Interest of the waist-to-height ratio to predict metabolic syndrome in type 2 diabetic patients

INTRODUCTION

Metabolic syndrome (MetS) is defined as a cluster of risk factors for cardiovascular disease.

AIM

To determine the optimal cut-off point of the waist-to-height ratio (WHtR) at which MetS can be identified with maximum sensitivity and specificity in a sample of Tunisian type 2 diabetic patients.

METHODS

We enrolled 457 type 2 diabetic patients in a cross-sectional study. Blood pressure, anthropometric indices, fasting glucose, and lipid profile were measured. WHtR was calculated. MetS was defined according to the IDF criteria. Receiver operating characteristic (ROC) curve analysis was used to identify the optimal cut-off value of WHtR in MetS screening with maximum sensitivity and specificity.

RESULTS

The overall prevalence of MetS was 79.8%, it was higher in women than in men (85.5% vs 61.4%; p.

Associations Between Erythrocyte Membrane Fatty Acid Compositions and Biomarkers of Vascular Health in Adults With Type 1 Diabetes With and Without Insulin Resistance: A Cross-Sectional Analysis

OBJECTIVES

The aim of this study was to assess the relationship between specific erythrocyte fatty acid levels and vascular health in type 1 diabetes (T1D) with and without insulin resistance (IR).

METHODS

We analyzed baseline pretreatment data in a subset of 23 patients with T1D from a previously published randomized controlled trial consisting of comprehensive erythrocyte-derived fatty acid profiles and a panel of inflammation-associated endothelial markers. Estimated glucose disposal rate was used to identify and categorize patients with IR. We utilized principal component analysis (PCA) to cluster vascular biomarkers to compute a single "vascular signal" and utilized univariate linear regression models to investigate the association with IR and fatty acid profiles.

RESULTS

Subjects with IR displayed significantly higher levels of linoleic acid (p=0.001), lower levels of eicosapentaenoic acid (EPA) (p<0.001), lower levels of omega-3 polyunsaturated fatty acid (n-3PUFA) (p<0.006) and an increased omega-6 (n-6)PUFA:n-3PUFA ratio (p=0.001). IR was associated with significantly higher linoleic acid levels, total n-6PUFA and an increased ratio of n-6PUFA:n-3PUFA, and negatively associated with arachidonic acid and EPA levels, total saturated fatty acid and total n-3PUFA. The PCA-derived vascular biomarker cluster was positively associated with linoleic acid and n-6PUFA:n-3PUFA ratio, and inversely associated with EPA.

CONCLUSIONS

Specific erythrocyte membrane fatty acid compositions are associated with impaired vascular health and IR in adults with T1D. These findings suggest that IR and risk of associated complications may be influenced by specific fatty acid profiles, and thus potentially modified by the selective targeting of dietary fatty acids.

Impact of sleeve gastrectomy on abnormalities in carbohydrate tolerance in obese adult

INTRODUCTION

Facing the repeated failures of the medical management of obesity, bariatric surgery offers a promising therapeutic option in terms of achieving weight loss and metabolic benefits.

AIM

To evaluate the impact of sleeve gastrectomy on the carbohydrate profile of a group of obese subjects.

METHODS

It is a prospective study including 40 obese patients (7 Men and 33 Women) who underwent sleeve gastrectomy between 2016 and 2018. Clinical and biological parameters were collected before the intervention, at six months and one year after. Insulin resistance was defined by a HOMA-IR index ≥2.4. Remission of diabetes was determined using the American Society for Metabolic and Bariatric Surgery's (ASMBS) criteria.

RESULTS

The mean patients' age was 34.65 ± 8.17 years. The mean body mass index (BMI) was 50.23 ± 8.3 kg/m². One year after sleeve gastrectomy, the frequency of insulin resistance, decreased from 89% to 4% (p<0.05). The evolution of carbohydrate tolerance abnormalities was marked by the diabetes and prediabetes remission in 75% and 100% of cases, respectively. The mean excess weight loss was 55.8% at 12 months.

CONCLUSION

These results have expanded our knowledge of the short-term sleeve gastrectomy's effectiveness on the carbohydrate profile of obese subjects. However, it would be interesting to check the durability of this metabolic benefit in the medium and long term.

Rosemary extract activates AMPK, inhibits mTOR and attenuates the high glucose and high insulin-induced muscle cell insulin resistance

