IntroductionGlycemic dysregulation is a hallmark of type 2 diabetes (T2D) and contributes to skeletal muscle (SKM) loss and frailty risk, especially in older adults. Glycemic control and physical function are supported by SKM capillarization and mitochondrial function, and their impairment contributes to T2D development. While high-intensity interval training (HIIT) is a promising intervention, adherence and effectiveness remain concerns for prescribing HIIT among older adults at risk for T2D. Local heat therapy (LHT) may be a more practical initial strategy to improve SKM architectural factors and precondition SKM, enhancing physiological adaptations to exercise in this population.Methods and analysisHeat and Exercise in Aging as Therapy (HEAT) is a two-phase, randomized, sham-controlled clinical trial investigating the efficacy of LHT to improve glycemic control and decrease frailty risk via improved SKM architecture among older adults with prediabetes. LHT is tested as a standalone intervention and as a means to precondition SKM for subsequent HIIT, improving exercise adaptations. In Phase 1, LHT and sham (CON) groups apply heat pads for 90 minutes/day, 6 days/week, for 12 weeks. A separate HIIT group completes 4x4-minute cycling intervals at 90-95% VO₂peak, 3 days/week. In Phase 2, LHT and CON groups begin HIIT. Participants (≥50 years) have impaired fasting glucose (100-125 mg/dL) and/or HbA1c (5.7-6.4%). Biospecimen collection and clinical assessments occur at baseline (T1), after Phase 1 (T2), and Phase 2 (T3). To our knowledge, this is the first study to determine the use of local heat pad on pre-diabetic older population. If successful, LHT may be a practical, scalable, non-invasive intervention to improve glycemic control and reduce frailty risk in older adults with prediabetes, preventing progression to T2D.

BACKGROUND:With pulmonary hypertension (PH), a pulmonary artery wedge pressure (PAWP)>15 mm Hg is used to diagnose left heart dysfunction, but some patients with adjudicated group 1 PH demonstrate PAWP>15 mm Hg. The primary objective of the study was to evaluate group 1 PH with high PAWP>15 mm Hg. METHODS:Patients with adjudicated group 1 PH from PVDOMICS between 2016 and 2019 were separated into high PAWP(>15 mm Hg) or normal PAWP and compared with adjudicated combined pre- and postcapillary (Cpc) PH related to heart failure with preserved ejection fraction (HFpEF). Participants underwent dynamic right heart catheterization and metabolomics. Findings were validated in 3 independent cohorts with adjudicated group 1 PH (validation cohorts 1 and 2 with exercise right heart catheterization and validation cohort 3 with resting right heart catheterization). RESULTS:Of 325 patients with group 1 PH (73% women, mean age 53.0±14.3 years), 15% (n=48) had high PAWP. Group 1 PH+high PAWP demonstrated greater obesity, left ventricular hypertrophy (P<0.0002), left ventricular strain impairment (P<0.0001), and decreased left ventricular compliance (P<0.0001) compared with group 1 PH+normal PAWP, with changes comparable to Cpc-PH HFpEF (n=75). Compared with Cpc-PH HFpEF, left atrial function was better in group 1 PH+high PAWP with lower PAWP V wave, higher left atrial compliance, and left atrial ejection fraction (P<0.0001 for all). Metabolomics demonstrated little difference between group 1 PH with high versus normal PAWP but large differences between group 1 PH+high PAWP versus Cpc-PH HFpEF (100 metabolites altered at false discovery rate P<0.05). Elevated PAWP was also observed in 18% of group 1 PH in the validation cohort 1 (n=402), with exercise PAWP response intermediately abnormal in group 1 PH+high PAWP relative to Cpc-PH HFpEF and group 1 PH+normal PAWP (interaction P<0.0001). Elevated PAWP was similarly observed in 22% and 19% of group 1 PH in validation cohorts 2 (n=55) and 3 (n=787), respectively. CONCLUSIONS:Approximately 1 in 5 adjudicated patients with group 1 PH has elevation in resting PAWP despite severe pulmonary vascular dysfunction and metabolomics consistent with traditionally defined group 1 PH. Despite resting PAWP elevation, these patients with group 1 PH were metabolomically and biologically distinct from Cpc PH HFpEF, with better left atrial function and diastolic reserve during exercise. These data emphasize the limitations of using resting PAWP alone to separate group 1 PH from HFpEF and call for development of more integrated clinical diagnostic criteria.

