. Ultimately, the clinical syndrome of T1D becomes evident when the majority of beta-cells have been destroyed and frank hyperglycemia supervenes. Given this sequence of events, for which it is possible to envision intervention to interdict the process, it is not surprising that much research effort has been expended to identify individuals at risk of the disease.

Increasing the accuracy of oral glucose tolerance testing and extending its application to individuals with normal glucose tolerance for the prediction of type 1 diabetes: the Diabetes Prevention Trial-Type 1

OBJECTIVE

We assessed the extent to which both standard and alternative indexes from 2-h oral glucose tolerance testing predict type 1 diabetes and whether oral glucose tolerance tests (OGTTs) predict type 1 diabetes in individuals with normal glucose tolerance.

RESEARCH DESIGN AND METHODS

The prediction of type 1 diabetes from baseline OGTTs was studied in 704 Diabetes Prevention Trial-Type 1 participants (islet-cell autoantibody [ICA]-positive relatives of type 1 diabetic patients). The maximum follow-up was 7.4 years. Analyses utilized receiver-operator curves (ROCs), proportional hazards models, and survival curves.

RESULTS

ROC areas under the curve (ROCAUCs) for both the AUC glucose (0.73 +/- 0.02) and an OGTT prediction index (0.78 +/- 0.02) were higher (P < 0.001) than those for the fasting (0.53 +/- 0.02) and 2-h glucose (0.66 +/- 0.02). ROCAUCs for the 60- and 90-min glucose (0.71 +/- 0.02 and 0.72 +/- 0.02, respectively) were also higher (P < 0.01) than those for the fasting and 2-h glucose. Among individuals with normal glucose tolerance, OGTTs were highly predictive, with 4th versus 1st quartile hazard ratios for the 2-h glucose, AUC glucose, and OGTT prediction index ranging from 3.77 to 5.30 (P < 0.001 for all).

CONCLUSIONS

Certain alternative OGTT indexes appear to better predict type 1 diabetes than standard OGTT indexes in ICA-positive relatives of type 1 diabetic patients. Moreover, even among those with normal glucose tolerance, OGTTs are strongly predictive. This suggests that subtle metabolic abnormalities are present several years before the diagnosis of type 1 diabetes.

Prospective familial assessment in dilated cardiomyopathy: cardiac autoantibodies predict disease development in asymptomatic relatives

BACKGROUND

In autoimmune disorders, circulating autoantibodies identify healthy relatives at risk years before clinical presentation. Healthy relatives of patients with dilated cardiomyopathy (DCM) who have echocardiographic changes, including left ventricular enlargement or depressed fractional shortening at baseline, have increased medium-term risk for DCM development. Approximately one third of relatives have serum anti-heart autoantibodies (AHAs) at baseline; we intended to assess their potential role in predicting DCM development.

METHODS AND RESULTS

Baseline evaluation, including electrocardiography, echocardiography, and AHA, was performed in 592 asymptomatic relatives of 169 consecutive DCM patients (291 males and 301 females; mean age 36+/-16 years). Relatives were classified in accordance with published echocardiographic criteria; those who did not have DCM were followed up (median of 58 months). DCM among relatives was diagnosed by echocardiography at follow-up. Of the 592 individuals evaluated, 77% were assessed as normal, 4.4% as having DCM, and 19% as possibly affected on the basis of depressed fractional shortening without ventricular dilatation in 17 and left ventricular enlargement without systolic dysfunction in 94. Five-year follow-up of 311 relatives revealed that 26 had progressed (13 to DCM, 11 to left ventricular enlargement, and 2 to depressed fractional shortening). Relatives who developed DCM were more frequently AHA-positive than those who did not (69% versus 37%, P=0.02). Five-year probability of progression to DCM, among normal or possibly affected relatives, was higher in AHA-positive cases (P=0.03). By Cox regression, positive AHAs at baseline were independent predictors of progression (RR 2.26, CI 1 to 5.1, P=0.03).

CONCLUSIONS

Among healthy relatives of DCM patients, AHAs are independent predictors of disease development within 5 years.

Dental management of patients with diabetes

Diabetes is a disease of metabolism resulting from impaired insulin secretion, varying degrees of insulin resistance, or both. Management of the diabetic dental patients must take into consideration the impact of dental disease and dental treatment on the management of diabetes as well as an appreciation for the comorbidities that accompany long-standing diabetes. Those comorbidities include obesity, hypertension, and dyslipidemia. Central to the management of diabetes is the intensive regulation of plasma glucose along with management of comorbidities comprising the "metabolic syndrome." Management of the diabetic dental patient should focus on periodontal health and the delivery of comprehensive dental care with minimal disruption of metabolic homeostasis and recognition of diabetic comorbidities.