Impaired action of insulin in skeletal muscle, termed insulin resistance, leads to increased blood glucose levels resulting in compensatory increase in insulin levels. The elevated blood glucose and insulin levels exacerbate insulin resistance and contribute to the pathogenesis of type 2 diabetes mellitus. In previous studies we found attenuation of free fatty acid-induced muscle cell insulin resistance by rosemary extract (RE). In the present study we investigated the effects of RE on high glucose (HG) and high insulin (HI)-induced muscle cell insulin resistance. Exposure of L6 myotubes to 25 mmol/L glucose and 100 nmol/L insulin for 24 h, to mimic hyperglycemia and hyperinsulinemia, abolished the acute insulin-stimulated glucose uptake, increased the serine phosphorylation of IRS-1 and the phosphorylation/activation of mTOR and p70S6K. Treatment with RE significantly improved the insulin-stimulated glucose uptake and increased the acute insulin-stimulated tyrosine phosphorylation while reducing the HG+HI-induced serine phosphorylation of IRS-1 and phosphorylation of mTOR and p70S6K. Additionally, treatment with RE significantly increased the phosphorylation of AMPK, its downstream effector ACC and the plasma membrane GLUT4 levels. Our data indicate a potential of RE to counteract muscle cell insulin resistance and more studies are required to investigate its effectiveness in vivo. Novelty: RE phosphorylated muscle cell AMPK and ACC under both normal and HG+HI conditions. The HG+HI-induced serine phosphorylation of IRS-1 and activation of mTOR and p70S6K were attenuated by RE. RE restored the insulin-stimulated glucose uptake by enhancing GLUT4 glucose transporter translocation to plasma membrane.

Prior ingestion of a ketone monoester supplement reduces postprandial glycemic responses in young healthy-weight individuals

The main objective of this study was to determine whether acute ingestion of a ketone monoester (KME) supplement impacted mixed-meal tolerance test (MMTT) glucose area under the curve (AUC). Nineteen healthy young volunteers (10 males/9 females; age, 24.7 ± 4.9 years; body mass index, 22.7 ± 2.4 kg/m²) participated in a double-blind, placebo-controlled crossover study. Following overnight fasting (≥10 h), participants consumed 0.45 mL/kg of a KME supplement or taste-matched placebo followed by an MMTT 15 min later. Blood samples were collected every 15-30 min over 2.5 h. KME supplementation acutely raised β-hydroxybutyrate AUC (590%, P < 0.0001, d = 2.4) and resulted in decreases in blood glucose AUC (-9.4%, P = 0.03, d = 0.56) and nonesterified fatty acid (NEFA) AUC (-27.3%, P = 0.023, d = 0.68) compared with placebo. No differences were found for plasma insulin AUC (P = 0.70) or gastric emptying estimated by co-ingested acetaminophen AUC (P = 0.96) between ketone and placebo. Overall, results indicate that KME supplementation attenuates postprandial glycemic and NEFA responses when taken 15 min prior to a mixed meal in young healthy individuals. Future studies are warranted to investigate whether KME supplementation may benefit individuals with impaired glycemic control. Novelty: Acute ketone monoester supplementation 15 min prior to a mixed meal decreased postprandial glucose and NEFA levels without significantly impacting postprandial insulin or estimates of gastric emptying. Glucose- and NEFA-lowering effects of ketone monoester supplementation are apparently not mediated by changes in insulin release or gastric emptying.

Greater Nutritional Risk Scores in 2-Year-Old Children Exposed to Gestational Diabetes Mellitus In Utero and Their Relationship to Homeostasis Model Assessment for Insulin Resistance at Age 5 Years

OBJECTIVES

Exposure to gestational diabetes mellitus (GDM) in utero may impact nutritional intake and lifestyle habits in early childhood. However, it is unclear whether nutritional status predicts greater risk for metabolic disturbances, such as insulin resistance (IR). The primary objectives were: 1) to determine parent-reported nutritional risk scores in 2-year-old children born to women with and without GDM and 2) to assess whether these scores predict IR in 5-year-old children.

METHODS

Children exposed (n=34) and unexposed (n=46) to GDM were screened at 2 years of age using the Toddler version of the Nutrition Screening Tool for Every Preschooler (NutriSTEP). At a 5-year follow up, IR was assessed using the Homeostatic Model Assessment for Insulin Resistance (HOMA-IR).

RESULTS

Total NutriSTEP scores ranged from 6 to 33, with higher scores indicating greater risk. After controlling for infant birthweight, sex of the child, child ethnicity, maternal age at time of pregnancy, breastfeeding status and maternal prepregnancy body mass index, average NutriSTEP scores were higher in children exposed to GDM compared with those unexposed (13.8±1.1 vs 11.2±1.1, p=0.03). NutriSTEP scores at 2 years emerged as a positive independent predictor of HOMA-IR at 5 years. For each unit increase in NutriSTEP score, suggesting greater nutritional risk, we saw a 0.48 (95% confidence interval, 0.17 to 0.80; p=0.003) increase in score on the HOMA-IR.

CONCLUSIONS

Parent-reported nutritional risk is greater in GDM-exposed children, and these nutritional behaviours developed during the first years of life may predispose to metabolic disturbance in early childhood.

Does high dietary protein intake contribute to the increased risk of developing prediabetes and type 2 diabetes?

