Bi-glandular and persistent enterovirus infection and distinct changes of the pancreas in slowly progressive type 1 diabetes mellitus.

In slowly progressive type 1 diabetes mellitus (SPIDDM), the pancreas shows sustained islet inflammation, pancreatitis, pancreatic acinar cell metaplasia/dysplasia (ADM), and intraepithelial neoplasia (PanIN), a precancerous lesion. The mechanisms underlying these changes remain unclear. The presence of enterovirus (EV) encoded-capsid protein 1 (VP1) and -2A protease (2Apro) and the innate immune responses of the pancreas were studied using immunohistochemistry and in situ hybridization in 12 SPIDDM and 19 non-diabetic control pancreases. VP1, 2Apro, and EV-RNA were detected in islets and the exocrine pancreas in all SPIDDM pancreases. Innate immune receptor, melanoma differentiation-associated gene 5 (MDA5), and interferon (IFN)-beta1 were intensified in the islets of SPIDDM patients with short disease duration. However, expressions of MDA5 and IFN-beta1were suppressed in those with longer disease duration. CD3+ T cell infiltration was observed in the VP1- and insulin-positive islets (insulitis) and exocrine acinar cells. CD11c+ dendritic cells (DCs) in islets were scarce in long-term SPIDDM. This study showed the consistent presence of EV, suggesting an association with inflammatory changes in the endocrine and exocrine pancreas in SPIDDM. Suppressed expressions of MDA5 and IFN-beta1, as well as decreased numbers of DCs in the host cells, may contribute to persistent EV infection and induction of ADM/PanIN lesions, which may potentially provide a scaffold for pancreatic neoplasms.

HLA typing of patients who developed subacute thyroiditis and Graves' disease after SARS-CoV-2 vaccination: a case report.

BACKGROUND: Cases of subacute thyroiditis (SAT) after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination have been reported. A human leukocyte antigen (HLA) allele, HLA-B*35, appears to be involved in the pathogenesis of SAT. CASE PRESENTATION: We conducted HLA typing of one patient with SAT and another with both SAT and Graves' disease (GD), which developed after SARS-CoV-2 vaccination. Patient 1, a 58-year-old Japanese man, was inoculated with a SARS-CoV-2 vaccine (BNT162b2; Pfizer, New York, NY, USA). He developed fever (38 °C), cervical pain, palpitations, and fatigue on day 10 after vaccination. Blood chemistry tests revealed thyrotoxicosis and elevated serum C-reactive protein (CRP) and slightly increased serum antithyroid-stimulating antibody (TSAb) levels. Thyroid ultrasonography revealed the characteristic findings of SAT. Patient 2, a 36-year-old Japanese woman, was inoculated twice with a SARS-CoV-2 vaccine (mRNA-1273; Moderna, Cambridge, MA, USA). She developed fever (37.8 °C) and thyroid gland pain on day 3 after the second vaccination. Blood chemistry tests revealed thyrotoxicosis and elevated serum CRP, TSAb, and antithyroid-stimulating hormone receptor antibody levels. Fever and thyroid gland pain persisted. Thyroid ultrasonography revealed the characteristic findings of SAT (i.e., slight swelling and a focal hypoechoic area with decreased blood flow). Prednisolone treatment was effective for SAT. However, thyrotoxicosis causing palpitations relapsed thereafter, for which thyroid scintigraphy with 99mtechnetium pertechnetate was conducted, and the patient was diagnosed with GD. Thiamazole treatment was then initiated, which led to improvement in symptoms. CONCLUSION: HLA typing revealed that both patients had the HLA-B*35:01, -C*04:01, and -DPB1*05:01 alleles. Only patient 2 had the HLA-DRB1*11:01 and HLA-DQB1*03:01 alleles. The HLA-B*35:01 and HLA-C*04:01 alleles appeared to be involved in the pathogenesis of SAT after SARS-CoV-2 vaccination, and the HLA-DRB1*11:01 and HLA-DQB1*03:01 alleles were speculated to be involved in the postvaccination pathogenesis of GD.

Comparing the clinical significance and antigen specificity of insulinoma-associated antigen-2 autoantibodies between radioimmunoassay and enzyme-linked immunosorbent assay in Japanese patients with type 1 diabetes.

