Whole-body Insulin Sensitivity Research Articles

Rapid downregulation of DICER is a hallmark of adipose tissue upon high-fat diet feeding

Adipose tissue regulates whole-body energy balance and is crucial for metabolic health. With energy surplus, adipose tissue expands, which may lead to local areas of hypoxia and inflammation, and consequently impair whole-body insulin sensitivity. We report that DICER, a key enzyme for miRNA maturation, is significantly lower in abdominal subcutaneous white adipose tissue of men with obesity compared with men with a lean phenotype. Furthermore, DICER is profoundly downregulated in mouse adipose tissue and liver within the first week on a high-fat diet (HFD), and remains low after prolonged HFD feeding. Downregulation of DICER in mice occurs in both mature adipocytes and stromal vascular cells. Mechanistically, chemically induced hypoxia in vitro shows DICER degradation via interaction with hypoxia-inducible factor 1-α (HIF1α). Moreover, DICER and HIF1α interact in brown adipose tissue post-HFD which may signal for DICER degradation. Finally, RNA sequencing reveals a striking time-dependent downregulation of total miRNA content in mouse subcutaneous adipose tissue after HFD feeding. Collectively, HFD in mice reduces adipose tissue DICER, likely due to hypoxia-induced interaction with HIF1α during tissue expansion, and significantly impacts miRNA content.

Nitric oxide donors rescue metabolic and mitochondrial dysfunction in obese Alzheimer’s model

Reduced nitric oxide (NO) bioavailability is a pathological link between obesity and Alzheimer’s disease (AD). Obesity-associated metabolic and mitochondrial bioenergetic dysfunction are key drivers of AD pathology. The hypothalamus is a critical brain region during the development of obesity and dysfunction is an area implicated in the development of AD. NO is an essential mediator of blood flow and mitochondrial bioenergetic function, but the role of NO in obesity-AD is not entirely clear. We investigated diet-induced obesity in female APPswe/PS1dE9 (APP) mouse model of AD, which we treated with two different NO donors (sodium nitrite or L-citrulline). After 26 weeks of a high-fat diet, female APP mice had higher adiposity, insulin resistance, and mitochondrial dysfunction (hypothalamus) than non-transgenic littermate (wild type) controls. Treatment with either sodium nitrite or L-citrulline did not reduce adiposity but improved whole-body energy expenditure, substrate oxidation, and insulin sensitivity. Notably, both NO donors restored hypothalamic mitochondrial respiration in APP mice. Our findings suggest that NO is an essential mediator of whole-body metabolism and hypothalamic mitochondrial function, which are severely impacted by the dual insults of obesity and AD pathology.

Two weeks of exercise alters neuronal extracellular vesicle insulin signaling proteins and pro-BDNF in older adults with prediabetes.

Adults with prediabetes are at risk for Alzheimer's Disease and Related Dementia (ADRD). While exercise may lower ADRD risk, the exact mechanism is unclear. We tested the hypothesis that short-term exercise would raise neuronal insulin signaling and pro-BDNF in neuronal extracellular vesicles (nEVs) in prediabetes. Twenty-one older adults (18F, 60.0 ± 8.6 yrs.; BMI: 33.5 ± 1.1 kg/m2) with prediabetes (ADA criteria; 75 g OGTT) were randomized to 12 supervised work-matched continuous (n = 13, 70% HRpeak) or interval (n = 8, 90% HRpeak and 50% HRpeak for 3 min each) sessions over 2-wks for 60 min/d. Aerobic fitness (VO2peak) and body weight were assessed. After an overnight fast, whole-body glucose tolerance (total area under the curve, tAUC) and insulin sensitivity (SIis) were determined from a 120 min 75 g OGTT. nEVs were acquired from 0 and 60 min time-points of the OGTT, and levels of insulin signaling proteins (i.e., p-IRS-1, total-/p-Akt, pERK1/2, pJNK1/2, and pp38) and pro-BNDF were measured. OGTT stimulatory effects were calculated from protein differences (i.e., OGTT 60-0 min). Adults were collapsed into a single group as exercise intensity did not affect nEV outcomes. Exercise raised VO2peak (+1.4 ± 2.0 mL/kg/min, p = 0.008) and insulin sensitivity (p = 0.01) as well as decreased weight (-0.4 ± 0.9 kg, p = 0.04) and whole-body glucose tAUC120min (p = 0.02). Training lowered 0-min pro-BDNF (704.1 ± 1019.0 vs. 414.5 ± 533.5, p = 0.04) and increased OGTT-stimulated tAkt (-51.8 ± 147.2 vs. 95 ± 204.5 a.u., p = 0.01), which was paralleled by reduced pAkt/tAkt at 60 min of the OGTT (1.3 ± 0.2 vs. 1.2 ± 0.1 a.u., p = 0.04). Thus, 2 weeks of exercise altered neuronal insulin signaling responses to glucose ingestion and lowered pro-BNDF among adults with prediabetes, thereby potentially lowering ADRD risk.