Insulin resistance is a complex metabolic disorder implicated in the development of many chronic diseases. While it is generally accepted that body mass loss should be the primary approach for the management of insulin resistance-related disorders in overweight and obese individuals, there is no consensus among researchers regarding optimal protein intake during dietary restriction. Recently, it has been suggested that increased plasma branched-chain amino acids concentrations are associated with the development of insulin resistance and type 2 diabetes. The exact mechanism by which excessive amino acid availability may contribute to insulin resistance has not been fully investigated. However, it has been hypothesised that mammalian target of rapamycin (mTOR) complex 1 hyperactivation in the presence of amino acid overload contributes to reduced insulin-stimulated glucose uptake because of insulin receptor substrate (IRS) degradation and reduced Akt-AS160 activity. In addition, the long-term effects of high-protein diets on insulin sensitivity during both weight-stable and weight-loss conditions require more research. This review focusses on the effects of high-protein diets on insulin sensitivity and discusses the potential mechanisms by which dietary amino acids can affect insulin signalling. Novelty: Excess amino acids may over-activate mTOR, resulting in desensitisation of IRS-1 and reduced insulin-mediated glucose uptake.

Substitution of parts of aerobic training by resistance training lowers fasting hyperglycemia in individuals with metabolic syndrome

We sought to determine the effects of substituting parts of aerobic training (AT) by resistance training (RT) on metabolic syndrome (MetS) factors. MetS patients (aged 56 ± 7 years; body mass index 33 ± 5 kg·m^-2 and 3.9 ± 0.8 MetS factors) were randomized to undergo 1 of the following isocaloric, 16-week long exercise programs: (i) cycling 4 bouts of 4-min at 90% of maximal heart rate (HR_max) followed by 3 sets of 12 repetitions of 3 lower limb free-weight exercises (high-intensity interval training (HIIT)+RT group; n = 33), (ii) cycling 5 bouts of 4 min at 90% of HR_max (HIIT+HIIT group; n = 33), or (iii) no exercise control group (n = 21). We measured the evolution of all 5 MetS components (z score), cardiorespiratory fitness (maximal oxygen uptake), leg strength and power (leg press 1-repetition maximum (1RM) and countermovement jump (CMJ)), fasting blood glucose (FG), fasting insulin, and insulin resistance (homeostasis model assessment 2). Both training groups improved maximal oxygen uptake similarly (170 ± 310 and 190 ± 210 mL O₂·min^-1; P < 0.001) and z score (-0.12 ± 0.29 and -0.12 ± 0.31 for HIIT+RT and HIIT+HIIT, respectively; P < 0.02). However, only HIIT+RT improved CMJ (P = 0.002) and leg press 1RM above the HIIT+HIIT group (21% vs 6%; P < 0.001). Furthermore, FG only decreased in the HIIT+RT group (5%; P = 0.026, time × group). Our findings suggest that substitution of part of HIIT by leg RT improves glucose control in MetS individuals. Novelty Most studies addressing the efficacy of endurance versus resistance training are not matched by energy expenditure. We found that substituting 20% of AT with RT reduces hyperglycemia in MetS individuals. Training recommendations to regain glycemic control in MetS individuals should include resistance training.

Hypoglycaemic effect of catalpol in a mouse model of high-fat diet-induced prediabetes

Type 2 diabetes mellitus is a major health problem and a societal burden. Individuals with prediabetes are at increased risk of type 2 diabetes mellitus. Catalpol, an iridoid glycoside, has been reported to exert a hypoglycaemic effect in db/db mice, but its effect on the progression of prediabetes is unclear. In this study, we established a mouse model of prediabetes and examined the hypoglycaemic effect, and the mechanism of any such effect, of catalpol. Catalpol (200 mg/(kg·day)) had no effect on glucose tolerance or the serum lipid level in a mouse model of impaired glucose tolerance-stage prediabetes. However, catalpol (200 mg/(kg·day)) increased insulin sensitivity and decreased the fasting glucose level in a mouse model of impaired fasting glucose/impaired glucose tolerance-stage prediabetes. Moreover, catalpol increased the mitochondrial membrane potential (1.52-fold) and adenosine triphosphate content (1.87-fold) in skeletal muscle and improved skeletal muscle function. These effects were mediated by activation of the insulin receptor-1/glucose transporter type 4 (IRS-1/GLUT4) signalling pathway in skeletal muscle. Our findings will facilitate the development of a novel approach to suppressing the progression of diabetes at an early stage. Novelty Catalpol prevents the progression of prediabetes in a mouse model of prediabetes. Catalpol improves insulin sensitivity in skeletal muscle. The effects of catalpol are mediated by activation of the IRS-1/GLUT4 signalling pathway.

Weight loss efficacy of alternate day fasting versus daily calorie restriction in subjects with subclinical hypothyroidism: a secondary analysis

This study compared the weight loss efficacy of alternate-day fasting (ADF) versus daily calorie restriction (CR) in adults with subclinical hypothyroidism. After 6 months, body weight decreased (P < 0.001) similarly by ADF (-7% ± 1%) and CR (-8% ± 2%). Insulin resistance decreased (P < 0.05) more by ADF versus CR. Free thyroxin and thyroid-stimulating hormone remained unchanged. Thus, ADF and CR produce similar weight loss in this population, without affecting thyroid hormone levels. Novelty Intermittent fasting and daily restriction produce similar reductions in body weight in subjects with subclinical hypothyroidism.

