An inflection point (IP) marking accelerated β-cell decline occurs ∼1-2 years before type 1 diabetes diagnosis. Precisely determining this timing could optimize clinical intervention. We developed machine learning models to predict proximity to the inferred metabolic IP using oral glucose tolerance test (OGTT) data from islet autoantibody-positive individuals in the TrialNet Pathway to Prevention study. OGTTs were retrospectively labeled by estimating time to the IP using thresholds from 1.2 to 1.6 years. Models were trained on engineered glucose and C-peptide dynamics, slopes, and composite indices, with feature selection by recursive feature elimination (RFE). Classifiers included support vector machines (SVM), random forests, and gradient boosting; a Cox proportional hazards model was also applied to estimate visit-level time to diagnosis and derive time-to-IP predictions. External validation was performed in the independent Diabetes Prevention Trial-Type 1 cohort. The best-performing model-SVM with RFE at the 1.4-year threshold-achieved an area under the curve of 0.77 (95% CI 0.72-0.82). The Cox model provided complementary numeric estimates of time to diagnosis and time to IP, sensitive to the cohort-level lead time offset (Δ). These findings show that machine learning and survival analysis can support early metabolic shift detection, enabling timely risk stratification and personalized monitoring in at-risk individuals.

We previously reported that transgenic overexpression of Nfkbid in NOD mice led to robust type 1 diabetes protection associated with enhanced negative selection of autoreactive T cells and expansion of regulatory T cells (Tregs) with increased suppressive capacity. The goal of this study was to further identify cellular and molecular mechanisms underlying strong protection from type 1 diabetes imbued by overexpressing Nfkbid. Transcript analysis of Tregs from Nfkbid-overexpressing NOD mice show enrichment of cellular replication pathways. Effector T cells from Nfkbid-overexpressing NOD mice have increased indicators of activation-induced exhaustion in pancreatic lymph nodes and islets. This trait is intrinsic to Nfkbid-overexpressing T cells, as ex vivo anti-CD3 stimulation of splenic-derived T cells can reproduce this phenotype. Anti-PD-1 administration breaks the diabetes protective effect. Furthermore, we found that Nfkbid-overexpressing dendritic cells, but not B cells, have an enhanced capacity to stimulate proliferation of diabetogenic AI4 CD8+ T cells (with wild-type levels of Nfkbid). Conversely, B cells, but not dendritic cells, drive enhanced de novo conversion of regulatory T cells from effector T cells. Together, this study documents additional mechanisms that likely synergize to contribute to the diabetes-protective effects of Nfkbid overexpression. Understanding the mechanisms underlying protection from Nfkbid overexpression may lead to novel therapeutic avenues.

The pentose phosphate pathway (PPP) furnishes NADPH for hepatic de novo lipogenesis, driving intrahepatic lipid (IHL) accumulation. The aim of the current study was to examine the association between the PPP, proxied by 24-h urinary erythritol, and IHL content at the population level. We used cross-sectional data from the Maastricht Study, a population-based cohort study (N = 1,494; mean ± SD age 59 ± 8 years; 49% women). We first assessed the relationship between 24-h urinary erythritol and IHL content (quantified with 3T Dixon MRI), with adjustment for age, sex, type 2 diabetes, proxies of socioeconomic status/lifestyle, MRI lag time, BMI, and intake of erythritol-containing food items. Second, we performed a genome-wide association study (GWAS) for 24-h urinary erythritol (N = 2,000) and Mendelian randomization (MR) study using common variants in genes associated with erythritol in relation to IHL content. In the fully adjusted model, 24-h urinary erythritol levels were associated with higher (10log) IHL content. The GWAS identified one genome-wide significant locus (rs72686491; TESK2) and replicated two previously reported genetic variants at nominal significance. MR analysis, using these three genetic instruments, did not reveal a statistically significant association between genetically predicted erythritol levels and IHL content. The findings of this population-based study show that higher PPP flux is associated with higher IHL content, a well-established risk factor for type 2 diabetes. An active role for erythritol per se was excluded by MR analysis.

