β-Cell dysfunction is associated with metabolic syndrome severity in adults

β-Aminoisobutyric Acid Relates to Favorable Glucose Metabolism through Adiponectin in Adults with Obesity Independent of Prediabetes

β-Aminoisobutyric acid (BAIBA) is secreted by skeletal muscle and promotes insulin sensitivity, fat oxidation, and anti-inflammation. While BAIBA is purportedly lower in individuals with obesity, no work has examined if prediabetes (PD) differentially impacts BAIBA concentrations in people with obesity. Methods. Adults were classified as normal glucose tolerant (NGT; n = 22 (20F); 48.0 ± 2.4 yrs; 36.9 ± 1.2 kg/m2) or PD (n = 23 (18F); 54.2 ± 1.6 yrs; 38.4 ± 1.2 kg/m2) based on ADA criteria. A 180-minute 75 g OGTT was used to estimate fasting (HOMA-IR (liver)) and postprandial (Matsuda index (muscle)) insulin sensitivity as well as β-cell function (disposition index (DI), glucose-stimulated insulin secretion adjusted for insulin sensitivity). Body composition and fasting measures of BAIBA, fat oxidation (indirect calorimetry), and adipokines were determined. Results. NGT and PD had similar BAIBA concentrations (1.4 ± 0.1 vs. 1.2 ± 0.1 μM, P = 0.23) and fat oxidation (P = 0.31), despite NGT having lower fasting (92.2 ± 1.2 vs. 104.1 ± 3.2 mg/dL, P = 0.002) and tAUC180min glucose (P < 0.001) compared to PD. Moreover, NGT had higher postprandial insulin sensitivity (P = 0.01) and higher total phase DIliver (P = 0.003) and DImuscle (P = 0.001). Increased BAIBA was associated with adiponectin (r = 0.37, P = 0.02), adiponectin/leptin ratio (r = 0.39, P = 0.01), and lower glucose and insulin at 180 minutes (r = -0.31, P = 0.03 and r = -0.39, P = 0.03, respectively). Adiponectin also correlated with lower glucose at 180 minutes (r = -0.45, P = 0.005), and mediation analysis showed that BAIBA was no longer a significant predictor of glucose at 180 minutes after controlling for adiponectin (P = 0.08). Conclusion. While BAIBA did not differ between NGT and PD, higher BAIBA is related to favorable glucose metabolism, possibly through an adiponectin-related mechanism. Additional work is required to understand how exercise and/or diet impact BAIBA in relation to type 2 diabetes risk.

The Values and Perspectives of Organoids in the Field of Metabolic Syndrome

Metabolic syndrome (MetS) has become a global health problem, and the prevalence of obesity at all stages of life makes MetS research increasingly important and urgent. However, as a comprehensive and complex disease, MetS has lacked more appropriate research models. The advent of organoids provides an opportunity to address this issue. However, it should be noted that organoids are still in their infancy. The main drawbacks are a lack of maturity, complexity, and the inability to standardize large-scale production. Could organoids therefore be a better choice for studying MetS than other models? How can these limitations be overcome? Here, we summarize the available data to present current progress on pancreatic and hepatobiliary organoids and to answer these open questions. Organoids are of human origin and contain a variety of human cell types necessary to mimic the disease characteristics of MetS in their development. Taken together with the discovery of hepatobiliary progenitors in situ, the dedifferentiation of beta cells in diabetes, and studies on hepatic macrophages, we suggest that promoting endogenous regeneration has the potential to prevent the development of end-stage liver and pancreatic lesions caused by MetS and outline the direction of future research in this field.

Relationship and Effects of Vitamin D on Metabolic Syndrome: A Systematic Review

Metabolic syndrome (MetS) is a persistent public health problem in the United States (U.S.) due to its increasing prevalence and its positive correlation with type-2 diabetes (T2DM) and cardiovascular disease (CVD). According to National Cholesterol Education Program's Adult Treatment Panel III (NCEP-ATP III) criteria, MetS has six main components, which are obesity, dyslipidemia, raised blood pressure (BP), insulin resistance (IR) or glucose intolerance, pro-inflammatory state, and prothrombotic state. Vitamin D (Vit D) regulates the absorption of calcium and phosphorus and thus, is universally accepted as an essential vitamin for bone strength as well as a facilitator of immune system function. Vit D was also shown to reduce the risks of CVD, multiple sclerosis, and developing seasonal flu. We conducted a systematic review to identify the general association between Vit D level and MetS, to highlight specific associations between Vit D level and individual components of MetS, and finally, to explore the effects of Vit D supplementation on each component of MetS. In this paper, we reviewed 14 recent studies investigating the relationships between Vit D, MetS, and components of MetS. From the review of seven studies, we confirmed a significant association between Vit D and MetS as a whole. Four out of the five observational studies we reviewed support that Vit D level is significantly associated with the following components of MetS: obesity and BMI, dyslipidemia, BP, and insulin and glucose metabolism. We did not discover any significant relationship between Vit D level and other MetS components. The review of seven additional randomized clinical trials (RCT)-based studies suggest that Vit D supplementation has significant effects on BP, abdominal obesity, and insulin and glucose metabolism.

Insulin stimulation reduces aortic wave reflection in adults with metabolic syndrome

Adults with metabolic syndrome (MetS) have increased fasting arterial stiffness and altered central hemodynamics that contribute, partly, to increased cardiovascular disease (CVD) risk. Although insulin affects aortic wave reflections in healthy adults, the effects in individuals with MetS are unclear. We hypothesized that insulin stimulation would reduce measures of pressure waveforms and hemodynamics in people with MetS. Thirty-five adults with obesity (27 women; 54.2 ± 6.0 yr; 37.1 ± 4.8 kg/m²) were selected for MetS (ATP III criteria) following an overnight fast. Pulse wave analysis was assessed using applanation tonometry before and after a 2-h euglycemic-hyperinsulinemic clamp (90 mg/dL, 40 mU/m²/min). Deconvolution analysis was used to decompose the aortic waveform [augmentation index corrected to heart rate of 75 beats/min (AIx@75); augmentation pressure (AP)] into backward and forward pressure components. Aerobic fitness (V̇o_2max), body composition (DXA), and blood biochemistries were also assessed. Insulin significantly reduced augmentation index (AIx@75, 28.0 ± 9.6 vs. 23.0 ± 9.9%, P < 0.01), augmentation pressure (14.8 ± 6.4 vs. 12.0 ± 5.7 mmHg, P < 0.01), pulse pressure amplification (1.26 ± 0.01 vs. 0.03 ± 0.01, P = 0.01), and inflammation [high-sensitivity C-reactive protein (hsCRP): P = 0.02; matrix metallopeptidase 7 (MMP-7): P = 0.03] compared to fasting. In subgroup analyses to understand HTN influence, there were no insulin stimulation differences on any outcome. V̇o_2max, visceral fat, and blood potassium correlated with fasting AIx@75 (r = -0.39, P = 0.02; r = 0.41, P = 0.03; r = -0.53, P = 0.002). Potassium levels were also associated with insulin-mediated reductions in AP (r = 0.52, P = 0.002). Our results suggest insulin stimulation improves indices of aortic reflection in adults with MetS.NEW & NOTEWORTHY This study is one of the first to investigate the effects of insulin on central and peripheral hemodynamics in adults with metabolic syndrome. We provide evidence that insulin infusion reduces aortic wave reflection, potentially through a reduction in inflammation and/or via a potassium-mediated vascular response.