Analysis of T-cell assays to measure autoimmune responses in subjects with type 1 diabetes: results of a blinded controlled study

Type 1 diabetes is a chronic autoimmune disease mediated by autoreactive T-cells. Several experimental therapies targeting T-cells are in clinical trials. To understand how these therapies affect T-cell responses in vivo, assays that directly measure human T-cell function are needed. In a blinded, multicenter, case-controlled study conducted by the Immune Tolerance Network, we tested responses in an immunoblot and T-cell proliferative assay to distinguish type 1 diabetic patients from healthy control subjects. Peripheral blood cells from 39 healthy control subjects selected for DR4 and 23 subjects with recently diagnosed type 1 diabetes were studied. Autoantibody responses were measured in serum samples. Positive responses in both assays were more common in peripheral blood mononuclear cells from new-onset type 1 diabetic patients compared with control subjects. The proliferative, immunoblot, and autoantibody assays had sensitivities of 58, 91, and 78% with specificities of 94, 83, and 85%, respectively. When cellular assays were combined with autoantibody measurements, the sensitivity of the measurements was 75% with 100% specificity. We conclude that cellular assays performed on peripheral blood have a high degree of accuracy in discriminating responses in subjects with type 1 diabetes from healthy control subjects. They may be useful for assessment of cellular autoimmune responses involved in type 1 diabetes.

Insulin and islet autoantibodies after pancreas transplantation

Autoimmune recurrence and subsequent diabetes after pancreas transplantation has been described. In this cross-sectional study 91 type 1 diabetic patients were examined after successful pancreas/kidney transplantation (SPK). We studied the prevalence of autoantibodies to insulin (IAA), glutamate decarboxylase (GAD) and tyrosine phosphatase (IA-2) as well as parameters of pancreas graft function. Graft recipients were grouped according to immunoreactivity: group 1: no immunoreactivity; group 2: immunoreactivity to one antigen; group 3: immunoreactivity to two or three antigens. Twenty-five percent of graft recipients displayed no immunoreactivity, 39% displayed positivity for one antigen and 36% were positive for two or three antigens. There were no significant differences concerning fasting glucose, HbA1(c), glucose tolerance and renal function between the groups. Patients with cyclosporine (n = 42) as first-line immunosuppression displayed more often immunoreactivity to IA-2 and IAA than patients treated with tacrolimus (n = 49) (31% vs. 14%, P = 0.04; 67% vs. 47%, P = 0.04). In addition methylprednisolone therapy was related to less immunoreactivity to IA-2. Immunological markers for type 1 diabetes can be determined in the majority of pancreas graft recipients despite adequate immunosuppression. However, immunoreactivity was not associated with impaired graft function. Patients with cyclosporine for immunosuppression and withdrawal of glucocorticoids therapy were more often immunoreactive to IAA and IA-2.

Patterns of metabolic progression to type 1 diabetes in the Diabetes Prevention Trial-Type 1

OBJECTIVE

There is little information regarding the pattern of metabolic deterioration before the onset of type 1 diabetes. The goal of this study was to utilize data from the Diabetes Prevention Trial-Type 1 (DPT-1) to obtain a picture of the metabolic progression to type 1 diabetes over a period of approximately 2.5 years before its diagnosis.

RESEARCH DESIGN AND METHODS

Fifty-four DPT-1 participants (22 in the parenteral trial and 32 in the oral trial) were studied. All had oral glucose tolerance tests (OGTTs) at 6-month intervals from approximately 30 to 6 months before diagnosis. The vast majority also had OGTTs at diagnosis. Changes in OGTT glucose and C-peptide indexes from 30 to 6 months before diagnosis were examined by calculating slopes of the indexes for each individual over that time period. Changes from 6 months before diagnosis to diagnosis were examined by paired comparisons of the OGTT metabolic indexes between the time points.

RESULTS

Glucose levels increased gradually from 30 to 6 months before diagnosis in both the parenteral and oral groups (P < 0.001 for all indexes). Area under the curve (AUC) C-peptide (P < 0.05) and AUC C-peptide-to-AUC glucose ratio (P < 0.001) values decreased in the oral group; peak C-peptide-to-2-h glucose ratio values decreased in both groups (P < 0.001). In participants who also had OGTTs at diagnosis, AUC C-peptide (parenteral group, P < 0.05) and peak C-peptide (oral group, P < 0.05) values decreased from the last 6 months before diagnosis; stimulated C-peptide-to-glucose ratio values decreased in both groups (P < 0.001). Conversely, fasting C-peptide levels increased in both groups (oral group, P < 0.01). Fasting C-peptide-to-fasting glucose ratio values remained constant throughout the 30-month follow-up.

CONCLUSIONS

These data indicate that over a period of at least 2 years, glucose tolerance gradually deteriorates as stimulated C-peptide levels slowly decline in a substantial number of individuals who develop type 1 diabetes. However, fasting C-peptide levels are maintained, even at diagnosis.

