Lipid-induced glucose intolerance is driven by impaired glucose kinetics and insulin metabolism in healthy individuals

An antireductant approach ameliorates misfolded proinsulin-induced hyperglycemia and glucose intolerance in male Akita mice

Protein folding in the endoplasmic reticulum (ER) requires a high ratio of oxidized to reduced glutathione (GSSG/rGSH). Since the GSSG/rGSH depends on total glutathione (tGSH = GSSG + rGSH) levels, we hypothesized that limiting GSH biosynthesis will ameliorate protein misfolding by enhancing the ER oxidative milieu. As a proof-of-concept, we used DL-buthionine-(S,R)-sulfoximine (BSO) to inhibit GSH biosynthesis in Akita mice, which are prone to proinsulin misfolding. We conducted a 2-week intervention to investigate if BSO was safe and a 6-week intervention to find its effect on glucose intolerance. In both cohorts, male heterozygous Akita (AK) and wild-type (WT) mice were continuously administered 15 mM BSO. No adverse effects were observed on body weight, food intake, and water intake in either cohort. Unaltered levels of plasma aspartate and alanine aminotransferases, and cystatin-C, indicate that BSO was safe. BSO-induced decreases in tGSH were tissue-dependent with maximal effects in the kidneys, where it altered the expression of genes associated with GSH biosynthesis, redox status, and proteostasis. BSO treatment decreased random blood glucose levels to 80% and 67% of levels in untreated mice in short-term and long-term cohorts, respectively, and 6-h fasting blood glucose to 82% and 74% of levels in untreated mice, respectively. BSO also improved glucose tolerance by 37% in AK mice in the long-term cohort, without affecting insulin tolerance. Neither glucose tolerance nor insulin tolerance were affected in WT. Data indicate that BSO might treat misfolded proinsulin-induced glucose intolerance. Future studies should investigate the effect of BSO on proinsulin misfolding and if it improves glucose intolerance in individuals with Mutant Insulin Diabetes of Youth.

The relationship between remnant cholesterol and young-onset myocardial infarction in patients with type 2 diabetes: a retrospective study

Background

Remnant cholesterol (RC) has emerged as a novel therapeutic target beyond low-destiny-lipoproteins cholesterol (LDL-c). While elevated RC levels are strongly associated with cardiovascular disease risk in the general population, their specific role in young-onset acute myocardial infarction (AMI) among patients with type 2 diabetes mellitus (T2DM) remains insufficiently explored and warrants further investigation.

Methods

This retrospective study included AMI patients with T2DM admitted to the First Affiliated Hospital of Xi'an Jiaotong University from 2018 to 2022. Patients were stratified into tertiles according to RC levels and compared using thresholds derived the commanded values from the PREDIMED cohort study. The primary outcome was young-onset AMI. Group differences were analyzed using the chi-square test and the Kruskal-Wallis H test, while Spearman correlation analyses assessed relationships between variables. Univariate and multivariate logistic regression analyses were employed to evaluate the association between RC and young-onset AMI.

Results

Among the 2,514 participants (mean age 61.58 ± 11.15 years), 802 (31.9%) had young-onset AMI. The increase of young-onset AMI increased significantly with rising RC levels (27.0% vs 29.7% vs 39.1%, P < 0.001). RC showed significant positive correlation with total cholesterol (TC, r = 0.497, P < 0.001), triglycerides (TG, r = 0.411, P < 0.001), and LDL-c (r = 0.166, P < 0.001). RC was independently associated with a higher risk of young-onset AMI (OR: 1.579; 95% CI: 1.354-1.842; P < 0.001), even after adjusting for other traditional risk factors of cardiovascular disease (OR: 1.415; 95% CI 1.189-1.684; P < 0.001). Notably, RC levels remained strongly linked to young-onset AMI regardless of whether LDL-c levels were within the desired range.

Conclusion

RC is a significant and independent risk factor for young-onset AMI in T2DM patients, irrespective of LDL-c level. These findings underscore the importance of monitoring and managing RC levels in clinical practice to mitigate cardiovascular risk in this population.

Effects of Hypertriglyceridemia With or Without NEFA Elevation on β-cell Function and Insulin Clearance and Sensitivity

CONTEXT

Hypertriglyceridemia is a risk factor for developing type 2 diabetes (T2D) and might contribute to its pathogenesis either directly or through elevation of nonesterified fatty acids (NEFAs).