Cannabinoid receptors are differentially regulated in the pancreatic islets during the early development of metabolic syndrome

The endocannabinoid system is found in tissues that regulate the glycemia, including adipose tissue, muscle, and pancreatic islets. Diet-induced metabolic syndrome changes the expression of the CB receptors in muscle, adipose tissue, and liver. However, it is poorly understood whether metabolic syndrome (MetS) affects the expression of CB receptors in pancreatic β cells. We analyzed the expression of CB receptors in pancreatic β cells under chronic high-sucrose diet (HSD)-induced MetS. Wistar rats fed an HSD as a model of MetS were used to investigate changes in cannabinoid receptors. After 8 weeks of treatment, we evaluated the appearance of the following MetS biomarkers: glucose intolerance, hyperinsulinemia, insulin resistance, hypertriglyceridemia, and an increase in visceral adiposity. To determine the presence of CB1 and CB2 receptors in pancreatic β cells, immunofluorescence of primary cell cultures and pancreatic sections was performed. For whole-islet quantification of membrane-bound CB1 and CB2 receptors, western-blotting following differential centrifugation was conducted. Our results revealed that an HSD treatment closely mimics the alterations seen in MetS. We observed that in primary cell culture, CB1 and CB2 receptors were expressed at a higher level in pancreatic β cells compared with non-β cells. MetS resulted in a reduction of CB1 in the islet, whereas abundant CB2 was observed after the treatment. CB1 and CB2 receptors are differentially expressed in pancreatic β cells during MetS development.

Bioactive Properties of Marine Phenolics

Phenolic compounds from marine organisms are far less studied than those from terrestrial sources since their structural diversity and variability require powerful analytical tools. However, both their biological relevance and potential properties make them an attractive group deserving increasing scientific interest. The use of efficient extraction and, in some cases, purification techniques can provide novel bioactives useful for food, nutraceutical, cosmeceutical and pharmaceutical applications. The bioactivity of marine phenolics is the consequence of their enzyme inhibitory effect and antimicrobial, antiviral, anticancer, antidiabetic, antioxidant, or anti-inflammatory activities. This review presents a survey of the major types of phenolic compounds found in marine sources, as well as their reputed effect in relation to the occurrence of dietary and lifestyle-related diseases, notably type 2 diabetes mellitus, obesity, metabolic syndrome, cancer and Alzheimer's disease. In addition, the influence of marine phenolics on gut microbiota and other pathologies is also addressed.

Exercise improves adiposopathy, insulin sensitivity and metabolic syndrome severity independent of intensity

NEW FINDINGS

What is the central question of this study? What are the effects of work-matched continuous versus high-intensity interval training for 2 weeks on adiposopathy and cardiometabolic risk in obese adults with prediabetes? What is the main finding and its importance? Independent of intensity, short-term exercise improves adiposopathy and insulin sensitivity. While both exercise intensities reduced fasting leptin concentrations and metabolic syndrome severity, only interval training elevated total adiponectin. In contrast to previous work, neither condition altered high-molecular weight adiponectin. Collectively, these data suggest that short-term exercise can improve adipokine profiles, which may aid in reducing cardiometabolic risk prior to clinically meaningful weight loss in adults with prediabetes.

ABSTRACT

Individuals with prediabetes who are overweight and obese are at an increased risk of developing endocrine disruption of fat tissue, known as adiposopathy. While short-term exercise improves adipokine profiles, the effects of exercise intensity when matched for energy expenditure on adiposopathy are unknown. We hypothesized that high-intensity exercise would elicit greater changes in adiposopathy compared to moderate exercise. Twenty-eight overweight and obese adults (age: 60.9 ± 8.4 years; BMI: 33.0 ± 5.4 kg m-2 ) with prediabetes were randomized to twelve 60-min sessions of either moderate-continuous (CONT; n = 14) or high-intensity interval (INT; n = 14) exercise training. Total and high molecular weight (HMW) adiponectin and leptin were collected to assess adiposopathy (ratio of total adiponectin to leptin; A/L). Insulin sensitivity (SIIS ) was determined using a 75 g oral glucose tolerance test before and after training. Cardiometabolic risk factors were measured and a z-score was calculated to determine metabolic syndrome (MetS) severity. CONT and INT increased A/L (P < 0.01) and decreased leptin (P < 0.01) and MetS severity (P = 0.04). Neither intervention altered circulating levels of HMW adiponectin (P = 0.76) and only INT increased total adiponectin levels (P = 0.02). Both intensities increased insulin sensitivity (P < 0.01), which was associated with improvements in A/L (r = 0.47, P = 0.01). Additionally, increases in A/L tended to relate to decreased MetS severity (r = -0.36, P = 0.09). Short-term exercise intensity, when matched for energy expenditure, does not differentially affect improvements in adiposopathy in overweight and obese adults with prediabetes. Further, 12 bouts of exercise improved insulin sensitivity and MetS severity, suggesting that improving adipokine profiles may aid in reducing cardiometabolic risk.

The Metabolic Syndrome: Emerging Novel Insights Regarding the Relationship between the Homeostasis Model Assessment of Insulin Resistance and other Key Predictive Markers in Young Adults of Western Algeria

Several biological markers have been identified as risk factors for cardiovascular disease and are associated with increased risk of metabolic syndrome (MetS). This study provides a factual information on promising biomarkers that are associated with MetS and can aid in early detection and management of MetS in young adults of Western Algeria. We studied a total of one hundred subjects aged between thirty and forty years with MetS, in which anthropometric measurements, insulin resistance, C peptide and HbA1c, lipid profile, circulating adipokines and glucagon-like peptide-1 were measured by suitable methods, in comparison to two groups of control. MetS is closely linked to altered glucose homeostasis, the plasma insulin/glucose ratio; i.e., the insulinogenic index helps to estimate the level of insulin secretion and also for assessing β-cell function. The correlation between homeostasis model assessment insulin resistance index (HOMA-IR) and HbA1c, body mass index or plasma triglycerides yielded positive and significant values. Biomarkers with a known and predictable association with MetS can provide a means to detect those at risk and intervene as needed. This could significantly decrease the burden complications impose on patients and the healthcare system.