The effects of chromium and vitamin D3 co-supplementation on insulin resistance and tumor necrosis factor-alpha in type 2 diabetes: a randomized placebo-controlled trial

The current study was conducted to assess the effects of simultaneous usage with vitamin D₃ and chromium picolinate (CrPic) supplementations on homeostasis model assessment of insulin resistance (HOMA-IR), fasting blood glucose (FBS), hemoglobin A1c (HbA1c), tumor necrosis factor-α (TNF-α), and lipid profile in type 2 diabetes mellitus (T2DM). Ninety-two patients with T2DM were randomly allocated to the following 4 groups for 4 months: (I) placebo of vitamin D₃ (n = 23); (II) vitamin D₃ supplement at a dose of 50 000 IU/week (n = 23); (III) CrPic supplement at a dose of 500 μg/day (n = 23); and (IV) both vitamin D₃ at a dose of 50 000 IU/week and CrPic at a dose of 500 μg/day (n = 23). HOMA-IR levels increased significantly in groups I and II after the intervention. However, this increase in group I was significantly higher than that in group II after the treatment. HOMA-IR levels were controlled in groups III and IV during the intervention. TNF-α decreased significantly in groups II, III, and IV after the intervention. FBS, HbA1c, and lipid profile did not change significantly in total groups after the intervention. It seems that chromium and vitamin D₃ co-supplementation are probably effective in controlling HOMA-IR by decreasing TNF-α in T2DM. Novelty Chromium alone and/or in simultaneous pretreatment with vitamin D₃ is more effective than vitamin D₃ in controlling HOMA-IR in T2DM. Chromium and vitamin D₃ alone and/or in simultaneous pretreatment decrease TNF-α in T2DM.

Egg oil from Portunus trituberculatus alleviates insulin resistance through activation of insulin signaling in mice

Marine bioactive lipids have been utilized to overcome insulin resistance. However, oil from swimming crab has never been studied. Here, we analyzed the constituents of egg oil from Portunus trituberculatus (Pt-egg oil) and investigated its protective effects against insulin resistance in mice on a high-fat diet. The results showed that Pt-egg oil contained 52.05% phospholipids, 8.61% free fatty acids (especially eicosapentaenoic acid and docosahexaenoic acid), 32.38% triglyceride, 4.79% total cholesterol, and ditissimus astaxanthin. Animal experiments showed that Pt-egg oil significantly mitigated insulin resistance and was associated with reductions in blood glucose, insulin, glucose tolerance, insulin tolerance, serum lipids, and hepatic glycogen. Pt-egg oil activated the phosphatidylinositol 3-hydroxy kinase (PI3K)/protein kinase B (Akt)/glucose transporter 4 pathway in skeletal muscle both at the transcriptional level and at the translational level. Pt-egg oil also promoted hepatic glycogen synthesis through activation of the PI3K/Akt/glycogen synthase kinase-3 beta pathway. These indicate that Pt-egg oil can be used as an alternative to marine bioactive lipids to improve insulin resistance.

Elevated insulin levels following 7 days of increased sedentary time are due to lower hepatic extraction and not higher insulin secretion

Higher insulin following sedentary behavior may be due to increased insulin secretion (IS), decreased hepatic insulin extraction (HIE), or a combination of both. Ten healthy adults completed glucose tolerance tests following 7 days of normal activity and 7 days of increased sitting. There were no differences in IS; however, HIE at 120 min after ingestion (85.4% ± 7.2% vs. 74.6% ± 6.6%, p < 0.05) and the area under the curve (73.6% ± 9.4% vs. 67.5% ± 11.3%, p < 0.05) were reduced following 7 days of increased sedentary time.

Impact of flaxseed and soy nuts as dietary supplements on lipid profile, insulin sensitivity, and GLUT4 expression in ovariectomized rats

We assessed the effects of a diet with flaxseed or soy nuts versus estradiol on the lipid profile, insulin sensitivity, and glucose transporter type 4 (GLUT4) expression in ovariectomized female rats. Forty-four female Wistar rats (90 days old) underwent ovariectomy and were divided into 4 groups: C (standard diet), E (standard diet + subcutaneous 17β-estradiol pellets), L (standard diet + flaxseed + subcutaneous placebo pellets), and S (standard diet + soy nuts + subcutaneous placebo pellets). Customized diets and the insertion of pellets were started 21 days after ovariectomy and were continued for another 21 days. We measured body mass, insulin tolerance, total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, triglycerides, and GLUT4 (in cardiac and adipose tissues). We found a lower body mass and a lower Lee index in group E and a trend toward improved insulin sensitivity in group S (p = 0.066). Groups L and S showed a better lipid profile when compared with group C. Microsomal GLUT4 increased in group L (in cardiac and adipose tissues), and plasma membrane GLUT4 increased in groups E, L, and S (in both tissues). We conclude that flaxseed and soy nuts as dietary supplements improve lipid profile and increase GLUT4 expression.