Nicotinamide protected first-phase insulin response (FPIR) and prevented clinical disease in first-degree relatives of type-1 diabetics

BACKGROUND

After a study of ICA prevalence among relatives of Type-1 diabetics (DM1) in Santiago, Chile, parents of those who tested positive asked us to go on forward with an intervention study.

METHODS

We had screened 1021 relatives, of which 30 had shown ICA > or = 20 JDF units (2.9%). Among the 26/30 who participated in the intervention study, the baseline screening showed normal glucose tolerance in all, and the first-phase insulin response (FPIR) was normal in 24/26 individuals, which were randomized into Nicotinamide (n = 12; oral Nicotinamide, 1200 mg m(-2) day(-1)) and Placebo (n = 12) groups. The FPIRs and ICAs were monitored yearly. Compliance was monitored by urine Nicotinamide.

RESULTS

The 1.5, 3.0 and 5-year life-table estimates of keeping the FPIR > or = 10th centile were, for Nicotinamide group 100% in all time points, and for Placebo these were 90.0% (c.i. = 100-71.4), 72.0% (c.i. = 100-37.1) and 0.0% (c.i. = 0.0-0.0) (p = 0.0091). The 5-year life-table estimates of remaining diabetes-free were 100% for Nicotinamide and 62.5% for Placebo (p = 0.0483). No adverse effects were observed.

CONCLUSIONS

Oral Nicotinamide protected beta-cell function and prevented clinical disease in ICA-positive first-degree relatives of type-1 diabetes.

Achieving antigen-specific tolerance in diabetes: regulating specifically

Autoreactive T cells that escape negative selection in the thymus do not normally cause productive immune responses to self-antigens because of a number of regulatory mechanisms. Studies with anti-CD3 monoclonal antibodies (mAbs) have suggested that immune regulatory mechanisms are induced by drug treatments that are able to stop on-going unwanted immune responses, such as type 1 diabetes, involving induction of regulatory T cells. TGF-beta dependent and independent mechanisms have been described involving CD4(+) as well as CD8(+) T cells. The challenge is now to apply these mechanisms in an antigen-specific manner and so that lasting tolerance to the autoimmune responses can be maintained. We discuss recent data concerning the mechanisms of anti-CD3 mAb treatment and the ways in which our understanding of these mechanisms can be used to develop adoptive immune therapy with regulatory T cells to treat patients with type 1 diabetes or other autoimmune diseases.

Drug Insight: new immunomodulatory therapies in type 1 diabetes

Animal models and human studies have provided strong evidence that the immune response that causes type 1A diabetes is initiated against a limited array of antigens but acquires breadth and depth until beta-cell mass has been critically compromised. Two recent trials confirmed the ability to identify relatives at risk for development of diabetes, but were unsuccessful in preventing disease. Treatment of at-risk individuals with oral insulin, which is postulated to be an antigen in the disease, did however show efficacy in a subgroup of these subjects, suggesting that antigen-specific prevention approaches might be successful in the right group of subjects at the right time. Earlier trials showed that the natural progression of disease can be altered with conventional immune suppression but these approaches have been supplanted by tolerance-induction strategies. Anti-CD3 monoclonal antibodies have shown efficacy in preventing the loss of insulin production over the first 2 years of disease without chronic immune suppression. The mechanisms are novel, and appear to involve induction of immune regulation by the monoclonal antibody. Ultimately, preservation and even improvement in beta-cell mass is the goal of therapy. The means needed to achieve this will depend on the timing and mechanisms of the immune intervention and might require combinations of agents.

Can we slow the rising incidence of childhood-onset autoimmune diabetes? The overload hypothesis

Overload of the beta cell, mediated by a variety of mechanisms, may sensitise it to immune damage and apoptosis, and thus accelerate ongoing autoimmune processes leading to its destruction. Environmental risk determinants that may exert such overload effects include insulin resistance due to excess fat cell accumulation, and increased insulin requirement due to a high growth rate, physical stress (infection, inflammation) or psychological stress. The increasing incidence of childhood diabetes, and the shift to younger age at onset, is unlikely to be driven by environmental risk factors that have been associated with initiation of autoimmunity, e.g. virus infections or early infant feeding. Risk factors that may accelerate beta cell destruction have shown a steady increase in the population, and are more plausible causes of such a pattern of change. Child growth, weight and birthweight are well-established estimates of community wealth and increase in most countries of Europe. Overfeeding of children early in life leads to both accelerated growth and weight, and even a moderate excess of child growth, not necessarily associated with obesity, is associated with risk of type 1 diabetes. New, safe and effective immune-modulating drugs for possible arrest of the autoimmune process may become available in time, but in the interim these accelerating factors may be targeted. Public health programmes for pregnant mothers and young families, aiming at changing overfeeding and the sedentary lifestyle of the children would be preferable to other alternatives. Interventions such as these would be safe and could potentially influence future risks of type 1 and type 2 diabetes and other major threats to adult health.

