Type 2 diabetes is a heterogeneous, progressive chronic condition for which management has traditionally focused on glycaemic control and cardiovascular risk factors, rather than focusing on altering long-term disease trajectory. Increasing evidence indicates that progression and complications might be modifiable, but the absence of a core outcome set for disease modification limits trial design and intervention comparison. To address this gap, we developed a core outcome set for disease modification in type 2 diabetes through a modified Delphi process conducted according to COMET guidance. Candidate outcomes were identified from the literature and refined by an international multidisciplinary steering group comprising clinicians, researchers, and people living with type 2 diabetes. Across two Delphi rounds involving health-care professionals, researchers, and patients (round one n=233; round two n=79), agreement was reached for 35 outcomes spanning 11 domains. This framework aims to support outcome selection, consistency across trials, comparison of interventions, and evaluation of disease-modifying strategies in type 2 diabetes.

Pancreatic α-cells are central regulators of glucose and amino acid homeostasis, yet the mechanisms that preserve α-cell identity and function remain incompletely understood. N⁶-methyladenosine (m⁶A) is a widespread mRNA modification that is essential for β-cell biology and pancreatic endocrine differentiation. Here we show that m⁶A is a key regulator of α-cell function and plasticity. In α-cells, metabolic cues that stimulate glucagon secretion such as L-arginine increase METTL3, METTL14 and m⁶A levels. Loss of m⁶A impairs amino acid-stimulated glucagon secretion, disrupts α-cell identity programmes and induces metabolic rewiring. In mice, α-cell-specific Mettl14 deletion reduces α-cell mass, increases β-cell mass and promotes α-to-β-cell conversion, accompanied by the emergence of late β-like states with features of incomplete maturation. Mechanistically, m⁶A-eCLIP identifies Yy1 as a direct m⁶A-sensitive target, and elevated YY1 links m⁶A loss to signalling rewiring and erosion of α-cell identity. These findings identify m⁶A as a central regulator of α-cell state and reveal an epitranscriptomic mechanism controlling endocrine cell plasticity.

A 41-year-old woman with history of hypoglycemic symptoms underwent sleeve gastrectomy for weight loss. Her postoperative course was complicated by cardiac arrest due to polymorphic ventricular tachycardia arising from QT interval prolongation. Weeks after surgery, hypoglycemic symptoms worsened, with postprandial capillary glucose as low as 33 mg/dL (SI: 1.2 mmol/L) (reference, 70-140 mg/dL [SI: 3.9-7.8 mmol/L]). An inpatient fast indicated appropriate suppression of insulin. The combination of worsening hypoglycemia early postoperatively and prolonged QT interval prompted genetic testing, which revealed a likely pathogenic variant in KCNE1, encoding a subunit of the voltage-gated potassium channel Kv7.1, expressed in cardiomyocytes and pancreatic β cells. The patient was treated with nutrition therapy and diazoxide for hypoglycemia and β-blocker for long QT syndrome (LQTS). Patients with KCNE1 pathogenic variants are known to have LQTS and have been reported to have postprandial hypoglycemia. This case highlights the importance of considering genetic etiologies when encountering concomitant hypoglycemia and LQTS, and that preexisting LQTS may confer risk for hypoglycemia after upper gastrointestinal surgery.

The islet of Langerhans (or pancreatic islet) is a unique endocrine organ that secretes multiple hormones that in turn orchestrate energy metabolism in humans. As in other metabolic organs, growth factor(s) regulate functional islet mass to maintain whole-body glucose homeostasis. Over the past decades, a large body of evidence has pointed to insulin and insulin-like growth factors (IGFs) as playing central roles in modulating diverse aspects of islet cell biology and a dysregulated insulin/IGF pathway has come to be recognized as a pathophysiological hallmark of type 2 diabetes (T2D). Several recent reports, especially focused on β-cells, highlight emerging aspects of insulin/IGF signaling, including a role for RNA modifications, transcriptional regulation by nuclear insulin and IGF-1 receptors, and the discovery of an insulin inhibitory receptor, inceptor. In this review, we summarize the functional roles of insulin/IGF signaling in regulating islet cell biology, the short- and long-term effects of insulin therapy in humans, and discuss potential strategies to maximize the beneficial effects of insulin action in islets to counter diabetes.