7568 Sickle Cell Variant Promotes Glycemic Dysregulation In A Mouse Model Of Human Sickle Cell Trait And Sickle Cell Disease

Abstract Disclosure: J.L. Zapater: None. B.T. Layden: None. Since cases of type 2 diabetes mellitus (T2DM) are rising due to environmental and societal factors, it is estimated that in the coming decades that T2DM will affect twenty percent of the United States population and that mortality from diabetic complications will continue to rise. It is therefore critical to accurately diagnose and treat T2DM early, however this proves difficult in certain populations. Sickle cell anemia is a common hemoglobinopathy in which changes in red blood cell turnover lead to inaccurate measurement of hemoglobin A1c and incongruencies between this and other glucose measures, making it difficult to establish a diagnosis of T2DM. The sickle cell variant has been linked to higher hemoglobin A1c, and with 1-in-10 African Americans having the sickle cell trait (SCT), an increasing prevalence of sickle cell disease (SCD), and a higher risk of diabetic complications in those with SCT or SCD, it is critical that we elucidate the precise mechanisms by which the sickle cell variant affects glycemic homeostasis. In this work, we utilized a mouse model of human sickle cell anemia to begin to determine the biochemical mechanisms governing glucose handling in the presence of the sickle cell variant by examining glycemic homeostasis under normal and obesogenic conditions. Townes sickle cell mice containing human hemoglobin with either two normal β-globin chains (littermate controls) or one normal and one sickle β-globin chain (SCT) were placed on either a normal chow diet or on a high fat diet (HFD) until 20 weeks of age to induce an obesogenic state. Although no overt glycemic phenotype was noted, 20-week-old HFD-fed SCT mice exhibited an increased glucose excursion following an oral glucose load compared to littermate controls. Though serum insulin levels were comparable, HFD-fed SCT mice also exhibited a reduced whole-body insulin sensitivity during insulin tolerance testing compared to controls, correlating with the noted increased glycemic excursion. With these findings, we have initiated work with Townes mice containing two normal α-chains and two sickle β-chains (SCD), which is found in human sickle cell anemia. Early results show that chow-fed SCD mice exhibit greater random and fasting glucose levels at 8 and 12 weeks of age, despite similar fasting insulin levels. These findings suggest that the presence of one sickle β-globin chain, as in SCT, promotes hyperglycemia in the obesogenic state through reduction of whole-body insulin sensitivity. Furthermore, the presence of two sickle β-globin chains, as in SCD, is sufficient to dysregulate glycemic control under normal conditions. In total, these findings demonstrate that the presence of the sickle cell variant promotes glucose dysregulation and hyperglycemia, meaning that it is essential to understand the glycemic regulation in patients with sickle cell trait and sickle cell anemia. Presentation: 6/1/2024

Effect of Weight Loss on Skeletal Muscle Bioactive Lipids in People with Obesity and Type 2 Diabetes.

Muscle sn-1,2-diacylglycerol (DAG) and C18:0 ceramide accumulation in sarcolemmal and mitochondrial compartments have been proposed to regulate muscle insulin sensitivity. Here, we evaluated whether weight loss-induced improvements in insulin sensitivity were associated with changes in muscle sn-1,2-DAG and ceramide content in people with obesity and type 2 diabetes. We measured skeletal muscle insulin sensitivity, assessed by using the hyperinsulinemic-euglycemic clamp procedure in conjunction with stable isotopically labeled glucose tracer infusion, and skeletal muscle sn-1,2-DAG and ceramide contents by using liquid chromatography-tandem mass spectrometry after subcellular fractionation and DAG isomer separation in 14 adults with obesity and type 2 diabetes before and after marked (18.6 ± 2.1%) weight loss. Whole-body insulin sensitivity doubled after weight loss. Sarcolemmal sn-1,2-DAG and C18:0 ceramide contents after weight loss were not different than values before weight loss. In contrast, mitochondrial/ER C18:0 ceramide content decreased by ∼20% after weight loss (from 2.16 ± 0.08 to 1.71 ± 0.13 nmol/g, P<0.005). These results suggest a decrease in muscle mitochondrial/ER C18:0 ceramide content could contribute to the beneficial effect of weight loss on skeletal muscle insulin sensitivity.

The effect of 60days of 6° head-down-tilt bed rest on circulating adropin, irisin, retinol binding protein-4 (RBP4) and individual metabolic responses in young, healthy males.