Effect of Different Volumes of Interval Training and Continuous Exercise on Interleukin-22 in Adults with Metabolic Syndrome: A Randomized Trial

INTRODUCTION

IL-22 may have a role in the alleviation of the metabolic syndrome (MetS) via protection of pancreatic beta and endothelial cells from oxidative and lipid-induced damage. We aimed to investigate the effects of moderate-intensity continuous training (MICT) and different volumes of high-intensity interval training (HIIT) on changes in circulating IL-22.

METHODS

This was a sub-study of the "Exercise in the prevention of Metabolic Syndrome" (EX-MET) a multi-center, randomized trial. This study used data collected at the Brisbane site. Thirty-nine individuals with MetS were randomized to one of three 16-wk interventions: 1) MICT (n=10, 30min at 60-70% HR peak, 5x/wk); 2) 4HIIT (n=13, 4x4min at 85-95% HR peak, interspersed with 3min of active recovery at 50-70% HR peak, 3x/wk); or 3) 1HIIT (n=16, 1x4min at 85-95% HR peak, 3x/wk). Serum IL-22 concentration was measured following a 12-hr fast via an enzyme linked immunosorbent assay, before and after the intervention. MetS severity, insulin resistance (IR), visceral adipose tissue (VAT), and cardiorespiratory fitness (CRF) were also measured via MetS z-score, HOMA-IR, dual-energy X-ray absorptiometry, and indirect calorimetry (maximal exercise test), respectively.

RESULTS

The median (IQR) IL-22% changes from pre- to post-intervention in the MICT, 4HIIT, and 1HIIT groups were -17% (-43.0% to 31.3%), +16.5% (-18.9% to 154.9%), and +15.9% (-28.7% to 46.1%), respectively. Although there were no significant between-group differences in IL-22 concentration change, there was a medium-to-large group × time interaction effect [F(2,35)=2.08, p=0.14, η²=0.14].

CONCLUSION

Although there was no statistically significant between-group difference in IL-22 change, the study suggests that different exercise intensities may have opposing effects on IL-22 concentration in individuals with MetS.

β-Cell function in obese children and adolescents with metabolic syndrome compared to isolated obesity

OBJECTIVE

To evaluate β-cell function in obese children and adolescents meeting clinical criteria for isolated obesity (iOB), isolated components of dysmetabolism (cMD), or metabolic syndrome (MS), and in obese children and adolescents with normal glucose tolerance (NGT), impaired glucose regulation (IGR), or type 2 diabetes (T2DM).

STUDY DESIGN

We undertook a prospective study of Han Chinese children and adolescents aged 8-16 years (median 11 ± 1.4) seen in an obesity clinic between May 2013 and 2018. Patients were classified as iOB (53), cMD (139), and MS (139) groups based on clinical criteria. The same patients were also classified as NGT (212), IGR (111), or T2DM (8) based on results of an oral glucose tolerance test (OGTT). The MS patients were classified as NGT [MS](59) and IGR [MS](72) for the further study. All participants also completed a mixed-meal tolerance test (MMTT).

RESULTS

Compared with the iOB group, the MS group had significantly higher area under the curve of C-peptide up to the 2 hours (AUC CP) (P = .03) and peak C-peptide (P = .03), adjusted for BMI, age and Tanner stage, on MMTT. However, there was no difference in the insulinogenic index (ΔI30/ΔG30) or oral disposition index (oDI) derived from the OGTT among the three groups. However, 52% of participants with MS had IGR, compared to 28% in the cMD group. Compared with the NGT group, the individuals with IGR had significantly lower ΔI30/ΔG30 (P = .001) and oDI (P < .001). Compared with the iOB group, the NGT[MS] had significantly higher AUC CP (P = .004), peak C-peptide (P = .004) and ΔI30/ΔG30 (P = .007) adjusted for age, but no difference in oDI. Compared with the NGT[MS], the IGR[MS] had significantly lower ΔI30/ΔG30 (P = .005) and oDI (P < .001), but the AUC CP and peak C-peptide had no difference.

CONCLUSION

Although the MS youth have β-cell hyperfunction as a whole, β-cell dysfunction is present in the early stages of dysmetabolism in obese youth with cMD or MS and worsened across the spectrum from iOB to cMD and MS, contributing to development of T2DM.

The relationship between pulse pressure, insulin resistance, and beta cell function in non-diabetic Korean adults

AIMS

The present study was conducted to assess the association of pulse pressure (PP) with insulin resistance and beta cell function in Korean non-diabetic populations.

METHODS

This study used the data from the 2015 Korean National Health and Nutrition Examination Survey including 4380 adults, aged 20 or older.

RESULTS

A multivariate analysis revealed that systolic blood pressure (SBP) (β=0.089, 95% confidence interval [CI], 0.004-0.011; p<0.001), diastolic blood pressure (DBP) (β=-0.057, 95% CI -0.014 to -0.003; p=0.002), and PP (β=0.069, 95% CI 0.004-0.011; p<0.001) were significant factors determining the homeostasis model assessment of insulin resistance (HOMA-IR). SBP (β=0.070, 95% CI, 0.113-0.420; p=0.001), DBP (β=-0.068, 95% CI -0.676 to -0.203; p<0.001), and PP (β=0.050, 95% CI 0.115-0.422; p=0.001) were significant factors determining the homeostasis model assessment of beta cell function (HOMA-B). In the analysis of covariance test, after adjusting for related variables (except age), the quartiles of PP were not associated with HOMA-IR (p=0.191) and were inversely associated with HOMA-B (p<0.001). However, when further adjusting for age, the quartiles of PP were positively associated with both HOMA-IR (p<0.001) and HOMA-B (p=0.027).

CONCLUSION

PP was positively associated with insulin resistance and beta cell function in non-diabetic Korean adults.

Relationship between metabolic syndrome and metabolic syndrome score with β-cell function by gender in non-diabetic Korean populations

Aims: The present study was conducted to assess the association of metabolic syndrome (MetS) and the MetS score (MSS) with β-cell function by gender in Korean non-diabetic populations. Methods: This study used the data from the 2015 Korean National Health and Nutrition Examination Survey including 4380 adults, aged 20 or older. Results: After adjusting for related variables (with exception of body mass index [BMI]), MetS (p < 0.001) and MSS (p < 0.001) were positively associated with homeostasis model assessment of β-cell function (HOMA-B), in both men and women. When further adjusting for BMI, MetS (p = 0.002) and MSS (p = 0.006) were positively associated with HOMA-B in women, whereas the association of MetS (p = 0.140) or MSS (p = 0.697) and HOMA-B was no longer significant in men. Conclusion: MetS and MSS increases were positively associated with β-cell function in non-diabetic Korean women, but not in non-diabetic Korean men.

