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.

Anatomic location of white adipose tissue is a determinant of cardiometabolic risk. To understand differences within/between adipose depots, we generated 65,668 single-nucleus transcriptomes from human subcutaneous or intraabdominal adipose tissue (SAT/IAT). Unsupervised analysis revealed 26 adipose-resident cell clusters including two subpopulations of mature adipocytes, characterized by high vs. low expression of adipocyte maturation genes (ADIPOMAT hi vs. ADIPOMAT lo ). ADIPOMAT lo adipocytes demonstrate a low-differentiation, pro-inflammatory, and pro-fibrotic transcriptome. IAT-resident ADIPOMAT lo were more abundant in higher BMI donors, while SAT-resident ADIPOMAT lo associated with impaired glycemia. TSHZ3 was identified as a candidate regulator of ADIPOMAT lo transcriptome. TSHZ3 knockdown in adipogenic progenitors inhibited differentiation, with downregulation of early adipogenic regulators (e.g. CEBPA/B, PPARG) and mature adipocyte genes. Heterozygous deletion of Tshz3 in mice reduced SAT and IAT weight. Here, we show that adipocyte subsets with distinct transcriptomic signature reside in human WAT; altered TSHZ3-mediated transcriptional regulation may contribute to low-maturation subpopulation linked to metabolic disease.

BACKGROUND:Refractory hypoglycemia is common in malignant insulin-secreting tumors and is associated with substantial morbidity. Ersodetug is a fully human monoclonal antibody that allosterically attenuates insulin receptor signaling with the potential to treat various forms of hyperinsulinism (HI). We retrospectively report outcomes from compassionate use of ersodetug in eight individuals with refractory hypoglycemia due to tumor HI. METHODS:Ersodetug was administered intravenously at 6 or 9 mg/kg every 1-2 weeks initially, followed by a frequency of every 2-5 weeks, as appropriate. Glycemic, functional, and safety outcomes were analyzed. RESULTS:Eight adults (4 M/4F; 24-74 years; Eastern Cooperative Oncology Group (ECOG) 1-3) received ersodetug for insulin-secreting tumors (metastatic insulinoma, n = 7; cervical neuroendocrine carcinoma, n = 1). No drug-related serious adverse events were observed. Most patients experienced improved glycemic control, including discontinuation of parenteral glucose in 6 of the 7 applicable patients (median, 4.5 days) and a 35.6% relative reduction from baseline in time in hypoglycemia (<70 mg/dL) by continuous glucose monitoring (mean 12.4% to 8.0%; pseudo-median paired change of -3.8 percentage points [90% CI, -8.2 to -1,1; P = 0.02). These glycemic improvements permitted hospital discharge and reductions in other antihypoglycemic therapies beyond glucose infusion rate (pseudo-median change, -2.5; 90% CI, -3.5 to -1.0; P = 0.02), with associated improvements in ECOG status. The median treatment duration with ersodetug (11.5 months, range 5-17) tended to correspond to patient lifespan in the setting of metastatic disease. CONCLUSIONS:Ersodetug therapy resulted in reduced hypoglycemia burden, ability to discontinue parenteral glucose infusion, allowing discharge from hospital, use of fewer antihypoglycemic therapies, and improved ECOG performance status in individuals with severe, refractory tumor HI.

Sperm aging impacts male fertility and offspring health, highlighting the need for reliable aging biomarkers to guide reproductive decisions. However, the molecular determinants of sperm fitness during aging remain ill-defined. Here, we profiled sperm small non-coding RNAs (sncRNAs) using PANDORA-seq, which overcomes RNA modification–induced detection bias to capture previously undetectable sncRNA species associated with mouse and human spermatozoa throughout the lifespan. We identified an “aging cliff” in mouse sperm RNA profiles—a sharp age-specific transition marked by significant shifts in genomic and mitochondrial tRNA-derived small RNAs (tsRNAs) and rRNA-derived small RNAs (rsRNAs). Notably, rsRNAs in mouse sperm heads exhibited a transformative length shift, with longer rsRNAs increasing and shorter ones decreasing with age, suggesting altered biogenesis or processing with age. Remarkably, this sperm head-specific shift in rsRNA length was consistently observed in two independent human aging cohorts. Moreover, transfecting a combination of tsRNAs and rsRNAs resembling the RNA species in aged sperm was able to induce transcriptomic changes in mouse embryonic stem cells, impacting metabolism and neurodegeneration pathways, mirroring the phenotypes observed in offspring fathered by aged sperm. These findings provide novel insights into longitudinal dynamics of sncRNAs during sperm aging, highlighting an rsRNA length shift conserved in mice and humans. The molecular determinants of sperm fitness during aging remain ill-defined. Here, advanced sequencing to profile sperm small non-coding RNAs (sncRNAs) during mouse aging uncovers a sperm-head–specific shift in RNA length, which is conserved in humans and functionally reprograms mouse embryonic stem cell (mESC) gene expression. Longitudinal PANDORA-seq profiling of small non-coding RNAs in spermatozoa uncovers unexpected dynamics during lifespan with functional relevance for gene expression.