OBJECTIVE

This study aimed at comparing the glucometabolic effects of acute hypertriglyceridemia alone or combined with NEFA elevation in subjects without diabetes.

METHODS

Twenty-two healthy lean volunteers underwent 5-hour intravenous infusions of either saline or Intralipid, without (n = 12) or with heparin (I + H; n = 10) to activate the release of NEFAs. Oral glucose tolerance tests (OGTTs) were performed during the last 3 hours of infusion. Insulin sensitivity, insulin secretion rate (ISR), model-derived β-cell function, and insulin clearance were measured after 2 hours of lipid infusion and during the OGTTs.

RESULTS

In fasting conditions, both lipid infusions increased plasma insulin and ISR and reduced insulin clearance without affecting plasma glucose and insulin sensitivity. These effects on insulin and ISR were more pronounced for I + H than Intralipid alone. During the OGTT, the lipid infusions markedly impaired glucose tolerance, increased plasma insulin and ISR, and decreased insulin sensitivity and clearance, without significant group differences. Intralipid alone inhibited glucose-stimulated insulin secretion (ie, β-cell glucose sensitivity) and increased β-cell potentiation, whereas I + H had neutral effects on these β-cell functions.

CONCLUSION

In healthy nonobese subjects, mild acute hypertriglyceridemia directly reduces glucose tolerance and insulin sensitivity and clearance, and has selective and opposite effects on β-cell function that are neutralized by NEFAs. These findings provide new insight into plausible biological signals that generate and sustain insulin resistance and chronic hyperinsulinemia in the development of T2D.

Pancreatic expression of CPT1A is essential for whole body glucose homeostasis by supporting glucose-stimulated insulin secretion

Pancreatic islet β-cells express the Cpt1a gene, which encodes the enzyme carnitine palmitoyltransferase 1A (CPT1A), an enzyme that facilitates entry of long-chain fatty acids into the mitochondria. Because fatty acids are required for glucose-stimulated insulin secretion, we tested the hypothesis that CPT1A is essential to support islet β-cell function and mass. In this study, we describe genetic deletion of Cpt1a in pancreatic tissue (Cpt1aPdx1-/-) using C57BL/6J mice. Islet morphology, β-cell transcription factor abundance, islet ATP levels, glucose transporter 2 abundance, and expression of the dedifferentiation marker ALDH1A3 were analyzed by immunofluorescent staining. Glucose and insulin tolerance were assessed to investigate the metabolic status of genetic reductions in Cpt1a. Glucose-stimulated insulin secretion was evaluated in vivo and in isolated islets ex vivo by perifusion. Pancreatic deletion of Cpt1a reduced glucose tolerance but did not alter insulin sensitivity. Glucose-stimulated insulin secretion was reduced both in vivo and in islets isolated from Cpt1aPdx1-/- mice relative to control islets. Pancreatic islets from Cpt1aPdx1-/- mice displayed elevations in ALDH1A3, a marker of dedifferentiation, but no reduction in nuclear abundance of the β-cell transcription factors MafA and Nkx6.1 or the GLUT2 glucose transporter. However, intracellular ATP abundance was markedly decreased in islets isolated from Cpt1aPdx1-/- relative to littermate control mice. We conclude that there is an important physiological role for pancreatic CPT1A to maintain whole body glucose homeostasis by supporting glucose-stimulated insulin secretion and maintaining intracellular ATP levels in male mice.

Postprandial hypoglycaemia after gastric bypass in type 2 diabetes: pathophysiological mechanisms and clinical implications

AIMS/HYPOTHESIS

Postprandial hypoglycaemia (PPHG) is a frequent late complication of Roux-en-Y gastric bypass (RYGB) in people without diabetes. We aimed to examine the pathogenetic mechanisms of PPHG and its clinical consequences in people with a history of type 2 diabetes.

METHODS

In this case-control study, 24 participants with type 2 diabetes treated with RYGB (14 women; median [IQR] age 53.5 [13.8] years, BMI 29.3 [6.3] kg/m2, HbA1c 36.0 [6.2] mmol/mol [5.4% (0.6%)]) underwent a dual-tracer, frequently sampled, 300 min, 75 g OGTT for the diagnosis of PPHG (glucose nadir <3.0 mmol/l, or <3.3 mmol/l with symptoms). Plasma glucose, glucose tracers, insulin, C-peptide, glucagon-like peptide-1, gastric inhibitory polypeptide, glucagon, adrenaline (epinephrine), noradrenaline (norepinephrine), cortisol and NEFAs were measured. Mathematical models were implemented to estimate glucose metabolic fluxes and beta cell function. ECG recordings, cognitive testing and hypoglycaemia awareness assessments were repeated during the OGTT. Glycaemic levels and dietary habits were assessed under free-living conditions.

