Glycemic Gap Predicts Mortality in a Large Multicenter Cohort Hospitalized With COVID-19.

CONTEXT: Diabetes or hyperglycemia at admission are established risk factors for adverse outcomes during hospitalization for COVID-19, but the impact of prior glycemic control is not clear. OBJECTIVE: We aimed to examine the associations between admission variables, including glycemic gap, and adverse clinical outcomes in patients hospitalized with COVID-19 infection. METHODS: We examined the relationship between clinical predictors, including acute and chronic glycemia, and clinical outcomes, including intensive care unit (ICU) admission, mechanical ventilation (MV), and mortality among 1786 individuals with diabetes or hyperglycemia (glucose > 10 mmol/L twice in 24 hours) who were admitted from March 2020 through February 2021 with COVID-19 infection at 5 university hospitals in the eastern United States. RESULTS: The cohort was 51.3% male, 53.3% White, 18.8% Black, 29.0% Hispanic, with age = 65.6 ± 14.4 years, BMI = 31.5 ± 7.9 kg/m2, glucose = 12.0 ± 7.5 mmol/L [216 ± 135 mg/dL], and HbA1c = 8.07% ± 2.25%. During hospitalization, 38.9% were admitted to the ICU, 22.9% received MV, and 10.6% died. Age (P < 0.001) and admission glucose (P = 0.014) but not HbA1c were associated with increased risk of mortality. Glycemic gap, defined as admission glucose minus estimated average glucose based on HbA1c, was a stronger predictor of mortality than either admission glucose or HbA1c alone (OR = 1.040 [95% CI: 1.019, 1.061] per mmol/L, P < 0.001). In an adjusted multivariable model, glycemic gap, age, BMI, and diabetic ketoacidosis on admission were associated with increased mortality, while higher estimated glomerular filtration rate (eGFR) and use of any diabetes medication were associated with lower mortality (P < 0.001). CONCLUSION: Relative hyperglycemia, as measured by the admission glycemic gap, is an important marker of mortality risk in COVID-19.

Signaling defects associated with insulin resistance in nondiabetic and diabetic individuals and modification by sex.

Insulin resistance is present in one-quarter of the general population, predisposing these people to a wide range of diseases. Our aim was to identify cell-intrinsic determinants of insulin resistance in this population using induced pluripotent stem cell-derived (iPSC-derived) myoblasts (iMyos). We found that these cells exhibited a large network of altered protein phosphorylation in vitro. Integrating these data with data from type 2 diabetic iMyos revealed critical sites of conserved altered phosphorylation in IRS-1, AKT, mTOR, and TBC1D1 in addition to changes in protein phosphorylation involved in Rho/Rac signaling, chromatin organization, and RNA processing. There were also striking differences in the phosphoproteome in cells from men versus women. These sex-specific and insulin-resistance defects were linked to functional differences in downstream actions. Thus, there are cell-autonomous signaling alterations associated with insulin resistance within the general population and important differences between men and women, many of which also occur in diabetes, that contribute to differences in physiology and disease.

A Cell-Autonomous Signature of Dysregulated Protein Phosphorylation Underlies Muscle Insulin Resistance in Type 2 Diabetes.

Skeletal muscle insulin resistance is the earliest defect in type 2 diabetes (T2D), preceding and predicting disease development. To what extent this reflects a primary defect or is secondary to tissue cross talk due to changes in hormones or circulating metabolites is unknown. To address this question, we have developed an in vitro disease-in-a-dish model using iPS cells from T2D patients differentiated into myoblasts (iMyos). We find that T2D iMyos in culture exhibit multiple defects mirroring human disease, including an altered insulin signaling, decreased insulin-stimulated glucose uptake, and reduced mitochondrial oxidation. More strikingly, global phosphoproteomic analysis reveals a multidimensional network of signaling defects in T2D iMyos going beyond the canonical insulin-signaling cascade, including proteins involved in regulation of Rho GTPases, mRNA splicing and/or processing, vesicular trafficking, gene transcription, and chromatin remodeling. These cell-autonomous defects and the dysregulated network of protein phosphorylation reveal a new dimension in the cellular mechanisms underlying the fundamental defects in T2D.