Background: Social determinants of health (SDOH) can affect metabolic health. Objective: To determine the effect of social vulnerability on the comparative effectiveness of metabolic bariatric surgery or medical and lifestyle intervention on glycemia and weight outcomes in people with type 2 diabetes (T2D). Design: Analysis of the effect modification of baseline Area Deprivation Index (ADI; a metric of social vulnerability) on longitudinal outcomes between randomized treatment groups using linear mixed-effects models. (ClinicalTrials.gov: NCT02328599) Setting: 4 U.S. academic centers. Participants: 258 participants with T2D enrolled in 4 randomized controlled trials of surgical versus medical management and a longitudinal observational follow-up study. Measurements: ADI linked to ZIP code data at randomization; weight loss and hemoglobin A(1c) (HbA(1c)) level at the end of the active intervention period (7 to 12 years). Results: Baseline characteristics were well balanced between the surgical and medical therapy groups after adjustment for study site and stratification by high versus low ADI. Surgery was more effective than medical therapy in reducing HbA(1c) level among persons with high ADI (net difference, -1.29% [95% CI, -1.95% to -0.63%]) and those with low ADI (net difference, -0.95% [CI, -1.29% to -0.62%]). Surgery was also more effective than medical therapy at producing weight loss across ADIs, with respective net differences of -10.6% (CI, -15.2% to -5.9%) for high ADI and -13.3% (CI, -15.7% to -10.9%) for low ADI. The interaction between ADI and intervention group was not significant for either HbA(1c) (P = 0.37) or weight loss (P = 0.31). Limitations: Small sample size; parent trials were not designed to address effect modification by ADI. Conclusion: Surgery was superior to medical therapy for people with T2D regardless of social deprivation. This study did not detect statistically significant differences in the comparative advantage of surgery over medical therapy by ADI. Primary Funding Source: National Institutes of Health.

OBJECTIVES:After bariatric surgery, many individuals experience debilitating bouts of hypoglycemia, termed post-bariatric hypoglycemia (PBH). Our mouse model of vertical sleeve gastrectomy (VSG) mimics key aspects of PBH in humans. As glucagon is a key element of the counterregulatory hormonal response to hypoglycemia, the objective of this manuscript is to understand if glucagon responses and sensitivity are altered after VSG in mice. METHODS:Mice underwent sham or VSG surgery. We measured glucagon responses to insulin-induced hypoglycemia and mixed meal tolerance tests. We then measured glucose and insulin responses to different doses of exogenous glucagon in fed and fasted states. Lastly, we performed in vitro experiments to examine glucagon responses to glucose and amino acids. RESULTS:Postprandial glucagon levels were elevated in mice after VSG, but glucose responses to low doses of exogenous glucagon were blunted in the fasted and postprandial state. Administration of low dose glucagon in the fed state led to hypoglycemia in some VSG mice in parallel with stimulation of insulin release. This effect was partially prevented by pretreatment with the GLP-1 receptor antagonist exendin9-39. In islets isolated from VSG mice, glucagon release in response to high glucose was suppressed, but glucagon responses to alanine and high glucose were not different compared to sham controls. CONCLUSIONS:Altogether, our data suggest both glucagon responses, and sensitivity to exogenous glucagon are altered by VSG. The glucagon dysregulation was not observed in isolated islets suggesting gut signaling may be critical in driving glucagon responses after VSG.

