Abstract Mass spectrometry imaging (MSI) enables spatially resolved metabolomics in intact tissue sections, but analysis remains challenging at scale. Existing MSI workflows often require users to combine multiple software tools, while others rely on proprietary vendor software that limits interoperability and reproducibility. To address these challenges, we developed spatialMET, an open-source framework that provides an end-to-end workflow for MSI analysis. spatialMET provides a unified platform for preprocessing, spatial domain detection, and visualization. Downstream analyses include differential abundance testing, spatial autocorrelation and gradient analysis, dimensionality reduction, and correlation network analysis. Spatial domain detection uses hcdist, a C-based hierarchical clustering implementation that substantially reduces runtime and memory use relative to existing R-based approaches. spatialMET can be run through an interactive R Shiny application or as a standalone command-line workflow for larger datasets or high-performance computing environments. Applied to mouse small cell lung cancer MALDI-MSI data containing 284,673 pixels, spatialMET identified tumor-associated, stromal, and adjacent lung spatial domains that aligned with matched histology. Differential abundance analysis identified 117 m/z features that differed between tumor and stromal regions, while spatial autocorrelation analyses revealed spatially structured abundance patterns. Applying spatialMET to mouse lung adenocarcinoma data from an entire lung lobe containing 338,477 pixels further demonstrated scalability and captured spatial heterogeneity across tumor and surrounding lung tissue. In summary, spatialMET provides a scalable, open-source framework for end-to-end spatial metabolomics analysis, and it is distributed as a Docker container for reproducible deployment. Source code and installation instructions are available at https://github.com/biodatalab/spatialMET .

Abstract Suspended animation, a state of profound metabolic, behavioral and developmental quiescence, is a remarkable yet poorly understood stress resilience strategy in animals. Here, we describe a previously uncharacterized form of suspended animation inducible by high-population density in isosmotic liquids in C. elegans throughout larval development and adulthood. Transcriptomic, metabolomic, and live-cell activity reporter imaging analyses reveal striking molecular and cellular landscape changes caused by such liquid-induced suspended animation (LISA), including remodeling of gene expression programs, energy metabolites, lysosomal and mitochondrial morphology. Genetic screens identify mutants with altered stress responses and survival against LISA. While key endo-lysosomal regulators promote survival during LISA, organelle remodeling and a neuronal axis via downstream neuropeptide and cAMP/PKA signaling orchestrate behavioral awakening from LISA. Our findings define a facile paradigm for reversible SA, providing a powerful model system to uncover key molecular and cellular mechanisms governing an extreme case of reversible life arrest and dormancy.

Abstract Background: Obesity-related metabolic dysfunction may promote colorectal carcinogenesis through sphingolipid pathways. Ceramides and related species regulate insulin resistance, inflammation, and intestinal stem-cell proliferation; however, prospective data linking circulating sphingolipids to colorectal cancer (CRC) are limited, particularly in African Americans. Methods: We conducted a nested case-control study within the Southern Community Cohort Study (SCCS) including 373 African American CRC cases and 373 matched control participants. Targeted lipidomic analysis quantified 165 sphingolipids including 78 ceramides, 36 sphingomyelins, 30 neutral glycosphingolipids, 14 glycerophosphocholines, 4 sphingoid base-1-phosphates, 4 sphingoid base homologs, and one ceramide-1-phosphate. Conditional logistic regression estimated odds ratios (OR) and 95% CI per standard deviation (SD), adjusting for age, sex, number of aliquot freeze-thaw cycles, education, body mass index, smoking status, physical activity, energy intake, fiber intake, red/processed meat intake, and alcohol intake. Results: Participants were aged 54±9 years, and 55% were female. In fully adjusted models, several very-long-chain ceramides and one sphingomyelin showed statistically significant inverse associations with CRC risk with adjustment for multiple comparisons at FDR q<0.05, including Cer(d16:1/23:0), Cer(d16:1/22:0), Cer(d17:1/22:0), Cer(d17:1/23:0), Cer(d18:2/23:0), and SM(d16:1/23:0) (OR per SD range 0.76 to 0.80, p range 0.001 to 0.009). Some long-chain dihydroceramides and ceramides previously linked to metabolic diseases were positively associated with CRC, though results did not reach statistical significance (e.g., dhCer(d18:0/18:0), OR 1.15, 95% CI 0.98-1.35; Cer(d18:1/18:0), OR 1.08, 95% CI 0.92-1.26). Conclusions: Pre-diagnostic very-long-chain ceramide species showed protective associations with CRC incidence in African Americans. Findings highlight potential metabolically actionable pathways for CRC prevention. Acknowledgement: U01CA202979 and U01CA272529 Citation Format: Sara Salas, Stephanie Richardson, Danxia Yu, Alan Maschek, James E. Cox, Joshua Alvarez, Emmanuel Onyegba, Monowarul Siddique, Steve Moore, Marc Gunter, Anna Ibele, Xiao-Ou Shu, Scott A. Summers, Cornelia M. Ulrich, Mary Playdon. Circulating sphingolipids and colorectal cancer risk in African American adults [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 2541.