The mechanisms driving progressive beta-cell dysfunction in type 2 diabetes (T2D) remain incompletely understood. This study aimed to identify pancreatic islet proteome changes that could predict diabetes onset. We isolated islets from non-diabetic subjects undergoing partial pancreatectomy, previously characterized for glucose tolerance, insulin sensitivity, and insulin secretion, using laser capture microdissection (LCM) and analyzed them via high-performance liquid chromatography-mass spectrometry (HPLC-MS). Proteomic analysis revealed that subjects with impaired glucose tolerance (IGT) had reductions in proteins regulating glycolysis (PGK1, G3P), lipid metabolism (ACBP, ARF1), glucose transport (14-3-3B), and insulin secretion (STARD10, CAPDS) compared to normal glucose tolerant (NGT) subjects. Additionally, IGT islets showed impaired expression of proteins involved in glucose- and incretin-stimulated insulin response (CREB1, IQGA1). Stratification by beta-cell glucose sensitivity (βGS) indicated that subjects with lower βGS exhibited reduced levels of insulin maturation (ERO1B) and anti-apoptotic proteins (CASP8, PAK2, SKP1), along with increased SEL1L, a factor promoting endocrine precursor differentiation. These findings suggest that early defects in glucose metabolism and insulin secretion characterize IGT, while reduced βGS may trigger compensatory mechanisms, through enhanced beta-cell survival or neogenesis, to delay T2D progression. Overall, proteomic alterations in prediabetic islets provide potential early predictive markers and targets for interventions aimed at preserving beta-cell function.

Extracellular vesicles (EVs) have shown great promise as minimally invasive biomarkers for a variety of diseases. However, challenges persist regarding EV isolation, particularly in their co-isolation with impurities such as soluble proteins and lipoproteins. Among the methods available for EV isolation, size-exclusion chromatography (SEC) is widely used, as it is reproducible and amenable to high-throughput with a rapid turnaround time. However, its size-based separation leads to the co-isolation of EVs with impurities of similar size. This study, for the first time to our knowledge, compares SEC columns with different pore sizes, 20 and 35 nm, to evaluate their efficacy in non-EV contaminant removal and EV recovery from pancreatic EndoC-ßH1 cell culture media and human plasma. To assess EV purity and yield, we compare EV particle concentration, the presence of unintended co-isolates, and RNA EV cargo. This study demonstrates that smaller pore size SEC columns enhance EV yield and purity, making them ideal for biomarker studies involving limited biological samples or downstream analysis sensitive to contaminants.

Progressive β-cell dysfunction precedes the onset of type 1 diabetes (T1D), yet the molecular mechanisms driving early T1D development remain poorly understood. Although single-cell RNA-sequencing has uncovered transcript-level changes in human islet cells, it offers limited insight into the heterogeneity of distinct islet microenvironments. Here, we applied a single-islet proteomics workflow to profile intra-donor islet heterogeneity in three stage 1 T1D cases with matched non-diabetic controls and define in situ protein signatures of pseudo-temporal islet dysfunction. Intra-donor analyses of ∼100 individual islets per donor revealed highly consistent proteomic patterns reflecting pseudo-time progression of islet immune responses and β-cell dysfunction. Several pathways, including extracellular matrix remodeling and mRNA processing, were identified as closely associated with progressive islet immune activation and loss of β-cell function. These findings provide robust proteome-wide evidence of the progression of islet dysfunction, offer a valuable resource for investigating early mechanisms of T1D pathogenesis— including novel candidates for functional studies—and underscore the utility of single-islet spatial proteomics for examining islet heterogeneity in T1D.

Type 1 diabetes (T1D) results from autoimmune-mediated destruction of insulin-producing β cells in the pancreatic islet. This process is modulated by pro-inflammatory cytokine signaling, which has been previously shown to alter protein expression in ex vivo islets. Herein, we applied top-down proteomics to globally evaluate proteoforms from human islets treated with proinflammatory cytokines (interferon-γ and interleukin-1β). We measured 1636 unique proteoforms across six donors and two time points (control and 24 h post-treatment) and observed consistent changes in abundance across the glicentin-related pancreatic polypeptide (GRPP) and major proglucagon fragment regions of glucagon, as well as the LF-19/catestatin and vasostatin-1/2 region of chromogranin-A. We also observe several proteoforms that increase after cytokine-treatment or are exclusively observed after cytokine-treatment, including forms of beta-2 microglobulin (B2M), high-mobility group N2 protein (HMGN2), and chemokine (C-X-C motif) ligands (CXCL). Together, our quantitative results provide a baseline proteoform profile for human islets and identify several proteoforms that may serve as interesting candidate markers for T1D progression or therapeutic intervention. SUMMARY: This work applies a top-down proteomics workflow for the characterization and label-free quantification of proteoforms from human islets in the context of inflammation. The workflow is optimized for challenges unique to the islet proteome including high disulfide-linkage content and frequent truncation events, resulting in many proteoforms < 5kDa. There are limited examples of top-down proteomics characterization of human islets, thus this study provides a baseline characterization of the proteoforms of major hormones including chromogranin-A (CHGA), chromogranin-B/ secretogranin-1 (CHGB/SCG1), chromogranin-C/ secretogranin-2 (CHGC/SCG2), islet amyloid polypeptide (amylin/IAPP), insulin (INS), glucagon (GCG), pancreatic polypeptide prohormone (PPY), somatostatin (SST), and neurosecretory protein VGF (VGF). The quantitative results of proteoform abundances before and after cytokine treatment, which mimics the proinflammatory environment during T1D progression, provides interesting insights on how prohormone processing is altered under a proinflammatory environment.