Effect of exercise on acute postprandial glucose concentrations and interleukin-6 responses in sedentary and overweight males

This study examined the effect of 2 forms of exercise on glucose tolerance and the concurrent changes in markers associated with the interleukin (IL)-6 pathways. Fifteen sedentary, overweight males (29.0 ± 3.1 kg/m2) completed 2 separate, 3-day trials in randomised and counterbalanced order. An oral glucose tolerance test (OGTT; 75 g) was performed at the same time on each day of the trial. Day 2 of each trial consisted of a single 30-min workload-matched bout of either high-intensity intermittent exercise (HIIE; alternating 100% and 50% of peak oxygen uptake) or continuous moderate-intensity exercise (CME; 60 % of peak oxygen uptake) completed 1 h prior to the OGTT. Venous blood samples were collected before, immediately after, 1 h after, and 25 h after exercise for measurement of insulin, C-peptide, IL-6, and the soluble IL-6 receptors (sIL-6R; soluble glycoprotein 130 (sgp130)). Glucose area under the curve (AUC) was calculated from capillary blood samples collected throughout the OGTT. Exercise resulted in a modest (4.4%; p = 0.003) decrease in the glucose AUC when compared with the pre-exercise AUC; however, no differences were observed between exercise conditions (p = 0.65). IL-6 was elevated immediately after and 1 h after exercise, whilst sgp130 and sIL-6R concentrations were reduced immediately after exercise. In summary, exercise was effective in reducing glucose AUC, which was attributed to improvements that took place between 60 and 120 min into the OGTT, and was in parallel with an increased ratio of IL-6 to sIL-6R, which accords with an increased activation via the "classical" IL-6 signalling pathway. Our findings suggest that acute HIIE did not improve glycaemic response when compared with CME.

Sex differences in the developmental origins of cardiometabolic disease following exposure to maternal obesity and gestational diabetes 1

Over the past 30 years, the worldwide prevalence of obesity has nearly doubled. In addition, more and more women in their child-bearing years are overweight or obese, which increases the risk of gestational diabetes mellitus (GDM). It is increasingly accepted by the scientific community that early life exposure to environmental stress influences the long-term health of an individual, which has been termed the Developmental Origins of Health and Disease theory. Evidence from human cohorts and epidemiological and animal studies has shown that maternal obesity and GDM condition the offspring for cardiometabolic disease development. These effects are most likely regulated by epigenetic mechanisms; however, biological sex is an important factor in defining the risk of the development of several metabolic health disorders. The aim of this review is to describe the current evidence from human cohort and animal model studies that implicates sex differences in the developmental origins of cardiometabolic disease following exposure to maternal obesity and GDM. In addition, this review addresses the potential mechanisms involved in these sex differences. In many studies, sex is ignored as an important variable in disease development; however, the results presented in this review highlight important differences between sexes in the developmental programming of biological responses to exposures during the fetal stage. This knowledge will ultimately help in the development of effective therapeutic strategies for the treatment of cardiometabolic diseases that exhibit sexual dimorphism.

Zinc supplementation reduces diet-induced obesity and improves insulin sensitivity in rats

Rates of obesity have been growing at alarming rates, compromising the health of the world population. Thus, the search for interventions that address the metabolic repercussions of obesity are necessary. Here we evaluated the metabolic and antioxidant effects of zinc and branched-chain amino acids (BCAA) supplementation on obese rats. Male Wistar rats were fed either a high-fat/high-fructose diet (HFD) or a standard diet (SD) for 19 weeks. From the fifteenth week until the end of the experiment, HFD- and SD-fed rats received zinc (6 mg/kg) or BCAA (750 mg/kg) supplementation. Body weight, abdominal fat, lipid profile, blood glucose, insulin, leptin, and hepatic transaminases were evaluated. In the liver, superoxide dismutase and catalase activities and lipid peroxidation were also analyzed. HFD-fed animals showed increased weight gain, abdominal fat pad, plasma insulin, leptin, and triglycerides levels in comparison with SD-fed rats. Zinc supplementation reduced all these parameters, suggesting a beneficial role for the treatment of obesity. BCAA, on the other hand, did not show any beneficial effect. Liver antioxidant enzymes and hepatic transaminases plasma levels did not change among groups. Lipid peroxidation was higher in HFD-fed rats and was not reverted by zinc or BCAA supplementation. In conclusion, zinc supplementation may be a useful strategy for the treatment of the metabolic dysfunction associated with obesity.

Improving hepatic mitochondrial biogenesis as a postulated mechanism for the antidiabetic effect of Spirulina platensis in comparison with metformin

