The dorsal raphe nucleus (DRN) is a key regulator of food intake and body weight. The DRN has historically been associated with feeding, as it houses the single largest population of serotonergic neurons in the mammalian brain. Few studies have demonstrated a direct role for DRN serotonergic neurons in regulating feeding; none of these studies have demonstrated effects near those elicited by serotonin, itself. There are many nonserotonergic cell types in the DRN that play an integral role in feeding. These DRN cell types play important roles in both hunger and satiation.

The underlying molecular pathogenesis of the Asian phenotype of insulin resistance remains to be understood. We carried out metabolic phenotyping of study participants without diabetes according to insulin sensitivity indices derived from hyperinsulinemic-euglycemic clamp procedures. We identified lipidomic signatures of insulin resistance and metabolic plasticity. These lipidomic signatures have the potential to help in risk stratification of insulin resistance and metabolic dysfunction for early intervention.

Sarcopenic obesity, a subtype of obesity, is marked by reduced skeletal muscle mass and function, or sarcopenia, and poses a significant health challenge to older adults as it affects an estimated 28.3% of people aged >60 years. This subtype is unique to older adults as aging exacerbates sarcopenia and obesity due to changes in energy metabolism, hormones and inflammatory markers, and lifestyle factors. Traditional treatments for sarcopenic obesity have been focused on exercise and dietary modifications to reduce fat while maintaining muscle mass. Newer glucagon-like peptide 1 receptor agonists (GLP-1RAs) and dual gastric inhibitory polypeptide/GLP-1 receptor agonists (GIP/GLP-1RAs), including liraglutide, semaglutide, and tirzepatide, have shown great promise to reduce weight, treat obesity-related complications, improve physical function, and improve quality of life, in younger clinical trial populations. However, the use of GLP-1RAs and GIP/GLP-1RAs has not been exhaustively evaluated in older adults with sarcopenic obesity. These medications come with the risk of loss of muscle mass and an increased rate of adverse events. Thus, clinicians should use them cautiously by weighing the potential benefits against their risks. Herein, we discuss a possible approach to using GLP-1RAs and GIP/GLP-1RAs in patients with sarcopenic obesity, including considerations for patient identification, monitoring, maintenance, and discontinuation. In this article we also discuss the emerging treatments that will be available, which may include activin type II receptor antibodies and selective androgen receptor agonists. We conclude by highlighting the advancement of geroscience as a promising field for individualizing treatments in the future.

Although imeglimin promotes β-cell proliferation and ameliorates β-cell apoptosis, the detailed metabolic changes induced by imeglimin in β-cells are unknown. Imeglimin increases adenylosuccinate (S-AMP), which is produced by adenylosuccinate synthase (ADSS) from inosine monophosphate and aspartate, and imeglimin also increases amino acid content, including aspartate, in mouse islets. Inhibition of S-AMP production by an ADSS inhibitor reduces the ability of imeglimin to increase β-cell proliferation and ameliorate β-cell apoptosis in mouse islets, human islets, porcine islets, and human pluripotent stem cell-derived β-cells. Imeglimin increases S-AMP to promote β-cell proliferation and ameliorate β-cell apoptosis.

The present study reveals a previously unknown molecular mechanism linking prediabetes to neurodegeneration, addressing a critical gap in understanding metabolic-neurological interplay. We investigated whether PTP1B mediates prediabetes-induced cognitive impairment. PTP1B impaired synaptic signaling and synaptic ultrastructure in hippocampal neurons, contributing to cognitive decline in prediabetes. PTP1B is a novel therapeutic target for prediabetes-associated neurodegeneration.

Cerebral microvascular disease can be triggered in people with diabetes who have chronic hyperglycemia. The aim of our study was to understand what effect diabetes has on the cerebral vasculature. In a rodent model, diabetes caused varying degrees of reduced cerebral vascular density and slowed cerebral blood flow in the brain striatum, basal forebrain, thalamus, hypothalamus, and hippocampus. There is a correlation between vessel density and blood flow velocity and the correlation changes in the diabetic state.