High Titer of Circulating Antiglutamic Acid Decarboxylase Antibodies in a Patient with Cerebellar Ataxia and Type 1 Diabetes.

A 24-year-old female who was recently diagnosed with Type 1 diabetes mellitus (TiD) presented with a five-year history of visible gait disturbance and slurred speech. Her neurologic examination was remarkable for dysarthria, bilateral nystagmus, dysdiadochokinesia, finger-nose incoordination, heel-knee incoordination, and ataxic gait. A brain MRI disclosed diffuse cerebellar atrophy. Her serum antiglutamic acid decarboxylase (GAD) antibody titer was elevated. Antinuclear antibody (ANA) test was positive with atiterofl:2560 and a speckledpattern. Genetictests for inherited ataxia, including Friedreich ataxia, were negative for mutations. Her cerebrospinal fluid (CSF) analysis revealed oligoclonal bands and she had a positive CSF GAD65 antibody. A diag- nosis of GAD antibody-induced cerebellar ataxia was considered. She developed GAD autoimmune antibody positive TiD during the course ofher dis- ease. GAD antibody-associated cerebellar ataxia is a rare entity, however it should be considered as a possibility in patients with associated autoimmune disease and positive anti-GAD antibody.

Methylation of insulin DNA in response to proinflammatory cytokines during the progression of autoimmune diabetes in NOD mice.

AIMS/HYPOTHESIS: Type 1 diabetes is caused by the immunological destruction of pancreatic beta cells. Preclinical and clinical data indicate that there are changes in beta cell function at different stages of the disease, but the fate of beta cells has not been closely studied. We studied how immune factors affect the function and epigenetics of beta cells during disease progression and identified possible triggers of these changes. METHODS: We studied FACS sorted beta cells and infiltrating lymphocytes from NOD mouse and human islets. Gene expression was measured by quantitative real-time RT-PCR (qRT-PCR) and methylation of the insulin genes was investigated by high-throughput and Sanger sequencing. To understand the role of DNA methyltransferases, Dnmt3a was knocked down with small interfering RNA (siRNA). The effects of cytokines on methylation and expression of the insulin gene were studied in humans and mice. RESULTS: During disease progression in NOD mice, there was an inverse relationship between the proportion of infiltrating lymphocytes and the beta cell mass. In beta cells, methylation marks in the Ins1 and Ins2 genes changed over time. Insulin gene expression appears to be most closely regulated by the methylation of Ins1 exon 2 and Ins2 exon 1. Cytokine transcription increased with age in NOD mice, and these cytokines could induce methylation marks in the insulin DNA by inducing methyltransferases. Similar changes were induced by cytokines in human beta cells in vitro. CONCLUSIONS/INTERPRETATION: Epigenetic modification of DNA by methylation in response to immunological stressors may be a mechanism that affects insulin gene expression during the progression of type 1 diabetes.

A Report of Three Cases With Acquired Generalized Lipodystrophy With Distinct Autoimmune Conditions Treated With Metreleptin.

CONTEXT: Acquired generalized lipodystrophy (AGL) is associated with leptin deficiency as a result of adipose tissue loss and hypertriglyceridemia, insulin resistance, and hepatic steatosis. It may coexist with other autoimmune diseases such as Hashimoto's thyroiditis, rheumatoid arthritis, hemolytic anemia, and chronic active hepatitis. Metreleptin therapy has been shown to improve metabolic abnormalities in lipodystrophy, but the effect on AGL patients with active autoimmune disease is unknown. CASE DESCRIPTION: We report 3 cases of pediatric patients with AGL and distinct active autoimmune diseases who were treated with metreleptin over a period of 4-6 years. Case 1 is a 9-year-old girl with active juvenile dermatomyositis, who was successfully treated with leptin with no worsening of her dermatomoysitis. Case 2 is a 16-year-old female with Graves' disease, who could discontinue all her antidiabetic medication completely with improved triglyceride levels. Case 3 is an 11-year-old boy with active autoimmune hepatitis and chronic urticaria, whose hyperphagia has resolved and his liver enzymes and hepatosplenomegaly have improved. CONCLUSION: Metreleptin therapy is of considerable clinical benefit to reduce insulin resistance and hypertriglyceridemia and did not appear to alter the clinical course of autoimmune disease nor clinical efficacy of immunosuppressive treatments. Our observations suggest that risk or presence of autoimmune disease should not lead to withholding of metreleptin treatment from patients with AGL, but should prompt close clinical follow up in light of cautionary preclinical data.