Utility of hemoglobin A1c in detecting risk of type 2 diabetes: comparison of hemoglobin A1c with other biomarkers

We have previously reported that the risk of type 2 diabetes, early impaired glucose tolerance, and insulin resistance can be predicted using fasting levels of adiponectin, leptin, and insulin. Here, we aimed to evaluate the utility of hemoglobin A1c in detecting the risk of type 2 diabetes compared with other well-known biomarkers. We randomly enrolled 207 volunteers with no history of diseases, who underwent 75-g oral glucose tolerance tests and were stratified into normal, borderline, abnormal, or diabetic groups. Eighty-one participants with normal baseline levels of hemoglobin A1c (<6.0%) were included in the normal groups of both glucose tolerance and insulin resistance. Hemoglobin A1c was significantly correlated with the plasma glucose and insulin resistance index. Leptin, adiponectin, glycoalbumin, and body mass index also were correlated well with plasma glucose levels and insulin resistance index. Normal hemoglobin A1c levels with abnormal glucose tolerance and insulin resistance were noted in 85 and 67 participants, respectively. Hemoglobin A1c did not strengthen the prediction algorithm of diabetes, determined by our proposed biomarkers, leptin, adiponectin, and insulin. In conclusion, hemoglobin A1c is a surrogate biomarker for risk of diabetes, with inadequate predictive value, and should be used in combination with other biomarkers.

Functional high-intensity exercise training ameliorates insulin resistance and cardiometabolic risk factors in type 2 diabetes

NEW FINDINGS

What is the central question of this study? Does short-duration, high-intensity exercise training that combines functional aerobic and resistance exercises into training sessions lasting 8-20 min benefit individuals with type 2 diabetes? What is the main finding and its importance? Functional high-intensity training improves insulin sensitivity and reduces cardiometabolic risk in individuals with type 2 diabetes. This type of exercise training may be an effective exercise mode for managing type 2 diabetes. The increase in insulin sensitivity addresses a key defect in type 2 diabetes.

ABSTRACT

Functional high-intensity training (F-HIT) is a novel fitness paradigm that integrates simultaneous aerobic and resistance training in sets of constantly varied movements, based on real-world situational exercises, performed at high-intensity in workouts that range from ∼8 to 20 min per session. We hypothesized that F-HIT would be an effective exercise mode for reducing insulin resistance in type 2 diabetes (T2D). We recruited 13 overweight/obese adults (5 males, 8 females; 53 ± 7 years; BMI 34.5 ± 3.6 kg m^-2 , means ± SD) with T2D to participate in a 6-week (3 days week^-1 ) supervised F-HIT programme. An oral glucose tolerance test was used to derive measures of insulin sensitivity. F-HIT significantly reduced fat mass (43.8 ± 83.8 vs. 41.6 ± 7.9 kg; P < 0.01), diastolic blood pressure (80.2 ± 7.1 vs. 74.5 ± 5.8; P < 0.01), blood lipids (triglyceride and VLDL, both P < 0.05) and metabolic syndrome z-score (6.4 ± 4.5 vs. -0.2 ± 5.2 AU; P < 0.001), and increased basal fat oxidation (0.08 ± 0.03 vs. 0.10 ± 0.04 g min^-1 ; P = 0.05), and high molecular mass adiponectin (214.4 ± 88.9 vs. 288.8 ± 127.4 ng mL^-1 ; P < 0.01). Importantly, F-HIT also increased insulin sensitivity (0.037 ± 0.010 vs. 0.042 ± 0.010 AU; P < 0.05). Increases in high molecular mass adiponectin and basal fat oxidation correlated with the change in insulin sensitivity (ρ, 0.75, P < 0.05 and ρ, 0.81, P < 0.01, respectively). Compliance with the training programme was >95% and no injuries or adverse events were reported. These data suggest that F-HIT may be an effective exercise mode for managing T2D. The increase in insulin sensitivity addresses a key defect in T2D and is consistent with improvements observed after more traditional aerobic exercise programmes in overweight/obese adults with T2D.

The association between metabolic syndrome severity and oxidative stress induced by maximal exercise testing - a cross-sectional study

Purpose: Oxidative stress (OS) has been implicated in the pathogenesis of metabolic syndrome (MetS). The acute change in OS biomarkers due to exercise, known as exercise-induced OS (EIOS), is postulated to be a more appropriate marker of OS compared to spot OS measures. These studies objectives were to investigate EIOS in participants with MetS and compare the associations between EIOS, spot OS measures and MetS severity. Methods: Sixty-three participants with MetS had MetS severity assessed using the MetS Z-score. Participants undertook a cardiorespiratory fitness test ( V O₂peak) to volitional exhaustion (∼8-12 minutes). Plasma OS (total F2-isoprostanes (IsoP), protein carbonyls (PCs)) and antioxidant (glutathione peroxidase (GPx), total antioxidant status (TAS)) biomarkers were measured from samples obtained before and five minutes post- V O₂peak test. Wilcoxon's signed-rank tests were used to determine changes in OS markers. Results: There were no significant (p > 0.05) changes in OS or antioxidant biomarkers from pre- to post-exercise (median (interquartile range): IsoP -15.5 (-71.8 to 47.8) pg/mL; PC -0.01 (-0.16 to 0.13) nmol/mg protein; GPx 0.76 (-4.94 to 9.82) U/L, TAS 0.03 (0.00-0.05) mmol/L). Conclusions: A V O₂peak test to exhaustion failed to induce OS in participants with MetS. There were no associations between MetS severity and spot OS or EIOS biomarkers.

A Whole-Grain Diet Increases Glucose-Stimulated Insulin Secretion Independent of Gut Hormones in Adults at Risk for Type 2 Diabetes

INTRODUCTION

The effect of whole-grain (WG) versus refined-grain (RG) diets on glucose-stimulated insulin secretion (GSIS) and β-cell function is unclear.

METHODS

In a double-blind crossover randomized controlled trial, 13 prediabetic adults (37.2 ± 1.8 y, BMI: 33.6 ± 1.4 kg m^-2 , 2 h glucose: 146.9 ± 11.6 mg dL^-1 ) are provided isocaloric-matched WG and RG diets for 8-weeks each, with an 8-10 week washout between diets. Glucose, insulin, and C-peptide are studied over 240 min following a 75 g OGTT. Incretins (GLP-1 and GIP), PYY, and total ghrelin are assessed at 0, 30, and 60 min. Mixed-meal diets for carbohydrate (54%), fat (28%), and protein (18%) contain either WG (50 g/1000 kcal) or equivalent RG.

RESULTS

Both diets induce fat loss (≈2 kg). While neither diet impacts early phase GSIS, the WG diet increases total GSIS (iAUC of C-peptide_0-240 /Glc_0-240 , p = 0.02) and β-cell function (disposition index; GSIS × insulin sensitivity, p = 0.02). GIP and PYY are unaltered by either diet, but GLP-1 is higher at 30 min following RG versus WG (p = 0.04). Ghrelin levels are higher at 60 min of the OGTT following both interventions (p = 0.01).

CONCLUSION

A WG-rich diet increases β-cell function independent of gut hormones in adults with prediabetes.