AIMS/INTRODUCTION: This study aimed to investigate the clinical significance and antigen specificity of autoantibodies to insulinoma-associated antigen-2 (IA-2A) by radioimmunoassay (RIA; IA-2A-RIA) and enzyme-linked immunosorbent assay (ELISA; IA-2A-ELISA) in Japanese patients with type 1 diabetes. MATERIALS AND METHODS: A total of 338 type 1 diabetic patients were enrolled, including 38 fulminant type 1 diabetes, 168 acute-onset type 1 diabetes and 137 slowly-progressive type 1 diabetes (SPIDDM). The concordance, correlation of autoantibody titer, and the relationship between IA-2A and progression to the insulin-deficient state were examined. Also, competitive assay was used to examine the antigen specificity. RESULTS: The prevalence of IA-2A-ELISA was 4-5% lower than that of IA-2A-RIA in both the acute-onset type 1 diabetes and SPIDDM, but the diagnostic sensitivities of both subtypes, when measured in combination with glutamic acid decarboxylase autoantibody, were comparable. The diagnosis of type 1 diabetes using either the RIA or ELISA methods showed substantial agreement with the exponential correlation of autoantibody titers detected by RIA and ELISA. Among the SPIDDM patients, the fasting C-peptide for IA-2A-positive cases by ELISA, but not the RIA method, was significantly lower than in the negative cases (P < 0.05). Furthermore, IA-2A-ELISA proved superior to the RIA method in predicting the progression to insulin deficiency in SPIDDM. Competitive analysis showed that even sera with discrepant results by RIA and ELISA have IA-2-specific autoantibodies. CONCLUSION: These results suggest that IA-2A-ELISA is a reliable marker not only for the diagnosis of type 1 diabetes, but also for the prediction of future insulin dependency; that is, detection of IA-2A-ELISA helps identify a subtype of SPIDDM patients who would likely progress onto insulin-deficient state.

Clinical characterization of patients with primary aldosteronism plus subclinical Cushing's syndrome.

BACKGROUND: Primary aldosteronism (PA) plus subclinical Cushing's syndrome (SCS), PASCS, has occasionally been reported. We aimed to clinically characterize patients with PASCS who are poorly profiled. METHODS: A population-based, retrospective, single-center, observational study was conducted in 71 patients (age, 58.2 ± 11.2 years; 24 males and 47 females) who developed PA (n = 45), SCS (n = 12), or PASCS (n = 14). The main outcome measures were the proportion of patients with diabetes mellitus (DM), serum potassium concentration, and maximum tumor diameter (MTD) on the computed tomography (CT) scans. RESULTS: The proportion of DM patients was significantly greater in the PASCS group than in the PA group (50.0% vs. 13.9%, p <  0.05), without a significant difference between the PASCS and SCS groups. Serum potassium concentration was significantly lower in the PASCS group than in the SCS group (3.2 ± 0.8 mEq/L vs. 4.0 ± 0.5 mEq/L; p <  0.01), without a significant difference between the PASCS and PA groups. Among the 3 study groups of patients who had a unilateral adrenal tumor, MTD was significantly greater in the PASCS group than in the PA group (2.7 ± 0.1 cm vs. 1.4 ± 0.1 cm; p <  0.001), without a significant difference between the PASCS and SCS groups. CONCLUSIONS: Any reference criteria were not obtained that surely distinguish patients with PASCS from those with PA or SCS. However, clinicians should suspect the presence of concurrent SCS in patients with PA when detecting a relatively large adrenal tumor on the CT scans.

Simultaneous development of Graves' disease and type 1 diabetes during anti-programmed cell death-1 therapy: A case report.

We present the first case of simultaneous development of Graves' disease and type 1 diabetes during anti-programmed cell death 1 therapy. A 48-year-old man with parotid gland adenocarcinoma and lung metastasis had received five courses of nivolumab. Fourteen days after administration of the sixth course, his casual plasma glucose and hemoglobin A1c levels were 379 mg/dL and 7.2%, respectively. Furthermore, thyrotoxicosis was detected with a blood test. Serum total ketone body and thyroid-stimulating hormone receptor antibody levels increased, and serum C-peptide level decreased to 0.01 ng/mL thereafter. Thus, we concluded that he simultaneously developed anti-programmed cell death 1 therapy-associated type 1 diabetes and Graves' disease. Among Japanese patients with autoimmune polyglandular syndrome type III, the frequency of human leukocyte antigen-DRB1*04:05 is higher in those with both type 1 diabetes and Graves' disease. Our case had human leukocyte antigen-DRB1*04:05, which might be associated with the simultaneous development of the two diseases.