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a progressive disorder marked by lipid accumulation, leading to metabolic dysfunction-associated steatohepatitis (MASH). A key feature of the transition to MASH involves oxidative stress resulting from defects in mitochondrial oxidative phosphorylation (OXPHOS). Here, we show that pathological alterations in the lipid composition of the inner mitochondrial membrane (IMM) directly instigate electron transfer inefficiency to promote oxidative stress. Specifically, mitochondrial cardiolipin (CL) was downregulated with MASLD/MASH in humans and in mice. Hepatocyte-specific CL synthase knockout (CLS-LKO) led to spontaneous and robust MASH with extensive steatotic and fibrotic phenotype. Loss of CL paradoxically increased mitochondrial respiratory capacity but also promoted electron leak primarily at sites III QO and II F of the electron transport chain (ETC), reduced the formation of I + III 2 + IV respiratory supercomplex, and disrupted the propensity of coenzyme Q to become reduced. Thus, low mitochondrial CL disrupts the ETC to promote oxidative stress and contributes to the pathogenesis of MASH.

Cardioplegia is often used prior to acquisition of human cardiac tissue to minimize warm ischemia time, which can severely confound studies of cardiac metabolism. However, there are several choices of cardioplegia solutions, and whether these solutions differentially impact tissue metabolism or metabolomic studies is not known. Here, we perform untargeted metabolomics, using both liquid chromatography-mass spectrometry and gas chromatography-mass spectrometry, on a large cohort of hearts transplanted for cardiomyopathy or from gift-of-life donors, and who have received different cardioplegia solutions. We show that different cardioplegia solutions distinctly impact cardiac metabolism and tissue metabolomic studies. Notably, these differences are mild relative to those seen comparing failing to nonfailing hearts, and identification of cardioplegia components in mass spectra should enable rigorous interpretation of changes between conditions. These data demonstrate how cardioplegia solutions may influence cardiac metabolism in human heart samples and underscore the need to report specific details of cardioplegia solution use in studies of human cardiac metabolism.