Autoantibody markers for the diagnosis and prediction of type 1 diabetes

Type 1 diabetes results from the autoimmune destruction of the insulin producing pancreatic beta-cells. For years, the notion that T-lymphocytes played a crucial role in the disorder's formation was considered such sound dogma, that interest in B-lymphocytes and autoantibodies as pathogenic variables was largely relegated to second-class status. However, much of our knowledge regarding the pathogenesis and natural history of this disease has been afforded by analysis of subjects having type 1 diabetes associated autoantibodies. While autoantibodies to more than two dozen autoantigens have been associated with this disease, a majority of interest has been directed at four autoantibodies; islet cell cytoplasmic (ICA), insulin (IAA), glutamic acid decarboxylase (GADA), and IA2/ICA512 autoantigen (IA2A). These autoantibodies, combined with other metabolic and genetic markers, are extremely effective for predicting eventual development of type 1 diabetes in otherwise healthy individuals. These autoantibodies have also aided in our understanding of disease heterogeneity and suggest that the autoimmune processes underlying type 1 diabetes initiate in the earliest stages of life (e.g., initial autoantibody formation at 9-18 months of age). Additional improvements are needed to more accurately define the time to disease onset, response to therapeutic intervention, the pathogenic features of the autoimmune response, and perhaps even the quantity of residual beta cell function.

A look to the future: prediction, prevention, and cure including islet transplantation and stem cell therapy

Type 1 diabetes mellitus (T1DM) is characterized by the almost complete absence of insulin secretion, which is secondary to an autoimmune destruction or dysfunction of the insulin-producing cells of the pancreatic islets of Langerhans. Because T1DM is an autoimmune disease with a long preclinical course, the predictive testing of individuals before the clinical onset of the disease has provided a real opportunity for the identification of risk markers and the design of therapeutic intervention. With such a high degree of predictability using a combination of immunologic markers, strategies to prevent T1DM may become possible. A number of novel therapeutic strategies are under investigation in newly diagnosed T1DM patients and might ultimately be applied to prevent T1DM.

Autoantibodies in diabetes

Islet cell autoantibodies are strongly associated with the development of type 1 diabetes. The appearance of autoantibodies to one or several of the autoantigens-GAD65, IA-2, or insulin-signals an autoimmune pathogenesis of beta-cell killing. A beta-cell attack may be best reflected by the emergence of autoantibodies dependent on the genotype risk factors, isotype, and subtype of the autoantibodies as well as their epitope specificity. It is speculated that progression to beta-cell loss and clinical onset of type 1 diabetes is reflected in a developing pattern of epitope-specific autoantibodies. Although the appearance of autoantibodies does not follow a distinct pattern, the presence of multiple autoantibodies has the highest positive predictive value for type 1 diabetes. In the absence of reliable T-cell tests, dissection of autoantibody responses in subjects of genetic risk should prove useful in identifying triggers of islet autoimmunity by examining seroconversion and maturation of the autoantibody response that may mark time to onset of type 1 diabetes. The complexity of the disease process is exemplified by multiple clinical phenotypes, including autoimmune diabetes masquerading as type 2 diabetes in youth and adults. Autoantibodies may also provide prognostic information in clinically heterogeneous patient populations when examined longitudinally.

Cytoplasmic islet cell antibodies remain valuable in defining risk of progression to type 1 diabetes in subjects with other islet autoantibodies

The discovery of islet cell antibodies (ICAs) was the prelude to the understanding that type 1 diabetes mellitus (T1DM) is a chronic autoimmune disease. The issue regarding whether or not the measurement of ICAs should be completely replaced by biochemical markers detecting islet autoantibodies (AAs) for the prediction of T1DM has been the subject of endless international debates. In light of this controversy, we assessed the current role of ICAs as a predictive marker for T1DM progression. We examined a cohort of 1484 first-degree relatives (FDRs) of T1DM probands from the Children's Hospital of Pittsburgh Registry. These relatives were consecutively enrolled between 1979 through 1984 and followed up to 22 yr. Serum obtained at the time of enrollment was assayed for ICAs, glutamic acid decarboxylase (GAD)65, insulin A (IA)-2 AA, and insulin AAs (IAAs). In FDRs who had ICAs in addition to GAD65 and IA-2 AAs, the cumulative risk of developing insulin-requiring diabetes was 80% at 6.7 yr of follow-up, whereas this risk in those with GAD65 and IA-2 AAs without ICAs was only 14% at 10 yr of follow-up (log rank: P < 0.00001). Cox regression analysis showed that diabetes risk was significantly associated with the presence of ICAs in both subjects with low titer and high titer GAD65 and IA-2 AAs. The addition of IAAs in GAD65 and IA-2 AA-positive relatives did not increase the cumulative risk for conversion to insulin-treated diabetes. We provide evidence that a subgroup of ICAs predicts a more rapid progression to insulin-requiring diabetes in GAD65 and IA-2 AA-positive relatives and should remain part of the assessment of T1DM risk for intervention trials. In addition, these findings provide impetus for efforts to identify a novel islet autoantigen(s) reactive with this ICA subset.

