Association of plasma acylcarnitines with insulin sensitivity, insulin secretion, and prediabetes in a biracial cohort

The Metabolic Signature of Cardiorespiratory Fitness

High cardiorespiratory fitness (CRF) is associated with better overall health. This study aimed to find a metabolic signature associated with CRF to identify health-promoting effects. CRF based on cardiopulmonary exercise testing, targeted and untargeted metabolomics approaches based on mass spectrometry, and clinical data from two independent cohorts of the Study of Health in Pomerania (SHIP) were used. Sex-stratified linear regression models were adjusted for age, smoking, and height to relate CRF with individual metabolites. A total of 132 (SHIP-START-2: 483 men with a median age of 58 years and 450 women with a median age of 56 years) and 118 (SHIP-TREND-0: 341 men and 371 women both with a median age of 51 years) metabolites were associated with CRF. Lipids showed bidirectional relations to CRF independent of sex. Specific subsets of sphingomyelins were positively related to CRF in men (SM (OH) C14:1, SM(OH)C22:2 SM C16:0, SM C20:2 SM(OH)C24:1) and inversely in women (SM C16:1, SM C18:0, SM C18:1). Metabolites involved in energy production (citrate and succinylcarnitine) were only associated with CRF in men. In women, xenobiotics (hippurate, stachydrine) were related to CRF. The sex-specific metabolic signature of CRF is influenced by sphingomyelins, energy substrates, and xenobiotics. The greater effect estimates seen in women may emphasize the important role of CRF in maintaining metabolic health. Future research should explore how this profile changes with different types of exercise interventions or diseases in diverse populations and how these metabolites could be implemented in primary prevention settings.

Metabolome Alterations Associated with Three-Month Sitting-Time Reduction Among Sedentary Postmenopausal Latinas with Cardiometabolic Disease Risk

Background: Incidence of cardiometabolic disease among U.S. Hispanics/Latinos is higher than in non-Hispanic Whites. Prolonged sitting duration is prevalent in older adults, and compounded with menopause, greatly increases cardiometabolic risk in postmenopausal women. Metabolomic analyses of interventions to reduce sitting are lacking and mechanistic understanding of health-promoting behavior change in postmenopausal Latinas is needed. Methods: To address this knowledge gap, an exploratory analysis investigated the plasma metabolome impact of a 12-week increased standing intervention among sedentary postmenopausal Latinas with overweight or obesity. From a parent-randomized controlled trial, a subset of Best Responders (n = 43) was selected using parameters of highest mean change in sitting bout duration and total sitting time; baseline variable-Matched Controls (n = 43) were selected using random forest modeling. Targeted LC-MS/MS analysis of archived baseline and 12-week plasma samples was conducted. Metabolite change was determined using a covariate-controlled general linear model and multivariate testing was performed. A false discovery rate correction was applied to all analyses. Results: Best Responders significantly changed time sitting (-110.0 ± 11.0 min; -21%), standing (104.6 ± 10.1 min; 40%), and sitting in bouts >30 min (-102.3 ± 13.9 min; -35%) compared to Matched Controls (7.1 ± 9.8 min, -7.8 ± 9.0 min, and -4.6 ± 12.7 min, respectively; all p < 0.001). Twelve-week metabolite change was significantly different between the two groups for 24 metabolites (FDR < 0.05). These were primarily related to amino acid metabolism, improved blood flow, and ATP production. Enzyme enrichment analysis predicted significant changes regulating glutamate, histidine, phenylalanine, and mitochondrial short-chain fatty acid catabolism. Pathway analysis showed significant intervention effects on glutamate metabolism and phenylalanine, tyrosine, and tryptophan biosynthesis, potentially indicating reduced cardiometabolic disease risk. Conclusions: Replacing nearly two hours of daily sitting time with standing and reduced prolonged sitting bouts significantly improved metabolomic profiles associated with cardiometabolic risk among postmenopausal Latinas.

Fidelity of BMI, Waist, and Waist-to-Height Ratio as Adiposity Measures in Normoglycemic Black vs White American Adults

Objective

To assess ethnic disparities in the association between indirect and direct measures of adiposity in African American (AA) and European American (EA) adults.