Unique Inflammatory Changes in Exocrine and Endocrine Pancreas in Enterovirus-Induced Fulminant Type 1 Diabetes.

CONTEXT: There are scant reports on the pathological changes of the exocrine and endocrine pancreas in fulminant type 1 diabetes mellitus (FT1DM). OBJECTIVE: To clarify the distinct pathological changes in the exocrine as well as the endocrine pancreas shortly after onset of diabetes in FT1DM. DESIGN: The exocrine and endocrine pancreases of 3 patients with FT1DM and 17 nondiabetic controls were immunohistochemically examined for islet and exocrine tissue inflammation, infiltrating mononuclear cell (MNC) CD subtype, enterovirus capsid protein 1 (VP1) localization, and CXC chemokine ligand 10 (CXCL10) and CXC chemokine receptor 3 (CXCR3) expressions. RESULTS: The median frequency of insulitis in the 3 FT1DM pancreases was 60%. In the nondiabetic control pancreases, no insulitis was observed. In the islets of FT1DM, the numbers of CD45+, CD3+, CD8+, CD68+, and CD11c+ MNCs were significantly higher than those of the control group. In the exocrine pancreas of FT1DM, the numbers of CD3+ T cells, CD8+ T cells, CD68+ macrophages, and CD11c+ dendritic cells were significantly higher than those of the control group. Infiltrating CD8+ T cells, CD68+ macrophages, and CD11c+ dendritic cells were observed around exocrine acinar cells in FT1DM. There was a close association between VP1 and CXCL10 expression in pancreatic exocrine ductal cells and acinar cells as well as islet cells in FT1DM. CXCL10+ exocrine cells were surrounded by CXCR3+ T cells. CONCLUSION: The pathological findings suggested that suppression of the activated CXCL10-CXCR3 axis in the exocrine as well as the endocrine pancreas is a novel therapeutic target in FT1DM and possibly in enterovirus-associated acute-onset type 1 diabetes.

Distinct Inflammatory Changes of the Pancreas of Slowly Progressive Insulin-dependent (Type 1) Diabetes.

OBJECTIVE: The aim of this study was to identify the distinct pathological changes on the endocrine and exocrine pancreas of slowly progressive insulin-dependent diabetes mellitus (SPIDDM) or latent autoimmune diabetes in adults. METHODS: The pancreases from 12 islet autoantibody-positive SPIDDM patients and 19 age-matched subjects with no diabetes were examined histologically for islet inflammation/insulitis, expressions of cytokines, and enterovirus VP1 protein, exocrine pancreatic inflammation, pancreatic ductal changes, major histocompatibility complex class I hyperexpression, and amylin-positive amyloid in the islets. RESULTS: Insulitis dominant for CD8 T-cells and CD68 macrophages was observed in all SPIDDM cases irrespective of duration of diabetes and weight of residual beta cells. Major histocompatibility complex class I hyperexpression on residual beta cells was observed in SPIDDM. All SPIDDM exocrine pancreases showed extensive inflammation, dilated pancreatic ducts, and periductal fibrosis. As many as 75% (9/12) of pancreases had pancreatic intraepithelial neoplasia, which is assumed to be associated with ductal obstruction/narrowing and exocrine pancreatic inflammation, in SPIDDM. Amylin-positive amyloid deposition was not detected in SPIDDM. CONCLUSIONS: Persistent insulitis with preserved beta cells and major histocompatibility complex class I hyperexpression and exocrine pancreatic inflammation with pancreatic intraepithelial neoplasia are distinct histological features of SPIDDM pancreas.

CD4+ T cell-dominant insulitis in acute-onset Type 1 diabetes mellitus associated with intraductal papillary mucinous adenoma.