RESULTS

PPHG occurred in 12 (50%) participants, mostly without symptoms, due to excessive tracer-derived glucose clearance (mean group difference ± SE in AUC0-180 min +261±72 ml min-1 kg-1 × min) driven by higher whole-body insulin sensitivity and early glucose-stimulated hyperinsulinaemia, the latter depending on lower insulin clearance and enhanced beta cell function, regardless of incretin hormones. PPHG participants also had defective counterregulatory hormone responses to hypoglycaemia, preventing a physiological increase in endogenous glucose production and the appearance of symptoms and signs of sympathetic cardiovascular activation and neuroglycopenia. PPHG was associated with more frequent and prolonged hypoglycaemia on 14 day continuous glucose monitoring and alterations in free-living dietary habits.

CONCLUSIONS

Our results demonstrate that post-bypass PPHG occurs frequently in individuals with a history of type 2 diabetes, often without warning symptoms, and expose its complex pathogenetic mechanisms, revealing potential therapeutic targets.

Evaluation of Hypoglycemic Polyphenolic Compounds in Blueberry Extract: Functional Effects and Mechanisms

Blueberries are rich in polyphenols, which exhibit significant anti-diabetic activity. In this study, polyphenolic compounds with potential hypoglycemic activity were identified from blueberry polyphenol extract (BPE). This research focused on assessing the hypoglycemic effects of BPE and its polyphenolic compounds (dihydroquercetin and gallic acid) on diabetic mice induced by streptozotocin (STZ) and high-fat diet (HFD), as well as the related fundamental mechanisms. The findings revealed that BPE treatment effectively reduced levels of fasting blood glucose (FBG) by decreasing hepatic oxidative stress, regulating lipid metabolism disorders and improving insulin resistance. Investigations into the insulin signaling pathway revealed that BPE can modulate the expression of Egfr, Insr, Irs-1, Pi3k and Akt, thereby influencing glucose metabolism. This study provides a research foundation for considering blueberry polyphenols as a nutritional dietary supplement for the prevention and intervention of diabetes.

Andrographis paniculata improves glucose regulation by enhancing insulin sensitivity and upregulating GLUT 4 expression in Wistar rats

CONTEXT

Although the hypoglycaemic effect of Andrographis paniculata (Burm.f.) Nees [Acanthaceae] has been documented, reports on its effect in an apparently healthy state are limited.

OBJECTIVE

This study investigated whether or not A. paniculata exerts hypoglycaemic effect in a non-diabetic state. It also explored the impact of A. paniculata on glycolytic enzymes and GLUT 4 protein expression, as a possible mode of action.

METHODS

Twenty male Wistar rats were randomly assigned into two groups (n = 10 rats/group). The control rats were vehicle-treated (0.5 ml of distilled water), while the A. paniculata-treated rats had 500 mg/kg of A. paniculata per os once daily for 35 days.

RESULTS

A. paniculata treatment led to improved insulin sensitivity evidenced by increased HOMA-β (88.08 ± 2.13 vs. 120.80 ± 1.52, p < 0.0001), HOMA-S (283.60 ± 8.82 vs. 300.50 ± 9.30, p = 0.0189), and reduced TyG index (4.22 ± 0.04 vs. 3.95 ± 0.07, p < 0.0002) and HOMA-IR (0.32 ± 0.01 vs. 0.25 ± 0.01, p < 0.0001) when compared with the control. It also improved glucose regulation as depicted by reduced fasting blood glucose (3.77 ± 0.10 vs. 3.24 ± 0.11, p < 0.0001) and glycated hemoglobin (HbA1c; 7.69 ± 1.15 vs. 5.95 ± 0.82, p = 0.0245), and atherogenic dyslipidaemia, including AIP (-0.12 ± 0.03 vs. -0.26 ± 0.03, p < 0.0001) and CRI-I (2.70 ± 0.29 vs. 1.84 ± 0.27, p < 0.0001). These findings were accompanied by enhanced hepatic and muscular redox state, increased activities of glycolytic enzymes, upregulated GLUT 4 (0.80 ± 0.27 vs. 6.20 ± 0.84, p < 0.0001), and increased circulating nitric oxide (5.45 ± 0.24 vs. 6.79 ± 0.33, p = 0.0002).