Various nutritional and medicinal potencies have been accredited to metabolites from the cyanobacteria, Spirulina platensis (Arthrospira platensis) sp. Hence, our study was designed to examine whether the Spirulina supplementation would possess beneficial effects in type 2 diabetes mellitus (T2DM) in comparison with metformin. High-fat diet/low-dose streptozotocin (HFD/STZ) model was adopted and the diabetic rats were orally treated with metformin (200 mg/kg) or Spirulina (250 or 500 or 750 mg/kg) for 30 days. Spirulina ameliorated the HFD/STZ-induced elevation of fasting blood glucose, insulin, and hepatic enzymes. Moreover, Spirulina successfully rectified disrupted serum lipid profile and exhibited an anti-inflammatory effect via tumor necrosis factor-α and adiponectin modulation. On the molecular level, Spirulina reduced the expression of hepatic sterol regulatory element binding protein-1c (SREBP-1c), confirming its lipotropic effect. Furthermore, Spirulina amended compromised hepatic mitochondrial biogenesis signaling by significantly increasing peroxisome proliferator-activated receptor-gamma coactivator-1α (PGC-1α), mitochondrial transcription factor A (Tfam), and mitochondrial DNA (mtDNA) copy number. On almost all parameters, the highest dose of Spirulina showed the best effects, which were comparable to that of metformin. To our knowledge, our study is the first to attribute the various aspects of the effect of Spirulina to the SREBP-1c and PGC-1α/Tfam/mtDNA pathways in liver. The present results clearly proved that Spirulina modulated glucose/lipid profile and exhibited prominent anti-inflammatory properties through SREBP-1c inhibition and hepatic mitochondrial biogenesis enhancement. Thus, Spirulina can be considered as an add-on to conventional antidiabetic agents and might influence the whole dynamics of the therapeutic approaches in T2DM.

The Association of Potato Intake With Risk for Incident Type 2 Diabetes in Adults

OBJECTIVES

Previous studies indicate that the risk for diabetes associated with high consumption of potato differs in various populations. We aimed to investigate the associations between total, boiled and fried potato intake and the risk for incident diabetes in Tehranian adults.

METHODS

This cohort study was conducted in 1,981 adults, aged 19 to 70 years, who participated in the Tehran Lipid and Glucose Study and were followed up for 6 years. Usual dietary potato intakes were assessed using a valid and reliable food-frequency questionnaire. Anthropometric, biochemical and blood pressure data were determined, and diabetes was defined according to the criteria of the American Diabetes Association.

RESULTS

The mean (± SD) age and potato intake of participants was 38.9±13.4 years and 30.2±30.7 g/day, respectively. The risk for incident diabetes in participants was 6.7% after 6 years of follow up. After adjusting for age, sex, body mass index, physical activity, smoking, family history of diabetes, hypertension, serum triglyceride levels, high-density lipoprotein cholesterol levels, energy intakes and consumption of saturated fat, fruit, whole grains, vegetables, nuts and legumes, the risk for incident diabetes was lower in subjects with higher intakes of total potato (OR=0.46; 95% CI 0.25 to 0.84) and boiled potato (OR=0.47; 95% CI 0.26 to 0.85) in comparison with those who had the lowest intakes (p for trend <0.05). However, there was no significant association between fried potato intake and risk for diabetes (OR=0.50; 95% CI 0.25 to 1.07; p for trend >0.05).

CONCLUSIONS

Our findings indicate that, in Tehranian adults, a moderate intake of dietary total and boiled, but not fried, potatoes may be associated with a lower risk for incident diabetes.

Dipeptidyl Peptidase-4 Inhibitor, Vildagliptin, Improves Trabecular Bone Mineral Density and Microstructure in Obese, Insulin-Resistant, Pre-diabetic Rats

OBJECTIVE

Obese insulin resistance and type 2 diabetes mellitus profoundly impair bone mechanical properties and bone quality. However, because several antidiabetes drugs, especially thiazolidinediones, further aggravate bone loss in individuals with diabetes, diabetic osteopathy should not be treated by using simply any glucose-lowering agents. Recently, incretins have been reported to affect osteoblast function positively. The present study aimed to investigate the effects of vildagliptin, an inhibitor of dipeptidyl peptidase-4, on bone of rats with high-fat-diet-induced prediabetes.

METHODS

Male rats were fed a high-fat diet for 12 weeks to induce obese insulin resistance and then treated with vildagliptin for 4 weeks. The effects of the drug on bone were determined by microcomputed tomography and bone histomorphometry.

RESULTS

Vildagliptin markedly improved insulin resistance in these obese insulin-resistant rats. It also significantly increased volumetric bone mineral density. Specifically, vildagliptin-treated obese insulin-resistant rats exhibited higher trabecular volumetric bone mineral density than vehicle-treated obese insulin-resistant rats, whereas cortical volumetric bone mineral density, cortical thickness and area were not changed. Bone histomorphometric analysis in a trabecular-rich area (i.e. tibial metaphysis) revealed greater trabecular bone volume and number and less trabecular separation without change in trabecular thickness, osteocyte lacunar area or cortical thickness in the vildagliptin-treated group.

CONCLUSIONS

Vildagliptin had a beneficial effect on the bone of obese insulin-resistant rats with prediabetes, particularly at the trabecular site. Such benefit probably results from enhanced bone formation rather than from suppressed bone resorption.