The Interconnection Between Immuno-Metabolism, Diabetes, and CKD

PURPOSE OF REVIEW

Metabolic reprogramming is increasingly recognized as an essential trait of functional activation of immune cells. Here, we describe the link between immuno-metabolism, diabetes, and diabetic nephropathy.

RECENT FINDINGS

Crosstalk between cellular metabolic functions and immune activation occurs when plasma levels of glucose, triglycerides, and free fatty acids increase, thus promoting systemic low-grade inflammation that further boosts the development of metabolic complications. In the long run, this settles an "apparent paradox," where, despite excessive inflammation, the immune system is suppressed, further promoting progression to end-stage renal disease (ESRD) and predisposing to premature deaths from infections and cardiovascular diseases. Reviewing the effects of diabetes treatments on immuno-inflammatory responses suggests that the benefit of these drugs might extend beyond the simple control of glucose homeostasis. Hyperglycemia and dyslipidemia correlate with enhancement of the immuno-inflammatory response that can promote and worsen metabolic diseases and support the progression toward ESRD. The identification of cellular checkpoints that modulate the immuno-metabolic machinery of immune cells opens new venues for metabolic drugs.

Etiology of Metabolic Syndrome and Dietary Intervention

The growing prevalence of metabolic syndrome (MetS) in the U.S. and even worldwide is becoming a serious health problem and economic burden. MetS has become a crucial risk factor for the development of type 2 diabetes mellitus (T2D) and cardiovascular diseases (CVD). The rising rates of CVD and diabetes, which are the two leading causes of death, simultaneously exist. To prevent the progression of MetS to diabetes and CVD, we have to understand how MetS occurs and how it progresses. Too many causative factors interact with each other, making the investigation and treatment of metabolic syndrome a very complex issue. Recently, a number of studies were conducted to investigate mechanisms and interventions of MetS, from different aspects. In this review, the proposed and demonstrated mechanisms of MetS pathogenesis are discussed and summarized. More importantly, different interventions are discussed, so that health practitioners can have a better understanding of the most recent research progress and have available references for their daily practice.

Early postpartum metabolic syndrome in women with or without gestational diabetes: Results from Life after Gestational Diabetes Ahvaz cohort study

AIMS

This study aimed to determine the prevalence rate of metabolic syndrome and its potential risk factors, 6-12 weeks postpartum in women with GDM compared to women with normal glucose tolerance.

METHODS

LAGAs is an ongoing population-based prospective cohort study that started in March 2015 in Ahvaz, Iran. During 11 months of study progression, 176 women with GDM pregnancy and 86 healthy women underwent a fasting glucose test, 75-g OGTT and fasting lipid tests at 6-12 weeks postpartum. GDM was defined based on IADPSG criteria. Postpartum glucose intolerance was defined according to ADA criteria and metabolic syndrome using 2 sets of criteria.

RESULTS

The overall rate of metabolic syndrome at 6-12 weeks postpartum was 16% by NCEP-ATP III criteria (18.2% in women with GDM and 11.6% in controls) and 19.1% by IDF criteria (21% in women with gestational diabetes and 15.1% in controls). Pre-pregnancy overweight or obesity, (OR 1.89, 95% CI: 1.05-3.38, P = .03), pregnancy systolic blood pressure (OR 1.03, 95% CI: 1.008-1.52, P = .006) and requiring insulin or metformin (OR 3.08, 95% CI: 1.25-7.60, P = 0.01), were associated risk factors for the presence of MetS in GDM-exposed women. In women with normal glucose during pregnancy, pre-pregnancy BMI ≥25 kg/m² was a risk factor of metabolic syndrome (OR 2.82, 95% CI: 1.11-7.15, P = .02).

CONCLUSION

The rate of metabolic syndrome in women with or without GDM at 6-12 weeks postpartum is high particularly in women with high BMI. An early postpartum prevention and screening program for cardiovascular risk factors is important for women with GDM.

Effects of immediate-release niacin and dietary fatty acids on acute insulin and lipid status in individuals with metabolic syndrome

BACKGROUND

The nature of dietary fats profoundly affects postprandial hypertriglyceridemia and glucose homeostasis. Niacin is a potent lipid-lowering agent. However, limited data exist on postprandial triglycerides and glycemic control following co-administration of high-fat meals with a single dose of niacin in subjects with metabolic syndrome (MetS). The aim of the study was to explore whether a fat challenge containing predominantly saturated fatty acids (SFAs), monounsaturated fatty acids (MUFAs) or MUFAs plus omega-3 long-chain polyunsaturated (LCPUFAs) fatty acids together with a single dose of immediate-release niacin have a relevant role in postprandial insulin and lipid status in subjects with MetS.

RESULTS

In a randomized crossover within-subject design, 16 men with MetS were given a single dose of immediate-release niacin (2 g) and ∼15 cal kg^-1 body weight meals containing either SFAs, MUFAs, MUFAs plus omega-3 LCPUFAs or no fat. At baseline and hourly over 6 h, plasma glucose, insulin, C-peptide, triglycerides, free fatty acids (FFAs), total cholesterol, and both high- and low-density lipoprotein cholesterol were assessed. Co-administered with niacin, high-fat meals significantly increased the postprandial concentrations of glucose, insulin, C-peptide, triglycerides, FFAs and postprandial indices of β-cell function. However, postprandial indices of insulin sensitivity were significantly decreased. These effects were significantly attenuated with MUFAs or MUFAs plus omega-3 LCPUFAs when compared with SFAs.

CONCLUSION

In the setting of niacin co-administration and compared to dietary SFAs, MUFAs limit the postprandial insulin, triglyceride and FFA excursions, and improve postprandial glucose homeostasis in MetS. © 2017 Society of Chemical Industry.

Early diagnosis of type 2 diabetes based on multiple biomarkers and non-invasive indices

We previously reported that type 2 diabetes risk, early impaired glucose tolerance and insulin resistance can be predicted by measuring the fasting levels of certain biomarkers. Here we validated these findings in randomly recruited healthy volunteers (n = 101) based on biomarker expression as well as various non-invasive indices. Weight, body mass index, waist circumference and visceral fat differed between individuals with impaired fasting glucose and/or impaired glucose tolerance, and normal subjects. Fasting plasma levels of glycated hemoglobin, leptin, pro-insulin and retinol binding protein 4 differed between impaired fasting glucose/impaired glucose tolerance and normal subjects group and between newly detected diabetes and normal subjects group. Insulin resistance was correlated with fasting levels of insulin and leptin/adiponectin (r = 0.913); of insulin, retinol binding protein 4 and leptin/adiponectin (r = 0.903); and of insulin, glycated albumin, and leptin/adiponectin (r = 0.913). Type 2 diabetes risk, early impaired glucose tolerance and insulin resistance were predicted with >98% specificity and sensitivity by comparing fasting glucose levels to the estimated Matsuda Index based on fasting levels of insulin, adiponectin and leptin with or without oxidative lineolate metabolites. Non-invasive indices are slightly correlated with glucose tolerance and insulin resistance but do not increase the accuracy of predicting type 2 diabetes risk.

