Insulin autoantibodies are associated with islet cell antibodies; their relation to insulin antibodies and B-cell function in diabetic children

Summary Blood was drawn from 74 children, 3–16 years old, at diagnosis of Type 1 (insulin-dependent) diabetes and before the first insulin injection. Insulin autoantibodies were detected with a polyethylen-glycol-method in 27/74 (36.4%) and with an immuno-electrophoretic method in 6/74 (8.1%). Islet cell cytoplasmic antibodies detected by indirect immuno-fluorescence were found in 49/74 patients (66.2%), who included as many as 23 of the 27 patients with insulin autoantibodies determined with the polyethylen-glycol-method (p<0.01). The proportion of insulin autoantibody-positive patients who developed insulin antibodies during the first 9 months of insulin treatment was not significantly greater (51.8%) than that of insulin autoantibody-negative patients (44.6%), but patients with both islet cell antibodies and insulin autoantibodies at diagnosis produced more insulin antibodies during the first 9 months (p<0.05). There was no difference in fasting or meal stimulated serum C-peptide after 3, 9 or 18 months as related to occurrence of insulin autoantibodies and/or islet cell antibodies. The correlation between insulin autoantibodies and islet cell antibodies indicates that both types of autoantibodies reflect the same immunological process, although the lack of correlation to C-peptide may indicate that they play a minor causal role. In addition, the results show that patients with an active autoimmune process evidently tend to produce more insulin antibodies during the first months of insulin treatment, but the islet cell antibodies and insulin autoantibodies-positive patients had at least as good residual B-cell function as patients without autoantibodies at diagnosis. If insulin antibodies produced as a response to exogenous insulin do have a negative effect on B-cell function our present results suggest that such mechanisms are of minor importance.     

Proinsulin levels in newborn siblings of Type 1 (insulin-dependent) diabetic children and their mothers

Summary Elevated proinsulin levels have been observed in healthy first degree relatives of Type 1 (insulin-dependent) diabetic patients. This elevation could reflect a sequele after a previous attack on the beta-cells not necessarily leading to diabetes, or represent a family trait related to the development of diabetes. When cord plasma levels of proinsulin, insulin and C-peptide from 14 newborn siblings of Type 1 diabetic patients were compared with 21 newborn control siblings unrelated to diabetic subjects, no differences were observed. Neither were any differences observed between their mothers at delivery when comparing the same parameters. In cord plasma the proinsulin levels (median and range) were higher than those in plasma from 35 adult fasting women unrelated to diabetic subjects (10, 5–83 pmol/l vs 4, 2–33 pmol/l;p<0.001) whereas the C-peptide levels (median and range) were lower (0.20, 0.11–0.56 nmol/l vs 0.37, 0.21–0.69 nmol/l;p<0.001). No differences in insulin levels using a highly specific insulin assay were observed. The results suggest that newborn children have high proinsulin and low C-peptide levels unrelated to heredity of diabetes and that the previously described elevated proinsulin level observed in older first degree relatives of diabetic subjects occurs later in life.     

Relationship between serum insulin autoantibodies,islet cell antibodies and Coxsackie-B4 and mumps virus-specific antibodies at the clinical manifestation of Type 1 (insulin-dependent) diabetes