Introduction and Objective: Metformin improves glycemic control primarily by suppressing hepatic glucose production; however, its effects on skeletal muscle remain unresolved, particularly regarding insulin signaling and mitochondrial function. This study examined the impact of long-term metformin administration on skeletal muscle (SkM) insulin sensitivity, mitochondrial function, and endurance capacity. Methods: In a 40-week double-blind, placebo-controlled trial, 40 older adults (60-85 years) with overweight/obesity and impaired fasting glucose (100-140 mg/dL) were randomized to metformin or placebo. Systemic insulin sensitivity was assessed using a mixed-meal tolerance test, while hepatic insulin sensitivity and β-cell function were measured using a hyperinsulinemic-euglycemic clamp. Brain insulin sensitivity was inferred utilizing 18FDG glucose uptake. SkM insulin sensitivity was evaluated in biopsied tissue obtained before and 60 minutes after the mixed meal via pAKT Ser473. Mitochondrial function was assessed by oxygen consumption, and ATP/ROS production. Results: Compared to placebo, metformin improved systemic and hepatic insulin sensitivity (p<0.05) and increased regional brain glucose uptake in insulin receptor-rich regions (p<0.05). In contrast, metformin attenuated the postprandial increase in SkM pAKT Ser473 (p<0.05) and did not alter any mitochondrial function parameters. Metformin was also associated with reduced leg lean mass and a modest decrease in VO2peak normalized to lean mass (p<0.05). Conclusion: Long-term metformin therapy improved systemic, hepatic, and regional brain insulin sensitivity in insulin-resistant older adults without altering SkM mitochondrial function. Blunted skeletal muscle insulin signaling likely reflects reduced circulating insulin from improved β-cell function rather than intrinsic muscle insulin resistance. The modest reduction in endurance capacity is consistent with loss of lean mass rather than impaired mitochondrial efficiency. Disclosure R.G. Leija: None. M. Pataky: None. K. Klaus: None. A. Prabha Kumar: None. K. Sevits: None. K. Nair: None. Funding National Institute of Aging (R21 AG060139)

Despite indisputable benefits of different exercise modes, the molecular underpinnings of their divergent responses remain unclear. We investigate post-translational modifications in human skeletal muscle following 12 weeks of high-intensity aerobic interval or resistance exercise training. High-intensity aerobic training induces acetylproteome modifications including several mitochondrial proteins, indicating post-translational regulation of energetics machinery, whereas resistance exercise training regulates phosphoproteomic modifications of contractile/cytoskeletal machinery, consistent with greater strength. Furthermore, despite similar transcriptional responses to a single acute bout of aerobic and resistance exercise, more robust phosphoproteomic and metabolomic responses occur with acute aerobic exercise, including phosphorylation of structural/contractile and membrane transport machinery, and the nascent polypeptide-associated complex-α, a regulator of protein translation. Together, our findings provide new insight on the intricate phosphoproteomic and acetylproteomic modifications in muscle that potentially explain physiological responses to different modes of chronic and acute exercise. This study is registered with ClinicalTrials.gov, numbers NCT01477164 and NCT04158375.