Alterations in the circulating concentrations and target-tissue action of organokines underpin the development of insulin resistance in microgravity and gravity deprivation. The purpose of this study was to examine changes in circulating adropin, irisin, retinol binding protein-4 (RBP4), and the metabolic response of healthy young males following 60days of 6° head-down-tilt (HDT) bed rest, with and without reactive jump training (RJT), to explore links with whole-body and tissue-specific insulin sensitivity. To our knowledge, this is the first time that adropin, irisin, and RBP4 have been studied in HDT bed rest. A total of 23 male subjects (29 ± 6years, 181 ± 6cm, 77 ± 7kg) were exposed to 60days of 6° HDT bed rest and randomized to a control (CTRL, n = 11) or a RJT (JUMP, n = 12) group (48 sessions with ≤4min total training time per session). Circulating adropin, irisin, and RBP4 were quantified in fasting serum before and after HDT bed rest. A subanalysis was performed a posteriori to investigate individual metabolic responses post-HDT bed rest based on subjects that showed an increase or decrease in whole-body insulin sensitivity (Matsuda index). There were significant main effects of time, but not group, for decreases in adropin, irisin, Matsuda index, and liver insulin sensitivity following HDT bed rest (p < 0.05), whereas RBP4 did not change. The subanalysis identified that in a subgroup with decreased whole-body insulin sensitivity (n = 17), RBP4 increased significantly, whereas adropin, irisin, and liver insulin sensitivity were all decreased significantly following HDT bed rest. Conversely, in a subgroup with increased whole-body insulin sensitivity (n = 6), liver insulin sensitivity increased significantly after HDT bed rest, whereas adropin, irisin, and RBP4 did not change. Investigating individual metabolic responses has provided insights into changes in circulating adropin, irisin, RBP4, in relation to insulin sensitivity following HDT bed rest. We conclude that adropin, irisin, and RBP4 are candidate biomarkers for providing insights into whole-body and tissue-specific insulin sensitivity to track changes in physiological responsiveness to a gravity deprivation intervention in a lean male cohort.

Sex-Specific Skeletal Muscle Gene Expression Responses to Exercise Reveal Novel Direct Mediators of Insulin Sensitivity Change.

Understanding the causal pathways, systems, and mechanisms through which exercise impacts human health is complex. This study explores molecular signaling related to whole-body insulin sensitivity (Si) by examining changes in skeletal muscle gene expression. The analysis considers differences by biological sex, exercise amount, and exercise intensity to identify potential molecular targets for developing pharmacologic agents that replicate the health benefits of exercise. The study involved 53 participants from the STRRIDE I and II trials who completed eight months of aerobic training. Skeletal muscle gene expression was measured using Affymetrix and Illumina technologies, while pre- and post-training Si was assessed via an intravenous glucose tolerance test. A novel gene discovery protocol, integrating three literature-derived and data-driven modeling strategies, was employed to identify causal pathways and direct causal factors based on differentially expressed transcripts associated with exercise intensity and amount. In women, the transcription factor targets identified were primarily influenced by exercise amount and were generally inhibitory. In contrast, in men, these targets were driven by exercise intensity and were generally activating. Transcription factors such as ATF1, CEBPA, BACH2, and STAT1 were commonly activating in both sexes. Specific transcriptional targets related to exercise-induced Si improvements included TACR3 and TMC7 for intensity-driven effects, and GRIN3B and EIF3B for amount-driven effects. Two key signaling pathways mediating aerobic exercise-induced Si improvements were identified: one centered on estrogen signaling and the other on phorbol ester (PKC) signaling, both converging on the epidermal growth factor receptor (EGFR) and other relevant targets. The signaling pathways mediating Si improvements from aerobic exercise differed by sex and were further distinguished by exercise intensity and amount. Transcriptional adaptations in skeletal muscle related to Si improvements appear to be causally linked to estrogen and PKC signaling, with EGFR and other identified targets emerging as potential skeletal muscle-specific drug targets to mimic the beneficial effects of exercise on Si.