Summary In order to elucidate the possible relationship between insulin autoantibodies (IAA), conventional (ICA-IgG) and complement-fixing (CF-ICA) islet cell antibodies and Coxsackie-B4 and mumps virus-specific antibodies (IgG, IgM and IgA classes), we studied 194 children and adolescents with newly diagnosed Type 1 (insulin-dependent) diabetes. Sixty-one (31.4%) of the subjects were IAA-positive at diagnosis and 73.8% (45/61) of these also had ICA-IgG compared to 51.1% (68/113, p<0.01) of IAA-negative children. CF-ICA showed no significant association with IAA. The levels of IAA were significantly higher in the patients with ICA-IgG compared to those without [5.9±1.6% (SEM) vs 2.5±0.3%, p<0.01]. The patients positive for IAA were younger at diagnosis than the IAA-negative ones; (7.1±0.5 vs 9.3±0.3 years, p<0.001) and this was also true for ICA-IgG-positive children (8.1±0.4 vs 9.4±0.5 years, p<0.05) in comparison to ICA-IgG-negative subjects. No significant associations were found between IAA or ICA on the one hand and a positive family history of Type 1 diabetes or metabolic derangements at diagnosis on the other. Subjects negative for ICA were more frequently positive for mumps virus specific IgG antibodies than the ICA-positive patients (50/80 vs 53/111, p<0.05), and Coxsackie-B4 virus-specific IgA antibodies were more common in the CF-ICA-negative than the CF-ICA-positive children (53/111 vs 29/80, p<0.05). There was no association between the IAA levels and Coxsackie-B4 or mumps virus specific antibodies. However, patients with serological evidence of a recent mumps infection (n=13) had higher IAA levels than the other children (4.4±7.7% vs 2.8±1.4%, p<0.02). Our data suggest a positive association between IAA and ICA-IgG, supporting the view that IAA are like ICA serological markers of autoimmune B cell damage. The inverse associations between autoantibodies and age and between ICA and viral antibodies support the hypothesis that autoimmune mechanisms may play a more crucial role in younger patients contracting Type 1 diabetes while environmental factors may be more important in older ones.     

Increased reduction in fasting C-peptide is associated with islet cell antibodies in Type 1 (insulin-dependent) diabetic patients

Summary A cohort of 82 patients with Type 1 (insulin-dependent) diabetes was followed prospectively for 24 months, and 54 of them for 30 months, to study the relationship between fasting levels of immunoreactive C-peptide and titres of islet cell antibodies. After diagnosis, fasting C-peptide rose temporarily for 1–6 months of insulin therapy and declined continuously thereafter. While islet cell antibodies were present among 55% of the newly diagnosed patients, only 31% remained positive at 30 months. Their antibody titres decreased from 181 at diagnosis to 13. Only 3 patients (4%) who were islet cell antibody negative at diagnosis became positive later. The median C-peptide values among the persistently islet cell antibody positive patients decreased from 0.11 pmol/ml at 18 months, to 0.09 pmol/ml at 24 months, to 0.06 pmol/ml at 30 months compared to 0.18 (p=0.04), 0.15 (p=0.05) and 0.16 (p< 0.003) pmol/ml, respectively, for the islet cell antibody negative patients. The median slope for the latter was –0.09 compared to –0.19 for the islet cell antibody positive patients (p=0.01). These differences were reflected in increasing dosages of insulin, since patients remaining antibody-positive for 30 months were given 1.3–1.4 times more insulin (p=0.01–0.004) than the antibody negative patients. This study demonstrates that islet cell antibodies may be a useful marker for predicting an increased rate by which endogenous B cell function is lost in Type 1 diabetes.     

Insulin autoantibodies at the clinical manifestation of Type 1 (insulin-dependent) diabetes — a poor predictor of clinical course and antibody response to exogenous insulin

Summary To study the possible clinical significance of the appearance of insulin autoantibodies prior to the diagnosis of Type 1 (insulin-dependent) diabetes, and their value in predicting the antibody response to exogenous insulin, we observed 46 newly diagnosed diabetic children and adolescents over the year following diagnosis for the occurrence and duration of clinical remission, daily insulin dose, metabolic control, residual B-cell function, insulin-binding antibodies and conventional as well as complement-fixing islet cell antibodies. Insulin-binding antibodies were determined using both monoiodinated human and porcine insulin. Sixteen children (34.7%) were positive for insulin autoantibodies upon diagnosis of Type 1 diabetes. These subjects were significantly younger (6.2±1.0 versus 10.8±0.8 years; mean±SEM, p<0.001), and their haemoglobin A₁ levels were lower (14.1±0.6 versus 16.0±0.8%, p<0.05) at diagnosis than in the insulin autoantibody negative group. There were no significant differences in the occurrence and duration of clinical remission between insulin autoantibody-positive and -negative test groups. Daily insulin dose, haemoglobin A₁ and serum C-peptide concentrations were of the same magnitude in both groups after the diagnosis, and no association could be found between the presence of insulin autoantibodies at diagnosis and persistently positive islet cell antibodies. In tests conducted 3 months after diagnosis, the group of patients with insulin autoantibodies showed significantly higher levels (p<0.05) of antibodies binding human insulin than the group negative for insulin autoantibodies, but no significant differences could be found between the insulin binding titres of the two groups in subsequent analyses. Those who were still positive for conventional islet cell antibodies one year after diagnosis had significantly higher levels of antibodies binding human insulin (34.6±6.1 versus 12.9±1.7%, p<0.05) as well as antibodies binding porcine insulin (33.0±5.9 versus 12.7±2.9%, p<0.05) than the other subjects. Our observations suggest that insulin autoantibodies developing before the diagnosis of Type 1 diabetes have no influence on the clinical course of the disease over the first year following diagnosis, and they appear to serve as a poor predictor of the antibody response to insulin treatment.     