Introduction and Objective: Insulin resistance (IR) increases the risk for Alzheimer’s disease and other dementias. Preclinical studies show that metformin normalizes alterations in brain mitochondrial functions induced by diet-induced IR, specifically in brain regions rich in insulin receptors. Here, we assessed the effect of 10-months of metformin treatment on cognitive function, brain network connectivity, glucose uptake, and regional volume in older people with IR. Methods: Forty participants aged 60-80 years (20 male, 20 female) with abdominal obesity, BMI ≥ 25 kg/m2, and fasting blood glucose of 100-125 mg/dL were studied. Participants were randomly assigned to metformin (2500 mg/d) or placebo (n = 20 per group) for 40 weeks. Pre- and post-treatment measurements included cognition (NIH Toolbox cognitive battery), volumetric MRI, resting-state fMRI, regional glucose uptake (18FDG-PET), and insulin sensitivity (mixed-meal tolerance test; MMTT). Results: Metformin improved processing speed and working memory concurrent to similar directional changes in amygdala and hippocampus volumes. Metformin increased white matter volume in the frontal and temporal lobes. Analysis of functional connectivity showed inverse associations between IR and connectivity strength between numerous brain regions, most notably between frontal and temporal lobe structures, potentially explaining improvement of processing speed. Increased glucose uptake in brain areas rich in insulin receptors, such as the prefrontal cortex, support that metformin enhanced insulin sensitivity in brain regions involved in memory and other cognitive functions as in the whole body noted by MMTT. Conclusion: These results support the notion that metformin ameliorates IR-related alterations in regional connectivity, brain volume, and brain glucose uptake with concurrent improvement of important aspects of cognition. G. Ruegsegger: None. H. Jo: None. M.W. Pataky: None. N. Stricker: None. K. Klaus: None. V.J. Lowe: Research Support; Eli Lilly and Company, Siemens Healthcare Diagnostics. J. Port: Consultant; Clario. K. Nair: None. National Institute of Aging (R21 AG 060139 and R01 062859)

Introduction and Objective: Amino acids (AAs) stimulate glucagon which increases hepatic AA catabolism. AA. Glucagon concentrations are increased in prediabetes. This led to the hypothesis that hepatic resistance (associated with hepatic fat content) to glucagon’s actions on AA metabolism leads to hyperglucagonemia and hyperglycemia. Methods: To test this hypothesis, we quantified hepatic fat by MRI as Proton Density Fat Fraction (PDFF) in lean (n = 10) and obese subjects (n = 20). Half of the latter group had a PDFF < 5%; the remainder a PDFF > 5%. After an overnight fast, femoral vein, femoral artery, and hepatic vein catheters were placed. At 0700 (-180 min), infusions of [3-3H] glucose (10 μCi prime, 0.1 μCi/min continuous), indocyanine green and L-[1-13C,15N]-Leucine (7.5μmol/kg prime, 7.5μmol/kg/hour continuous) started. At 1000 (0 min), insulin was infused at 0.8 mU/kg/min (0 - 240 min) alongside glucagon (1.5 ng/kg/min 0 - 120 min; 3.0 ng/kg/min 120 - 240 min). A hyperglycemic clamp maintained peripheral glucose at ~9.0 mmol/L. A mixture of AAs (Clinisol, Baxter, Healthcare, Deerfield, IL; 15%, 0.003ml/kg/min;) was also infused. Results: As expected, the glucose infusion rate necessary to maintain the clamp was lower in obese subjects (15.4 ± 1.3 vs. 4.9 ± 0.7 mg/kg/min, lean vs. obese respectively, p < 0.01). This was also the case for glucose disappearance (93 ± 7 vs. 35 ± 4 μmol/kg/min, p < 0.01) unlike endogenous glucose production (11 ± 2 vs. 9 ± 1 μmol/kg/min, p = 0.04). There was no effect of hepatic fat on these parameters (p > 0.10). Splanchnic extraction of glycine, but not other AAs, was increased (0.04 ± 0.02 vs. 0.23 ± 0.03, p = 0.01) in obesity (independent of PDFF) throughout the study. Conversion of Leucine to α-Keto IsoCaproic acid was unchanged by obesity (at 240 min: 461 ± 53 vs. 381 ± 65 μmol/kg/min, p = 0.42) or PDFF (p = 0.84). Conclusion: We conclude that increases in hepatic fat do not alter hepatic AA metabolic response to glucagon in postprandial conditions. H.E. Christie: None. S. Mohan: None. A.M. Egan: None. M.D. Jensen: Consultant; Novo Nordisk, Dexcom, Inc. K. Nair: None. A. Vella: Research Support; Novo Nordisk A/S, Dexcom, Inc. Advisory Panel; Boehringer-Ingelheim, Rezolute. National Institute of Health (DK116231-06)