Developments in the prediction of type 1 diabetes mellitus, with special reference to insulin autoantibodies

The prodromal phase of type 1 diabetes is characterised by the appearance of multiple islet-cell related autoantibodies (Aab). The major target antigens are islet-cell antigen, glutamic acid decarboxylase (GAD), protein-tyrosine phosphatase-2 (IA-2) and insulin. Insulin autoantibodies (IAA), in contrast to the other autoimmune markers, are the only beta-cell specific antibodies. There is general consensus that the presence of multiple Aab (> or = 3) is associated with a high risk of developing diabetes, where the presence of a single islet-cell-related Aab has usually a low predictive value. The most commonly used assay format for the detection of Aab to GAD, IA-2 and insulin is the fluid-phase radiobinding assay. The RBA does not identify or measure Aab, but merely detects its presence. However, on the basis of molecular studies, disease-specific constructs of GAD and IA-2 have been employed leading to somewhat improved sensitivity and specificity of the RBA. Serological studies have shown epitope restriction of IAA that can differentiate diabetes-related from unrelated IAA, but current assays do not distinguish between disease-predictive and non-predictive IAA or between IAA and insulin antibodies (IA). More recently, phage display technology has been successful in identifying disease-specific anti-idiotopes of insulin. In addition, phage display has facilitated the in vitro production of antibodies with high affinity. Identification of disease-specific anti-idiotopes of insulin should enable the production of a high affinity reagent against the same anti-idiotope. Such a development would form the basis of a disease-specific radioimmunoassay able to identify and measure particular idiotypes, rather than merely detect and titrate IAA.

Dynamic changes of GAD65 autoantibody epitope specificities in individuals at risk of developing type 1 diabetes

AIMS/HYPOTHESIS

Progression to type 1 diabetes is associated with intramolecular epitope spreading to disease-specific antibody epitopes located in the middle region of glutamic acid decarboxylase 65 (GAD65).

METHODS

The relationship between intramolecular epitope spreading of autoantibodies specific to GAD65 in relation to the risk of developing type 1 diabetes was tested in 22 high-risk individuals and 38 low-risk individuals. We determined the conformational epitopes in this longitudinal study by means of competition experiments using recombinant Fab of four GAD65-specific monoclonal antibodies.

RESULTS

Sera from high-risk children in the preclinical stage recognise a specific combination of GAD65 antibody epitopes located in the middle and the C-terminus of GAD65. High risk of progressing to disease is associated with the emergence of antibodies specific for conformational epitopes at the N-terminus and the middle region. Binding to already established antibody epitopes located in the middle and at the N-terminus increases and shows a significant relation (p=0.005) with HLA, which confers risk of developing diabetes.

CONCLUSIONS/INTERPRETATION

In type 1 diabetes, GAD65 antibodies are initially generated against the middle and C-terminal regions of GAD65. In genetically predisposed subjects the autoimmune response may then undergo intramolecular epitope spreading towards epitopes on the N-terminus and further epitopes located in the middle. These findings clearly demonstrate that the GAD65 autoantibody response in the preclinical stage of type 1 diabetes is dynamic and related to the HLA genotypes that confer risk of diabetes. GAD65-specific Fab should prove useful in predicting progression from islet autoimmunity to clinical onset of type 1 diabetes.

A new model for understanding the role of environmental factors in the origins of chronic illness: a case study of type 1 diabetes mellitus

There is a need for a new pathophysiological model explaining and linking the role of numerous non-genetic factors believed to contribute to origins of many chronic physical diseases. This article presents a theoretical model for explaining the confusing and often contradictory findings regarding the role of environmental influences in type 1 diabetes, a disease that has been widely studied, for which clear diagnostic criteria exist, and for which development of effective prevention strategies represents significant challenges. The model is formulated from the large database of research regarding increasing understanding of the interaction between environmental factors, physiology, and autonomic regulatory function. Data is integrated from research in the fields of the experience-dependent maturation of the nervous system and the neurophysiology of traumatic stress to demonstrate how disruptions in early bonding and attachment, including adverse events such as traumatic stress, are capable of causing: (1) long-term imbalances in autonomic regulatory function and (2) relative dominance of sympathetic or parasympathetic activity. The proposed model of autonomic dysfunction suggests that ongoing mechanisms promoting high glucose in the context of decreasing insulin production in type 1 diabetes represent a state of relative sympathetic dominance influenced by environmental factors affecting autonomic, immune and endocrine systems during critical period programming. The model further identifies a link between the many seemingly unrelated non-genetic risk factors, and appears capable of explaining contradictions and enigmas in epidemiological and clinical studies regarding non-genetic origins of type 1 diabetes, including the role of stress, variation in age of onset, and duration of the preclinical phase.