CONCLUSION

A. paniculata exerts positive effect on glucose metabolism and utilization by improving insulin sensitivity and upregulating the activities of glycolytic enzymes and GLUT 4 protein expression. This implies that A. paniculata may be beneficial in preventing insulin resistance and incident diabetes. Nonetheless, it should be used with caution to prevent hypoglycaemia in a non-diabetic state.

The relationship between remnant cholesterol and the risk of testosterone deficiency in US adults: a cross-sectional study based on the NHANES database

Background

Testosterone deficiency (TD) is an urgent health issue that requires attention, associated with various adverse health outcomes including cardiovascular diseases (CVD) and metabolic syndrome. Remnant cholesterol (RC) has emerged as a potential biomarker for cardiovascular risk, but its relationship with testosterone levels and TD has not been thoroughly investigated. This study aims to explore the association between RC and TD in adult American males using data from the National Health and Nutrition Examination Survey (NHANES).

Methods

This cross-sectional study utilized data from three NHANES cycles (2011-2016), including 2,848 adult male participants. RC was calculated as total cholesterol minus high-density lipoprotein cholesterol (HDL) and low-density lipoprotein cholesterol (LDL). TD was defined as total testosterone levels below 300 ng/dL. Multivariable linear and logistic regression analyses, as well as smooth curve fitting and generalized additive models, were performed to assess the associations between RC and total testosterone levels and TD, adjusting for potential confounders. Subgroup analyses were conducted based on age, BMI, smoking status, diabetes, hypertension, CVD, and chronic kidney disease (CKD).

Results

Higher RC levels were significantly associated with lower total testosterone levels (β = -53.87, 95% CI: -77.69 to -30.06, p<0.001) and an increased risk of TD (OR = 1.85, 95% CI: 1.29 to 2.66, p=0.002) in fully adjusted models. When RC was analyzed as quartiles, participants in the highest quartile (Q4) had significantly lower total testosterone levels (β = -62.19, 95% CI: -93.62 to -30.76, p<0.001) and higher odds of TD (OR = 2.15, 95% CI: 1.21 to 3.84, p=0.01) compared to those in the lowest quartile (Q1). Subgroup analyses revealed consistent associations across different age groups, particularly strong in participants over 60 years, and in never smokers. The associations remained significant in both hypertensive and non-hypertensive groups, as well as in those with and without CKD. No significant interactions were found across subgroups.

Conclusion

This study demonstrates a significant inverse association between RC levels and total testosterone levels, along with a positive association with the risk of TD. These findings suggest that RC could serve as a valuable biomarker for early identification of individuals at risk for TD. Future longitudinal studies are needed to confirm these findings and explore the underlying mechanisms.

Lipid profile alterations and biomarker identification in type 1 diabetes mellitus patients under glycemic control

BACKGROUND

Type 1 diabetes mellitus (T1DM) is well-known to trigger a disruption of lipid metabolism. This study aimed to compare lipid profile changes in T1DM patients after achieving glucose control and explore the underlying mechanisms. In addition, we seek to identify novel lipid biomarkers associated with T1DM under conditions of glycemic control.

METHODS

A total of 27 adults with T1DM (age: 34.3 ± 11.2 yrs) who had maintained glucose control for over a year, and 24 healthy controls (age: 35.1 + 5.56 yrs) were recruited. Clinical characteristics of all participants were analyzed and plasma samples were collected for untargeted lipidomic analysis using mass spectrometry.

RESULTS

We identified 594 lipid species from 13 major classes. Differential analysis of plasma lipid profiles revealed a general decline in lipid levels in T1DM patients with controlled glycemic levels, including a notable decrease in triglycerides (TAGs) and diglycerides (DAGs). Moreover, these T1DM patients exhibited lower levels of six phosphatidylcholines (PCs) and three phosphatidylethanolamines (PEs). Random forest analysis determined DAG(14:0/20:0) and PC(18:0/20:3) to be the most prominent plasma markers of T1DM under glycemic control (AUC = 0.966).