Insulin resistance (IR) is a modifiable risk factor for dementia, yet its effects on brain metabolism and function remain unclear. In older adults, greater IR was associated with reduced cerebral glucose uptake (indicating impaired mitochondrial metabolism), atrophy, and weakened connectivity between brain regions critical for cognition. In neuron-specific insulin receptor knockout mice, brain IR produced deficits in hippocampal- and prefrontal-dependent tasks accompanied by reduced brain mitochondrial ATP and elevated reactive oxygen species. To evaluate reversibility of IR-induced brain deficits, forty older adults with IR were randomized to 40-weeks of metformin or placebo. Metformin improved insulin sensitivity, increased brain glucose uptake, strengthened cognitive network connectivity, and preserved whole-brain and regional volumes implicated in decision-making and learning. Metformin also improved processing speed and working memory. Collectively, these findings highlight IR as a driver of brain metabolism and support the concept that insulin sensitization can prevent neurobiological deficits in older people with IR.

Skeletal muscle is a major organ for maintaining whole-body energy balance, yet how it adapts its transcriptional and metabolic programs to environmental cues remains unclear. Here, we report that histone mono-methyltransferase mixed lineage leukemia 4 (MLL4), a key enhancer regulator, directs muscle metabolic adaptation and systemic metabolism through AMPK signaling. Nutrient availability modulates MLL4 expression, and skeletal muscle-specific ablation of MLL4 in male mice protects against diet-induced obesity and improves glucose homeostasis despite reduced exercise endurance. These effects arise from enhanced fuel catabolism caused by marked activation of AMPK in MLL4-depleted muscles. Mechanistically, MLL4 cooperates with myocyte enhancer factor 2 to induce AMP-metabolizing enzymes cytosolic 5'-nucleotidase 1A and AMP-deaminase 3, which suppress AMPK activity. Pharmacologic inhibition of AMP-metabolizing pathway by Pentostatin activates muscle AMPK, confers resistance to obesity and improves metabolic health. These findings identify an enhancer regulator limiting AMPK-mediated muscle fuel catabolism, offering a potential strategy for treating obesity-related disorders.

Introduction and Objective: Human studies have shown that endurance exercise training (EET) increases the size of the hippocampus, critical for maintaining cognition and enhances brain glucose uptake. We determined whether the benefits of EET on the brain are related to enhanced mitochondrial function and how they could be related to hippocampal proteome abundance and post-translational modifications (PTMs). Methods: To do this we utilized 12-week-old C57BL/6 mice assigned to either a 6-week running wheel program or to a sedentary control group. Results: In the hippocampus, citrate synthase (Fig 1a) and cytochrome c oxidase activities (Fig 1b) were higher following EET which concurrently resulted in lower lactate dehydrogenase activity (Fig 1c). Together, these results suggest improved mitochondrial functions in the hippocampus of EET mice and a shift from a glycolytic to an oxidative profile. EET increased the levels of NAD+ and NADH in the hippocampus of animals. Further, global proteome, phosphoproteome, and acetylome were measured to determine EET effect on these post-translational events. We found substantial decrease in acetylated peptides (n=164) in the hippocampus (Fig 1e) with more robust effect in EET male mice compared to the sedentary group (Fig 1d). Conclusion: Overall, our results indicate that EET affects enzyme activity levels and deacetylation of proteins in the hippocampus, concurrent to improvement of NAD+ which may explain how EET improves cognition. Disclosure A.K. Asokan: None. R.G. Leija: None. C.J. Heppelmann: None. T. Dutta: None. K. Sevits: None. K. Klaus: None. G. Ruegsegger: None. M.W. Pataky: None. K. Nair: None.

Skeletal muscle atrophy was a characteristic of type 1 diabetes (T1DM) prior to insulin discovery and replacement. Indirect calorimetry during the post-absorptive state demonstrated that increased fuel oxidation during transient insulin deprivation in T1DM caused depletion of energy stores. Further, insulin has a critical role in preserving muscle mitochondrial content and function by enhancing mitochondrial biogenesis and proteostasis. Insulin deficiency not only inhibits mitochondrial biogenesis but also accelerates the degradation of mitochondrial proteins, causing a decline in mitochondrial content and efficiency. Inefficient mitochondrial respiration, reflected by the uncoupling of oxidative phosphorylation and consequent decline in ATP production, adversely affects many cellular functions and causes high oxidative stress. Oxidative stress adversely affects cardiovascular functions and damages many skeletal muscle proteins, accelerating their degradation and explaining muscle atrophy. Increased degradation of muscle proteins increases amino acid efflux that stimulates the liver to synthesize many non-insulin-dependent proteins, potentially contributing to macrovascular complications. This phenomenon explains a paradoxical increase in whole-body protein synthesis during insulin deficiency. Further, the mitochondrial biology of brain regions rich in insulin receptors concurrent with accelerated transport of ketones and lactate across the blood-brain barrier during insulin deficiency seems to protect the brain from oxidative stress. In contrast, insulin resistance associated with less ketone and lactate production renders the brain susceptible to protein oxidative damage. Oxidative damage and reduced ATP production potentially explain the higher prevalence of dementia in insulin-resistant people. Enhancement of insulin sensitivity by aerobic exercise and metformin in pre-clinical studies prevents mitochondrial dysfunction and oxidative damage to the brain.