Age increases MCP-1 level in association with bariatric surgery operating time and metabolic risk severity

Objective

Assess the role of inflammation on operating time in younger vs. older bariatric surgery patients.

Methods

Fifty‐five younger (F: 46, Age: 34.9 ± 4.0 years, body mass index [BMI]: 48.2 ± 1.0 kg m⁻²) and 48 older (F: 34, Age: 57.0 ± 5.1 years, BMI: 46.8 ± 1.0 kg m⁻²) adults were studied prior to surgery. Blood pressure, glycaemic control (fasting glucose/insulin, HbA_1c), lipids (high‐density lipoprotein and triglycerides) and inflammation (monocyte chemoattractant protein‐1 [MCP‐1]) were assessed. Metabolic risk severity z‐scores were calculated from clinical outcomes. Omental adipose biopsies were collected at surgery for MCP‐1 protein analysis. Operating time was used to characterize surgical difficulty.

Results

Older vs. younger adults had higher HbA_1c (P = 0.03). There was no difference in BMI, lipids, metabolic risk severity or insulin between groups, but operating time was longer in older vs. younger individuals (P = 0.04). Circulating MCP‐1 was also elevated in older vs. younger adults (P = 0.04) independent of HbA_1c, although this was not explained by omental fat. Nevertheless, serum MCP‐1 was associated with increased metabolic risk severity (R = 0.27, P = 0.01). In addition, operating time was linked to HbA_1c (R = 0.30, P = 0.01) and omental MCP‐1 protein (R = 0.31, P < 0.01).

Conclusions

MCP‐1 is associated with longer operating time and increased metabolic risk severity in older bariatric patients independent of glycaemic control. Pre‐operative treatment of inflammation may be required to enhance surgery effectiveness.

Prediabetes Exhibits Decreased Disposition Index Correlated with Deterioration of Glycemic Parameters in Nonobese Japanese Subjects: A Cross-Sectional Study from Medical Examination

BACKGROUND

Prediabetes, defined as impaired fasting glucose (IFG) and impaired glucose tolerance (IGT), likely develops to type 2 diabetes mellitus (DM) and independently increases cardiovascular risk. We employed disposition index (DI), a new metabolic parameter indicating the pancreatic beta cell function adjusted for insulin resistance, and investigated whether it could be altered in Japanese population with prediabetes and associated with early glucose intolerance.

METHODS

A total of 102 adults who underwent an oral glucose tolerance test at the medical screening were designated to normal glucose tolerance (NGT), IFG, IGT, and DM. We calculated insulinogenic index (IGI) and homeostasis model assessment (HOMA) of β cell function (HOMA-β) as insulin secretory function, HOMA-insulin resistance (HOMA-IR), and quantitative insulin sensitivity check index (QUICKI) as insulin resistance and DI, and assessed correlations between these indices and glycemic parameters.

RESULTS

We observed graded increase of glycemic parameters in the order of NGT, IFG, IGT, and DM. HOMA-IR was significantly higher only in DM compared with NGT, although HOMA-β, IGI, and QUICKI showed no significant differences among the groups. In contrast, DI was significantly lower in IFG, IGT, and DM compared with NGT. In correlation analysis, glycemic parameters related positively to HOMA-IR, but inversely to DI. Only two parameters, IGI and particularly DI, were significantly decreased in the subjects with 1-hr postload glucose >8.6 mmol/L previously proposed as a predictor of type 2 diabetes.

CONCLUSIONS

Our results suggest that reduction of DI promptly reflects the alteration of early glucose intolerance in Japanese population presenting with prediabetes.

Higher Ratio of Abdominal Subcutaneous to Visceral Adipose Tissue Related with Preservation of Islet β-Cell Function in Healthy Individuals

OBJECTIVE

To investigate the relationship between abdominal adipose tissue distribution, β-cell function, and insulin sensitivity (IS) in a Chinese population.

METHODS

One hundred and eighty-eight healthy subjects (healthy group), 239 with normal glucose, and 1~4 abnormal metabolic traits (metabolic dysfunction group, MD group) and 125 with hyperglycemia (hyperglycemia group) were studied. HOMA-IR, HOMA-B, Matsuda index, early- (I_0-30/G_0-30) and late-phase (I_30-120/G_30-120) insulin responses and the corresponding disposition indexes (DI) were calculated. The area of abdominal subcutaneous adipose tissue (ASAT) and visceral adipose tissue (VAT) was measured and the ratio of ASAT to VAT (SVR) was calculated.

RESULTS

SVR was correlated positively with Matsuda index in healthy, MD, and hyperglycemia groups, and inversely with HOMA-IR. SVR positively related with both early- and late-phase DI in the healthy group only. In the healthy group, the hyperbolas of I_0-30/G_0-30 and I_30-120/G_30-120 versus Matsuda index in the highest quarter of SVR were significantly right shifted compared to those in the lowest (both P < 0.05).

CONCLUSIONS

In healthy adults, higher SVR was a protective factor for β-cell function and IS, while in those with glucometabolic abnormality, higher SVR contributed to a relative better IS, indicating SVR is possible to be an early predicator of type 2 diabetes development.

The effect of different volumes of high-intensity interval training on proinsulin in participants with the metabolic syndrome: a randomised trial

AIMS/HYPOTHESIS

The continuous demand for insulin in the face of insulin resistance, coupled with the glucolipotoxic environment associated with the metabolic syndrome (MetS), adversely affects the quality of insulin produced and secreted by the pancreatic beta cells. This is depicted by increased circulating intact proinsulin concentration, which is associated with increased MetS severity and risk of cardiovascular (CV) mortality. High-intensity interval training (HIIT) has been shown to reduce insulin resistance and other CV disease risk factors to a greater degree than moderate-intensity continuous training (MICT). We therefore aimed to investigate the impact of MICT and different volumes of HIIT on circulating intact proinsulin concentration.

METHODS

This was a substudy of the 'Exercise in prevention of Metabolic Syndrome' (EX-MET) multicentre trial. Sixty-six individuals with MetS were randomised to 16 weeks of: (1) MICT (n = 21, 30 min at 60-70% peak heart rate [HRpeak], five times/week); (2) 4HIIT (n = 22, 4 × 4 min bouts at 85-95% HRpeak, interspersed with 3 min of active recovery at 50-70% HRpeak, three times/week); or (3) 1HIIT (n = 23, 1 × 4 min bout at 85-95% HRpeak, three times/week). A subanalysis investigated the differential impact of these training programmes on intact proinsulin concentration in MetS individuals with type 2 diabetes (MICT, n = 6; 4HIIT, n = 9; 1HIIT, n = 12) and without type 2 diabetes (MICT, n = 15; 4HIIT, n = 13; 1HIIT, n = 11). Intact proinsulin, insulin and C-peptide concentrations were measured in duplicate via ELISA, following a 12 h fast, before and after the exercise programme. Fasting intact proinsulin concentration was also expressed relative to insulin and C-peptide concentrations.