Impaired insulin sensitivity measured by estimated glucose disposal rate is associated with decreased myocardial mechano-energetic efficiency in non-diabetic individuals

Background and aimsImpaired myocardial mechano-energetic efficiency (MEE) has been associated with cardiac insulin resistance measured by dynamic positron emission tomography (PET) with 18F-fluorodeoxyglucose (18F-FDG) combined with euglycemic–hyperinsulinemic clamp. Estimate glucose disposal rate (eGDR) index has a good correlation with whole-body insulin sensitivity. It remains unsettled whether eGDR index is a suitable proxy of cardiac insulin sensitivity as well as its association with myocardial MEE. The aims of this study were: 1) to compare eGDR index with HOMA-IR, QUICKI and FIRI indexes for association with myocardial glucose metabolic rate (MrGlu); and 2) to determine the association of eGDR index with myocardial MEE. MethodsWe evaluated MrGlu using PET with 18F-FDG combined with euglycemic–hyperinsulinemic clamp in 50 individuals without history of coronary heart disease. Myocardial MEE per gram of left ventricular mass (MEEi) was measured in 1181 subjects by echocardiography. eGDR (mg kg-1/min) was calculated as: 21.158 - (0.09 × waist circumference in cm) - (3.407 × hypertension, 1 = yes 0 = no) - (0.551 × HbA1c%). ResultseGDR index was more strongly associated with myocardial MrGlu than HOMA-IR, QUICKI, and FIRI indexes (r = -0.662, r = -0.492, r = 0.570, and r = -0.492, respectively). Individuals in the lower tertiles of eGDR exhibited a significant reduction of MEEi as compared to those in the highest tertile (P < 0.001). In a stepwise multivariate linear regression analysis eGDR index was the major determinant of MEEi independently of well-established cardio-metabolic risk factors. ConclusionsThese data suggest that the eGDR index may be a useful marker to identifying individuals at high cardiovascular risk.

KIC (ketoisocaproic acid) and leucine have divergent effects on tissue insulin signaling but not on whole-body insulin sensitivity in rats.

Plasma levels of branched-chain amino acids and their metabolites, the branched-chain ketoacids are increased in insulin resistance. Our previous studies showed that leucine and its metabolite KIC suppress insulin-stimulated glucose uptake in L6 myotubes along with the activation of the S6K1-IRS-1 pathway. Because other tissue and fiber types can be differentially regulated by KIC, we analyzed the effect of KIC gavage on whole-body insulin sensitivity and insulin signaling in vivo. We hypothesized that KIC gavage would reduce whole-body insulin sensitivity and increase S6K1-IRS-1 phosphorylation in various tissues and muscle fibers. Five-week-old male Sprague-Dawley rats were starved for 24 hours and then gavaged with 0.75ml/100g of water, leucine (22.3g/L) or KIC (30g/L) twice, ten minutes apart. They were then euthanized at different time points post-gavage (0.5-3h), and muscle, liver, and heart tissues were dissected. Other sets of gavaged animals underwent an insulin tolerance test. Phosphorylation (ph) of S6K1 (Thr389), S6 (Ser235/6) and IRS-1 (Ser612) was increased at 30 minutes post leucine gavage in skeletal muscles irrespective of fiber type. Ph-S6 (Ser235/6) was also increased in liver and heart 30 minutes after leucine gavage. KIC gavage increased ph-S6 (Ser235/6) in the liver. Neither Leucine nor KIC influenced whole-body insulin tolerance, nor ph-Akt (Ser473) in skeletal muscle and heart. BCKD-E1 α abundance was highest in the heart and liver, while ph-BCKD-E1 α (Ser293) was higher in the gastrocnemius and EDL compared to the soleus. Our data suggests that only leucine activates the S6K1-IRS-1 signaling axis in skeletal muscle, liver and heart, while KIC only does so in the liver. The effect of leucine and KIC on the S6K1-IRS-1 signaling pathway is uncoupled from whole-body insulin sensitivity. These results suggest that KIC and leucine may not induce insulin resistance, and the contributions of other tissues may regulate whole-body insulin sensitivity in response to leucine/KIC gavage.

The different associations of serum gamma-glutamyl transferase and alanine aminotransferase with insulin secretion, β-cell function, and insulin resistance in non-obese Japanese

The present study investigated the associations of serum gamma-glutamyl transferase (GGT), a marker of fatty liver and oxidative stress, and ALT/AST, a marker of fatty liver, with percentage trunk fat and postload glucose, insulin resistance, and β-cell function in middle-aged Japanese individuals, whose BMI averaged < 23.0 kg/m2. Pancreatic β-cell function was assessed using the disposition index calculated by a product of the insulinogenic index (IGI) and Matsuda insulin sensitivity index, a biomarker of early-phase glucose-stimulated insulin secretion and whole-body insulin sensitivity, respectively. Multivariate linear regression analyses revealed that the disposition index was associated inversely with GGT independently of percentage trunk fat, homeostasis model assessment insulin resistance (HOMA-IR), a marker of insulin resistance, and Matsuda index. When IGI was included instead of the disposition index, IGI (inversely) and HOMA-IR were associated with GGT independently of percentage trunk fat and Matsuda index. When the area under the glucose concentration curve (AUCg) during an oral glucose tolerance test was included instead of the disposition index, AUCg and HOMA-IR emerged as independent determinants of GGT. ALT/AST was associated with HOMA-IR alone. Results suggest a different pathophysiologic basis between GGT and ALT/AST in predicting diabetic risk in non-obese Japanese.