Methods

We analyzed the indirect [weight, body mass index (BMI), waist circumference (WC), waist-to-height ratio (WHtR)] and direct [total fat, trunk fat, fat-free mass (FFM)] adiposity measures in healthy AA and EA adults. Assessments included anthropometry, oral glucose tolerance test, body composition by dual-energy X-ray absorptiometry (DXA), and calculation of direct-to-indirect adiposity ratios (total fat/BMI, trunk fat/WC, trunk fat/WHtR, and FFM/weight).

Results

A total of 314 subjects (167 AA, 147 EA) underwent DXA. All participants (mean age 44.2 ± 10.6 years) had normal fasting and 2-hour glucose values. The BMI (AA vs EA) was 31.2 ± 7.42 kg/m2 vs28.8 ± 6.78 kg/m2 (P = .0014); WC 95.3 ± 16.0 cm vs 92.9 ± 15.0 cm (P = .15). Significant correlations (P < .0001) were observed between BMI and total fat (r = 0.68), WC, and trunk fat (r = 0.61) and WHtR vs trunk fat (r = 0.77) for the combined cohort, with heterogeneity in the strength of association by sex and ethnicity. Fat-free mass was higher in AA vs EA participants (P = .03). Total fat/BMI was lower in AA vs EA participants (P = .0047); trunk fat/WC (P = .004) and trunk fat/WHtR (P = .0026) were lower in AA men vs EA men.

Conclusion

The BMI overestimated body fat in AA participants vs EA participants, and WC overestimated trunk fat in AA men vs EA men. These data indicate ethnic disparities in the fidelity of indirect measures of adiposity and argue for ethnic-specific BMI thresholds for determination of overweight/obesity.

Serum concentrations of lipids, ketones and acylcarnitines during the postprandial and fasting state: the Postprandial Metabolism (PoMet) study in healthy young adults

To improve the interpretation and utilisation of blood lipids, ketones and acylcarnitine concentrations as biomarkers in clinical assessments, more information is needed on their dynamic alterations in response to dietary intake and fasting. The aim of this intervention study was to characterise the changes in serum lipid, ketone and acylcarnitine concentrations 24 h after a standardised breakfast meal. Thirty-four healthy subjects (eighteen males and sixteen females) aged 20-30 years were served a breakfast meal (∼500 kcal, 36 E% fat, 46 E% carbohydrates, 16 E% protein, 2E% fibre), after which they consumed only water for 24 h. Blood samples were drawn before and at thirteen standardised timepoints after the meal. Metabolite concentrations were plotted as a function of time since the completion of the breakfast meal. Results demonstrated that concentrations of HDL-cholesterol and LDL-cholesterol decreased until ∼2 h (-4 % for both), while TAG concentrations peaked at 3 h (+27 %). Acetoacetate and β-hydroxybutyrate were highest 24 h after the meal (+433 and +633 %, respectively). Acetylcarnitine, butyrylcarnitine, hexanoylcarnitine, octanoylcarnitine, decanoylcarnitine and dodecanoylcarnitine reached the lowest values at 60 min (decreases ranging from -47 to -70 %), before increasing and peaking at 24 h after the meal (increases ranging from +86 to +120 %). Our findings suggest that distinguishing between fasting and non-fasting blood samples falls short of capturing the dynamics in lipid, ketone, carnitine and acylcarnitine concentrations. To enhance the utility of serum acylcarnitine analyses, we strongly recommend accounting for the specific time since the last meal at the time of blood sampling.

Plasma Ceramides and Other Sphingolipids in Relation to Incident Prediabetes in a Longitudinal Biracial Cohort

CONTEXT

Sphingolipids are linked to the pathogenesis of type 2 diabetes.

OBJECTIVE

To test the hypothesis that plasma sphingolipid profiles predict incident prediabetes.

DESIGN

A case-control study nested in the Pathobiology of Prediabetes in a Biracial Cohort study, a 5-year follow-up study.

SETTING

Academic health center.

PARTICIPANTS

Normoglycemic adults enrolled in the Pathobiology of Prediabetes in a Biracial Cohort study. Assessments included oral glucose tolerance test, insulin sensitivity, and insulin secretion. Participants with incident prediabetes were matched in age, sex, and ethnicity with nonprogressors.

INTERVENTIONS

We assayed 58 sphingolipid species (ceramides, monohexosyl ceramides, sphingomyelins, and sphingosine) using liquid chromatography/tandem mass spectrometry in baseline plasma levels from participants and determined association with prediabetes risk.