This post hoc analysis assessed sustainability of lowered glycated hemoglobin (HbA1c) and weight with tirzepatide in people with type 2 diabetes and increased cardiovascular risk. Participants achieving HbA1c ≤48 mmol/mol (6.5%) or weight loss ≥10% at 52 weeks were evaluated for sustained glycemic or weight control and predictors of initial and sustained efficacy. For tirzepatide-treated participants achieving HbA1c ≤48 mmol/mol (6.5%) at 52 weeks, 75-84% sustained this until study end (median 81 weeks). Factors predicting achievement were higher tirzepatide dose, shorter diabetes duration, and lower HbA1c, higher HOMA of β-cell function (HOMA-B), metformin alone, and absence of albuminuria at baseline. Factors predicting sustained glycemic control were greater weight loss, smaller fasting glucose decrease, no sulfonylurea, and higher HOMA-B at 52 weeks. For participants achieving ≥10% weight loss at 52 weeks, 79-82% maintained weight loss. Factors predicting achievement were higher tirzepatide dose, female sex, no cardiovascular disease history, and lower baseline HbA1c, estimated glomerular filtration rate, and triglycerides. Greater decrease in LDL-cholesterol to 52 weeks predicted maintained weight loss. Greater weight loss and better β-cell function achieved with tirzepatide were the main predictors for sustained glycemic control in this post hoc analysis; no clinically meaningful predictor was identified for sustained weight control.

Type 1 diabetes-associated autoimmune mechanisms have not been thoroughly examined in pancreatitis-associated diabetes. We assessed the prevalence of four islet autoantibodies in serum from a large prospective cohort of patients with acute, recurrent acute, or chronic pancreatitis. Diabetes was present in 11 (12%) of 94 participants with acute pancreatitis, 69 (27%) of 273 with recurrent acute pancreatitis, and 235 (43%) of 560 with chronic pancreatitis. Excluding those with only insulin autoantibody positivity, which is confounded by insulin treatment, islet autoantibodies were identified in 51 (5.5%) of 927 participants, and 30 (3.2%) of 297 were positive for two or more autoantibodies. Our findings suggest pancreatitis may elicit islet autoimmunity in a subset of patients, necessitating prospective longitudinal follow-up.

Treatment responses to behavioral, surgical, and pharmacological approaches in obesity are highly variable in quantity and quality. Here we refer to high-quality weight loss as a high proportion of fat to skeletal muscle mass lost. Given the role of skeletal muscle in energy expenditure, glucose homeostasis, metabolic flexibility, mobility, and strength, excessive loss of skeletal muscle during weight loss is a concern for overall health. Challenges in accurately measuring body composition, especially skeletal muscle, limit our understanding of muscle loss during obesity treatment. Recent incretin-related pharmacotherapies improve muscle metabolic health by enhancing glucose uptake and reducing muscle lipids but, like other weight loss interventions, are associated with muscle loss. Newer pharmacological interventions are being developed to minimize muscle loss, but many questions remain. This article examines the metabolic importance of skeletal muscle and its measurement clinically, as well as key genetic and metabolic factors influencing skeletal muscle and the quality of weight loss. Genetics can affect muscle composition (e.g., fiber types) and function. Together with metabolic factors, including neurohormonal responses and skeletal muscle metabolic efficiency and adaptation, there is variability in weight loss outcomes. In future research investigators should continue to focus on factors affecting skeletal muscle and on personalized strategies to optimize weight loss quality preserving the physical and metabolic functions of skeletal muscle.

The primary treatment for obesity involves calorie restriction (CR) to promote dietary weight loss achieved through interventions including behavioral modification, bariatric surgery, and antiobesity medications. In adults with obesity, CR-induced weight loss enhances physical function and improves quality of life, while also reducing the burden of various obesity-related chronic conditions, including hypertension, diabetes, obstructive sleep apnea, and atherosclerotic heart disease. However, it is also associated with a decline in lean mass and bone mineral density, which increases the risk of sarcopenia and osteoporosis. When performed alongside CR, progressive resistance training (RT) attenuates this loss of lean mass and bone mass, while the addition of aerobic training (AT) further improves cardiorespiratory fitness. The individual benefits of RT and AT are complementary, and combining both exercise training modalities during CR provides the most optimal benefits for body composition and physical function. The World Health Organization recommends that adults engage in at least 150 min of moderate-intensity or 75 min of vigorous-intensity AT weekly and participate in RT activities involving major muscle groups at least 2 days per week. While this recommendation applies to the general adult population, regular exercise training that incorporates both RT and AT is particularly crucial for adults with obesity undergoing weight loss interventions. This clinical perspective highlights the benefits of exercise training alongside current weight loss strategies, such as lifestyle changes, bariatric surgery, and pharmacotherapy, with a focus on incretin-based therapies.