CONCLUSIONS

The levels of all metabolites from the 13 lipid classes were changed in T1DM patients under glycemic control, with TAGs, DAGs, PCs, PEs, and FFAs demonstrating the most significant decrease. This research identified DAG(14:0/20:0) and PC(18:0/20:3) as effective plasma biomarkers in T1DM patients with controled glycemic levels.

Insulin resistance potentiates the effect of remnant cholesterol on cardiovascular mortality in individuals without diabetes

BACKGROUND AND AIMS

Remnant cholesterol (RC) and insulin resistance (IR) have been independently associated with cardiovascular risk. Here, we evaluated the role of IR and RC on cardiovascular disease (CVD) mortality.

METHODS

We conducted an analysis of 16,113 individuals ≥20 years without diabetes from the National Health and Nutrition Examination Survey (NHANES-III/IV). RC levels were calculated using total cholesterol, non-HDL-c, and LDL-c; IR was defined as HOMA2-IR≥2.5 and CVD mortality as a composite of cardiovascular and cerebrovascular mortality. Multiple linear regression was used to assess the relationship between HOMA2-IR and RC and Cox regression models to assess their joint role in CVD mortality. Causally ordered mediation models were used to explore the mediating role of IR in RC-associated CVD mortality.

RESULTS

We identified an association between higher HOMA2-IR and higher RC levels. The effect of IR on CVD mortality was predominant (HR 1.32, 95%CI 1.18-1.48) and decreased at older ages (HR 0.934, 95%CI 0.918-0.959) compared to RC (HR 0.983, 95%CI 0.952-1.014). Higher risk of CVD mortality was observed in individuals with IR but normal RC (HR 1.37, 95%CI 1.25-1.50) and subjects with IR and high RC (HR 1.24, 95%CI 1.13-1.37), but not in subjects without IR but high RC. In mediation models, HOMA2-IR accounted for 78.2% (95%CI 28.11-98.89) of the effect of RC levels on CVD mortality.

CONCLUSIONS

Our findings suggest that RC potentiates the risk of CVD mortality through its effect on whole-body insulin sensitivity, particularly among younger individuals.

Impact of Lipids on Insulin Resistance: Insights from Human and Animal Studies

Insulin resistance (IR) is a complex pathological condition central to metabolic diseases such as type 2 diabetes mellitus (T2DM), cardiovascular disease, non-alcoholic fatty liver disease, and polycystic ovary syndrome (PCOS). This review evaluates the impact of lipids on insulin resistance (IR) by analyzing findings from human and animal studies. The articles were searched on the PubMed database using two keywords: (1) "Role of Lipids AND Insulin Resistance AND Humans" and (2) "Role of Lipids AND Insulin Resistance AND Animal Models". Studies in humans revealed that elevated levels of free fatty acids (FFAs) and triglycerides (TGs) are closely associated with reduced insulin sensitivity, and interventions like metformin and omega-3 fatty acids show potential benefits. In animal models, high-fat diets disrupt insulin signaling and increase inflammation, with lipid mediators such as diacylglycerol (DAG) and ceramides playing significant roles. DAG activates protein kinase C, which eventually impairs insulin signaling, while ceramides inhibit Akt/PKB, further contributing to IR. Understanding these mechanisms is crucial for developing effective prevention and treatment strategies for IR-related diseases.

Proprotein convertase subtilisin/kexin type 9 deficiency in extrahepatic tissues: emerging considerations

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is primarily secreted by hepatocytes. PCSK9 is critical in liver low-density lipoprotein receptors (LDLRs) metabolism. In addition to its hepatocellular presence, PCSK9 has also been detected in cardiac, cerebral, islet, renal, adipose, and other tissues. Once perceived primarily as a "harmful factor," PCSK9 has been a focal point for the targeted inhibition of both systemic circulation and localized tissues to treat diseases. However, PCSK9 also contributes to the maintenance of normal physiological functions in numerous extrahepatic tissues, encompassing both LDLR-dependent and -independent pathways. Consequently, PCSK9 deficiency may harm extrahepatic tissues in close association with several pathophysiological processes, such as lipid accumulation, mitochondrial impairment, insulin resistance, and abnormal neural differentiation. This review encapsulates the beneficial effects of PCSK9 on the physiological processes and potential disorders arising from PCSK9 deficiency in extrahepatic tissues. This review also provides a comprehensive analysis of the disparities between experimental and clinical research findings regarding the potential harm associated with PCSK9 deficiency. The aim is to improve the current understanding of the diverse effects of PCSK9 inhibition.