Increased proinsulin levels as an early indicator of B-cell dysfunction in non-diabetic twins of Type 1 (insulin-dependent) diabetic patients

Summary Glucose tolerance and insulin secretion were studied in two groups of non-diabetic identical twins of recently-diagnosed Type 1 (insulin-dependent) diabetic patients: (1) a group of 5 twins with islet cell antibodies, and (2) a group of 6 twins without. Despite similar fasting glucose, insulin and C-peptide concentrations both groups of twins had significantly higher fasting proinsulin concentrations than the control group (p<0.05). The twins with complement-fixing islet cell antibodies had reduced glucose tolerance and clearance, whilst the twins without islet cell antibodies did not. Neither group of twins showed any abnormality in insulin, C-peptide or proinsulin response to oral or intravenous glucose. We conclude that increased fasting proinsulin levels precede abnormalities of insulin secretion, and are an early indication of minor B-cell damage in these twins irrespective of their risk of developing diabetes.     

Effect of nicotinamide therapy upon B-cell function in newly diagnosed Type 1 (insulin-dependent) diabetic patients

Summary This study describes the effects of nicotinamide therapy on B-cell function in Type 1 (insulin-dependent) diabetes. C-peptide secretion was studied in 20 patients newly diagnosed with Type 1 diabetes at basal state and also after an i.v. glucagon stimulus. Patients were randomly allocated according to a single-blind schedule, to one of the following treatments over a 45-day period: Group 1: 10 patients, nicotinamide 1 g/day; Group 2: 10 patients, placebo. The C-peptide secretion tests were performed before treatment and on days 15, 45, 180, 365 of the follow-up. The clinical and metabolic data were similar in the two groups of patients. Basal and stimulated C-peptide levels increased by 45 days in both groups, but the increase in stimulated C-peptide response was greater in the nicotinamide group (p<0.01). However, the B-cell function decreased after the period of nicotinamide administration. No difference in the number of clinical remissions or insulin requirement and HbA₁ between the groups was observed. These data suggest that treatment of Type 1 diabetes with nicotinamide at diagnosis is associated with a moderate increase of C-peptide secretion recovery.     

Islet cell surface antibodies in Type 1 (insulin-dependent) diabetes mellitus: Use of human fetal pancreas cultures as substrate

Summary Sixteen pancreases from 11–24 week old human fetuses were cultured for up to 11 days to investigate islet cell surface antibodies. Hormonal content and presence of cytoplasmic autoantigen were assessed by immunofluorescence with specific antihormone sera and high titre cytoplasmic islet cell antibody positive sera. Viable islet cells cultured on coverslips were tested with 21 islet cell antibody positive sera from Type 1 (insulin-dependent) diabetics, one islet cell antibody positive serum from a non-diabetic and four normal control sera. Surface binding immunoglobulins were detected by indirect immunofluorescence in nine out of 11 newly diagnosed Type 1 diabetics and in two out of ten longstanding diabetics with another coexistent autoimmune endocrinopathy. The four-layer double immunofluorescence technique showed that the surface antibody stained insulin secreting cells, but owing to rarity of A and D cells in the fetal cultures it has not yet been possible to exclude the reactivity of islet cell surface antibodies with glucagon or somatostatin cells.     