Oral Insulin Therapy to Prevent Progression of Immune-Mediated (Type 1) Diabetes

Repeated ingestion of insulin has been suggested as an immune tolerization therapy to prevent immune-mediated (type 1) diabetes. We performed a placebo-controlled, two-dose, oral insulin tolerance trial in newly diagnosed (< 2 years) diabetic patients who had required insulin replacement for less than 4 weeks and were found to have cytoplasmic islet cell autoantibodies (ICAs). No oral hypoglycemic agents were permitted during the trial. Endogenous insulin reserves were estimated at six-month intervals by plasma C-peptide responses to a mixed meal. Positive ICAs were found in 262 (31%) of the 846 patients screened. Of the 197 who agreed to participate, 187 could be followed for 6 to 36 months. Endogenous insulin retention was dependent upon initial stimulated C-peptide response, age at diabetes onset, and numbers of specific islet cell autoantibodies found. Oral insulin improved plasma C-peptide responses in patients diagnosed at ages greater than 20 years, best seen at the low (1 mg/day) over the high (10 mg/day) insulin dose (P = .003 and P = .01, respectively). In patients diagnosed before age 20 years, the 1 mg dose was ineffective, whereas the 10 mg dose actually accelerated C-peptide loss (P = .003). There were no adverse effects. If confirmed, these findings suggest that diabetic patients over age 20 years with ICA evidence of late-onset immune-mediated diabetes should be considered for oral insulin at 1 mg/day to better retain endogenous insulin secretion.

Preservation of C-peptide secretion in subjects at high risk of developing type 1 diabetes mellitus--a new surrogate measure of non-progression?

Individuals at high risk of developing type 1 diabetes mellitus can be identified using immunologic, genetic, and metabolic parameters. In the Diabetes Prevention Trial-1 (DPT-1), annual intravenous infusions of low doses of regular insulin, together with daily subcutaneous injection of a single low dose of Ultralente insulin at nighttime, failed to prevent or delay the onset of type 1 diabetes in high-risk non-diabetic relatives. In our study, we attempted to achieve beta-cell rest by administering higher doses of neutral protamine Hagedorn (NPH) insulin twice daily to high-risk non-diabetic subjects in an effort to prevent or delay the onset of the disease. The maximum tolerable dose was given with the dose reduced for any hypoglycemia (mean dose 0.33 +/- 0.15; range 0.09-0.66 units/kg/d). We treated 26 subjects who were confirmed to have islet cell antibodies (ICAs) and a low first-phase insulin response (FPIR) to intravenous glucose. Fourteen had normal glucose tolerance and 12 impaired glucose tolerance (IGT). The median duration of follow-up was 5.5 yr. Diabetes occurred in 10 of 12 subjects with IGT and five of 14 subjects with normal glucose tolerance. The cumulative incidence of diabetes was the same as with that seen in a matched, observation group (subjects followed prospectively as part of the University of Florida natural history studies) (age, sex, ICA, insulin autoantibodies, duration of ICA prior to enrollment, FPIR, and glucose intolerance; p = 0.39), as was the rate of progression (p = 0.79). There was a higher rate of progression to diabetes in the group with abnormal glucose tolerance at baseline than in those with normal baseline glucose tolerance (p = 0.003). Interestingly, in non-progressors, as opposed to progressors, there was no fall in C-peptide (peak and area under the curve) production regardless of the type of tolerance testing (mixed meal, oral or intravenous) over time (p < 0.001). In this study, in the dose and regimen of NPH insulin used, insulin did not delay or prevent the development of type 1 diabetes. However, preservation of C-peptide production in the prediabetic period appears to indicate non-progression to clinical disease and may serve as a new surrogate for determining response to preventative efforts.

Autoimmune diabetes: ongoing development of immunological intervention strategies targeted directly against autoreactive T cells

It is well known that autoimmunity associated with the onset of insulin-dependent diabetes mellitus (IDDM) involves the generation of autoreactive T and B cells. The findings that diabetics mount humoral and cellular immune responses against islet cell antigens (ICAs) have led to the testing of ICAs and their analogs as candidates for therapeutic agents for better treatment of IDDM at its prediabetic and diabetic stages. Apart from this type of approach, various immunological intervention strategies aimed at direct targeting of the autoreactive T cells have also been investigated. The present review covers the ongoing aspects of these developments focusing on the preclinical findings made in NOD (nonobese diabetic) mice which have been commonly used as a disease model for human autoimmune diabetes. Other types of approaches involving the mobilization of regulatory T cells to indirectly control or modulate the pathological activity of autoreactive T cells will not be discussed within this scope.