Proteomic predictors of individualized nutrient-specific insulin secretion in health and disease

Population-level variation and mechanisms behind insulin secretion in response to carbohydrate, protein, and fat remain uncharacterized. We defined prototypical insulin secretion responses to three macronutrients in islets from 140 cadaveric donors, including those with type 2 diabetes. The majority of donors' islets exhibited the highest insulin response to glucose, moderate response to amino acid, and minimal response to fatty acid. However, 9% of donors' islets had amino acid responses, and 8% had fatty acid responses that were larger than their glucose-stimulated insulin responses. We leveraged this heterogeneity and used multi-omics to identify molecular correlates of nutrient responsiveness, as well as proteins and mRNAs altered in type 2 diabetes. We also examined nutrient-stimulated insulin release from stem cell-derived islets and observed responsiveness to fat but not carbohydrate or protein-potentially a hallmark of immaturity. Understanding the diversity of insulin responses to carbohydrate, protein, and fat lays the groundwork for personalized nutrition.

Alterations in Adipose Tissue Distribution, Cell Morphology, and Function Mark Primary Insulin Hypersecretion in Youth With Obesity

Excessive insulin secretion independent of insulin resistance, defined as primary hypersecretion, is associated with obesity and an unfavorable metabolic phenotype. We examined the characteristics of adipose tissue of youth with primary insulin hypersecretion and the longitudinal metabolic alterations influenced by the complex adipo-insular interplay. In a multiethnic cohort of adolescents with obesity but without diabetes, primary insulin hypersecretors had enhanced model-derived β-cell glucose sensitivity and rate sensitivity but worse glucose tolerance, despite similar demographics, adiposity, and insulin resistance measured by both oral glucose tolerance test and euglycemic-hyperinsulinemic clamp. Hypersecretors had greater intrahepatic and visceral fat depots at abdominal MRI, hypertrophic abdominal subcutaneous adipocytes, higher free fatty acid and leptin serum levels per fat mass, and faster in vivo lipid turnover assessed by a long-term 2H2O labeling protocol. At 2-year follow-up, hypersecretors had greater fat accrual and a threefold higher risk for abnormal glucose tolerance, while individuals with hypertrophic adipocytes or higher leptin levels showed enhanced β-cell glucose sensitivity. Primary insulin hypersecretion is associated with marked alterations in adipose tissue distribution, cellularity, and lipid dynamics, independent of whole-body adiposity and insulin resistance. Pathogenetic insight into the metabolic crosstalk between β-cell and adipocyte may help to identify individuals at risk for chronic hyperinsulinemia, body weight gain, and glucose intolerance.

ARTICLE HIGHLIGHTS

Proteomic predictors of individualized nutrient-specific insulin secretion in health and disease

Population level variation and molecular mechanisms behind insulin secretion in response to carbohydrate, protein, and fat remain uncharacterized despite ramifications for personalized nutrition. Here, we define prototypical insulin secretion dynamics in response to the three macronutrients in islets from 140 cadaveric donors, including those diagnosed with type 2 diabetes. While islets from the majority of donors exhibited the expected relative response magnitudes, with glucose being highest, amino acid moderate, and fatty acid small, 9% of islets stimulated with amino acid and 8% of islets stimulated with fatty acids had larger responses compared with high glucose. We leveraged this insulin response heterogeneity and used transcriptomics and proteomics to identify molecular correlates of specific nutrient responsiveness, as well as those proteins and mRNAs altered in type 2 diabetes. We also examine nutrient-responsiveness in stem cell-derived islet clusters and observe that they have dysregulated fuel sensitivity, which is a hallmark of functionally immature cells. Our study now represents the first comparison of dynamic responses to nutrients and multi-omics analysis in human insulin secreting cells. Responses of different people's islets to carbohydrate, protein, and fat lay the groundwork for personalized nutrition.

ONE-SENTENCE SUMMARY

Deep phenotyping and multi-omics reveal individualized nutrient-specific insulin secretion propensity.

Early time-restricted carbohydrate consumption vs conventional dieting in type 2 diabetes: a randomised controlled trial

AIMS/HYPOTHESIS

Early time-restricted carbohydrate consumption (eTRC) is a novel dietary strategy that involves restricting carbohydrate-rich food intake to the morning and early afternoon to align with circadian variations in glucose tolerance. We examined the efficacy, feasibility and safety of eTRC in individuals with type 2 diabetes under free-living conditions.