Rationale: A subset of patients with group 1 pulmonary hypertension (PH) have superimposed left heart abnormalities with unclear metabolic implications. Objectives: To compare serum/transpulmonary metabolome between group 1 PH stratified by heart failure with preserved ejection fraction (HFpEF) probability. Methods: Patients with group 1 PH were stratified into low (<25%) and high (⩾75%) HFpEF-ABA (age, body mass index, and atrial fibrillation) probability, with healthy control subjects and subjects with clinical HFpEF used for comparison of venous and transpulmonary metabolomics. Measurements and Main Results: Group 1 PH + high HFpEF probability (n = 131) was associated with a significant increase in 207 metabolites (false discovery rate [FDR] P < 0.05 and fold change >1) (n = 193, t test) and a significant decrease in 231 metabolites (FDR P < 0.05 and fold change <1) (n = 193, t test) compared with group 1 PH + low HFpEF probability (n = 62). Group 1 PH + high HFpEF probability was associated with enhanced tryptophan metabolism with higher downstream kynurenine metabolite concentrations and lower serotonin concentrations (FDR P < 0.002 for all, n = 193, t test). Linoleate (precursor to arachidonic acid and prostaglandins) and arginine and homoarginine (precursors to nitric oxide) were all lower in group 1 PH + high HFpEF probability (FDR P < 0.03 for all, n = 193, t test). Metabolome changes in group 1 PH + high HFpEF probability overlapped with clinical HFpEF (n = 240) but were abnormal relative to control subjects (n = 85) (P < 0.0001 for all, n = 456, t test). There was no evidence of differential transpulmonary uptake/release of most metabolites, suggesting probable nonpulmonary origin (except for serotonin, interaction P = 0.04; and kynurenine, interaction P = 0.03; n = 433, mixed model). Conclusions: Patients with group 1 PH + high HFpEF probability have a unique metabolome characterized by enhanced tryptophan-kynurenine pathway breakdown, deficiency of amino acids (such as glycine and serine), lower serotonin, and decreased prostaglandin and nitric oxide precursors. Despite fulfilling clinical criteria for group 1 PH, these metabolome changes were comparable with clinical HFpEF, supporting biological overlap between these two forms of PH.

Introduction and Objective: Metformin reduces hepatic glucose production by inhibiting gluconeogenic enzymes and altering liver mitochondrial function through Complex I inhibition, and suppressing gluconeogenesis. In skeletal muscle, the largest tissue for glucose disposal, there are conflicting reports on the molecular regulation of metformin on mitochondrial respiration and aerobic exercise capacity (VO2max). The objective was to determine the effects of long-term metformin administration on muscle mitochondrial function. Methods: We conducted a 40-week double-blind placebo-controlled trial to test the effect of oral metformin administration in 40 older (age 60-85) men and women with overweight/obesity (BMI 25-38) and high fasting glucose (100-140mg/dL) on skeletal muscle mitochondrial function. An oral mixed meal tolerance test was performed following an overnight fast. Muscle biopsies were obtained before and 1hr following and meal to measure isolated mitochondrial function (Oxygraph-2K) under fasted and fed conditions. Two-way ANOVAs were used to test the effect of intervention (metformin vs placebo) and time (pre vs post). Results: 40-weeks of metformin, but not placebo, significantly reduced glucose (P=0.002), insulin (P=0.008), and c-peptide (P=0.007) AUC during a meal tolerance test and reduced HbA1c (-0.24%, P=0.03). However, no significant differences in muscle mitochondrial function (including state 2, 3, or 4 respiration, uncoupled respiration, H2O2 production, or ATP production; per tissue weight or protein content) in the fasted or post-meal states were detected following metformin or placebo. Furthermore, 40-weeks of metformin had no effect on VO2max. Conclusion: These results indicate that long-term metformin therapy in older people with insulin resistance improves whole body glucose metabolism without impacting skeletal muscle mitochondrial function or aerobic capacity. M.W. Pataky: None. K. Klaus: None. A. Prabha Kumar: None. K. Sevits: None. J.A. Jungwirth: None. K. Nair: None. National Institute of Aging (R21 AG060139)