European Nicotinamide Diabetes Intervention Trial (ENDIT): a randomised controlled trial of intervention before the onset of type 1 diabetes

BACKGROUND

Results of studies in animals and human beings suggest that type 1 diabetes is preventable. Nicotinamide prevents autoimmune diabetes in animal models, possibly through inhibition of the DNA repair enzyme poly-ADP-ribose polymerase and prevention of beta-cell NAD depletion. We aimed to assess whether high dose nicotinamide prevents or delays clinical onset of diabetes in people with a first-degree family history of type 1 diabetes.

METHOD

We did a randomised double-blind placebo-controlled trial of nicotinamide in 552 relatives with confirmed islet cell antibody (ICA) levels of 20 Juvenile Diabetes Federation (JDF) units or more, and a non-diabetic oral glucose tolerance test. Participants were recruited from 18 European countries, Canada, and the USA, and were randomly allocated oral modified release nicotinamide (1.2 g/m2) or placebo for 5 years. Random allocation was done with a pseudorandom number generator and we used size balanced blocks of four and stratified by age and national group. Primary outcome was development of diabetes, as defined by WHO criteria. Analysis was done on an intention-to-treat basis.

FINDINGS

There was no difference in the development of diabetes between the treatment groups. Of 159 participants who developed diabetes in the course of the trial, 82 were taking nicotinamide and 77 were on placebo. The unadjusted hazard ratio for development of diabetes was 1.07 (95% CI 0.78-1.45; p=0.69), and the hazard ratio adjusted for age-at-entry, baseline glucose tolerance, and number of islet autoantibodies detected was 1.01 (0.73-1.38; p=0.97). Of 168 (30.4%) participants who withdrew from the trial, 83 were on placebo. The number of serious adverse events did not differ between treatment groups. Nicotinamide treatment did not affect growth in children or first-phase insulin secretion.

INTERPRETATION

Large-scale controlled trials of interventions designed to prevent the onset of type 1 diabetes are feasible, but nicotinamide was ineffective at the dose we used.

Beta cell death and protection

Type 1 diabetes is an immune-mediated disease critically dependent upon the interaction between antigen-presenting cells and T cells. Clearly, both CD4+ and CD8+ T cells are required, but activated CD4+ T cells are both necessary and sufficient in causing disease. The mechanism of the Th1/Th2 immunoregulatory imbalance is unclear and needs to be further investigated. CD8+ T cells are not commonly sufficient in causing disease, but CD8 T cells are necessary in initiation (<14 weeks in the NOD mouse), but not in the later (>14 weeks) effector phase of the disease. It is still unclear whether the CD8+ T cell exerts its function as a classical effector cell or mainly as an immunomodulatory cell acting in synergy with the CD4+ T cell. The relative role of T cell effector mechanisms such as Fas/FasL, perforin/granzyme, and the TRAIL systems is unclear. Proinflammatory cytokines, reactive oxygen species, and other immune mediators seem to be involved in beta cell destruction, but much is to be learned about signaling, molecular mechanisms, and in vivo importance.

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.

Genetic epidemiology of type 1 diabetes

Family and twin studies indicate that a substantial fraction of susceptibility to type 1 diabetes is attributable to genetic factors. These and other epidemiologic studies also implicate environmental factors as important triggers. Although the specific environmental factors that contribute to immune-mediated diabetes remain unknown, several of the relevant genetic factors have been identified using two main approaches: genome-wide linkage analysis and candidate gene association studies. This article reviews the epidemiology of type 1 diabetes, the relative merits of linkage and association studies, and the results achieved so far using these two approaches. Prospects for the future of type 1 diabetes genetics research are considered.

Prospects for the prevention and reversal of type 1 diabetes mellitus

Type 1 (insulin-dependent) diabetes mellitus results from selective immune-mediated destruction of pancreatic islet beta cells. Strategies to prevent or reverse the development of diabetes can be divided into three groups, depending on whether they focus on beta-cell protection, regeneration or replacement. Prevention of immune beta-cell destruction involves either halting the immune attack directed against beta cells or making beta cells better able to withstand immune attack, for example, by making them resistant to free radical damage. The recent identification of beta-cell growth factors and development of stem cell technologies provides an alternative route to the reversal of diabetes, namely beta-cell regeneration. Interestingly, stem cell-derived islets appear to be less sensitive to recurrent immune destruction that is normally seen in response to islet transplantation. The last alternative is beta-cell replacement or substitution. This covers a wide range of interventions including human whole pancreas transplantation, xenotransplantation, genetically modified beta cells, mechanical insulin sensing and delivery devices, and the artificial pancreas. This review describes recent advances in each of these research areas and aims to provide clinicians with an idea of where and when an effective strategy to prevent or reverse diabetes development will become available.