Elevated serum placental isoferritin in newly diagnosed Type 1 (insulin-dependent) diabetes mellitus. A possible marker for identification of high risk subjects

Summary Placental isoferritin is produced by activated T lymphocytes and may, therefore, be considered as a manifestation of T cell involvement. Placental isoferritin is measured using CM-H-9 monoclonal antibody which binds exclusively to placental isoferritin. Placental isoferritin has been determined in the serum of 80 patients with Type I (insulin-dependent) diabetes mellitus, 100 healthy first degree relatives and 81 healthy children. Serum levels which were measured in Type 1 diabetic patients, (24,0–140 U/ml; median and range) were significantly higher than those of family members (0,0–73; median and range; p<0.0001) and normal control subjects (0,0–48; median and range; p<0.0001). Using 0–10 U/ml as the upper limit of normal, it was found that 31 of 50 (62%) of Type 1 diabetic patients, 25 of 100 (25%) family members and 7 of 81 (8.6%) healthy control subjects had abnormal placental isoferritin levels. Islet cell antibodies were positive in 31 of 44 tested diabetic patients and, in 8 of 71 tested family members, and among them 54.8% and 50% respectively also had elevated placental isoferritin levels. However, no statistically significant correlation was found between islet cell antibodies and placental isoferritin levels. Treatment of Type 1 diabetic patients with insulin was accompanied by a significant decrease (p<0.002) of serum placental isoferritin within 2–4 weeks of treatment. It is noteworthy that placental isoferritin was below detection in 34 of 35 Type 2 (non-insulin-dependent) diabetic patients. Our findings suggest that placental isoferritin may be a marker of T cell involvement in autoimmune diabetes and that it could be used to identify high risk healthy first degree relatives.     

Prospective analysis of islet cell antibodies in children with Type 1 (insulin-dependent) diabetes

Summary The prevalence of islet cell antibodies in children with Type 1 (insulin-dependent) diabetes was determined in a cohort of 678 children. The natural course of islet cell antibodies was followed in 375 children at 1 year, 252 and 135 children after 2 and 3 years respectively. Islet cell antibodies were determined by indirect immunofluorescence on cryostat sections of human pancreas. At diagnosis of diabetes 85% of the children had detectable islet cell antibodies (mean titre 10.4). After 3 years 62% of the children were still islet cell antibody positive (mean titre 2.9) indicating a greater persistence of islet cell antibodies than described in earlier studies. In this large cohort a significant correlation between islet cell antibody prevalence or persistence and sex, age or HLA-DR type was not observed except for a faster loss of islet cell antibodies in very young boys and in patients lacking HLA-DR types 3 and 4. Complement fixing islet cell antibodies correlated with high titre islet cell antibodies. Greater persistence of islet cell antibodies was seen for cases with high antibody titre and in children with diagnosis of diabetes during the first half of the year.     

Transfer of Type 1 (insulin-dependent) diabetes mellitus associated autoimmunity to mice with severe combined immunodeficiency (SCID)

Summary Pancreatic beta-cell destruction and development of Type 1 (insulin-dependent) diabetes mellitus are associated with circulating islet cell antibodies. Mice with severe combined immunodeficiency (SCID mice) were reconstituted with peripheral blood mononuclear cells from Type 1 diabetic patients, one who was antibody positive and one antibody negative, and from healthy individuals. Reconstituted mice were subsequently immunized with rat islets in incomplete Freunds adjuvant or adjuvant alone. Seventeen mice received peripheral blood mononuclear cells obtained at three different time points from the islet cell antibody positive patient. Before immunization with rat islets two mice developed antibodies to glutamic acid decarboxylase, a major target for antibodies in Type 1 diabetes, whereas none were positive for cytoplasmic islet cell antibodies. Following immunization with rat islets, glutamic acid decarboxylase antibodies were detected by immunoprecipitation in three additional mice, two of which also became positive for cytoplasmic islet cell antibodies. Of 22 mice which received peripheral blood mononuclear cells from either the islet cell antibody negative patient (n = 5) or from two healthy individuals (n = 17), none were positive for islet cell autoantibodies before or after immunization. None of the islet cell antibody positive mice became hyperglycaemic, showed impaired glucose tolerance or islet cell damage when studied 40 days after immunization (i.e. 100 days after reconstitution). In conclusion these results show that human B lymphocytes producing diabetes-associated autoantibodies can be transferred to SCID mice and remain antigen sensitive, but also that autoantibodies alone are not sufficient to induce beta-cell destruction.     