RESULTS

Following the exercise training, there were no significant (p > 0.05) changes in fasting intact proinsulin concentration indices in all participants (pre- vs post-programme proinsulin, proinsulin:insulin, proinsulin:C-peptide: MICT 19% decrease, 6% increase, 4% increase; 4HIIT 19% decrease, 8% decrease, 11% decrease; 1HIIT 34% increase, 49% increase, 36% increase). In participants who did not have type 2 diabetes, only 4HIIT significantly (p < 0.05) reduced fasting intact proinsulin concentration indices from pre to post intervention (pre- vs post-programme proinsulin, proinsulin:insulin, proinsulin:C-peptide: 4HIIT 32% decrease, 26% decrease, 32% decrease, p < 0.05; 1HIIT, 14% increase, 32% increase, 16% increase, p > 0.05; MICT 27% decrease, 17% decrease, 11% decrease), with a group × time interaction effect, indicating a greater reduction in intact proinsulin indices following 4HIIT compared with MICT and 1HIIT. There were no significant (p > 0.05) changes in intact proinsulin concentration indices in participants with type 2 diabetes.

CONCLUSIONS/INTERPRETATION

Higher-volume HIIT (4HIIT) improved insulin quality in MetS participants without type 2 diabetes.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01676870 FUNDING: The study was funded by the Norwegian University of Science and Technology and from an unrestricted research grant from the Coca-Cola company. Funding for the collection of physical activity data was derived from a 'UQ New Staff Start Up' grant awarded to B. Clark.

A Whole-Grain Diet Reduces Cardiovascular Risk Factors in Overweight and Obese Adults: A Randomized Controlled Trial

BACKGROUND

Increased dietary whole-grain intake may protect against cardiovascular disease (CVD).

OBJECTIVE

The objective was to evaluate the efficacy of whole grains compared with refined grains on body composition, hypertension, and related mediators of CVD in overweight and obese adults.

METHODS

We conducted a double-blind, randomized, controlled crossover trial in 40 overweight or obese men and women aged <50 y with no known history of CVD. Complete whole-grain and refined-grain diets were provided for two 8-wk periods, with a 10-wk washout between diets. Macronutrient composition was matched, except for the inclusion of either whole grains or refined grains (50 g/1000 kcal in each diet). Measurements included blood pressure, body composition, blood lipids and adiponectin, and markers of inflammation and glycemia.

RESULTS

Thirty-three participants (6 men and 27 women) completed the trial [mean ± SD age: 39 ± 7 y; mean ± SD body mass index (in kg/m2): 33.1 ± 4.3]. Decreases in diastolic blood pressure were -5.8 mm Hg (95% CI: -7.7, -4.0 mm Hg) after the whole-grain diet and -1.6 mm Hg (95% CI: -4.4, 1.3 mm Hg) after the control diet (between effect, P = 0.01). Decreases in plasma adiponectin were -0.1 (95% CI: -0.9, 0.7) after the whole-grain diet and -1.4 (95% CI: -2.6, -0.3) after the control diet (between effect, P = 0.05). Decreases in diastolic blood pressure correlated with the circulating adiponectin concentration (r = 0.35, P = 0.04). Substantial reductions in body weight, fat loss, systolic blood pressure, total cholesterol, and LDL cholesterol were observed during both diet periods, with no relevant difference between them.

CONCLUSIONS

The improvement in diastolic blood pressure was >3-fold greater in overweight and obese adults when they consumed a whole-grain compared with a refined-grain diet. Because diastolic blood pressure predicts mortality in adults aged <50 y, increased whole-grain intake may provide a functional approach to control hypertension. This may benefit patients at risk of vascular-related morbidity and mortality. This trial was registered at clinicaltrials.gov as NCT01411540.

Evaluation of insulin sensitivity and secretion in primary aldosteronism

In primary aldosteronism (PA), insulin response to glucose is not fully understood. Insulin action was elucidated using indices in 32 PA and 21 essential hypertension (EH) patients. These patients were evaluated using homeostasis model assessment (HOMA) indices, quantitative insulin sensitivity check index (QUICKI), and insulinogenic index (IGI), which were expressed for insulin sensitivity/secretion and the early phase of insulin secretion. Insulin sensitivity and early phase of insulin secretion were decreased in PA, and there was a negative correlation between serum potassium concentration and insulin sensitivity indices. These findings suggest that glucose intolerance in PA may be caused by hypokalemia-induced insulin resistance and hypokalemia-independent impairment of early-phase insulin secretion.

Hyperglycemic clamp-derived disposition index is negatively associated with metabolic syndrome severity in obese subjects

OBJECTIVE

Metabolic syndrome is associated with insulin resistance and increased future risk of type 2 diabetes. This study investigates the relationship between insulin secretion, insulin resistance and individual metabolic syndrome components in subjects without a prior diagnosis of diabetes.

RESEARCH DESIGN AND METHODS

We assessed insulin secretion during hyperglycemic clamps by infusing dextrose to maintain hyperglycemia (200mg/dL), followed by L-arginine administration. Studies in 98 individuals (mean age 45.3±1.2years, 56% female, 22% African-American, 49% with metabolic syndrome) were analyzed. We tested the association between the number of metabolic syndrome components and individual outcome variables using linear mixed-effects models to adjust for potential confounding effects of age, sex, and race.

RESULTS

Insulin sensitivity index was reduced in the presence of 1 or more metabolic syndrome components. Insulin sensitivity was independently associated with age, waist circumference, male gender and decreased HDL cholesterol. The acute insulin response was greater with two or more metabolic syndrome components, and late glucose-stimulated and L-arginine-stimulated insulin responses exhibited a similar trend. In contrast, the disposition index, a measure of beta cell compensation for insulin resistance, was linearly lower with the number of metabolic syndrome components, and was negatively associated with age, Caucasian race, waist circumference, fasting glucose, and decreased HDL cholesterol.

CONCLUSIONS

The insulin secretory response in metabolic syndrome is inadequate for the worsening insulin sensitivity, as demonstrated by a decline in disposition index. A dysfunctional insulin secretory response is evident in non-diabetic individuals and worsens with accumulation of metabolic syndrome components.

Cardiorespiratory fitness is positively associated with increased pancreatic beta cell function independent of fatness in individuals with the metabolic syndrome: Fitness versus fatness

OBJECTIVES

The vulnerability of individuals with the metabolic syndrome (MetS) to cardiovascular events (CVEs) is attenuated by increased cardiorespiratory fitness (CRF), despite the presence of obesity as a usual component of MetS. To better understand the importance of CRF and body fat in treating this condition, we investigated the relationship between fitness and fatness with pancreatic beta cell function (BCF) indices that are known independent predictors of CVEs.

DESIGN

Cross sectional study.