METHODS

In this randomised, parallel-arm, open label, controlled trial, participants with type 2 diabetes and overweight/obesity (age 67.2±7.9 years, 47.8% women, BMI 29.4±3.7 kg/m2, HbA1c 49±5 mmol/mol [6.6±0.5%]) were randomised, using computer-generated random numbers, to a 12 week eTRC diet or a Mediterranean-style control diet with matched energy restriction and macronutrient distribution (50% carbohydrate, 30% fat and 20% protein). The primary outcome was the between-group difference in HbA1c at 12 weeks. Body composition, 14 day flash glucose monitoring and food diary analysis were performed every 4 weeks. Mixed meal tolerance tests with mathematical beta cell function modelling were performed at baseline and after 12 weeks.

RESULTS

Twelve (85.7%) participants in the eTRC arm and 11 (84.6%) participants in the control arm completed the study, achieving similar reductions in body weight and fat mass. The two groups experienced comparable improvements in HbA1c (-3 [-6, -0.3] mmol/mol vs -4 [-6, -2] mmol/mol, corresponding to -0.2 [-0.5, 0]% and -0.3 [-0.5, -0.1]%, respectively, p=0.386), fasting plasma glucose, flash glucose monitoring-derived glucose variability and mixed meal tolerance test-derived glucose tolerance, insulin resistance, insulin clearance and plasma glucagon levels, without changes in model-derived beta cell function parameters, glucagon-like peptide-1, glucose-dependent insulinotropic polypeptide and non-esterified fatty acid levels. The two diets similarly reduced liver function markers and triglyceride levels, being neutral on other cardiometabolic and safety variables. In exploratory analyses, diet-induced changes in body weight and glucometabolic variables were not related to the timing of carbohydrate intake.

CONCLUSIONS/INTERPRETATION

The proposed eTRC diet provides a feasible and effective alternative option for glucose and body weight management in individuals with type 2 diabetes, with no additional metabolic benefits compared with conventional dieting.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05713058 FUNDING: This study was supported by the European Society for Clinical Nutrition and Metabolism (ESPEN) and the Italian Society of Diabetology (SID).

Postprandial Triglyceride, Glucose and Insulin Levels 10 Years After Bariatric Surgery in Women With Severe Obesity - A Pilot Study: Part 1 - Laparoscopic Greater Curvature Plication

The long-term effects of bariatric surgery on postprandial profiles in patients with obesity and type 2 diabetes (T2D) have not yet been investigated. Therefore, this study examined postprandial profiles before laparoscopic greater curvature plication (LGCP), and then at 2 and 10 years after surgery.The studied cohort included 10 women (mean age= 54.4±5 years) with obesity (mean BMI= 42.5±7.8 kg/m?) and T2D who underwent LGCP. All subjects underwent a standardized liquid mixed-meal test. For statistical evaluation, ANOVA with Bonferroni multiple comparison was used. Mean postprandial levels were significantly decreased 2 years after surgery. Responses 10 years after the surgery also remained significantly lower than before surgery. Changes observed during the follow-up were significant: glucose: F=34.5, p<0.001; insulin: F=49.3, p<0.001; triglycerides F=9.2, p<0.001. The long-term favorable effects of bariatric surgery on cardiometabolic health may be partly mediated by reductions in postprandial glucose, insulin, and triglyceride levels.

Interaction between the GCKR rs1260326 variant and serum HDL cholesterol contributes to HOMA-β and ISIMatusda in the middle-aged T2D individuals

This study aims to investigate the correlations between islet function/ insulin resistance and serum lipid levels, as well as to assess whether the strength of such correlations is affected by the GCKR rs1260326 variant in healthy and T2D individuals. We performed an oral glucose tolerance test (OGTT) on 4889 middle-aged adults, including 3135 healthy and 1754 T2D individuals from the REACTION population study in the Nanjing region. We also measured their serum lipid levels and genotyped for rs1260326. We found that serum high-density lipoprotein (HDL) cholesterol and triglyceride (TG) levels were independently correlated with indexes of islet function (HOMA-β and IGI [insulinogenic index]) and insulin resistance (HOMO-IR and ISIMatsuda) in both healthy and T2D individuals. The correlations were significantly decreased in T2D individuals, with significant heterogeneities compared to healthy controls (I2 > 75%, Phet < 0.05). Although no correlation was observed between serum total cholesterol (TC) level and islet function/ insulin resistance in healthy controls, significant correlations were found in T2D individuals, with significant heterogeneity to healthy controls in the correlation with ISIMatsuda(I2 = 85.3%, Phet = 0.009). Furthermore, we found significant interactions of the GCKR rs1260326 variant for the correlations between serum HDL cholesterol and HOMA-β/ISIMatsuda in T2D subjects (P = 0.015 and 0.038, respectively). These findings illustrate that distinct correlations between serum lipid levels and islet function/ insulin resistance occurred in T2D subjects compared to healthy individuals. Common gene variants, such as rs1260326, might interact substantially when studied in specific populations, especially T2D disease status.