Risk for developing Type 1 (insulin-dependent) diabetes mellitus and the presence of islet 64K antibodies

Summary First-degree relatives of Type 1 (insulin-dependent) diabetic patients are at increased risk for developing clinical diabetes. The presence of islet cell or insulin autoantibodies further identifies relatives at greater risk, but not all immunologic-marker-positive relatives progress to disease. Beta-cell dysfunction, however, seems to be more prevalent than clinical Type 1 diabetes, since stable subclinical pancreatic Beta-cell dysfunction may occur. Antibodies against a M_r 64,000 (64K) islet Beta-cell protein, identified as glutamic acid decarboxylase, have been reported both at and several years prior to the clinical onset of Type 1 diabetes. We measured 64K antibodies in first-degree relatives with varying degrees of Beta-cell dysfunction and risk for subsequent Type 1 diabetes to determine whether 64K antibodies improve the predictive power of islet cell antibodies and/or insulin autoantibodies. In the Seattle Family Study first-degree relatives of Type 1 diabetic patients are followed prospectively using detailed Beta-cell function tests, insulin sensitivity, quantitative evaluation of islet cell antibodies and fluid phase assay insulin autoantibodies. 64K antibodies were measured using dog islets. Relatives were selected, based on Beta-cell function to represent individuals at high (n=6) and low (n=30) risk for subsequent Type 1 diabetes. The 30 low-risk individuals followed-up for 78 months, had stable Beta-cell function, and six (20%) were negative for all autoantibodies, ten (33%) were positive for insulin autoantibodies, 16 (53%) were islet cell antibody positive while six (20%) were positive for 64K antibodies. In contrast, of the six subjects with progressively declining Beta-cell function who are therefore at high risk, two of whom have already developed Type 1 diabetes, two (33%) were positive for insulin autoantibodies, four (67%) were islet cell antibody positive, while all six (100%) were positive for 64K antibodies. We conclude that antibodies to the M_r 64,000 islet protein correlate with progressive Beta-cell dysfunction more closely than either islet cell antibodies or insulin autoantibodies, but can sometimes be present in individuals whose Beta-cell function remains stable over several years.     

Twenty-four hour profiles of plasma C-peptide in Type 1 (insulin-dependent) diabetic children

Summary Twenty-four hour profiles of plasma C-peptide an index of endogenous insulin secretion, were performed in 15 Type 1 (insulin-dependent) diabetic children. Plasma C-peptide was detectable in six children, of whom four (C-peptide producers) had peak values above normal fasting levels. In each of the six children with residual B cell function, there was a close correlation between plasma C-peptide and simultaneous blood glucose (r> 0.50, p< 0.05). Post-breakfast peak blood glucose was 10.2 ± 1.7 mmol/l (mean ±SEM) in the C-peptide producers and 18.7 ± 1.7 mmol/l in the 11 children with low or no detectable C-peptide. Mean M-value, an index of deviation from an ideal blood glucose, was lower in the C-peptide producers (p<0.05). It is concluded that residual functioning B cells in diabetic children behave physiologically in that insulin secretion fluctuates in accordance with the prevailing blood glucose; and that the pattern of action of injected insulin is more critical in non-C-peptide producers who lack the post-prandial dampening effect provided by residual endogenous insulin secretion.     

Pancreatic cytokeratin: an antigen of pancreatic exocrine cell autoantibodies in Type 1 (insulin-dependent) diabetes mellitus

Summary Autoantibodies reacting with human pancreatic exocrine cells were investigated by immunofluorescent techniques in 107 patients with Type 1 (insulin-dependent) diabetes mellitus, 20 first-degree relatives of the Type 1 diabetic patients, 347 patients with Type 2 (non-insulin-dependent) diabetes, 34 with alcoholic pancreatitis, 26 with rheumatoid arthritis and 107 normal control subjects. Both immunoblotting analysis and double-immunostaining methods were used to characterize the antigens targeted by the pancreatic exocrine cell autoantibodies. Sera positive for human pancreatic exocrine cell cytoplasm, producing a fine fibrillar pattern, were found in 21% (23/107) of the Type 1 diabetic patients. The autoantibodies were present in 39% (15/38) of Type 1 diabetic patients diagnosed within 3 months, and the prevalence decreased with duration of diabetes. The antibodies were of the IgM class in 87% (13/15) of recent-onset Type 1 diabetes cases, but IgG-autoantibodies became more prevalent with increasing duration of diabetes. Three out of 347 (0.9%) Type 2 diabetic patients and 4 of 20 (20%) first-degree relatives of Type 1 diabetic patients had autoantibodies targeted against pancreatic exocrine cells. None of the patients with alcoholic pancreatitis or rheumatoid arthritis and none of the control subjects had these antibodies. Immunoblotting analysis and double-immunostaining demonstrated that the autoantibodies reacted with 40 kilodalton cytokeratin in pancreatic exocrine cell cytoplasm. The antibody was absorbed by the Triton X-100-insoluble fraction of pancreatic extract. These results indicate the presence of distinct autoantibodies to pancreatic exocrine cells in Type 1 diabetes. This suggests the provocative concept that the cytoskeletal system of pancreatic exocrine cells is involved in the pathogenetic process of Type 1 diabetes.     