N⁶-methyladenosine (m⁶A) is among the most abundant mRNA modifications, yet its cell-type-specific regulatory roles remain unclear. Here we show that m⁶A methyltransferase-like 14 (METTL14) differentially regulates transcriptome in brown versus white adipose tissue (BAT and WAT), leading to divergent metabolic outcomes. In humans and mice with insulin resistance, METTL14 expression differs significantly from BAT and WAT in the context of its correlation with insulin sensitivity. Mettl14-knockout in BAT promotes prostaglandin secretion, improving systemic insulin sensitivity. Conversely, Mettl14-knockout in WAT triggers adipocyte apoptosis and systemic insulin resistance. m⁶A-seq and RNA-seq integration revealed upregulated prostaglandin biosynthesis pathways in BAT and apoptotic pathways in WAT with Mettl14 deficiency. Stable METTL14-knockout hBAs/hWAs show METTL14-mediated m⁶A promotes mRNA decay of PTGES2 and CBR1 in hBAs and TRAIL and TNFR1 in hWAs. These data shed light on the ability of m⁶A to impact metabolism in a cell-type-specific manner with implications for influencing the pathophysiology of metabolic diseases.

© 2025. The Author(s).

Aims/hypothesis: Progression to type 1 diabetes is associated with genetic factors, the presence of autoantibodies and a decline in beta cell insulin secretion in response to glucose. Very little is known regarding the molecular changes that occur in human insulin-secreting beta cells prior to the onset of type 1 diabetes. Herein, we applied an unbiased proteomics approach to identify changes in proteins and potential mechanisms of islet dysfunction in islet-autoantibody-positive organ donors with pre-symptomatic stage 1 type 1 diabetes (HbA_1c ≤42 mmol/mol [6.0%]). We aimed to identify pathways in islets that are indicative of beta cell dysfunction.

Methods: Multiple islet sections were collected through laser microdissection of frozen pancreatic tissues from organ donors positive for single or multiple islet autoantibodies (AAb⁺, n=5), and age (±2 years)- and sex-matched non-diabetic (ND) control donors ( n=5) obtained from the Network for Pancreatic Organ donors with Diabetes (nPOD). Islet sections were subjected to MS-based proteomics and analysed with label-free quantification followed by pathway and functional annotations.

Results: Analyses resulted in ~4500 proteins identified with low false discovery rate (<1%), with 2165 proteins reliably quantified in every islet sample. We observed large inter-donor variations that presented a challenge for statistical analysis of proteome changes between donor groups. We therefore focused on only the donors with stage 1 type 1 diabetes who were positive for multiple autoantibodies (mAAb⁺, n=3) and genetic risk compared with their matched ND controls (n=3) for the final statistical analysis. Approximately 10% of the proteins (n=202) were significantly different (unadjusted p<0.025, q<0.15) for mAAb⁺ vs ND donor islets. The significant alterations clustered around major functions for upregulation in the immune response and glycolysis, and downregulation in endoplasmic reticulum (ER) stress response as well as protein translation and synthesis. The observed proteome changes were further supported by several independent published datasets, including a proteomics dataset from in vitro proinflammatory cytokine-treated human islets and single-cell RNA-seq datasets from AAb⁺ individuals.

Conclusions/interpretation: In situ human islet proteome alterations in stage 1 type 1 diabetes centred around several major functional categories, including an expected increase in immune response genes (elevated antigen presentation/HLA), with decreases in protein synthesis and ER stress response, as well as compensatory metabolic response. The dataset serves as a proteomics resource for future studies on beta cell changes during type 1 diabetes progression and pathogenesis.