GRP78/BiP/HSPA5 is a widely expressed endoplasmic reticulum (ER) chaperone that also performs the critical role of regulating the unfolded protein response, an adaptive mechanism that maintains ER homeostasis. As the exclusive source of circulating insulin, pancreatic β-cells are prone to ER stress due to proinsulin synthesis workload. GRP78 is important for the ER stress response, but it is unknown whether β-cells require GRP78 in the absence of metabolic stress. Here, we report the impact of genetic deletion of GRP78 in β-cells of healthy adult mice during normal metabolic conditions. Glucose intolerance occurred in both sexes, mildly in females but profoundly in males, concomitant with weight loss. Islet size and β-cell mass were reduced only in males. Both sexes showed similar increases in β-cell death and residual α-cell proportion, but females more robustly showed increased β-cell proliferation. Intriguingly, dedifferentiation was prominent in males, both in vivo and ex vivo, and male islet cells showed hyperactive induction of ATF6 target genes during ex vivo Grp78 deletion compared with female. We conclude that GRP78 is essential for β-cell health, even in resting conditions, and that sex differences exist in the β-cell ER stress response.

Noninvasive measurement of pancreatic β-cell mass remains an important unmet need in type 1 diabetes because conventional surrogate markers, such as C-peptide, often lack sensitivity in advanced disease. This study evaluated the glucagon-like peptide 1 receptor-targeted positron emission tomography tracer, 18F-labeled exendin-4-based probe conjugated with polyethylene glycol, [18F]FB(ePEG12)12-exendin-4 (18F-exendin-4), to determine its ability to visualize pancreatic β-cell mass. Positron emission tomography/computed tomography performed at 60 and 120 min after tracer injection in individuals with type 1 diabetes was compared with data from healthy control participants. No serious adverse events occurred. Pancreatic uptake was consistently lower in individuals with type 1 diabetes and showed clear separation between individuals with insulin-dependent diabetes and healthy control participants at 120 min. Pancreatic uptake at 120 min correlated with fasting C-peptide index and inversely with hemoglobin A1c and daily insulin dose per body weight. These findings support [18F]FB(ePEG12)12-exendin-4 positron emission tomography/computed tomography as a noninvasive approach for assessing β-cell mass and disease status.

Diabetic kidney disease (DKD) is a major complication of diabetes characterized by progressive renal dysfunction driven by oxidative stress and inflammation involving mammalian target of rapamycin (mTOR) and NADPH oxidase (NOX) pathways. Mesenchymal stem cells (MSCs) have gained attention for their regenerative and immunomodulatory properties in attenuating DKD, but the mechanisms behind their protective effects are still being explored. Moreover, concerns regarding tumorigenic risks hinder their direct clinical use. In this study, we compared MSCs and their conditioned media (MSCs-CM; secretome) in a type 1 diabetic rodent model, demonstrating that both treatments attenuated glomerular injury, preserved podocyte integrity, reduced NOX4 expression and activity, and tempered inflammation, by inhibiting mTORC1 and mTORC2 signaling. Importantly, MSCs-CM replicated the renoprotective effects of MSCs, indicating that soluble factors mediate these benefits. To our knowledge, this is the first study to directly compare MSCs and their conditioned media (MSCs-CM) in DKD, revealing that MSCs-CM delivers equivalent therapeutic efficacy while circumventing the safety concerns inherent to cell-based therapies. These findings identify the mTOR/NOX axis as a therapeutic target and support MSCs-CM as a promising, safer, cell-free alternative for DKD treatment, potentially advancing regenerative strategies to mitigate diabetic renal injury.

Prestroke hyperglycemia and insulin resistance (IR) independently correlate with poor stroke outcomes in type 2 diabetes (T2D), although their causative effect is undetermined. Interestingly, an increasing body of evidence points toward the importance of IR in determining stroke outcomes. Filling this gap is fundamental to identifying effective anti-T2D strategies to improve stroke prognosis in people with T2D. The aim of this study was to determine experimentally whether normalizing IR rather than hyperglycemia before stroke improves stroke outcomes in T2D. To address this research question, hyperglycemia or IR was normalized with intermediate-acting insulin or long-acting selective glucagon receptor agonist (La-GCGRa), respectively, in obese/T2D mice before inducing stroke. Functional recovery (primary outcome) was assessed by neurological testing. Systemic inflammation, infarct size, and neuroinflammation (secondary outcomes) were assessed by ELISA and immunohistochemistry, respectively. The results showed that insulin treatment normalized hyperglycemia without affecting IR and did not improve functional recovery. On the contrary, La-GCGRa normalized IR without affecting hyperglycemia and improved functional recovery. This effect occurred in association with reduced systemic and stroke-induced neuroinflammation. Neither treatment affected infarct size. The data demonstrate that targeting IR in T2D is crucial for improving stroke outcomes and may have significant implications for human therapy.