Autoantibodies to 64,000-Mr islet cell protein in long-term Type 1 (insulin-dependent) diabetic patients

Summary Autoantibodies to the 64,000-M_r (64K) islet cell protein, identified as glutamic acid decarboxylase, were assayed in 46 Type 1 (insulin-dependent) diabetic patients with a disease duration of more than 5 years. Of 46 Type 1 diabetic patients, 18 (39.1 %) were found to be positive for 64K antibodies and 12 of these patients had been diagnosed with autoimmune thyroid disease. Serum C-peptide levels were not detectable in 15 of 18 patients positive for 64K antibodies. The samples were also tested for titres of islet cell antibodies. Islet cell antibodies were detected in 15 (32.6%) of the 46 patients and all the islet cell antibody positive patients were also found to be positive for 64K antibodies. Furthermore, of these 15 patients 12 had previously been diagnosed with autoimmune thyroid disease. A correlation between levels of 64K antibodies and islet cell antibody titre revealed that higher levels of 64K antibodies were observed in patients who had higher islet cell antibody titre. These results demonstrate that most long-term Type 1 diabetic patients with 64K antibodies were also positive for islet cell antibodies complicated by autoimmune thyroid disease.     

Human pancreatic islet function at the onset of Type 1 (insulin-dependent) diabetes mellitus

Summary Viable human pancreatic islets isolated from a recent-onset Type 1 (insulin-dependent) diabetic patient were used to perform in vitro studies. Pre-proinsulin mRNA and insulin content, as well as insulin response were analysed. Insulin response to glucose and forskolin was completely absent in diabetic islets, as compared to control islets. Insulin content was reduced to only one-third of control values (395.0±3.5 vs 989.0±46.3 U/islet) and 20.7±3.9% of islets from the diabetic pancreas contained insulin-positive cells in immunofluorescence studies. Northern blot analysis revealed a severe reduction in the content of pre-proinsulin mRNA in diabetic pancreatic tissue. Our results indicate that although markedly decreased, beta cells in human pancreatic islets at the onset of Type 1 diabetes are still present. Never-theless, pancreatic islet function is disproportionately impaired with a complete absence of an insulin response.     

A trial of nicotinamide in newly diagnosed patients with Type 1 (insulin-dependent) diabetes mellitus

Summary Various agents have been tried in subjects with newly diagnosed Type 1 (insulin-dependent) diabetes mellitus in an attempt to preserve Beta-cell function. In this double-blind study, nicotinamide or placebo were given for one year to 35 children and adolescents with newly-diagnosed Type 1 diabetes. All subjects were within six weeks of diagnosis and were between the ages of 6 and 18 years. Nicotinamide, a poly-(ADP-ribose) synthetase inhibitor, was given in a dose of 100 mg/year of age up to a maximum of 1.5 g/day. There were no initial differences between the 17 control and the 18 test subjects in relation to mean age, sex distribution, or severity at onset. Mean insulin dosages and HbA₁ values were similar for the two groups during the year of study. Fasting and glucagon-stimulated C-peptide levels were similar for the control and nicotinamide treated groups at the beginning and after 4 and 12 months. There were no differences in remission rates between the two groups. Nicotinamide, at this dosage, does not preserve residual insulin secretion in subjects with newly diagnosed Type 1 diabetes.     