METHODS

This study included 84 individuals with MetS. BCF indices were derived from a fasted steady state (basal disposition index [DI], proinsulin, proinsulin:insulin, and proinsulin:C-peptide) and dynamic conditions via an oral glucose tolerance test (1st and 2nd phase DI). CRF and body fat percentage (BF%) were assessed via indirect calorimetry (during a maximal exercise test) and dual energy X-ray absorptiometry, respectively.

RESULTS

CRF was positively associated with basal DI (r=0.40, p<0.001), 1st phase DI (r=0.49, p<0.005), and 2nd phase DI (r=0.38, p=0.02). Hierarchical multiple regression analysis showed CRF was associated with basal DI (β=0.18, p=0.04), 1st phase DI (β=0.36, p=0.04), and 2nd phase DI (β=0.33, p=0.03), independent of BF% and other confounding factors including age, sex, diabetic status, anthropometric measures, lipid profile, and insulin sensitivity. No significant associations were found between CRF and proinsulin measures. BF% was not significantly correlated with BCF indices.

CONCLUSIONS

Increased CRF was independently associated with enhanced BCF. This study provides evidence that equal, if not more attention should be dedicated to CRF improvement relative to fat-loss for favorable pancreatic BCF and thus possible reduction in CV risk in individuals with MetS.

Risk factors of diabetes in North Indians with metabolic syndrome

AIM

Metabolic syndrome progresses to diabetes and determinants of this progression like hyperinsulinemia, hypertriglyceridemia and genetic factors have been speculative. The present study was aimed at quantifying the insulin resistance and influence of family history of diabetes in subjects with metabolic syndrome developing prediabetes and diabetes.

METHODS

Consecutive subjects attending the endocrine clinic were evaluated for metabolic syndrome as per definition of International Diabetes Federation, 2005. The family history of diabetes in their first degree relatives was ascertained and Homeostasis model assessment of Insulin resistance (HOMA-IR), Homeostasis model assessment for beta cell function (HOMA-B) and Quantitative insulin sensitivity check index (QUICKI) were calculated in 163 subjects enrolled.

RESULTS

HOMA-IR was higher (p<0.05) but HOMA-B and QUICKI were lower (p<0.0001) in subjects with metabolic syndrome+prediabetes or diabetes compared to metabolic syndrome with normal glucose tolerance. HOMA-B was lower and prevalence of prediabetes and diabetes was higher in metabolic syndrome subjects with family history of diabetes than in those without such family history (p<0.05).

CONCLUSIONS

subjects with metabolic syndrome having prediabetes and diabetes had more severe insulin resistance than those with metabolic syndrome only. Beta cell dysfunction was remarkable and prevalence of prediabetes was high in metabolic syndrome subjects with family history of diabetes. Both the severity of the insulin resistance and family history of diabetes are therefore proposed to be determinants of diminished Beta cell function leading to diabetes in metabolic syndrome.

Attenuated improvements in adiponectin and fat loss characterize type 2 diabetes non-remission status after bariatric surgery

AIM

To identify the metabolic determinants of type 2 diabetes non-remission status after bariatric surgery at 12 and 24 months.

METHODS

A total of 40 adults [mean ± sd body mass index 36 ± 3 kg/m(2) , age 48 ± 9 years, glycated haemoglobin (HbA1c) 9.7 ± 2%) undergoing bariatric surgery [Roux-en-Y gastric bypass (RYGB) or sleeve gastrectomy (SG)] were enrolled in the present study, the Surgical Treatment and Medication Potentially Eradicate Diabetes Efficiently (STAMPEDE) trial. Type 2 diabetes remission was defined as HbA1c <6.5% and fasting glucose <126 mg/dl (i.e. <7 mmol/l) without antidiabetic medication. Indices of insulin secretion and sensitivity were calculated from plasma glucose, insulin and C-peptide values during a 120-min mixed-meal tolerance test. Body fat, incretins (glucagon-like polypeptide-1, gastric inhibitory peptide, ghrelin) and adipokines [adiponectin, leptin, tumour necrosis factor-α, high-sensitivity C-reactive protein (hs-CRP)] were also assessed.

RESULTS

At 24 months, 37 patients had available follow-up data (RYGB, n = 18; SG, n = 19). Bariatric surgery induced type 2 diabetes remission rates of 40 and 27% at 12 and 24 months, respectively. Total fat/abdominal fat loss, insulin secretion, insulin sensitivity and β-cell function (C-peptide0-120 /glucose0-120 × Matsuda index) improved more in those with remission at 12 and 24 months than in those without remission. Incretin levels were unrelated to type 2 diabetes remission, but, compared with those without remission, hs-CRP decreased and adiponectin increased more in those with remission. Only baseline adiponectin level predicted lower HbA1c levels at 12 and 24 months, and elevated adiponectin correlated with enhanced β-cell function, lower triglyceride levels and fat loss.

CONCLUSIONS

Smaller rises in adiponectin level, a mediator of insulin action and adipose mass, characterize type 2 diabetes non-remission up to 2 years after bariatric surgery. Adjunctive strategies promoting greater fat loss and/or raising adiponectin may be key to achieving higher type 2 diabetes remission rates after bariatric surgery.

Adjusting glucose-stimulated insulin secretion for adipose insulin resistance: an index of β-cell function in obese adults

OBJECTIVE

The hyperbolic relationship between insulin secretion and sensitivity has been used to assess in vivo β-cell function (i.e., the disposition index). The disposition index emphasizes the importance of taking into account both skeletal muscle and hepatic insulin resistance to depict insulin secretion. However, we propose that adipose tissue insulin resistance also needs to be accounted for when characterizing glucose-stimulated insulin secretion (GSIS) because elevated plasma free fatty acids (FFAs) impair β-cell function.

RESEARCH DESIGN AND METHODS

To characterize the adipose disposition index, we used [1-(14)C] palmitate infusion to determine basal FFA turnover rate/adipose insulin resistance and an oral glucose tolerance test to characterize the first (i.e., 0-30 min) and second phase (i.e., 60-120 min) of GSIS. We validated a simplified version of the tracer infusion calculation as the product of (1/plasma FFA concentration × plasma insulin concentration) × GSIS in 44 obese insulin-resistant subjects.

RESULTS

The plasma FFA and palmitate tracer infusion calculations of the first- and second-phase disposition index were strongly correlated (r = 0.86, P < 0.000001 and r = 0.89, P < 0.000001, respectively). The first- and second-phase adipose disposition index derived from plasma FFA also was tightly associated with fasting hyperglycemia (r = -0.87, P < 0.00001 and r = -0.89, P < 0.00001, respectively) and 2-h glucose concentrations (r = -0.86, P < 0.00001 and r = -0.90, P < 0.00001).

CONCLUSIONS

Adjusting GSIS for adipose insulin resistance provides an index of β-cell function in obese subjects across the glucose spectrum. Plasma FFA-derived calculations of β-cell function may provide additional insight into the role of adipose tissue in glucose regulation.