ß cell death and dysfunction during type 1 diabetes development in at-risk individuals.

UNLABELLED: Role of the funding source: Funding from the NIH was used for support of the participating clinical centers and the coordinating center. The funding source did not participate in the collection or the analysis of the data. BACKGROUND: The ß cell killing that characterizes type 1 diabetes (T1D) is thought to begin years before patients present clinically with metabolic decompensation; however, this primary pathologic process of the disease has not been measured. METHODS: Here, we measured ß cell death with an assay that detects ß cell-derived unmethylated insulin (INS) DNA. Using this assay, we performed an observational study of 50 participants from 2 cohorts at risk for developing T1D from the TrialNet Pathway to Prevention study and of 4 subjects who received islet autotransplants. RESULTS: In at-risk subjects, those who progressed to T1D had average levels of unmethylated INS DNA that were elevated modestly compared with those of healthy control subjects. In at-risk individuals that progressed to T1D, the observed increases in unmethylated INS DNA were associated with decreases in insulin secretion, indicating that the changes in unmethylated INS DNA are indicative of ß cell killing. Subjects at high risk for T1D had levels of unmethylated INS DNA that were higher than those of healthy controls and higher than the levels of unmethylated INS DNA in the at-risk progressor and at-risk nonprogressor groups followed for 4 years. Evaluation of insulin secretory kinetics also distinguished high-risk subjects who progressed to overt disease from those who did not. CONCLUSION: We conclude that a blood test that measures unmethylated INS DNA serves as a marker of active ß cell killing as the result of T1D-associated autoimmunity. Together, the data support the concept that ß cell killing occurs sporadically during the years prior to diagnosis of T1D and is more intense in the peridiagnosis period. TRIAL REGISTRATION: Clinicaltrials.gov NCT00097292. FUNDING: Funding was from the NIH, the Juvenile Diabetes Research Foundation, and the American Diabetes Association.

Analysis of ß-cell death in type 1 diabetes by droplet digital PCR.

Type 1 diabetes (T1D) and other forms of diabetes are due to the killing of ß-cells. However, the loss of ß-cells has only been assessed by functional studies with a liquid meal or glucose that can be affected by environmental factors. As an indirect measure of ß-cell death, we developed an assay using a novel droplet digital PCR that detects INS DNA derived from ß-cells. The release of INS DNA with epigenetic modifications (unmethylated CpG) identifies the ß-cellular source of the DNA. The assay can detect unmethylated DNA between a range of approximately 600 copies/µL and 0.7 copies/µL, with a regression coefficient for the log transformed copy number of 0.99. The assay was specific for unmethylated INS DNA in mixtures with methylated INS DNA. We analyzed the levels of unmethylated INS DNA in patients with recent onset T1D and normoglycemia subjects at high risk for disease and found increased levels of unmethylated INS DNA compared with nondiabetic control subjects (P < .0001). More than one-third of T1D patients and one-half of at-risk subjects had levels that were more than 2 SD than the mean of nondiabetic control subjects. We conclude that droplet digital PCR is a useful method to detect ß-cell death and is more specific and feasible than other methods, such as nested real-time PCR. This new method may be a valuable tool for analyzing pathogenic mechanisms and the effects of treatments in all forms of diabetes.

A humanized mouse model of autoimmune insulitis.