The loss of insulin-producing pancreatic ß-cells in Type 1 diabetes mellitus (DM) is presumably the result of a T cell-mediated process. In general, CD8+ T cells are the predominant lymphocytes in the insulitis lesions, and CD4+ T cell-dominant insulitis is very rare. We present a case of a 72-year-old woman presented with excessive thirst and a 3-month history of weight loss. She was in a state of ketosis, and her plasma glucose concentration and HbA1c value were elevated. Moreover, anti-islet autoantibodies were positive, thus acute-onset Type 1 DM was diagnosed. At the time of diagnosis, a tumour was detected in the pancreas; total pancreatectomy was carried out 2 months later. The pathological diagnosis was intraductal papillary mucinous adenoma. Immunohistochemical staining of a sample of non-tumorous pancreatic tissue revealed 13 insulitis lesions infiltrated by both CD4+ and CD8+ T cells, and interestingly there were more CD4+ T cells than CD8+ T cells in the lesions. Moreover, B cells and macrophages had also infiltrated the lesions, and these two cell frequencies were both positively correlated with CD4+ as well as CD8+ T cell frequencies. This was a rare case with acute-onset Type 1 DM characterized by CD4+ T cell-dominant insulitis. Proinflammatory cytokines that can promote ß-cell apoptosis or CD8+ T cell function are reported to be secreted from CD4+ T cells. Thus, together with B cells and macrophages, CD4+ T cell-associated immune responses may have, directly and/or indirectly, played a role in the pathogenesis of the Type 1 DM in this patient.

Higher Body Mass Index and Increased Prevalence of Paranasal Sinus Disease.

BACKGROUND: We hypothesized that higher body mass index (BMI) was associated with increased prevalence of paranasal sinus disease and examined the hypothesis in Japanese adults. METHODS: This was a cross-sectional study including 1350 Japanese adults aged 40 years or more who participated in a health check-up program focusing on brain diseases and metabolic syndrome. Participants were divided into quartiles of BMI levels. Paranasal sinus disease was confirmed by a head MRI scan. The association between BMI and paranasal sinus disease was examined using logistic regression analysis, which was adjusted for age, sex, waist:hip ratio, hemoglobin A1c, systolic blood pressure, smoking status, alcohol intake, and white blood cell count. RESULTS: Of the 1350 participants, 151 (11.2%) had paranasal sinus disease. In relation to those in the lowest quartile of BMI, the odds ratios of having the disease among those in the 2nd, 3rd, and 4th quartiles of BMI were 1.89 (95% confidence interval [CI], 1.03-3.48), 2.26 (95% CI, 1.20-4.23) and 2.26 (95% CI, 1.14-4.51), respectively. When BMI was analysed as a continuous variable, an increase of one unit in BMI was significantly associated with increased odds of having the disease, with an OR of 1.08 (95% CI, 1.01-1.16). CONCLUSIONS: The present study suggests that patients with higher BMI are more likely to have paranasal sinus disease.

Clinical Background of Patients with Sperm in Their Urinary Sediment.

INTRODUCTION: The detection rate and associated factors of at least one sperm in urinary sediment is not well-known in real clinical practice. AIMS: The aim of the present study was to evaluate the clinical features associated with the presence of sperm in urinary sediment in a large number of samples. METHODS: We conducted a cross-sectional study at Tokyo Saiseikai Central Hospital. We identified 5,005 males who were aged ≥20 years in whom urinary sedimentation had been performed at least twice between May 2011 and June 2012. The sperm group included patients in whom at least one urinary sediment test performed under a microscope had detected at least one sperm. We evaluated the associations between the presence of at least one sperm in urinary sediment and clinical parameters such as various diseases and the use of particular oral medicines. MAIN OUTCOMES: In total, 1.6% (339/20,937) of urinary sediment samples contained at least one sperm. The sperm group consisted of 282 subjects (5.6%), and the no-sperm group included 4,723 subjects (94.3%). RESULTS: Multivariate analysis demonstrated that younger age (<65) (odds ratio [OR]: 1.71, 95% confidence interval [CI]: 1.32-2.21), the total number of examinations (≥4) (OR: 1.46, 95%CI: 1.11-1.92), diabetes (OR: 1.72, 95%CI: 1.31-2.25), a history of pelvic surgery for colon cancer (OR: 4.89, 95%CI: 2.38-10.02), alpha-1 blocker use (OR: 1.55, 95%CI: 1.16-2.08), a history of trans-urethral resection of the prostate (OR: 2.77, 95%CI: 1.46-5.13), and selective serotonin reuptake inhibitor use (OR: 2.12, 95%CI: 1.07-4.19) were independent predictors of the presence of at least one sperm in urinary sediment. CONCLUSION: There is considerable overlap between the factors associated with the presence of at least one sperm in urinary sediment and those that are strongly associated with ejaculatory disorders.

Association between diabetes and increased prevalence of paranasal sinus disease: a cross-sectional study in Japanese adults.