Diabetic retinopathy (DR) is a leading cause of vision loss in working-age adults and often progresses to proliferative diabetic retinopathy (PDR) with irreversible complications. Anti-vascular endothelial growth factor (VEGF) therapy remains the first-line treatment; however, resistance poses a significant challenge, necessitating alternative therapeutic targets. This study explores the role of angiopoietin-like protein 4 (ANGPTL4) in PDR pathogenesis, emphasizing vascular-immune-lymphatic interactions. We found significantly elevated ANGPTL4 and VEGF-C levels in the vitreous humor of patients with PDR, which were not affected by anti-VEGF therapy. In vivo, full-length ANGPTL4 and its C-terminal fragment promoted pathological angiogenesis and lymphatic-like remodeling in diabetic murine retinas, characterized by increased lymphatic vessel endothelial hyaluronan receptor 1, prospero homeobox 1, and VEGF receptor 3 (VEGFR3) expression. Single-cell sequencing further revealed ANGPTL4-driven immune dysregulation, with abnormal infiltration of CD4+ T cells and dendritic cells. Knockdown of ANGPTL4 in mice with oxygen-induced retinopathy alleviated retinal hypoxia, neovascularization, and vascular leakage. Mechanistically, retinal hypoxia markedly increased ANGPTL4 expression levels in the retina, which activated the activator protein-1 (AP-1) transcription factor complex and promoted Cd83 transcription in mouse heart microvascular endothelial cells. Additionally, ANGPTL4 bound to neuropilin-1 (NRP1)/VEGFR3, driving human lymphatic endothelial cell proliferation and lymphatic vessel ingrowth from the optic nerve sheath into the retina, a finding that suggests a novel pathway independent of angiopoietin-Tie signaling. These findings establish ANGPTL4 as a key mediator of immune-vascular interactions in PDR and a potential therapeutic target to address both pathological angiogenesis and lymphatic dysfunction.

Individuals who undergo pancreatic resection are at increased risk of developing hepatic steatosis. Glucagon is a key regulator of hepatic glucose, amino acids, and lipid metabolism, and the change in circulating glucagon is suggested to contribute to the pathogenesis of postoperative steatotic liver disease. Here, we aimed to elucidate hepatic and metabolic changes induced by pancreatic resection. Fifty individuals scheduled to undergo pancreatic surgery were recruited and evaluated by blood samples and a liver biopsy obtained during surgery. One year after surgery, 21 eligible participants (15 following pancreaticoduodenectomy, 6 following total pancreatectomy) met for a follow-up visit, with the remaining being excluded because of recurrent disease, comorbidities, or death. Follow-up MRS indicated increased liver fat in 12 of 19 participants despite a mean numerical decrease in body weight. Five eligible participants underwent a liver biopsy at follow-up, demonstrating increased liver fat content (largest individual increase: 80 percentage points). Circulating glucagon and C-peptide were significantly reduced at follow-up, with no detection of either following total pancreatectomy. No significant changes in fasting plasma glucose or HbA1c were observed, attributed to relevant exogenous insulin supplementation. Amino acids were markedly increased after both pancreaticoduodenectomy and total pancreatectomy, correlating negatively with remnant endocrine pancreatic function. In conclusion, our data suggest that reduced circulating glucagon levels may contribute to the increased liver fat content and hyperaminoacidemia observed after pancreatic resection.

Diabetic cardiomyopathy (DCM), characterized by myocardial hypertrophy and fibrosis, is a severe complication of diabetes. Activation of Yes-associated protein (Yap) has been implicated in myocardial remodeling and cardiac dysfunction. This study aimed to elucidate the role and underlying molecular mechanisms of Yap in DCM. Yap expression was evaluated in mice with type 2 diabetes mellitus (T2DM) and in neonatal rat cardiomyocytes (NRCMs) treated with high glucose (HG) or HG + palmitic acid (PA). Adeno-associated virus transfection, adenovirus infection, and a transgenic mouse model were used to modulate Yap expression both in vivo and in vitro. RNA sequencing and miRNA sequencing were used to identify Yap's downstream targets and related mechanisms. Functional assays, including assessment of molecular markers, cell morphology, and echocardiography, were conducted to evaluate cardiomyocyte hypertrophy and fibrosis. Results showed that Yap expression was elevated in HG or HG+PA-treated NRCMs and hearts of T2DM mice, promoting myocardial hypertrophy and fibrosis. Inhibition of Yap reduced cardiomyocyte cross-sectional area, collagen deposition, and levels of hypertrophy markers atrial natriuretic peptide and β-myosin heavy chain. RNA sequencing identified Sirt1 as a downstream target of Yap. Bioinformatics analysis indicated that Yap positively regulated miR-22-3p, which in turn inhibited Sirt1. Yap inhibition increased Sirt1 expression, alleviating myocardial remodeling. Conversely, Sirt1 knockdown reversed the protective effects of Yap inhibition, exacerbating hypertrophy and fibrosis. In conclusion, Yap promotes the progression of DCM by upregulating miR-22-3p expression and suppressing Sirt1 expression. Therapeutically targeting the newly identified Yap-miR-22-3p-Sirt1 axis could mitigate multiple aspects of diabetic cardiac remodeling.