Abstract Background: Cancer-related fatigue (CRF) is the most frequently reported symptom among patients with colorectal cancer (CRC), with limited therapeutic options. Alterations in metabolic pathways related to lipid metabolism have been shown to play a role in non-cancer fatigue-associated diseases, and are hypothesized to influence CRF. The purpose of the present study was to investigate serum lipidomic biomarkers to identify longitudinal predictors of CRF in a prospective cohort of patients with CRC. Methods: The ColoCare Study enrolled men and women ages 18 to 89 with newly diagnosed primary stage I-IV CRC at six U.S. sites and one German site. CRF was measured using the fatigue subscale of the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire C30 (EORTC QLQ-C30) at T0 (CRC surgery/baseline), T1 (6 months post-surgery), T2 (12 months), and T3 (24 months). Using blood collected at each time point, we performed targeted lipidomics following comprehensive protocols for measurement and quality control. For the present study, participants with stage I-III disease and at least one measurement of CRF and lipidomic profiling (N=863) were included. Using linear mixed effects models with an interaction term with time point and subject-specific random intercepts, we assessed associations between individual lipids and CRF at each time point. We adjusted for multiple testing using the Benjamini-Hochberg correction for false-discovery rate. Models also adjusted for age, sex, tumor site, stage, body mass index, chemotherapy, radiation, and study site. We used elastic net regression on a training subset (n=176) to identify lipids at T1 (when first-line treatment was nearing completion) that were predictive of fatigue at T2. Further analyses validating prediction models and using metabolic pathway analyses are ongoing. Results: Mean age was 61.6 years (SD: 12.7). N=305 total lipids were identified. In linear mixed effects models, no lipids were associated with CRF at T0 or T1. At T2 and T3, higher levels of ceramides (20), monohexosylceramides (11), gangliosides (4), trihexosylceramides (1), and sphingomyelins (16) were associated with lower CRF after adjustment for multiple testing. Predictive modeling identified higher levels of three sphingolipids at T1 associated with lower CRF at T2 and higher levels of two lipids (one diglyceride and one ceramide) at T1 associated with higher CRF at T2. Conclusions: Specific sphingolipids, including ceramides, monohexosylceramides, and sphingomyelins, were inversely associated with CRF, suggesting a protective role. Predictive modeling supports their potential as targetable biomarkers of fatigue. These findings highlight lipid metabolism as a promising target for understanding and mitigating fatigue in cancer survivors, warranting external validation and mechanistic research. Citation Format: Nicole C. Loroña, Mary C. Playdon, James E. Cox, Alan Maschek, Xiaoyin Li, Aasha I. Hoogland, Maria F. Gomez, Patricia A. Erickson, Mmadili N. Ilozumba, Victoria Damerell, Ildiko Strehli, Megan Mclaws, Lyen C. Huang, Paul Stewart, Sheetal Hardikar, Jennifer Ose, Anita R. Peoples, Brent Small, David Shibata, Doratha A. Byrd, Adetunji T. Toriola, Christopher I. Li, Cornelia M. Ulrich, Biljana Gigic, Heather S. Jim, Jane C. Figueiredo. Identifying novel therapeutic targets for cancer-related fatigue in colorectal cancer patients using lipidomics: Results from the ColoCare Study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 875.

Supplemental Table 1: Primers used

Histidine containing dipeptides (HCDs) such as N-acetylcarnosine are endogenous metabolites that are ergogenic and mitigate metabolic dysfunction. We previously demonstrated that short-term N-acetylcarnosine treatment is highly efficacious in protecting muscle atrophy induced by disuse. Here we demonstrate that a 6-months treatment of N-acetylcarnosine attenuates a broad spectrum of age-associated maladies and improved survival by ~50% in female mice. A comprehensive survey of organ systems revealed that N-acetylcarnosine prevents decline in adiposity, diastolic function, vasodilation, muscle strength, and bone density. Together, N-acetylcarnosine substantially delays the onset of system-wide end-stage pathology to prolong lifespan. As an endogenously present metabolite, treatment with N-acetylcarnosine may be a safe and promising intervention to promote healthy aging in humans.

BackgroundType 2 immunity is initiated through a synergistic response between innate and adaptive immune cells to facilitate host-pathogen defense and wound repair, yet aberrant responses can contribute to chronic inflammation and allergic disease. CD4+ type 2 helper T (Th2) cells facilitate the adaptive immune response through the secretion of cytokines such as IL-4, IL-5, and IL-13. While the Th2 program is governed by the transcription factor GATA3, less is known about regulators that fine-tune the Th2 cytokine response.MethodWe used a proximity labeling system to map proteins associated with the transcriptional co-regulator OCA-B, encoded by Pou2af1, in T cells. We used a series of genomic, biochemical and immunological assays to probe the interaction with one particular hit from the screen.ResultsWe find that OCA-B indirectly associates with GATA3. ChIP-seq analysis reveals coenrichment of Gata3 and the transcription factor Oct1, a partner protein of OCA-B, at genomic locations responsible for the Th2 program including Il4, Il13, Il5, Gata3, and Irf4. DNA binding data using recombinant proteins and reporter data using T cell lines are consistent with a model in which OCA-B restricts transcription at the Th2 locus control region and subsequent IL-4 and IL-13 secretion. Finally, in an in vivo papain allergy model we show OCA-B expression in T cells limits the frequency of T cells within the lung.ConclusionThese findings shown that OCA-B helps restrict Th2 function at least in part through communication with GATA3.