Liver fat accumulation is associated with increased insulin secretion independent of total, visceral, and pancreatic fat.

Studies in heterogenous groups of people with respect to sex, body mass index (BMI), and glycemic status (normoglycemia, impaired glucose tolerance, diabetes), indicate no relationship between liver fat accumulation and pancreatic insulin secretion. To better understand the association of liver fat with insulin secretion. Cross-sectional analysis of 61 men with abdominal obesity who had high liver fat (HLF, ≥5.6% by magnetic resonance spectroscopy, n=28) or low liver fat (LLF, n=33), but were balanced on BMI, total body fat, visceral adipose tissue (VAT), and pancreatic fat. A frequently sampled 5-hour oral glucose tolerance test with 11 samples, in conjunction with mathematical modeling, was used to compute indices of insulin sensitivity and insulin secretion (oral minimal model). Compared to subjects with LLF, those with HLF had significantly greater fasting glucose, insulin, C-peptide, and triglyceride; lower high-density lipoprotein-cholesterol; but similar glycated hemoglobin. Areas under the 5-hour curve for glucose, insulin, and C-peptide were greater in the HLF group than the LLF group (by ∼10%, ∼38%, and ∼28%, respectively); fasting and total postprandial insulin secretion rates were ∼37% and ∼50% greater, respectively (all P<0.05); whereas the insulinogenic index was not different. HLF subjects had lower whole-body and hepatic insulin sensitivity, disposition index, and total insulin clearance than LLF subjects (all P<0.05). Accumulation of liver fat is associated with increased insulin secretion independently of total adiposity, abdominal fat distribution, and pancreatic fat. Thereby, hyperinsulinemia in fatty liver disease is partly because of insulin hypersecretion and partly because of impaired insulin clearance.

Dysglycemia and liver lipid content determine the relationship of insulin resistance with hepatic OXPHOS capacity in obesity

Hepatic mitochondrial respiration is higher in steatosis, but lower in overt type 2 diabetes. We hypothesized that hepatic OXPHOS capacity increases with a greater degree of insulin resistance in obesity, independent of other metabolic diseases. We analysed 65 humans without diabetes (BMI 50±7 kg/m2, HbA1c 5.5±0.4%) undergoing bariatric surgery. MASLD stages were assessed by histology, whole-body insulin sensitivity (PREDIcted-M index) by oral glucose tolerance tests, and maximal ADP-stimulated mitochondrial OXPHOS capacity by high-resolution respirometry of liver samples. Prediabetes was present in 30 participants, and MASLD in 46 participants. Thereof, 25 had metabolic dysfunction-associated steatohepatitis (MASH), and seven had F2-F3 fibrosis. While simple regression did not detect an association of insulin sensitivity with hepatic OXPHOS capacity, interaction analyses revealed that the regression coefficient of OXPHOS capacity depended on fasting plasma glucose (FPG) and liver lipid content. Interestingly, the respective slopes were negative for FPG ≤100 mg/dl, but positive for FPG >100 mg/dl. Liver lipid content displayed similar behavior, with a threshold value of 24%. Post-challenge glycemia affected the association between insulin sensitivity and OXPHOS capacity normalized for citrate synthase activity. Presence of prediabetes affected hepatic insulin signaling, mitochondrial dynamics and fibrosis prevalence, while the presence of MASLD related to higher biomarkers of hepatic inflammation, cell damage and lipid peroxidation in people with normal glucose tolerance. Rising liver lipid contents and plasma glucose concentrations, even in the non-diabetic range, are associated with a progressive decline of hepatic mitochondrial adaptation in people with obesity and insulin resistance. CLINTRIALS. NCT01477957.

Greater molecular potential for glucose metabolism in adipose tissue and skeletal muscle of women compared with men.