Autoimmune diabetes presenting in infancy or with additional autoimmune disorders can be the result of highly penetrant variants in key immune homeostasis genes. An example of this is observed with biallelic pathogenic variants in IL2RA (CD25), which causes immunodeficiency 41 (IMD41). IL2RA encodes the α-chain of the interleukin-2 receptor, which helps regulate the growth and activity of T cells. The diabetes phenotype in IMD41 has not been systematically described. We sequenced IL2RA in 290 individuals with diabetes diagnosed <6 months and in 64 individuals diagnosed <10 years who had additional autoimmunity. We also reviewed all previously reported IMD41 cases. We identified five new unrelated individuals with biallelic pathogenic IL2RA variants. Four presented with diabetes in the first month of life with very low/absent C-peptide, and all were GAD antibody-positive. Of 17 previously reported cases, 9 had diabetes, yielding a total of 14 of 22 (64%) with early-onset diabetes. No relationship between variant location/type and diabetes development was observed. Autoimmune diabetes is therefore a common and early feature of IMD41. IL2RA should be included in genetic testing panels for neonatal and monogenic autoimmune diabetes. These findings highlight the important role of IL2RA in immune tolerance and β-cell protection.

Type 1 diabetes (T1D) is the most common chronic autoimmune disease in children, driven by a breakdown in self-tolerance and T cell-mediated immune attack of pancreatic β-cells. There are no biomarkers to effectively diagnose autoimmunity before disease onset and clinical symptom development. Here, we applied deep multiparametric immunophenotyping to compare immune landscapes in 38 patients with new-onset T1D, 24 siblings, and 18 healthy control participants (HCs). Patients with T1D underwent clinical and metabolic evaluations. Immune populations in fresh whole-blood samples were analyzed using a panel of 26 antibodies, detecting 39 different cell populations. Memory regulatory T cells (memory Tregs) were significantly increased in patients with T1D (P < 0.05) and their siblings (P < 0.01) compared with HCs but not between patients with T1D and siblings. Memory Tregs were associated with disease status and age in multivariable analysis. There was a positive correlation between age and memory Tregs in the HC and sibling groups but not in patients with T1D. Baseline memory Treg levels in siblings resembled those of patients with T1D. These findings highlight the existence of an age-independent, disease-specific immune fingerprint that could serve as a minimally invasive biomarker for early diagnosis and personalized immunotherapy. Further studies using functional and single-cells analysis are needed to confirm memory Tregs as a pathogenic trait.

Gestational diabetes mellitus (GDM) is a heterogeneous condition diagnosed solely through glucose. It is characterized by profound perturbations in the metabolome, with specific metabolic profiles linked to adverse birth outcomes. Metabolomics can reveal population heterogeneity in health and disease. Here, we used nontargeted metabolomics to systematically profile the circulating metabolome in 2,050 pregnant women during midpregnancy, identifying 30 metabolites that define the GDM metabolic signature (mGDM). Participants were stratified into four groups by distinct glycemic and metabolic profiles, namely normoglycemic non-mGDM, hyperglycemic non-mGDM, normoglycemic mGDM, and hyperglycemic mGDM, and associations with subsequent adverse birth outcomes were assessed. Compared with normoglycemic non-mGDM, normoglycemic mGDM demonstrated nearly a twofold increased risk of preterm birth (odds ratio [OR] 1.93, 95% CI 1.02-3.65) and large for gestational age (OR 2.11, 95% CI 1.53-2.92). Conversely, the hyperglycemic non-mGDM group did not show elevated risks in adverse birth outcomes versus the normoglycemic group. The hyperglycemic mGDM profile was associated with higher risks of preterm birth (OR 2.37, 95% CI 1.04-5.39), large for gestational age (OR 2.28, 95% CI 1.50-3.47), congenital malformations (OR 1.87, 95% CI 1.03-3.39), and neonatal intensive care unit (NICU) admissions (OR 1.69, 95% CI 1.09-2.61). We observed a stepwise increase in adverse outcome risk across the four-level metabolic-glycemic categories (P for trend < 0.001 for large for gestational age, 0.013 for preterm birth, and 0.018 for NICU admission). Taken together, our study outlines the metabolic profile of GDM and reveals clinically relevant heterogeneity in adverse pregnancy outcomes by metabolic signature. Integrating blood glucose and metabolomics may improve risk stratification and advance precision maternal care.