Ceramide accumulation impairs adipocytes' ability to efficiently store and utilize nutrients, leading to energy and glucose homeostasis deterioration. Using a comparative transcriptomic screen, we identified the non-canonical, non-secreted fibroblast growth factor FGF13 as a ceramide-regulated factor that impairs adipocyte function. Obesity robustly induces FGF13 expression in adipose tissue in mice and humans and is positively associated with glycemic indices of type 2 diabetes. Pharmacological or genetic inhibition of ceramide biosynthesis reduces FGF13 expression. Using mice with loss and gain of function of FGF13, we demonstrate that FGF13 is both necessary and sufficient to impair energy and glucose homeostasis independent of ceramides. Mechanistically, FGF13 exerts these effects by inhibiting mitochondrial content and function, metabolic elasticity, and caveolae formation, which cumulatively impairs glucose utilization and thermogenesis. These studies suggest the therapeutic potential of targeting FGF13 to prevent and treat metabolic diseases.

Approximately 1 in 8 women will develop breast cancer in their lifetime, and over 40,000 women in the United States die from breast cancer every year. Post-menopausal breast cancer risk and mortality rates are exacerbated by those who are classified as obese, such that a 5-unit increase in body mass index is linked to a 12% increase in risk. The rising rates of obesity make understanding the link between obesity and the incidence, progression, and mortality of breast cancer of high priority. Obesity is marked by an expansion of white adipose tissue, which accounts for 90% of the breast cancer microenvironment. While several studies have identified paracrine factors secreted by obese adipose tissue that promote tumorigenesis, the role that lean adipose tissue plays in breast cancer progression remains underexplored. In this study, I screened the secretome of primary adipocytes isolated from multiple fat pads from both lean and obese mice for the ability to modulate the growth of breast cancer cell lines across multiple different subtypes. I discovered a potent role of lean mammary adipocytes in selectively inhibiting breast cancer cells in vivo and in vitro. This inhibitory function is specific to lean mammary adipocytes, as the secretomes of obese mammary adipocytes or adipocytes isolated from visceral fat depots do not inhibit breast cancer cell growth. Further, I discovered that the lean mammary adipocytes, but not obese adipocytes, secrete an oxylipin called 9S-HODE, an oxidized metabolite derived from the essential fatty acid linoleic acid. I show that lean adipocytes and 9S-HODE inhibit breast cancer cell growth by triggering ferroptosis. However, normal breast epithelial cells are protected from 9(S)-HODE-induced ferroptosis by transiently growth-arresting and rapidly forming lipid droplets. We propose that lean adipocytes actively inhibit the growth of breast cancer cells by secreting the ferroptosis inducer 9(S)-HODE, and that in patients with obesity, breast cancer is accelerated, at least in part, due to the loss of 9(S)-HODE-mediated tumor suppression. Citation Format: Meghan Curtin, Guoying Wang, John Maschek, David Lum, James Cox, Keren Hilgendorf. Lean adipocyte-secreted oxylipin, 9S-HODE, triggers ferroptosis and protects against obesity-accelerated breast cancer [abstract]. In: Proceedings of the San Antonio Breast Cancer Symposium 2024; 2024 Dec 10-13; San Antonio, TX. Philadelphia (PA): AACR; Clin Cancer Res 2025;31(12 Suppl):Abstract nr P3-06-20.

BackgroundMetabolic dysfunction-associated steatotic liver disease (MASLD), formerly called non-alcoholic fatty liver disease (NAFLD) is the hepatic manifestation of the metabolic syndrome. Although MASLD has been widely studied in persons with Type 2 diabetes (T2D), far less in known about the pathogenesis and severity of MASLD in Type 1 diabetes (T1D).ObjectivesDetermine metabolic perturbations associated with MASLD in persons with T1D.Study DesignWe conducted a cross-sectional study of 30 participants with T1D. Based on the results of a FibroScan, participants were stratified as cases (MASLD) or controls. Metabolomic analyses were performed on plasma obtained from all participants after an overnight (after midnight) fast.Results17 of 30 participants were classified as cases (MASLD) and 13 as controls. Cases had higher BMI (p=<0.001) and were taking higher daily insulin doses than controls (p=0.003). Metabolomic analyses revealed that those with MASLD had elevated levels of gluconeogenic substrates pyruvate (p=0.001) and lactate (p=0.043), gluconeogenic amino acids alanine (p<0.001) and glutamate (p=0.004), phenylalanine (p=0.003), and anthranilic acid (p=0.015). Lipidomics revealed, elevated ceramides (P=0.02), diacylglycerols (p=0.0009) and triacylglycerols (P=0.0004) in MASLD group. In those with MASLD, the acylcarnitines, isovalerylcarnitine (CAR.5.0) (P=0.002) and L-Palmitoylcarnitine (CAR.16.0) (P=0.048), were elevated. Pathway analyses using MetaboAnalyst 5.0 Software revealed that, pathways including phenylalanine and tyrosine metabolism, tryptophan metabolism, glucose-alanine cycle, glutamate metabolism, and glutathione metabolism were significantly enriched in those with MASLD.ConclusionParticipants with T1D and MASLD manifest features of insulin resistance and metabolite perturbations suggesting enhanced gluconeogenesis, dysfunctional fat synthesis, and perturbed TCA cycle activity.