Introduction and Objective: Bariatric/metabolic surgery induces sustained weight loss and improved glycemic control for Type 2 diabetes (T2D), yet the molecular mechanisms underlying its metabolic benefits and diabetes remission remain incompletely defined. Methods: We analyzed buffy coat samples previously collected during longitudinal followup for 3 years in the SLIMM-T2D trial, in which participants with T2D were randomized to Roux-en-Y gastric bypass (RYGB) (n:17) or nonsurgical medical/lifestyle intervention (MLI) (n:16). DNA was isolated from leukocytes collected at baseline and 3, 12 and 36 months and analyzed for DNA methylation (DNAm) using the Infinium MethylationEPIC array. Data were processed and analyzed using SeSAMe and Limma, with significance FDR<0.05. Results: DNAm analysis revealed progressive epigenetic remodeling over 36 months, with RYGB inducing a significantly greater effect than MLI. Both groups showed few differentially methylated CpG loci (DML) at 3 months. By 36 months, there were 27,961 DML in RYGB vs. baseline, with predominant hypermethylation (19,276 CpGs), in comparison with only 14821 vs. baseline in MLI. In weighted models, no significant DML associations with HbA1c or BMI were detected (FDR<0.05) and adjustment for these variables minimally altered the magnitude or trajectory of DNAm changes, suggesting that RYGB-associated epigenetics changes are largely independent of glycemic control or adiposity. Conclusion: Our findings demonstrate that RYGB induces a robust, progressive and durable reprogramming of DNAm that exceeds changes observed in MLI. Future analysis will seek to identify mechanisms contributing to surgery-induced alterations in DNAm. Disclosure R. Ferraz-Bannitz: None. L. Osterwalder: None. A. Goncalves da Cruz: None. B. Ozturk: None. D.C. Simonson: Board Member; Current; Phase V Technologies, Inc. Stock/Shareholder; Current; GI Windows. H. Pan: None. J. Dreyfuss: None. M. Patti: Other - My institution receives research funding for clinical trial.; Current; Recordati S.p.A, Amylyx. Other - Data Safety Monitoring Board; Current; Fractyl Health, Inc. Funding Joslin/BILH Epigenetics Initiative Grant

Adults presenting with atypical diabetes, especially those with unexplained hypoglycemia, often pose a significant diagnostic challenge. Here, we describe a 53-year-old woman initially treated for type 2 diabetes who later developed recurrent hypoglycemia, with increased severity after fundoplication surgery, despite medication cessation, exhibiting persistent, and paradoxical glycemic variability. Detailed metabolic investigation ultimately revealed a heterozygous ABCC8 p.Arg1352His pathogenic variant, confirming a diagnosis of maturity-onset diabetes of the young, type 12. This case underscores the crucial role of genetic testing in diagnosing complex, monogenic glycemic disorders and illustrates the unique management complexities of a dual hyperglycemic-hypoglycemic phenotype, emphasizing the need for heightened clinical suspicion of an underlying genetic disorder potentially exacerbated by upper gastrointestinal surgery.

Post-bariatric hypoglycemia (PBH), characterized by excessive postprandial incretin and insulin secretion, is a common complication of bariatric surgery. Here, we investigate the relationship between PBH and growth differentiation factor 15 (GDF15) in individuals with PBH after Roux-en-Y gastric bypass (RYGB), post-RYGB individuals who remain asymptomatic (Asx), and individuals with overweight/obesity but without history of surgery (Ow/Ob). Fasting plasma GDF15 is higher in PBH vs. Ow/Ob and further increases postprandially, coinciding with hypoglycemia symptoms. During a hyperinsulinemic hypoglycemic clamp, GDF15 progressively increases in PBH and correlates with hypoglycemia survey symptoms, including weakness, difficulty concentrating, feeling cold, and tingling lips. In mice, insulin-induced hypoglycemia also results in elevated GDF15 levels, and exogenous recombinant GDF15 (rGDF15) reduces food intake in response to hypoglycemia. Our data suggest that GDF15 modulates the counterregulatory response to hypoglycemia in both PBH individuals and mice and that elevated GDF15 levels contribute to hypoglycemia-related postprandial symptoms. This study was registered at ClinicalTrials.gov (NCT04428866).