Follow-up of cyclosporin A treatment in Type 1 (insulin-dependent) diabetes mellitus: lack of long-term effects

Summary In the Canadian/European randomized controlled study on cyclosporin A (CsA) in recent onset Type 1 (insulin-dependent) diabetes, treatment with the immunosuppressive drug had increased and maintained Beta-cell function and clinical remission during the first 12 months. Following discontinuation of the study drug and double-blinding after a mean of 13.8 months former CsA patients doubled the daily insulin dose within 6 months reaching the level of former placebo patients. The difference in Beta-cell function between the two groups was also lost. Metabolic control (HbA_1c) was transiently worse in the former CsA group. Adverse effects of cyclosporin A on systolic blood pressure, haemoglobin levels, serum potassium and creatinine levels also remitted during that time. We conclude that treatment with cyclosporin A for a mean of 13.8 months had no long-lasting effect on the course of Type 1 diabetes persisting beyond drug discontinuation.Prepared by the authors on behalf of The Canadian/European Randomized Control Trial Group (Please see acknowledgements for complete listing).     

Immunogenetic heterogeneity in Type 1 (insulin-dependent) diabetes among Japanese — HLA antigens and organ-specific autoantibodies

Summary HLA phenotypes and haplotypes in relation to organ-specific autoantibody responses were studied in 82 Japanese patients with Type 1 (insulin-dependent) diabetes. HLA-DRw9 antigen and HLA phenotype of DRw9/X (X: not DR4) were increased in patients with organ-specific autoantibodies other than islet cell antibody (CP<0.02, RR=4.02 and p<0.05, RR=2.30, respectively); whereas HLA-DR4 antigen and HLA phenotype of DR4/X (X: not DRw9) were increased in those without the autoantibodies (CP<0.001, RR=3.95 and p<0.01, RR=2.46, respectively). HLA haplotype of Bw61-DRw9 was increased in patients with the autoantibodies (p<0.005, RR=4.94), and HLA haplotype of Bw54-DR4 was increased in those without the autoantibodies (p<0.001, RR=5.52). The relative risk of HLA-DR4/DRw9 was the highest among all HLA-DR phenotypes or genotypes in patients either with or without the autoantibodies. No association was, however, found between the incidence of islet cell antibody and HLA-DR phenotypes. These findings suggest that Type 1 diabetes among Japanese is immunogenetically heterogeneous as is Type 1 diabetes among Caucasians; and the differences in HLA-association of Type 1 diabetes among ethnic groups might give a clue to understanding of a role of HLA-antigens in the development of Type 1 diabetes.     

Factors affecting and patterns of residual insulin secretion during the first year of Type 1 (insulin-dependent) diabetes mellitus in children

Summary We measured serum C-peptide, glucose, pH, islet antibodies and insulin antibody binding at diagnosis in 84 children with Type 1 (insulin-dependent) diabetes. In a subgroup of 33 children, residual insulin secretion (basal and peak C-peptide response to Sustacal), insulin antibody binding and HbA_1c were measured at 10 days, 1, 3, 6 and 12 months. At presentation C-peptide correlated positively with age at onset and negatively with the blood glucose concentration. Median C-peptide concentration at diagnosis was low, rose significantly (p<0.05) at 10 days, reached a maximum at 1–3 months and declined gradually to 1 year. C-peptide concentration both at diagnosis and at 10 days correlated with that at 3 and 6 months. Of the factors investigated, only age (p<0.005) and sex (higher in females, p<0.01) were found to have a significant influence on basal/peak C-peptide levels throughout the first year. In particular there was no relationship between C-peptide, HbA_1c and insulin dose during this period. A peak C-peptide response at 3–6 months>/<0.32 nmol/l was used to divide the group into two: 16 had a peak response <0.32 nmol/l (low secretors) while in 17, the peak C-peptide was >0.32 nmol/l (high secretors). While the low secretors had significantly (p<0.05) lower C-peptide levels during the first year, there were no differences between low and high secretors in HbA_1c or insulin dose. These data suggest that there are two patterns of residual insulin secretion during the first 12 months after diagnosis of Type 1 diabetes. One pattern shows good amplitude and duration of residual insulin secretion, while both these features are significantly (p<0.05) reduced in the other. The C-peptide concentration both at diagnosis and at 10 days, as well as age at onset and sex are important predictors of the pattern to be followed. Our data suggest further that the magnitude of residual insulin secretion does not play a decisive role in metabolic control during this period.