Effect of 7 days of exercise on exogenous carbohydrate oxidation and insulin resistance in children with obesity

The capacity to match carbohydrate (CHO) oxidation with CHO availability (deemed metabolic flexibility (MetFlex)) may be important for type 2 diabetes prevention. In adults, impaired MetFlex is associated with insulin resistance (IR), which can be improved with as little as 7 days of exercise. Whether this occurs similarly in children is unknown. We hypothesized that 7 consecutive days of exercise would improve MetFlex and IR in children with obesity. Twelve children (8 boys, 4 girls) completed 2 study visits before (PRE) and 2 study visits after (POST) exercise training. At visit 1, fasting blood was collected, and anthropometry and maximal oxygen uptake were assessed. At visit 2, a ¹³C-enriched CHO drink was ingested before exercise (3 × 20 min) at ∼59% maximal oxygen uptake. Exogenous CHO oxidative efficiency, used as a surrogate measurement of MetFlex, was calculated from breath samples. During training, participants alternated between continuous and high-intensity interval cycling sessions at home under supervision. In spite of good training adherence, there was no improvement in MetFlex (PRE: 20.7% ± 1.8%, POST: 18.9% ± 4.9%, p = 0.22) or homeostasis model assessment of insulin resistance (PRE: 8.7 ± 4.6, POST: 8.1 ± 6.0, p = 0.51). Future research should investigate exercise volume, sex, and pubertal effects on the early responsiveness of MetFlex to exercise therapy.

The influence of adiposity and acute exercise on circulating hepatokines in normal-weight and overweight/obese men

Hepatokines are liver-secreted proteins with potential to influence glucose regulation and other metabolic parameters. This study investigated differences in adiposity status on 5 novel hepatokines and characterised their response to acute moderate-intensity exercise in groups of normal-weight and overweight/obese men. Twenty-two men were recruited into normal-weight and overweight/obese groups (body mass index: 18.5 to 24.9 and 25.0 to 34.9 kg·m^-2). Each completed 2 experimental trials, exercise and control. During exercise trials, participants performed 60 min of moderate-intensity treadmill exercise (∼60% peak oxygen uptake) and then rested for 6 h. Participants rested throughout control trials. Circulating fibroblast growth factor-21 (FGF21), follistatin, leukocyte cell-derived chemotaxin 2 (LECT2), fetuin-A, and selenoprotein-P (SeP) were measured throughout. Fasted (resting) FGF21 and LECT2 were higher in overweight/obese individuals (129% and 55%; P ≤ 0.01) and correlated with indices of adiposity and insulin resistance; whereas circulating follistatin was lower in overweight/obese individuals throughout trial days (17%, P < 0.05). In both groups, circulating concentrations of FGF21 and follistatin were transiently elevated after exercise for up to 6 h (P ≤ 0.02). Circulating fetuin-A and SeP were no different between groups (P ≥ 0.19) and, along with LECT2, were unaffected by exercise (P ≥ 0.06). These findings show that increased adiposity is associated with a modified hepatokine profile, which may represent a novel mechanism linking excess adiposity to metabolic health. Furthermore, acute perturbations in circulating FGF21 and follistatin after exercise may contribute to the health benefits of an active lifestyle.

Plasma Palmitoyl-Carnitine (AC16:0) Is a Marker of Increased Postprandial Nonesterified Incomplete Fatty Acid Oxidation Rate in Adults With Type 2 Diabetes

OBJECTIVES

Enhanced mitochondrial fatty acid utilization is known to increase radical oxidative stress and induce insulin resistance. An increased level of plasma acylcarnitine (AC) has been proposed to indicate mitochondrial energy substrate overload, a possible mechanism leading to insulin resistance. The aim of our study was to determine fasting and postprandial plasma acetyl-carnitine (AC2:0), palmitoyl-carnitine (AC16:0), oleoyl-carnitine (AC18:1) and linoleoyl-carnitine (AC18:2) levels and their relationships with plasma nonesterified fatty acid appearance and oxidation rates and insulin sensitivity in participants with type 2 diabetes and normoglycemic offspring of 2 parents with type 2 diabetes (FH+) compared to healthy participants without family histories of type 2 diabetes (FH-).

METHODS

All participants underwent 3 metabolic protocols: 1) a euglycemic hyperinsulinemic clamp at fasting; 2) a 6-hour steady-state oral standard liquid meal and 3) an identical 6-hour steady-state meal intake study with a euglycemic hyperinsulinemic clamp. AC levels were measured by liquid chromatography with tandem mass spectrometry, and fatty acid oxidation (FAO) rates were measured by stable isotopic tracer techniques with indirect respiratory calorimetry.

RESULTS

During the insulin clamp at fasting, AC16:0 was significantly higher in the group with type 2 diabetes vs. FH- (p<0.05). In the postprandial state, AC2:0, AC16:0 and AC18:1 decreased significantly, but this reduction was blunted in type 2 diabetes, even during normalization of postprandial glucose levels during the insulin clamp. Fasting AC16:0 correlated with FAO (ρ=+0.604; p=0.0002); triacylglycerol (ρ=+0.427; p<0.02) and waist circumference (ρ=+0.416; p=0.02).

CONCLUSIONS

Spillover of AC occurs in type 2 diabetes but is not fully established in FH+. AC16:0 can be a useful biomarker of excessive FAO.

Computer Simulation Model to Train Medical Personnel on Glucose Clamp Procedures

OBJECTIVE

A glucose clamp procedure is the most reliable way to quantify insulin pharmacokinetics and pharmacodynamics, but skilled and trained research personnel are required to frequently adjust the glucose infusion rate. A computer environment that simulates glucose clamp experiments can be used for efficient personnel training and development and testing of algorithms for automated glucose clamps.