HLA genes associated with autoimmunity and progression to disease in type 1 diabetes

Insulin dependent diabetes mellitus (type I DM) is caused by an autoimmune process which culminates in destruction of pancreatic beta cells with resultant loss of insulin production. Preceding the clinical diagnosis of type I DM is a preclinical stage characterized by autoantibodies to insulin, glutamic acid decarboxylase (GAD) and a tyrosine phosphatase-like molecule (IA-2). We have studied both HLA class I and class 2 allele distributions in diabetic probands and autoantibody positive individuals in members of 452 families recruited for the Australian type I diabetes DNA repository. The results demonstrate that progression to autoimmunity as measured by the appearance of autoantibodies is strongly associated with the class 2 alleles DRB1*03 and DRB*04 and with DRB1*03/04 heterozygosity. In contrast, the progression to clinical disease appears associated with class I alleles A24, A30 and B18 while A1, A28, B14 and B56 appear negatively associated. The class 2 alleles appear to have a minimal role in the progression from autoantibody positivity to clinical disease. These results are consistent with the view that CD4+ T cells responding to peptides in the context of class 2 molecules are responsible for initiating autoantibody production, while the destruction of islet cells leading to clinical expression of the disease is the function of CD8+ T cells recognizing relevant peptides in the context of class I molecules.

Development of autoantibodies to islet antigens during childhood: implications for preclinical type 1 diabetes screening

OBJECTIVE

Serum islet antibodies signify increased risk for type 1 diabetes (T1D). Knowledge of the relationship between age and seroconversion would guide screening for at-risk individuals. We aimed to determine the effectiveness of islet antibody screening in early childhood, in particular the proportion of negative children who subsequently seroconverted.

METHODS

We identified 554 children with a first-degree relative with T1D who had tested negative for islet cell antibodies (ICA) and insulin autoantibodies (IAA) when first screened at a mean age of 7.2 yr. Of 423 who were eligible, 350 consented to re-testing for ICA and IAA and antibodies to glutamic acid decarboxylase (GADAb) and tyrosine phosphatase-like insulinoma antigen IA-2 (IA2Ab) at a mean age of 11.1 yr. GADAb and IA2Ab were measured in 239 of the initial stored samples.

RESULTS

Of the 350 children who tested negative at first screening, 12 (3.4%) subsequently seroconverted, becoming positive for ICA (n = 4), IAA (n = 7), GADAb (n = 6) or IA2Ab (n = 2). Of 239 initially negative for ICA and IAA, 8/239 (3.3%) now tested positive for GADAb (n = 7) or IA2Ab (n = 1). Four of these children were positive for GADAb in both tests; the one child initially positive for IA2Ab only was positive for all four antibodies 4.6 yr later and developed diabetes.

CONCLUSION

Screening for ICA and IAA failed to identify 2-3% of genetically at-risk children who subsequently developed islet antibodies. Testing for GADAb and IA2Ab would not have avoided this. Maximizing the sensitivity of detecting risk for T1D requires repeat screening for islet antibodies throughout childhood.

Maternal first-trimester enterovirus infection and future risk of type 1 diabetes in the exposed fetus

Previous studies have suggested that enterovirus infections during pregnancy may increase the risk of type 1 diabetes in the offspring. Our aim was to evaluate the role of first trimester enterovirus infections in a larger cohort of pregnant women. Two series of pregnant women were analyzed as follows: 948 women (series 1) and 680 women (series 2) whose child developed clinical diabetes before the ages of 15 or 7 years, respectively. An equal number of control women with a nondiabetic child was selected. Acute enterovirus infections were diagnosed by measuring IgM class antibodies against coxsackievirus B5 (series 1) and a mixture of coxsackievirus B3, coxsackievirus A16, and echovirus 11 antigens (series 2). In series 2, all sera were also analyzed for IgG class antibodies against an enterovirus peptide antigen. In addition, 152 randomly selected case-control pairs and all IgM-positive mothers' sera were tested for enterovirus RNA (series 2). In series 1, 3.1% of case women had IgM antibodies against coxsackievirus B5 antigen compared with 4.1% of control women (NS). In series 2, 7.1% of case and 5.3% of control women had IgM against the mixture of enterovirus antigens (NS). IgG class enterovirus antibodies did not differ between the groups. Enterovirus RNA was found only in one case woman (0.3%) of the subgroup of samples and in 5.7% of 70 IgM-positive women. The results suggest that enterovirus infection during the first trimester of pregnancy is not associated with increased risk for type 1 diabetes in the child.