Association of lipoprotein subfractions with incidence of type 2 diabetes among five U.S. Race and Ethnic groups: The Mediators of Atherosclerosis in South Asians Living in America (MASALA) and Multi-Ethnic study of Atherosclerosis (MESA)

AIMS

We examined associations between lipoprotein subfractions and prevalent and incident T2D in two race/ethnically diverse cohort studies.

METHODS

Adults self-identifying as White, Black, Chinese, Hispanic and South Asian-American without cardiovascular disease, with fasting serum, demographic, and clinical data at enrollment and after 5 years of follow-up were included. Lipoprotein subfractions were measured at enrollment using NMR spectrometry. LASSO regularized logistic regression models adjusted for age, sex, race/ethnicity, lipid-lowering agent use, and waist circumference assessed odds of incident T2D in pooled analyses.

RESULTS

There were 4474 participants with lipoprotein subfraction data at enrollment and 3839 participants without prevalent diabetes, mean age 62 years, 51 % women, with 234 incident T2D cases at 5 years. Triglycerides in small, dense LDL-5 [OR 1.26 (95 % CI 1.11,1.43)], VLDL triglycerides 1.30** [1.16,1.46] and phospholipids in VLDL-1 [OR 1.31 (1.17,1.47)] were associated with higher odds of incident T2D, while free cholesterol in large HDL-1 [OR 0.75 (95 % CI 0.63,0.89)] was inversely associated. The results were similar for prevalent diabetes and did not vary by race/ethnic group.

CONCLUSIONS

Composition of lipoprotein subfractions is differentially associated with prevalent and incident T2D without difference by race/ethnic group. Assessment of lipoprotein composition may enhance targeted risk reduction for T2D.

Atherosclerosis indexes and incident T2DM in middle-aged and older adults: evidence from a cohort study

BACKGROUND

Type 2 diabetes mellitus (T2DM) is an expanding global health problem, requiring effective methods for predicting and diagnosing in its early stages of development. Previous studies reported the prognostic value of the atherosclerosis indexes in both cardiovascular diseases and T2DM. However, the predictive performance of Non-HDL-C, AI, AIP, TG/HDL-C and LCI indexes on the risk of T2DM remains unclear. This study aims to compare the five atherosclerosis indexes for predicting T2DM in middle-aged and elderly Chinese.

METHODS

Data are collected from wave 2011 and wave 2015 of China Health and Retirement Longitudinal Study (CHARLS). Multi-variate logistic regression models were used to estimate odds ratio (OR) with 95% confidence interval (CI) of incident T2DM with five atherosclerosis indexes, and the restricted cubic splines were used to visualize the dose-response relationships. Receiver operating characteristic (ROC) curve was drawn and the areas under the curve (AUC) were used to compare the performance of the five atherosclerosis indexes in predicting T2DM.

RESULTS

A total of 504 (10.97%) participants had T2DM. Multi-variate logistic regression analysis showed that five atherosclerosis indexes were associated with T2DM, with adjusted ORs (95% CIs) of 1.29 (1.15-1.45), 1.29 (1.18-1.42), 1.45 (1.29-1.62), 1.41 (1.25-1.59) and 1.34 (1.23-1.48) for each IQR increment in Non-HDL-C, TG/HDLC, AI, AIP and LCI, respectively. Restricted cubic spline regression showed a nonlinear correlation between five atherosclerosis indexes and the risk of T2DM (p for nonlinear < 0.001). According to the ROC curve analysis, LCI had the highest AUC (0.587 [0.574-0.600]).

CONCLUSION

We found that LCI, compared with other indexes, was a better predictor in the clinical setting for identifying individuals with T2DM in middle-aged and elderly Chinese. LCI monitoring might help in the early identification of individuals at high risk of T2DM.