OBJECTIVE:Glucagon-like peptide-1 receptor agonists (e.g., semaglutide) potently induce weight loss, thereby reducing obesity-related complications. However, weight regain occurs when treatment is discontinued. An increase in skeletal muscle oxidative phosphorylation (OXPHOS) efficiency upon diet-mediated weight loss has been described, which may contribute to reduced systemic energy expenditure and weight regain. We set out to determine the unknown effect of semaglutide on muscle OXPHOS efficiency. METHODS:C57BL/6J mice were fed a high-fat diet for 12 weeks before receiving semaglutide or vehicle for 1 or 3 weeks. The rates of ATP production and oxygen (O2) consumption were measured via high-resolution respirometry and fluorometry to determine OXPHOS efficiency in muscle at these two time points. RESULTS:Semaglutide treatment led to significant reductions in fat and lean mass. Semaglutide improved skeletal muscle OXPHOS efficiency, measured as ATP produced per O2 consumed in permeabilized muscle fibers. Mitochondrial proteomic analysis revealed changes restricted to two proteins linked to complex III assembly (LYRM7 and TTC19; p < 0.05 without multiple corrections) without substantial changes in the abundance of OXPHOS subunits. CONCLUSIONS:These data indicate that weight loss with semaglutide treatment increases skeletal muscle mitochondrial efficiency. Future studies could test whether it contributes to weight regain.

BACKGROUND:The coupling of oxygen consumption to ATP synthesis via oxidative phosphorylation (OXPHOS) is central for cellular energy homeostasis. Some studies suggest exercise training increases the efficiency of ATP synthesis, but the molecular mechanisms are unclear. We have previously shown that exercise remodels the lipid composition of mitochondrial membranes, and some of these changes in mitochondrial lipids might influence OXPHOS efficiency (ATP produced per O2 consumed, referred to as P/O). Peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α) is a transcriptional co-activator that coordinately regulates exercise-induced adaptations, including mitochondria. We hypothesized that increased PGC-1α activity might remodel mitochondrial membrane lipids and promote energy efficiency. METHODS:Mice with skeletal muscle-specific overexpression of PGC-1α (MCK-PGC-1α) and their wildtype littermates were used for this study. Lipid mass spectrometry and quantitative PCR were used to assess muscle mitochondrial lipid composition and their biosynthesis pathway. The abundance of OXPHOS enzymes was determined by Western blotting. High-resolution respirometry and fluorometry analyses were performed to characterize mitochondrial bioenergetics (ATP production, O2 consumption and P/O) for permeabilized fibres and isolated mitochondria. Respiratory supercomplexes were assessed by blue native PAGE. RESULTS:Lipidomic analyses of skeletal muscle mitochondria from wildtype and MCK-PGC-1α mice revealed that PGC-1α increases the concentrations of cone-shaped lipids such as phosphatidylethanolamine (PE; +25%, p < 0.0001), cardiolipin (CL; +184%, p < 0.0001) and lysophospholipids (+34%-94%, all p < 0.01), while decreasing the concentrations of phosphatidylcholine (PC; -4%, p = 0.0020), phosphatidylinositol (PI; -17%, p < 0.0001) and phosphatidic acid (PA; -35%, p < 0.0001). However, while PGC-1α overexpression increased the abundance of OXPHOS enzymes (two- to fourfold, p < 0.0001), the rate of O2 consumption (1.5-fold, p = 0.0030), or the respiratory supercomplexes (~1.5-fold, p < 0.01), P/O values were unaffected by PGC-1α overexpression in permeabilized fibres or isolated mitochondria. CONCLUSIONS:Collectively, overexpression of PGC-1α promotes the biosynthesis of mitochondrial PE and CL, but neither PGC-1α nor the mitochondrial membrane lipid remodelling induced in MCK-PGC-1α mice is sufficient to increase the efficiency of mitochondrial ATP synthesis. These findings indicate that PGC-1α-dependent mechanisms or changes in mitochondrial membrane lipids may be insufficient to alter P/O. While muscles from MCK-PGC-1α mice are known not to completely phenocopy adaptations with exercise training, our findings also highlight that there is a need to examine whether exercise training indeed improves P/O in mouse skeletal muscle.