Roux-en-Y gastric bypass improves glycemic control in patients with type 2 diabetes, but the impact of the improved glycemic control on β-cell sensitivity to glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic peptide (GIP) is sparsely described. GLP-1 and GIP potentiated insulin secretion during clamped hyperglycemia before and after surgery, but, when related to the response to glucose alone, the relative potentiating effects of GIP (on first-phase insulin secretion) and GLP-1 (on first- and second-phase insulin secretion) were reduced postoperatively. The improvement in β-cell function after Roux-en-Y gastric bypass in patients with type 2 diabetes is not driven by improved β-cell sensitivity to incretins but rather other factors, including improved β-cell sensitivity to the changed glucose response and exaggerated postprandial GLP-1.

Vesicle-associated membrane protein 8 (VAMP8) localizes to endosomal vesicles and mediates their exocytosis in pancreatic β-cells. VAMP8-dependent vesicle fusion delivers glucagon-like peptide 1 receptor and GLUT2 to the plasma membrane. VAMP8 overexpression inhibits insulin granule exocytosis. "Newcomer" exocytosis likely involves endosomal compartments, not insulin granules.

The recent identification of liver-expressed antimicrobial peptide 2 (LEAP2) as an endogenous antagonist and inverse agonist of the growth hormone secretagogue receptor (GHSR) has revived interest in targeting the ghrelin-GHSR pathway for obesity treatment. Here, we assessed the preclinical efficacy of treatment with a long-acting LEAP2 (LA-LEAP2) analog for weight loss and explored its potential as an adjunct to semaglutide to enhance weight reduction and mitigate weight regain. We found that LA-LEAP2 lowered body weight in obese mice, which was reflected in reduced energy intake and preserved energy expenditure. While not uniformly observed across all experiments, some studies demonstrated superior weight reduction with the combination of LA-LEAP2 and semaglutide compared with semaglutide monotherapy. Notably, the combination also attenuated weight regain more effectively than semaglutide alone. Importantly, no signs of discomfort or behavioral aversion were detected following LA-LEAP2 administration. Collectively, these data indicate that LEAP2 analogs have the potential to enhance the efficacy of glucagon-like peptide 1 receptor agonism and support durable weight loss.

Fasting is associated with increased risk of hypoglycemia in patients with type 1 diabetes (T1D); however, little is known about how the counterregulatory responses to low blood sugar are affected under these metabolic conditions. During insulin-induced hypoglycemia, fasting (compared with eating normal meals for breakfast and lunch) glucagon concentrations were lower by 42% and endogenous glucose production by 47% in individuals with T1D. The secretion of other counterregulatory hormones during hypoglycemia was not affected by fasting (e.g., epinephrine, norepinephrine, cortisol). Fasting diminishes glucagon levels under hypoglycemic conditions in those with T1D, which may increase their susceptibility to hypoglycemia.

It has been hypothesized that dietary proteins act as environmental factors in type 1 diabetes pathogenesis. This study investigated whether gliadin-specific T cells are present in the small intestine of children with type 1 diabetes, without or with celiac disease comorbidity. No sign of gliadin-reactive T cells, either proinflammatory or regulatory, was observed in the gut mucosa of children with type 1 diabetes negative for celiac disease autoimmunity. Interferon-γ-producing T cells were detected in gut mucosa biopsy specimens of children with diabetes seropositive for antitissue transglutaminase antibodies. Our study does not support a pathogenic role of intestinal T cell-mediated immunity to gluten in type 1 diabetes pathogenesis.

Abnormal glucose tolerance (AGT) in youth has become an alarming global public health issue; however, approaches to identify high-risk population among young people have not been well-established. Can the long-term risk of AGT be stratified by the subclasses of glucose trajectories defined in childhood? Subclasses defined in childhood can efficiently stratify the risk of AGT in adolescence and young adulthood. The subclass membership was strongly associated with cardiometabolic disorders in childhood and maternal cardiometabolic disorders during pregnancy. This subclass method provides a potential strategy to identify those at risk of later cardiometabolic disorders from childhood for more intensive evaluation of intervention. The close relationship between maternal cardiometabolic disorders and subclass membership of children highlighted the potential influence of gestational cardiometabolic health on the development of cardiometabolic disorders in offspring.

Understanding the role of micropeptides (miPs) in metabolic regulation could enhance insights into metabolic diseases and open new pathways for treatment. Small integral membrane protein 30 (Smim30), an adipose tissue macrophage-expressed miP, maintains insulin sensitivity and safeguards systemic metabolic homeostasis. Smim30 modulates inflammatory responses and macrophage-adipocyte communication in adipose tissue. Smim30 could serve as a potential diagnostic biomarker and therapeutic target for metabolic disorders.