Many mechanisms of and treatments for type 1 diabetes studied in the NOD mouse model have not been replicated in human disease models. Thus, the field of diabetes research remains hindered by the lack of an in vivo system in which to study the development and onset of autoimmune diabetes. To this end, we characterized a system using human CD4(+) T cells pulsed with autoantigen-derived peptides. Six weeks after injection of as few as 0.5 × 10(6) antigen-pulsed cells into the NOD-Scid Il2rg(-/-) mouse expressing the human HLA-DR4 transgene, infiltration of mouse islets by human T cells was seen. Although islet infiltration occurred with both healthy and diabetic donor antigen-pulsed CD4(+) T cells, diabetic donor injections yielded significantly greater levels of insulitis. Additionally, significantly reduced insulin staining was observed in mice injected with CD4(+) T-cell lines from diabetic donors. Increased levels of demethylated ß-cell-derived DNA in the bloodstream accompanied this loss of insulin staining. Together, these data show that injection of small numbers of autoantigen-reactive CD4(+) T cells can cause a targeted, destructive infiltration of pancreatic ß-cells. This model may be valuable for understanding mechanisms of induction of human diabetes.

Immune therapy and ß-cell death in type 1 diabetes.

Type 1 diabetes (T1D) results from immune-mediated destruction of insulin-producing ß-cells. The killing of ß-cells is not currently measurable; ß-cell functional studies routinely used are affected by environmental factors such as glucose and cannot distinguish death from dysfunction. Moreover, it is not known whether immune therapies affect killing. We developed an assay to identify ß-cell death by measuring relative levels of unmethylated INS DNA in serum and used it to measure ß-cell death in a clinical trial of teplizumab. We studied 43 patients with recent-onset T1D, 13 nondiabetic subjects, and 37 patients with T1D treated with FcR nonbinding anti-CD3 monoclonal antibody (teplizumab) or placebo. Patients with recent-onset T1D had higher rates of ß-cell death versus nondiabetic control subjects, but patients with long-standing T1D had lower levels. When patients with recent-onset T1D were treated with teplizumab, ß-cell function was preserved (P < 0.05) and the rates of ß-cell were reduced significantly (P < 0.05). We conclude that there are higher rates of ß-cell death in patients with recent-onset T1D compared with nondiabetic subjects. Improvement in C-peptide responses with immune intervention is associated with decreased ß-cell death.

Immunologic and metabolic biomarkers of ß-cell destruction in the diagnosis of type 1 diabetes.

Type 1 diabetes (T1D), also known as insulin-dependent diabetes mellitus, is a chronic disorder that results from autoimmune destruction of insulin-producing ß cells in the islets of Langerhans within the pancreas ( Atkinson and Maclaren 1994). This disease becomes clinically apparent only after significant destruction of the ß-cell mass, which reduces the ability to maintain glycemic control and metabolic function. In addition, it continues for years after clinical onset until, generally, there is complete destruction of insulin secretory capacity. Because prevention and therapy strategies are targeted to this pathologic process, it becomes imperative to have methods with which it can be monitored. This work discusses current research-based approaches to monitor the autoimmunity and metabolic function in T1D patients and their potential for widespread clinical application.

Detection of ß cell death in diabetes using differentially methylated circulating DNA.

In diabetes mellitus, ß cell destruction is largely silent and can be detected only after significant loss of insulin secretion capacity. We have developed a method for detecting ß cell death in vivo by amplifying and measuring the proportion of insulin 1 DNA from ß cells in the serum. By using primers that are specific for DNA methylation patterns in ß cells, we have detected circulating copies of ß cell-derived demethylated DNA in serum of mice by quantitative PCR. Accordingly, we have identified a relative increase of ß cell-derived DNA after induction of diabetes with streptozotocin and during development of diabetes in nonobese diabetic mice. We have extended the use of this assay to measure ß cell-derived insulin DNA in human tissues and serum. We found increased levels of demethylated insulin DNA in subjects with new-onset type 1 diabetes compared with age-matched control subjects. Our method provides a noninvasive approach for detecting ß cell death in vivo that may be used to track the progression of diabetes and guide its treatment.