Intermuscular adipose tissue (IMAT) is an anatomically distinct depot that is associated with metabolic dysfunction and aging. IMAT decreases with exercise in older adults with obesity, but less is known about how exercise influences IMAT in healthy, nonobese older adults in relation to insulin sensitivity. The purpose of this study was to determine whether lower leg IMAT accumulates in healthy older adults in the absence of obesity, diabetes, or frailty and its relationship to insulin sensitivity. We also determined the influence of exercise training on lower leg IMAT. Twenty-nine young (25.0 ± 3.8 yr) and 22 older (76.0 ± 5.0 yr) adults underwent MRI-based measurements of lower leg IMAT and insulin sensitivity measurements by hyperinsulinemic euglycemic clamp before and after 12 wk of exercise training. IMAT was higher in older compared with young adults (2,512 ± 1,178 mm3 vs. 4,492 ± 2,025 mm3; P < 0.0001). The glucose infusion rate (GIR) during hyperinsulinemia was similar in young and older adults [14.4 ± 2.8 mg/kg fat-free mass (FFM)/min vs. 13.3 ± 4.4 mg/kg FFM/min; P = 0.31), but negatively associated with IMAT (r = -0.43; P = 0.002), particularly in older adults (r = -0.55; P = 0.01). Exercise training reduced IMAT in young (P = 0.04) but not older adults. GIR increased in response to exercise but dissociated from changes in IMAT. These data demonstrate that lower leg IMAT accumulated even in healthy aging, and although IMAT may have metabolic implications, the metabolic improvements with exercise training appear to be independent of lower leg IMAT in this population of older adults.NEW & NOTEWORTHY Intermuscular adipose tissue (IMAT) accumulates in the lower leg musculature of healthy older adults. IMAT was negatively associated with the rate of glucose infusion during a hyperinsulinemic-euglycemic clamp and muscle oxidative capacity. Exercise training decreased IMAT to a greater extent in young compared with older adults. Together these data support the implication that IMAT accumulation is linked with metabolic derangements in older adults but the restorative potential of exercise in older adults needs further evaluation.

Introduction Almonds have prebiotic potential to maintain gut health and regulate glycaemia. Western studies have shown their positive effects on preventing non-communicable diseases like diabetes and cardiovascular diseases. However, there is a lack of research involving Asian Indians, who have a higher predisposition to diabetes due to their unique ‘Asian phenotype’. Therefore, this study aims to evaluate the impact of almond supplementation on glycaemic control and gut health in adults with pre-diabetes in rural India through a randomised clinical trial.Methods and analysis A parallel cluster randomised controlled trial with 178 participants with pre-diabetes (assigned 1:1) aged 20–50 years, of both genders, with a body mass index of 18.9–25 kg/m2, will be conducted in rural areas of Chikkaballapur, Kolar and Rural Bangalore districts in India. The intervention group will receive 56 g of almonds as mid-morning snacks for 16 weeks, while the control group will receive cereal/pulse-based traditional isocaloric snacks under the closed supervision of the study investigators. The primary outcome of the study is HbA1c measured at the 16th week. The secondary outcomes—anthropometry, clinical and other biochemical parameters—will be measured at 0th, 8th and 16th weeks, and a subgroup of 120 participants will undergo gut health analysis. Glucagon-like peptide 1 analysis will be conducted on 30 participants at 0th and 16th weeks. Statistical analysis will be performed using SPSS for Windows V.27.0, and both intention-to-treat and per-protocol analyses will be conducted.Ethics and dissemination Ethics approval was obtained from the Institutional Ethics Committee at Ramaiah Medical College, Bangalore, Karnataka, India (DRPEFP7672021). We will obtain the informed written consent of the participants prior to screening and enrolling them in the study. Results from this trial will be disseminated through publication in peer-reviewed journals and scientific gatherings.Trial registration number Clinical Trial Registry of India (CTRI/2023/03/050421).