Women typically have less muscle mass and more fat mass than men, while at the same time possessing similar or even greater whole-body insulin sensitivity. Our study aimed to investigate the molecular factors in primarily adipose tissue, but also in skeletal muscle, contributing to this sex difference. In healthy, moderately active premenopausal women and men with normal weight (28 ± 5 and 23 ± 3 years old; BMI 22.2 ± 1.9 and 23.7 ± 1.7) and in healthy, recreationally active women and men with overweight (32.2 ± 6 and 31.0 ± 5 years old; BMI 29.8 ± 4.3 & 30.9 ± 3.7) matched at age, BMI, and fitness level, we assessed insulin sensitivity and glucose tolerance with a hyperinsulinemic-euglycemic clamp or oral glucose tolerance test and studied subcutaneous adipose tissue and skeletal muscle samples with western blotting. Additionally, we traced glucose-stimulated glucose disposal in adipose tissues of female and male C57BL/6J littermate mice aged 16 weeks and measured glucose metabolic proteins. Our findings revealed greater protein expression related to glucose disposal in the subcutaneous adipose tissue (AKT2, insulin receptor, glucose transport 4) and skeletal muscle (hexokinase II, pyruvate dehydrogenase) in women compared to matched men with normal weight and with overweight. This increased protein capacity for glucose uptake extended to white adipose tissues of mice accompanied with ~2-fold greater glucose uptake compared to male mice. Furthermore, even in the obese state, women displayed better glucose tolerance than matched men, despite having 46% body fat and 20 kg less lean mass. In conclusion, our findings suggest that the superior potential for glucose disposal in female subcutaneous adipose tissue and skeletal muscle, driven by greater expression of various glucose metabolic proteins, compensates for their lower muscle mass. This likely explains women's superior glucose tolerance and tissue insulin sensitivity compared to men.

Sleep Duration Alters Overfeeding-mediated Reduction in Insulin Sensitivity.

Weight gain and sleep restriction both reduce insulin sensitivity. However, it is not known if sleep duration alters glucose metabolism in response to overfeeding. To examine the effect of sleep duration on overfeeding-mediated alterations in carbohydrate metabolism and insulin sensitivity. Retrospective exploratory analysis of a longitudinal overfeeding study in healthy participants (n = 28, age: 26.9 ± 5.5 years, body mass index: 25.74 ± 2.45 kg/m2). After providing baseline study measures, participants were overfed 40% above weight maintenance calorie requirements for 8 weeks. Insulin sensitivity was determined by a 2-step hyperinsulinemic-euglycemic clamp. Baseline habitual sleep duration was estimated by accelerometry, and sleep groups were created based on median sleep duration (5.2 hours/night). Overfeeding led to an average body weight gain of 7.3 ± .4 kg. Habitual sleep duration did not alter overfeeding-mediated body weight gain, fat gain, and fat distribution (all P > .15). Compared to participants with more sleep, fasting insulin (P = .01) and homeostatic model assessment for insulin resistance (P = .02) increased while fasting glucose remained unchanged (P = .68) with overfeeding in participants with shorter sleep duration. Glucose infusion rate during high insulin dose was reduced with overfeeding in participants with short sleep duration but not in participants with more sleep (P < .01). Overfeeding mediated weight gain reduced liver, adipose, and whole-body insulin sensitivity prominently in individuals with short sleep duration but not in individuals with longer sleep duration. This suggests that promoting adequate sleep during short periods of overeating may prevent detrimental effects on glucose metabolism.

Maintaining Stabilization of Blood Sugar Levels in Diabetes Mellitus Patients with Foot Exercises: Case Report

The chronic hyperglycemia of diabetes is associated with long-term damage, dysfunction, and failure of different organs. Physical activity is one of the factors that affect glycemic management. This case study aims to maintain the stability of blood sugar levels in DM patients by applying leg exercises. The design of this research is a case report with a nursing process approach carried out on Diabetes Mellitus patients with nursing problems of unstable blood sugar levels. Nursing care was carried out for seven days at the Muhammadiyah Ponorogo General Hospital. The intervention implemented is foot exercises. The results of the case study are presented in the form of nursing documentation. The case study results showed that the patient's blood sugar levels tended to be stable starting on the second day of the intervention.Exercise-induced glycemic control is mostly explained by an increase in whole-body insulin sensitivity. The long-term advantages of frequent exercise on glycemic control appear to be related to the cumulative effect of transitory gains in insulin sensitivity and glycemic control after each bout of exercise, rather than structural changes in insulin sensitivity. Keywords: blood sugar level; diabetes mellitus; foot exercise

Different effects of bariatric surgery on epigenetic plasticity in skeletal muscle of individuals with and without type 2 diabetes