BACKGROUND: The association between diabetes and paranasal sinus disease has not been thoroughly investigated. METHODS: We cross-sectionally investigated the association between diabetes and the presence of paranasal sinus disease, which was confirmed by a head MRI scan in 1350 adults who underwent a health screening program focusing on brain diseases and metabolic syndrome. Logistic regression, which was adjusted for age, sex, body mass index, waist-to-hip ratio, hypertension, smoking status, alcohol intake, and white blood cell count, was performed to calculate the odds ratio (OR) of having paranasal sinus disease among adults with diabetes in relation to those without. The dose-response relationship between hemoglobin A1c (HbA1c) levels and the presence of paranasal sinus disease was also investigated. RESULTS: Of the 1350 participants (mean age, 61.6 ± 10.0 years; 71.6% men), 220 diabetes cases were identified. Paranasal sinus disease was diagnosed in 151 adults. The adjusted OR of having paranasal sinus disease was 1.74 (95% confidence interval [CI], 1.12-2.71) in those with diabetes. The odds of having paranasal sinus disease increased with HbA1c levels. Compared to those with HbA1c of ≤5.4%, those with HbA1c of 5.5%-6.4%, 6.5%-7.9%, and ≥8.0% were more likely to have paranasal sinus disease, with adjusted ORs of 1.32 (95% CI, 0.88-1.98), 1.63 (95% CI, 0.86-3.09) and 2.71 (95% CI, 1.12-6.61), respectively (P for trend = 0.019). CONCLUSIONS: Diabetes may be significantly associated with higher prevalence of paranasal sinus disease in Japanese adults. We should keep this increased risk in mind when a diabetic patient is suspected of having paranasal sinus disease.

Association of glycemic status with impaired lung function among recipients of a health screening program: a cross-sectional study in Japanese adults.

BACKGROUND: The dose-response relationship between glycemic status and lung function has not been thoroughly investigated. We hypothesized that there are continuous and inverse associations between glycemic measures and lung function tests and examined the hypothesis in Japanese adults. METHODS: We cross-sectionally investigated associations of hemoglobin A1c (HbA1c) and fasting plasma glucose (FPG) with forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) in 3161 adults who participated in a health screening from 2008 to 2011. The study participants included both diabetic and non-diabetic adults. Multiple linear regression analyses were performed to examine the associations. RESULTS: Inverse associations were observed in both sexes, which were attenuated in women after adjustment for multiple variables. A 1% absolute increase in HbA1c was associated with a -52-mL (95% confidence interval [CI] -111 to 8 mL) difference in FVC and a -25-mL (95% CI -75 to 25 mL) difference in FEV1 in women, and a -128-mL (95% CI -163 to -94 mL) difference in FVC and a -73-mL (95% CI -101 to -44 mL) difference in FEV1 in men. A 10-mg/dL increase in FPG was associated with a -11-mL (95% CI -29 to 8 mL) difference in FVC and a -8-mL (95% CI -24 to 7 mL) difference in FEV1 in women, and a -32-mL (95% CI -44 to -21 mL) difference in FVC and a -19-mL (95% CI -28 to -9 mL) difference in FEV1 in men. CONCLUSIONS: Inverse associations between glycemic measures and lung function were observed. Men seem more susceptible to the alteration in FVC and FEV1 than women.

Ligand-bound thyroid hormone receptor contributes to reprogramming of pancreatic acinar cells into insulin-producing cells.

One goal of diabetic regenerative medicine is to instructively convert mature pancreatic exocrine cells into insulin-producing cells. We recently reported that ligand-bound thyroid hormone receptor α (TRα) plays a critical role in expansion of the ß-cell mass during postnatal development. Here, we used an adenovirus vector that expresses TRα driven by the amylase 2 promoter (AdAmy2TRα) to induce the reprogramming of pancreatic acinar cells into insulin-producing cells. Treatment with l-3,5,3-triiodothyronine increases the association of TRα with the p85α subunit of phosphatidylinositol 3-kinase (PI3K), leading to the phosphorylation and activation of Akt and the expression of Pdx1, Ngn3, and MafA in purified acinar cells. Analyses performed with the lectin-associated cell lineage tracing system and the Cre/loxP-based direct cell lineage tracing system indicate that newly synthesized insulin-producing cells originate from elastase-expressing pancreatic acinar cells. Insulin-containing secretory granules were identified in these cells by electron microscopy. The inhibition of p85α expression by siRNA or the inhibition of PI3K by LY294002 prevents the expression of Pdx1, Ngn3, and MafA and the reprogramming to insulin-producing cells. In immunodeficient mice with streptozotocin-induced hyperglycemia, treatment with AdAmy2TRα leads to the reprogramming of pancreatic acinar cells to insulin-producing cells in vivo. Our findings suggest that ligand-bound TRα plays a critical role in ß-cell regeneration during postnatal development via activation of PI3K signaling.