Introduction and Objective: Post-bariatric hypoglycemia (PBH) is a recognized complication of bariatric surgery and typically occurs postprandially. Growth differentiation factor 15 (GDF15) is a secreted peptide induced by multiple physiological stressors. Here we investigate relationships between GDF15, hypoglycemia, and hypoglycemia-related symptoms. Methods: We measured plasma GDF15 levels in PBH (n=15), asymptomatic post-RYGB (RYGB non-hypo, n=15), and obese non-surgical controls (CON, n=10) during mixed meal testing and hyperinsulinemic hypoglycemic clamp. Hypoglycemia symptoms were assessed using Edinburgh Hypoglycemia Symptom Scale (EHSS). The impact of insulin-induced hypoglycemia on GDF15 levels was assessed in C57BL/6 mice. Results: Plasma GDF15 was increased in PBH vs. CON in the fasting state (69%, p=0.03). Likewise, at 120 minutes after mixed meal, GDF15 was higher in PBH vs. both RYGB non-hypo and CON (71% and 91% higher, p<0.01 for both). During hyperinsulinemic hypoglycemic clamp, GDF15 levels were progressively increased in PBH vs. both RYGB non-hypo and CON at 90, 110 and 120 minutes (1.1, 1.2, and 1.5-fold; and 1.7, 1.9, and 2.2-fold, respectively; all p<0.05). In mice, insulin-induced hypoglycemia increased plasma GDF15 (88% vs. saline, p=0.04). GDF15 levels associated with higher EHSS scores during the hypoglycemic clamp at 90 (r=0.62, p=0.01), 110 (r=0.87, p<0.0001), and 120 (r=1.0, p=0.005) minutes in PBH. Weakness (90 min: r=0.53, p=0.04; 110min: r=0.63, p=0.01), difficulty concentrating (baseline: r=0.53, p=0.04; 110min: r=0.56, p=0.03), and tingling of lips (90min: r=0.57, p=0.03; 110min: r=0.72, p=0.003) were positively correlated with GDF15. During mixed meal, GDF15 was correlated with “feeling cold” (120 min: r=0.89, p=0.01) in PBH. Conclusion: GDF15 may be a novel counterregulatory peptide response to hypoglycemia in both mice and humans with PBH. Elevated GDF15 may contribute to hypoglycemia-related symptoms in individuals experiencing PBH. R. Ferraz-Bannitz: None. L. Pei: Stock/Shareholder; Eli Lilly and Company. H. Wang: None. B. Ozturk: None. P. Casanova: None. H. Saeed: None. L. Poulos: None. H.S.M. Saifeldin: None. C.J. Cummings: None. M. Farahmandsadr: None. A.E. Amore: None. A.L. Sheehan: None. D.C. Simonson: Stock/Shareholder; GI Windows. Consultant; Phase V Technologies. M. Patti: Research Support; Dexcom, Inc. Other Relationship; Recordati, Fractyl Health, Inc. Consultant; Spruce Biosciences, Premier, Cello, Alpha sight, Boxer Capital. Other Relationship; Amylyx.

Adipose tissue (AT) is a complex connective tissue with a high relative proportion of adipocytes, which are specialized cells with the ability to store lipids in large droplets. AT is found in multiple discrete depots throughout the body, where it serves as the primary repository for excess calories. In addition, AT has an important role in functions as diverse as insulation, immunity and regulation of metabolic homeostasis. The Human Cell Atlas Adipose Bionetwork was established to support the generation of single-cell atlases of human AT as well as the development of unified approaches and consensus for cell annotation. Here, we provide a first roadmap from this bionetwork, including our suggested cell annotations for humans and mice, with the aim of describing the state of the field and providing guidelines for the production, analysis, interpretation and presentation of AT single-cell data. In this Review, the authors present a roadmap towards achieving consensus on development, analysis and interpretation of single-cell transcriptomics data in adipose tissue, including discussion of roadblocks, best practices and ideal cell-type markers for annotation of adipose tissue cell types in mice and humans.

While Roux-en-Y gastric bypass is an effective treatment for obesity and type 2 diabetes, up to one-third of patients develop post-bariatric hypoglycaemia (PBH). Individuals with PBH exhibit increased postprandial secretion of the intestinal hormone fibroblast growth factor 19 (FGF19, Fgf15 in mice). However, the underlying mechanisms contributing to PBH remain uncertain. Here we demonstrate that faecal and plasma bile acid (BA) profiles are significantly altered in postoperative individuals with PBH versus those without hypoglycaemia. Furthermore, altered BAs in PBH induce FGF19 secretion in intestinal cells in a manner dependent on the apical sodium-dependent BA transporter (ASBT). We demonstrate that ASBT inhibition reduces Fgf15 expression and increases postprandial glucose in hypoglycaemic mice. Our data suggest that dysregulation of luminal BA profiles and transport may contribute to PBH and provide proof of concept that ASBT inhibition could be developed as a new therapeutic strategy for PBH. FGF19 increase in post-bariatric hypoglycaemia is mediated by bile acid dysregulation, and can be countered by inhibiting bile acid transport.

Medicare's current coverage policy for continuous glucose monitoring (CGM) restricts their use to people with diabetes. This restriction is based on an older National Coverage Determination (NCD 40.2) that limits blood glucose testing to people with diabetes. The CGM coverage policy also requires that CGM be used only in accordance with an Food and Drug Administration (FDA) indication for its use. However, the law, regulation, and subregulatory guidance do not require such a restriction. Multiple conditions unrelated to diabetes are associated with risk of hypoglycemic events, such as postbariatric and other upper gastrointestinal surgery, glycogen storage diseases, kidney and liver failure, neuroendocrine tumors that secrete insulin, other forms of tumor-associated hyperinsulinism, and autoimmune conditions. To avoid life-threatening hypoglycemic events, these patients need access to CGM to monitor their glucose levels. Thus, the Centers for Medicare & Medicaid Services should rescind NCD 40.2. The durable medical equipment Medicare administrative contractors (MACs) responsible for establishing CGM coverage policy should remove the requirement that CGM be used only in accordance with an FDA indication for its use. This would allow the MACs to extend coverage for CGM to populations at high risk for hypoglycemia, as the evidence supports such an approach.