AimBariatric surgery is highly effective for the treatment of obesity in individuals without (OB11OB: individuals with obesity.) and in those with type 2 diabetes (T2D22T2D: individuals with obesity and type 2 diabetes.). However, whether bariatric surgery triggers similar or distinct molecular changes in OB and T2D remains unknown. Given that individuals with type 2 diabetes often exhibit more severe metabolic deterioration, we hypothesized that bariatric surgery induces distinct molecular adaptations in skeletal muscle, the major site of glucose uptake, of OB and T2D after surgery-induced weight loss. MethodsAll participants (OB, n = 13; T2D, n = 13) underwent detailed anthropometry before and one year after the surgery. Skeletal muscle biopsies were isolated at both time points and subjected to transcriptome and methylome analyses using a comprehensive bioinformatic pipeline. ResultsBefore surgery, T2D had higher fasting glucose and insulin levels but lower whole-body insulin sensitivity, only glycemia remained higher in T2D than in OB after surgery. Surgery-mediated weight loss affected different subsets of genes with 2,013 differentially expressed in OB and 959 in T2D. In OB differentially expressed genes were involved in insulin, PPAR signaling and oxidative phosphorylation pathways, whereas ribosome and splicesome in T2D. LASSO regression analysis revealed distinct candidate genes correlated with improvement of phenotypic traits in OB and T2D. Compared to OB, DNA methylation was less affected in T2D in response to bariatric surgery. This may be due to increased global hydroxymethylation accompanied by decreased expression of one of the type 2 diabetes risk gene, TET2, encoding a demethylation enzyme in T2D. ConclusionOB and T2D exhibit differential skeletal muscle transcriptome responses to bariatric surgery, presumably resulting from perturbed epigenetic flexibility.

Daily standing time, dietary fiber, and intake of unsaturated fatty acids are beneficially associated with hepatic insulin sensitivity in adults with metabolic syndrome.

Obesity is associated with impaired glucose metabolism and hepatic insulin resistance. The aim was to investigate the associations of hepatic glucose uptake (HGU) and endogenous glucose production (EGP) to sedentary behavior (SB), physical activity (PA), cardiorespiratory fitness, dietary factors, and metabolic risk markers. Forty-four adults with metabolic syndrome (mean age 58 [SD 7] years, BMI ranging from 25-40kg/; 25 females) were included. HGU was measured by positron emission tomography during the hyperinsulinemic-euglycemic clamp. EGP was calculated by subtracting the glucose infusion rate during clamp from the glucose rate of disappearance. SB and PA were measured with hip-worn accelerometers (26 [SD3] days). Fitness was assessed by maximal bicycle ergometry with respiratory gas measurements and dietary intake of nutrients by 4-day food diaries. HGU was not associated with fitness or any of the SB or PA measures. When adjusted for sex, age, and body fat-%, HGU was associated with whole-body insulin sensitivity (β=0.58), water-insoluble dietary fiber (β=0.29), energy percent (E%) of carbohydrates (β=-0.32), saccharose (β=-0.32), mono- and polyunsaturated fatty acids (β=0.35, β=0.41, respectively). EGP was associated with whole-body insulin sensitivity (β=-0.53), and low-density lipoprotein cholesterol [β=-0.31], and when further adjusted for accelerometry wear time, EGP was associated with standing [β=-0.43]. (p-value for all< 0.05). Standing more, consuming a diet rich in fiber and unsaturated fatty acids, and a lower intake of carbohydrates, especially sugar, associate beneficially with hepatic insulin sensitivity. Habitual SB, PA, or fitness may not be the primary modulators of HGU and EGP. However, these associations need to be confirmed with intervention studies.

Hypoxia-Induced Insulin Resistance Mediates the Elevated Cardiovascular Risk in Patients with Obstructive Sleep Apnea: A Comprehensive Review.

Patients with obstructive sleep apnea (OSA) experience insulin resistance and its clinical consequences, including hypertriglyceridemia, reduced high density lipoprotein-associated cholesterol (HDL-c), visceral adiposity, hepatic steatosis, increased epicardial fat thickness, essential hypertension, glucose intolerance, increased risk for type 2 diabetes, chronic kidney disease, subclinical vascular damage, and increased risk for cardiovascular events. Obesity is a major contributor to OSA. The prevalence of OSA is almost universal among patients with severe obesity undergoing bariatric surgery. However, insulin resistance and its clinical complications occur in OSA patients irrespective of general obesity (body mass index). In OSA patients, apnea episodes during sleep induce oxyhemoglobin desaturation and tissue hypoxia. Insulin resistance is an adaptive response to tissue hypoxia and develops in conditions with limited tissue oxygen supply, including healthy subjects exposed to hypobaric hypoxia (high altitude) and OSA patients. Indicators of oxyhemoglobin desaturation have been robustly and independently linked to insulin resistance and its clinical manifestations in patients with OSA. Insulin resistance mediates the elevated rate of type 2 diabetes, chronic kidney disease, and cardiovascular disease unexplained with traditional cardiovascular risk factors present in OSA patients. Pathophysiological processes underlying hypoxia-induced insulin resistance involve hypoxia inducible factor-1 upregulation and peroxisome proliferator-activated receptor-gamma (PPAR- ) downregulation. In human adipose tissue, PPAR- activity promotes glucose transport into adipocytes, lipid droplet biogenesis, and whole-body insulin sensitivity. Silencing of PPAR- in the adipose tissue reduces glucose uptake and fat accumulation into adipocytes and promotes insulin resistance. In conclusion, tissue hypoxia drives insulin resistance and its clinical consequences in patients with OSA, regardless of body mass index.