Background: Insulin resistance can be present in otherwise healthy, normal weight adults. Whether there are phenotype/sex-differences between normal weight insulin-resistant (NWIR) and normal weight insulin-sensitive (NWIS) Caucasians and whether there are differences in adverse health outcomes are unknown. Our goal was to define phenotypes and intermediate-term health outcomes of NWIR versus NWIS Caucasian adults. Methods: We analyzed data from 227 healthy volunteers body mass index 18 to <25.0 kg/m2 who underwent insulin clamp studies between January 1987 and January 2017 at Mayo Clinic to identify those in the top (NWIS, n = 56) and bottom (NWIR, n = 56) quartiles of insulin action. We compared the phenotypical characteristics and were able to collect medical records data for 80% of NWIS and 88% of NWIR to identify time to onset of hypertension, hyperglycemia, coronary heart disease, cerebrovascular disease, peripheral vascular disease, and all cause death; the follow-up averaged 11 (4, 20) years. Results: Body fat was significantly greater and peak VO2 was significantly less in both NWIS than NWIR males and females. Only in females was abdominal subcutaneous fat by computed tomography significantly greater in NWIR than NWIS. In NWIR males high-density lipoprotein-cholesterol and fat free mass were significantly less, and fasting insulin was greater than NWIS males. For the entire NWIS population, Kaplan-Meier disease-free survival analysis showed longer times free of hypertension, hyperglycemia, and some cardiovascular diseases than for NWIR. Conclusions: There are sex-specific phenotypes of NWIR in Caucasian adults. NWIR may be associated with accelerated onset of some adverse medical outcomes.

Background: Cystic Fibrosis (CF) patients historically suffered from undernutrition, infection and inflammation. Insulin insufficiency-related protein catabolism further compromised health. We aimed to determine whether insulin improves protein catabolism in CF youth with abnormal glucose tolerance (AGT). Methods: This double-masked, placebo-controlled trial in CF youth age 10-25 with AGT who were in their usual state of health used triple-tracer stable-isotope methodology to measure protein turnover during a baseline test meal and after four weeks of insulin/placebo treatment. Healthy controls were assessed once. CF patients were randomized 1:1:1 to once-daily long-acting insulin (0.25 U/kg/d), three-times daily rapid-acting insulin (0.5 U/ 15gr carbohydrate), or injectable placebo. Results: Thirty CF patients completed the study. There were no differences in any measure of protein turnover between insulin- and placebo-treated subjects, including endogenous protein breakdown (primary study endpoint). In contrast to earlier studies, protein turnover in the 37 CF patients who completed the baseline meal was normal compared to 20 healthy controls. Meal isotope appeared in plasma earlier in CF than controls, suggesting more rapid gut emptying. The study was interrupted by the pandemic; futility analysis led to study discontinuation before the planned remaining 15 CF patients were studied. Conclusions: Recent advances in CF have led to remarkable clinical improvements. In this study, CF youth with AGT had normal protein catabolism at baseline. Pre-meal or daily basal insulin therapy, while safe and well tolerated, did not significantly enhance protein turnover and does not appear to be necessary in clinically stable patients prior to development of CFRD.