Chronic low-grade inflammation underlies many microvascular complications of diabetes, including diabetic kidney disease (DKD). Lipoxins (LXs), an endogenously produced family of lipid mediators, resolve inflammation and protect against renal scarring as occurs in DKD. This study examined the mechanism by which LXs protect against DKD, focusing on the regulation of VCAM-1 and the recruitment of macrophages to the diabetic glomerulus. LXA4 and two fourth-generation mimetics were assessed in diabetic ApoE knockout mice, followed by in vitro studies in the main renal cell populations, including podocytes, proximal tubular, mesangial, and glomerular endothelial cells. LXs attenuated albuminuria, mesangial expansion, and collagen and fibronectin deposition as both a preventive and delayed intervention in experimental DKD. LXs also consistently attenuated the TNF-α-induced expression of VCAM-1 in all the human and mouse renal cell populations examined. Further analysis identified that the renoprotection was in part mediated by an epigenetic modification of the VCAM-1 gene through H3K4 monomethylation, which did not appear to be dependent on NF-κB activation in human glomerular endothelial cells. LXs protect against DKD by modulating glomerular endothelial cell inflammation and via a novel LX-mediated epigenetic mechanism regulating the VCAM-1 promoter in these cells.

Adipose tissue (AT) lipolysis insulin resistance results in excess free fatty acid (FFA) release. We tested the hypothesis that the ability of insulin to suppress AT lipolysis is unrelated to the ability of niacin to suppress lipolysis, because niacin acts through a different proximal signaling pathway. Ten volunteers (5 women and 5 men) with upper-body obesity and/or type 2 diabetes mellitus (T2DM) underwent two study visits with overnight intravenous infusions of niacin (1.4 mg/min) or saline, followed by a hyperinsulinemic-euglycemic clamp. FFA-palmitate Ra was measured using [U-13C] and [2H9]palmitate infusions; abdominal AT biopsies were performed before and during the insulin clamp. The suppression of FFA-palmitate Ra by insulin on the saline control day and by niacin after an overnight infusion were highly correlated (r = -0.93, P < 0.001). Fasting AT Akt (pAktS473/474-to-panAkt ratio, P = 0.01) and perilipin 1 (PLN1) (pPLN1S552-to-panPLN1 ratio, P = 0.02) phosphorylation were less during niacin treatment than in the saline control study. Because the suppression of lipolysis by insulin and niacin are highly correlated within individuals and because niacin and insulin act through different proximal signaling pathways, we propose dysregulated AT lipolysis in obesity/T2DM is due to dysfunction(s) in distal lipolysis proteins rather than isolated "insulin resistance."

Pancreatic β-cells play a central role in type 2 diabetes mellitus (T2DM), yet the interactions between β-cells and stromal components within the islet microenvironment remain poorly defined. We investigated the contribution of pancreatic fibroblasts to β-cell dysfunction and T2DM progression. We used single-cell sequencing technology and in vitro experiments to investigate the mechanisms by which bariatric surgery ameliorates T2DM. We introduce the novel concept of a "metabolic synapse" to describe the interaction between pancreatic fibroblasts and β-cells. Our findings reveal that pancreatic fibroblasts secrete excessive glutamate in the early stages of T2DM. Elevated glutamate concentrations within the islet microenvironment subsequently activate N-methyl-d-aspartic acid receptors (NMDARs), triggering PANoptosis in pancreatic β-cells and accelerating T2DM progression. Consistent with this, significant changes in NMDAR expression were observed in human pancreatic samples from patients with T2DM. These findings uncover a previously unrecognized fibroblast-β-cell communication pathway in the islet niche, provide mechanistic insights into T2DM pathogenesis, and highlight the glutamate-NMDAR axis as a potential therapeutic target for nonsurgical intervention.