MAIN OUTCOME MEASURE

The primary outcome was progression from normoglycemia to prediabetes, defined as impaired fasting glucose or impaired glucose tolerance.

RESULTS

The mean age of participants (N = 140; 50% Black, 50% female) was 48.1 ± 8.69 years, body mass index 30.1 ± 5.78 kg/m2, fasting plasma glucose 92.7 ± 5.84 mg/dL, and 2-hour plasma glucose 121 ± 23.3 mg/dL. Of the 58 sphingolipid species assayed, higher ratios of sphingomyelin C26:0/C26:1 (OR, 2.73 [95% CI, 1.172-4.408], P = .015) and ceramide C18:0/C18:1 (OR, 1.236 [95% CI, 1.042-1.466], P = .015) in baseline plasma specimens were significantly associated with progression to prediabetes during the 5-year follow-up period, after adjustments for age, race, sex, body mass index, fasting plasma glucose, 2-hour plasma glucose, insulin sensitivity, and insulin secretion.

CONCLUSION

We conclude that the saturated-to-monounsaturated ratios of long-chain ceramide C18:0/C18:1 and very-long-chain sphingomyelin C26:0/C26:1 are potential biomarkers of prediabetes risk among individuals with parental history of type 2 diabetes.

Exploring the Effect of Exercise versus Metformin on Insulin Resistance amongst Nigerians with Pre-diabetes: A Randomised Controlled Trial

BACKGROUND

Pre-diabetes is an important risk factor for the development of type 2 diabetes and is common in Nigeria. Effective intervention can reverse the underlying pathogenesis of insulin resistance in pre-diabetes. This study aimed to determine and compare the impact of moderate exercise and metformin interventions on insulin resistance among participants with pre-diabetes.

MATERIALS AND METHODS

Using a randomised placebo-controlled design, 54 Nigerians with pre-diabetes were selected using simple random sampling. They were offered metformin, moderate exercise or placebo treatment and followed up for 12 weeks. Insulin resistance was assessed before and after the interventions and the outcome was compared.

RESULTS

Forty-nine participants with pre-diabetes completed the study. Participants in both the exercise and metformin groups had significantly decreased insulin resistance compared to placebo after 12 weeks of intervention. However, there was a decrease in insulin resistance by 77.3% (homeostasis model assessment-insulin resistance [HOMA-IR]) and an increase in insulin sensitivity by 81.2% (quantitative insulin sensitivity check index [QUICKI]) in the exercise group. In comparison, participants in the metformin group had a decrease in insulin resistance by 66.3% (HOMA-IR) and an increase in insulin sensitivity by 76.2% (QUICKI).

CONCLUSION

Amongst Nigerians with pre-diabetes, both moderate exercise and metformin have significantly higher efficacy than placebo in improving insulin resistance. However, moderate exercise improved insulin resistance more than the metformin intervention. Participants in this study need to be followed up for a longer period to assess the long-term effects of these interventions.

Characterization of lipid signatures in the plasma and insulin-sensitive tissues of the C57BL/6J mice fed on obesogenic diets

Diet-induced obesity mouse models are widely utilized to investigate the underlying mechanisms of dyslipidemia, glucose intolerance, insulin resistance, hepatic steatosis, and type 2 diabetes mellitus (T2DM), as well as for screening potential drug compounds. However, there is limited knowledge regarding specific signature lipids that accurately reflect dietary disorders. In this study, we aimed to identify key lipid signatures using LC/MS-based untargeted lipidomics in the plasma, liver, adipose tissue (AT), and skeletal muscle tissues (SKM) of male C57BL/6J mice that were fed chow, LFD, or obesogenic diets (HFD, HFHF, and HFCD) for a duration of 20 weeks. Furthermore, we conducted a comprehensive lipid analysis to assess similarities and differences with human lipid profiles. The mice fed obesogenic diets exhibited weight gain, glucose intolerance, elevated BMI, glucose and insulin levels, and a fatty liver, resembling characteristics of T2DM and obesity in humans. In total, we identified approximately 368 lipids in plasma, 433 in the liver, 493 in AT, and 624 in SKM. Glycerolipids displayed distinct patterns across the tissues, differing from human findings. However, changes in sphingolipids, phospholipids, and the expression of inflammatory and fibrotic genes showed similarities to reported human findings. Significantly modulated pathways in the obesogenic diet-fed groups included ceramide de novo synthesis, sphingolipid remodeling, and the carboxylesterase pathway, while lipoprotein-mediated pathways were minimally affected.