Lipid saturation is a key determinant of membrane function and organelle health, with changes in saturation triggering adaptive quality control mechanisms to maintain membrane integrity. Among cellular membranes, the outer mitochondrial membrane (OMM) is an important interface for many cellular functions, but how lipid saturation impacts OMM function remains unclear. Here, we show that increased intracellular unsaturated fatty acids (UFA) remodel the OMM by promoting the formation of multilamellar mitochondrial-derived compartments (MDC), which sequester proteins and lipids from the OMM. These effects depend on the incorporation of UFAs into membrane phospholipids, suggesting that changes in membrane bilayer composition mediate this process. Furthermore, elevated UFAs impair the assembly of the OMM protein translocase (TOM, translocase of the outer membrane) complex, with unassembled TOM components captured into MDCs. Collectively, these findings suggest that alterations in phospholipid saturation may destabilize OMM protein complexes and trigger an adaptive response to sequester excess membrane proteins through MDC formation.

Supplemental Table 2: Secretome proteomics

Obesity is predicted to become the largest modifiable risk factor for breast cancer in postmenopausal women, yet the mechanisms underlying this association are unclear. We identified a novel role for the endogenous oxylipin 9S-HODE, secreted by lean adipocytes, to induce ferroptosis in breast cancer cells while sparing normal breast epithelial cells. Obese adipocytes fail to secrete 9S-HODE, suggesting that the loss of ferroptosis induction significantly contributes to the acceleration of obesity-associated breast cancer. Consequently, the inhibition of ferroptosis accelerates breast cancer in lean, but not obese, mice. Further, 9S-HODE inhibits the growth of patient-derived breast cancer organoids, and supplementing 9S-HODE into tumors in obese mice is sufficient to reduce tumor burden, underscoring its potential as a therapeutic agent.

Metabolic dysfunction-associated steatotic liver disease (MASLD) is the hepatic manifestation of metabolic syndrome. Hepatic lipotoxicity and inflammation are two key factors driving progression of steatosis to metabolic dysfunction-associated steatohepatitis (MASH). The presence of MASH increases the risk of cardiovascular events, cirrhosis, hepatocellular carcinoma (HCC) and non-liver malignancies. Although MASLD and lipid species have been extensively examined in persons with type 2 diabetes, much less is known in type 1 diabetes. We examined the association of key lipid species with MASLD in individuals with type 1 diabetes. We designed a cross-sectional study of 30 participants with type 1 diabetes recr1uited from our institutional diabetes clinics. All participants had fasting blood drawn for targeted lipidomics and underwent a FibroScan. Those with steatosis score of ≥ 248 as determined by controlled attenuation parameter (CAP) were categorized as cases (n = 17); those with steatosis score < 248 were categorized as controls (n = 13). BMI was significantly higher in cases than controls (P = 0.0007) and used significantly higher 24-h insulin doses than controls (P = 0.004). Cases displayed significantly higher circulating levels of total ceramides (P = 0.02), diacylglycerols (P = 0.0009) and triacylglycerols (P = 0.0004). The two groups displayed similar levels of hexosylceramides, dihydrosphingomyelins, sphingomyelins, and phosphatidylcholines. Similar to previous findings, numerous sphingolipids species, diacylglycerols, and triacylglycerols were found to correlate positively with higher BMI and 24-h insulin dose. Total circulating dihydroceramides, ceramides, diacylglycerols, and triacylglycerols levels significantly correlated with steatosis score (P < 0.05). None of the lipid species correlated with fibrosis score. These results suggest that persons with type 1 diabetes and MASLD have a higher BMI, are likely to be insulin resistant, and display elevated circulating levels of dihydroceramides, ceramides, diacylglycerols, and triacylglycerols, which are strongly associated with the pathogenesis of steatotic liver disease.