Hyperplastic islets observed in "reversed" NOD mice treated without hematopoietic cells.

At the onset of type 1 diabetes, most of the insulin-producing pancreatic beta cells are destroyed by effector cells, and therefore, the following two factors, at a minimum, are necessary for "reversing" hyperglycemia in autoimmune diabetes; depletion of effector cells and enhancement of beta cell regeneration. In this study, we tried a novel approach for "reversing" autoimmune diabetes in a murine model. Here we show that remission could be achieved with a combination therapy of a single injection of complete Freund's adjuvant (CFA) and a single intraperitoneal injection of a pancreatic beta cell line, MIN6N-9a, in recent-onset diabetic NOD (non-obese diabetic) mice. Five out of seven mice (71%) receiving MIN6N-9a and CFA became normoglycemic within 120 days after treatment, whereas only two of nine (22%) receiving vehicle instead of MIN6N-9a achieved remission. Histological examination of pancreatic specimens from "reversed" mice showed decreased islet number, but each islet was markedly hyperplastic; being about six times larger than those from controls. Although it has been reported that hematopoietic cells such as splenocytes differentiate into insulin-producing cells and play a key role, our data indicate that they are not an absolute requirement for the "reversal" of autoimmune diabetes.

Frequency of CTLA-4 gene CT60 polymorphism may not be affected by vitamin D receptor gene Bsm I polymorphism or HLA DR9 in autoimmune-related type 1 diabetes in the Japanese.

One of the CTLA-4 SNPs, +6230G>A (CT60), has recently been reported to be related to susceptibility to type 1 diabetes and autoimmune thyroid disease. We have previously reported an association between acute-onset type 1 diabetes in Japanese and the Vitamin D receptor (VDR) gene Bsm I large B polymorphism, which is related to the Th1-type response. Moreover, we found a significant correlation between autoimmune-related type 1 diabetes with HLA DR9 and detection of GAD-reactive Th1 (T helper 1)-type cells. In the present article, we tried to clarify whether the frequency of one of the CTLA-4 SNPs, +6230G>A (CT60), is affected by the VDR gene Bsm I polymorphism or by HLA DR9 in Japanese type 1 diabetics. The frequency of the CT60 GG genotype did not appear to be affected by either the VDR gene Bsm I large B polymorphism or HLA DR9.

Assessment of beta cell mass and oxidative peritoneal exudate cells in murine type 1 diabetes using adoptive transfer system.

Because it is controversial how the beta cell mass is reduced during the disease process in type 1 diabetes, we transferred splenocytes from Non-obese diabetic (NOD) to NOD-scid mice and evaluated the relation between the status of the pancreas in donors and the time taken to transfer diabetes to the recipients. We also evaluated the usefulness of assessment of the proportion of oxidative peritoneal exudate cells (PEC) as a novel marker of disease activity in this system. We examined the proportion of oxidative PEC, pancreatic insulin content and pancreatic histology in 16-18-week-old female NOD mice (donors), and transferred their splenocytes into 5-week-old female NOD-scid mice (recipients). After the onset of diabetes in NOD-scid recipients, we assessed the relation between insulin content (or severity of insulitis) of NOD donors and the time taken to transfer diabetes to NOD-scid recipients. The insulin content of "diabetes-prone" donors whose disease status was considered to be just before the onset of diabetes ("malignant" donors) was the same as that of diabetic mice, whereas the insulin content of "diabetes-prone" donors excluding "malignant" donors ("benign" donors) was the same as that of "non-diabetes-prone" donors. Because its proportion of oxidative PEC was inversely correlated with the severity of insulitis, we then evaluated the relation between the proportion of oxidative PEC and the time taken to transfer diabetes. "Malignant" donors had less proportion of oxidative PEC (< 10%), as compared to "benign" and "non-diabetes-prone" donors. These results suggest that a marked reduction of beta cell mass occurs at the very late prediabetic stage, and assessment of the proportion of oxidative PEC is useful to evaluate disease activity in type 1 diabetes.