The impact of short-term eucaloric low- and high-carbohydrate diets on liver triacylglycerol content in males with overweight and obesity: a randomized crossover study

BackgroundIntrahepatic triacylglycerol (liver TG) content is associated with hepatic insulin resistance and dyslipidemia. Liver TG content can be modulated within days under hypocaloric conditions. ObjectivesWe hypothesized that 4 d of eucaloric low-carbohydrate/high-fat (LC) intake would decrease liver TG content, whereas a high-carbohydrate/low-fat (HC) intake would increase liver TG content, and further that alterations in liver TG would be linked to dynamic changes in hepatic glucose and lipid metabolism. MethodsA randomized crossover trial in males with 4 d + 4 d of LC and HC, respectively, with ≥2 wk of washout. 1H-magnetic resonance spectroscopy (1H-MRS) was used to measure liver TG content, with metabolic testing before and after intake of an LC diet (11E% carbohydrate corresponding to 102 ± 12 {mean ± standard deviation [SD]) g/d, 70E% fat} and an HC diet (65E% carbohydrate corresponding to 537 ± 56 g/d, 16E% fat). Stable [6,6-2H2]-glucose and [1,1,2,3,3-D5]-glycerol tracer infusions combined with hyperinsulinemic-euglycemic clamps and indirect calorimetry were used to measure rates of hepatic glucose production and lipolysis, whole-body insulin sensitivity and substrate oxidation. ResultsEleven normoglycemic males with overweight or obesity (BMI 31.6 ± 3.7 kg/m2) completed both diets. The LC diet reduced liver TG content by 35.3% (95% confidence interval: −46.6, −24.1) from 4.9% [2.4–11.0] (median interquartile range) to 2.9% [1.4–6.9], whereas there was no change after the HC diet. After the LC diet, fasting whole-body fat oxidation and plasma beta-hydroxybutyrate concentration increased, whereas markers of de novo lipogenesis (DNL) diminished. Fasting plasma TG and insulin concentrations were lowered and the hepatic insulin sensitivity index increased after LC. Peripheral glucose disposal was unchanged. ConclusionsReduced carbohydrate and increased fat intake for 4 d induced a marked reduction in liver TG content and increased hepatic insulin sensitivity. Increased rates of fat oxidation and ketogenesis combined with lower rates of DNL are suggested to be responsible for lowering liver TG. This trial was registered at clinicaltrials.gov as NCT04581421.

BCAAs acutely drive glucose dysregulation and insulin resistance: role of AgRP neurons

BackgroundHigh-protein diets are often enriched with branched-chain amino acids (BCAAs) known to enhance protein synthesis and provide numerous physiological benefits, but recent studies reveal their association with obesity and diabetes. In support of this, protein or BCAA supplementation is shown to disrupt glucose metabolism while restriction improves it. However, it is not clear if these are primary, direct effects of BCAAs or secondary to other physiological changes during chronic manipulation of dietary BCAAs.MethodsThree-month-old C57Bl/6 mice were acutely treated with either vehicle/BCAAs or BT2, a BCAA-lowering compound, and detailed in vivo metabolic phenotyping, including frequent sampling and pancreatic clamps, were conducted.ResultsUsing a catheter-guided frequent sampling method in mice, here we show that a single infusion of BCAAs was sufficient to acutely elevate blood glucose and plasma insulin. While pre-treatment with BCAAs did not affect glucose tolerance, a constant infusion of BCAAs during hyperinsulinemic–euglycemic clamps impaired whole-body insulin sensitivity. Similarly, a single injection of BT2 was sufficient to prevent BCAA rise during fasting and markedly improve glucose tolerance in high-fat-fed mice, suggesting that abnormal glycemic control in obesity may be causally linked to high circulating BCAAs. We further show that chemogenetic over-activation of AgRP neurons in the hypothalamus, as present in obesity, significantly impairs glucose tolerance that is completely normalized by acute BCAA reduction. Interestingly, most of these effects were demonstrated only in male, but not in female mice.ConclusionThese findings suggest that BCAAs per se can acutely impair glucose homeostasis and insulin sensitivity, thus offering an explanation for how they may disrupt glucose metabolism in the long-term as observed in obesity and diabetes. Our findings also reveal that AgRP neuronal regulation of blood glucose is mediated through BCAAs, further elucidating a novel mechanism by which brain controls glucose homeostasis.