We investigated the link between enhancement of insulin sensitivity (SI) (by hyperinsulinemic-euglycemic clamp) and muscle metabolites following 12-weeks of aerobic (high-intensity interval training, HIIT), resistance (RT), or combined (CT) exercise training in 52 lean healthy people. Muscle RNA-sequencing revealed a significant association between SI following both HIIT and RT and the branched chain amino acid (BCAA) metabolic pathway. Concurrent to increased expression and activity of branched chain ketoacid dehydrogenase enzyme, many muscle amino metabolites including BCAAs, glutamate, phenylalanine, aspartate, asparagine, methionine, and GABA increased by HIIT, supporting substantial impact of HIIT on amino acid metabolism. Short-chain C3 and C5 acylcarnitines were reduced in muscle by all three training modes, but unlike RT, both HIIT and CT increased TCA metabolites and cardiolipins, supporting greater mitochondrial activity by aerobic training. Conversely, RT and CT increased more plasma membrane phospholipids than HIIT, suggesting a resistance exercise effect on cellular membrane protection against environmental damage. Sex and age contributed modestly to the exercise-induced changes in metabolites and their association to cardiometabolic parameters. Integrated transcriptomic and metabolomic analyses suggest various clusters of genes and metabolites are involved in distinct effects of HIIT, RT, and CT. These distinct metabolic signatures of different exercise modes independently link each type of exercise training to improved SI and cardiometabolic risk. ARTICLE HIGHLIGHTS: · We aimed to understand the link between skeletal muscle metabolites and cardiometabolic health after exercise training. · Although aerobic, resistance, and combined exercise training each enhance muscle insulin sensitivity as well as other cardiometabolic parameters, they disparately alter amino and citric acid metabolites as well as lipidome, linking these metabolomic changes independently to improvement of cardiometabolic risks by each exercise training mode. · These findings reveal an important layer of the unique exercise mode-dependent changes in muscle metabolism which may eventually lead to more informed exercise prescription for improving SI.

Insulin is a key regulator of amino acid metabolism. Many plasma amino acids, including lysine and its metabolite, α-aminoadipic acid (α-AA), a predictor for developing diabetes, are elevated in insulin resistance (IR). In 18 overweight women with IR and polycystic ovary syndrome compared with 12 lean control women, high physiological insulin during a euglycemic clamp failed to normalize many elevated amino acid metabolites, including branched-chain and aromatic amino acids, α-aminobutyric acid, and lysine, but normalized α-AA. To understand the underpinnings of differential responses of lysine and its metabolic product α-AA to high physiological insulin in IR compared with control participants, we developed a kinetic model using [α-15N1]-lysine and [13C1]-α-AA as tracers and measured the two tracers simultaneously in α-AA by innovative mass spectrometry. High insulin increased lysine conversion to α-AA in the IR and control groups but failed to normalize plasma lysine concentrations in IR due to a decrease in lysine metabolic clearance rate (MCR). In contrast, despite higher conversion rates of lysine to α-AA by high insulin, α-AA concentration decreased in IR because of the sustained greater MCR of α-AA. The abnormal amino acids and metabolites, even while on high physiological insulin, could potentially explain many functional derangements in IR. ARTICLE HIGHLIGHTS:

The aim of this paper was to provide policymakers with a set of evidence on the effectiveness of Conditional cash transfer (CCT) Programs in low and middle income countries. This is a policy prescription paper based on the systematic review evidence on “Conditional Cash Transfer for Improving Uptake of Health Interventions in Low and Middle Income Countries”. In this review, we have assessed the effectiveness of CCT programs on improving health services and health outcomes in Low and middle income countries. The review evidence suggests, positive health outcomes from this programs and the following paper gives an overview of the evidence as a policy prescription for policy makers.

Subcutaneous white adipose tissue (scWAT) is a dynamic storage and secretory organ that regulates systemic homeostasis, yet the impact of endurance exercise training (ExT) and sex on its molecular landscape is not fully established. Utilizing an integrative multi-omics approach, and leveraging data generated by the Molecular Transducers of Physical Activity Consortium (MoTrPAC), we show profound sexual dimorphism in the scWAT of sedentary rats and in the dynamic response of this tissue to ExT. Specifically, the scWAT of sedentary females displays -omic signatures related to insulin signaling and adipogenesis, whereas the scWAT of sedentary males is enriched in terms related to aerobic metabolism. These sex-specific -omic signatures are preserved or amplified with ExT. Integration of multi-omic analyses with phenotypic measures identifies molecular hubs predicted to drive sexually distinct responses to training. Overall, this study underscores the powerful impact of sex on adipose tissue biology and provides a rich resource to investigate the scWAT response to ExT. Using a multi-omics approach, the authors examine the molecular drivers of sexual dimorphism in the subcutaneous adipose tissue from sedentary and endurance-trained rats. These data provide a valuable resource for adipose tissue-related research.