Advanced Meditation and Vegan Diet Increased Acylglycines and Reduced Lipids Associated with Improved Health: A Prospective Longitudinal Study

Introduction: Samyama is an Isha Yoga 8-day residential meditation/yoga retreat combined with 60 days of preparation with vegan diet. We showed earlier Samyama retreat was associated with lower systemic inflammation and favorable lipid profiles along with other physical and mental health benefits. There is no mechanistic study on the impact of an advanced meditative process on multiple blood lipids and their implications on meditation-related improved physical and mental wellbeing. Methods: Sixty-four Samyama participants on vegan diet had blood sampled immediately before and immediately after the 8-day retreat for lipidomic analysis. The complex plasma lipidome was characterized using high-resolution mass spectrometric analysis and tandem mass spectrometry. Results: Pre- and post-Samyama blood samples of 64 Samyama participants were analyzed. Acylglycines (acetyl, propionyl, butyryl, and valeryl) were increased in the plasma post-Samyama compared with pre-Samyama (p < 0.001). Levels of glycerophosphocholines, glycerophosphoethanolamines, di-unsaturated ethanolamine plasmalogens, cholesterol esters, acylcarnitines, and acylgylcerines (triacylglycerols and diacylglycerols) decreased after the Samyama meditation. Plasma levels of glycerophosphoserines or glycerophosphoinositols were unchanged. Conclusion: An 8-day advanced meditation retreat resulted in increased acylglycines, an endocannabinoid-like fatty acid amide associated with increased cellular anandamide levels, anti-inflammation, analgesia, and vascular relaxation. Other serum lipid levels, including some that are associated with increased risk of atherosclerosis, were reduced following the Samyama program. ClinicalTrials.gov Registration: Identifier: NCT04366544.

Outcome of lifestyle intervention in relation to duration of pre-diabetes: the Pathobiology and Reversibility of Prediabetes in a Biracial Cohort (PROP-ABC) study

INTRODUCTION

In studies that enrolled people with prevalent pre-diabetes of unknown duration, lifestyle intervention (LI) delayed progression to type 2 diabetes (T2D) but did not reverse pre-diabetes in most participants. Here, we assessed the effects of LI among individuals with pre-diabetes of known duration to determine whether outcomes are related to duration of pre-diabetes.

RESEARCH DESIGN AND METHODS

The Pathobiology and Reversibility of Prediabetes in a Biracial Cohort study initiated LI in subjects with incident pre-diabetes during follow-up of initially normoglycemic African Americans and European Americans with parental T2D. Participants were stratified into those initiating LI after <3, 3-5, or >5 years of pre-diabetes diagnosis. Assessments included anthropometry, body fat, fasting and 2-hour plasma glucose (FPG, 2hPG), and insulin sensitivity and secretion. The outcomes were normal glucose regulation (NGR; ie, normal FPG and 2hPG), persistent pre-diabetes, or T2D. Participants who maintained normal FPG and normal 2hPG levels during follow-up served as the control. The control subjects did not receive lifestyle or other intervention to alter the course of glycemia or body weight.

RESULTS

Of 223 participants (age 53.3±9.28 years, body mass index 30.6±6.70 kg/m²), 72 (control) maintained normoglycemia during follow-up and 138 subjects with incident pre-diabetes initiated LI after 4.08±2.02 years (range 3 months-8.3 years) of diagnosis. Compared with control, LI participants showed decrease in glucose, weight, and body fat; 42.8% reverted to NGR, 50% had persistent pre-diabetes, and 7.2% developed T2D after 5 years. These outcomes were similar across race and pre-diabetes duration strata, but greater glycemic decrease occurred when LI was initiated within 5 years of pre-diabetes diagnosis.

CONCLUSIONS

Ninety-three per cent of adults with parental T2D who initiated LI within 3 months to 8.3 years of developing pre-diabetes did not progress to T2D; nearly half reverted to NGR.Trial registration number NCT02027571.