METHODS

We built 17 virtual healthy subjects (mean age, 25±6 years; mean body mass index, 22.2±3 kg/m²), each comprising a mathematical model of glucose regulation and a unique set of parameters. Each virtual subject simulates plasma glucose and insulin concentrations in response to intravenous insulin and glucose infusions. Each virtual subject provides a unique response, and its parameters were estimated from combined intravenous glucose tolerance test-hyperinsulinemic-euglycemic clamp data using the Bayesian approach. The virtual subjects were validated by comparing their simulated predictions against data from 12 healthy individuals who underwent a hyperglycemic glucose clamp procedure.

RESULTS

Plasma glucose and insulin concentrations were predicted by the virtual subjects in response to glucose infusions determined by a trained research staff performing a simulated hyperglycemic clamp experiment. The total amount of glucose infusion was indifferent between the simulated and the real subjects (85±18 g vs. 83±23 g; p=NS) as well as plasma insulin levels (63±20 mU/L vs. 58±16 mU/L; p=NS).

CONCLUSIONS

The virtual subjects can reliably predict glucose needs and plasma insulin profiles during hyperglycemic glucose clamp conditions. These virtual subjects can be used to train personnel to make glucose infusion adjustments during clamp experiments.

Exercise improves femoral whole-bone and tissue-level biomechanical properties in hyperphagic OLETF rats

An often-overlooked comorbidity of type 2 diabetes (T2D) is increased fracture risk. Since traditional T2D therapies focus solely on glucose homeostasis, there is an increased need for effective treatment strategies that improve both metabolic and bone health. The current study evaluated if previously reported protective effects of exercise (EX) on cortical bone geometry and biomechanical properties are due to the prevention of obesity compared with obese Otsuka Long-Evans Tokushima Fatty (OLETF) rats or the unique skeletal effects of exercise. Four-week-old male OLETF rats were randomly assigned to 1 of 3 groups, each fed a standard rodent chow diet until 40 weeks of age: ad libitum-fed sedentary (O-SED), ad libitum-fed EX (O-EX), or a control group body-weight-matched to the O-EX group by caloric restriction (O-CR). Ad libitum-fed sedentary Long-Evans Tokushima Otsuka (L-SED) rats were used as a lean control. EX or CR prevented the excess body mass accumulation and elevated HbA1c observed in O-SED. Total-body bone mineral density was greater in O-EX than O-CR, but similar to L-SED and O-SED. O-EX and O-CR had lower osteocalcin and TRAP5b than O-SED and L-SED. EX or CR prevented the ∼3-fold increase in CTx in O-SED versus L-SED. EX increased femoral cortical mass accumulation and expansion at the mid-diaphysis compared with O-CR. EX or CR significantly increased tissue-level stiffness and strength compared with O-SED and L-SED, but O-EX had greater whole-bone stiffness than all other groups. In summary, EX has distinct advantages over CR for improving bone biomechanical properties in hyperphagic OLETF rats.

Dietary intake and cardiometabolic biomarkers in relation to insulin resistance and hypertension in a middle-aged and elderly population in Beijing, China

This study investigated the relationships of dietary intake and cardiometabolic biomarkers with insulin resistance and hypertension in rural middle-aged and elderly people in China. One hundred and eight middle-aged and elderly adults were recruited in Zhangfang village in May 2014. We measured blood pressure, anthropometric parameters, and biochemical indexes, including high-sensitivity C-reactive protein (hsCRP), soluble intercellular adhesion molecule-1 (sICAM-1), glucose, insulin, and blood lipids. Homeostasis model assessment of insulin resistance index (HOMA-IR) was assessed on the basis of fasting glucose and insulin. We recorded participant demographic characteristics, dietary intake, and lifestyle using questionnaires. Hypertensive participants had higher levels of triglycerides (TG), hsCRP, sICAM-1, body fat percentage (BF%), arm muscle circumference (AMC) and HOMA-IR than nonhypertensive individuals. Hypertensive participants had higher carbohydrate intake but lower intakes of protein and fat. Carbohydrate intake was positively correlated with hsCRP, sICAM-1, TG, BF%, and HOMA-IR, and was negatively correlated with AMC. Protein and fat intakes were negatively correlated with hsCRP and sICAM-1. Protein intake was also significantly negatively correlated with TG and HOMA-IR, and positively correlated with AMC. HOMA-IR was positively correlated with hsCRP, sICAM-1, TG and BF%, and negatively correlated with AMC. Multivariable linear regression indicated that TG, sICAM-1, and hsCRP were significantly associated with HOMA-IR. In conclusion, in a rural Chinese population, high intake of carbohydrate and low intake of fat and protein were associated with insulin resistance and hypertension, possibly by increasing inflammatory factors such as sICAM-1 and hsCRP, increasing BF% and increasing the level of plasma TG.

Early Metabolic Improvement After Bariatric Surgery: The First Steps Toward Remission of Type 2 Diabetes

The introduction of bariatric surgery into clinical practice in the 1980s was followed by a relatively long watch-and-wait period before the very rapid accumulation of scientific literature, over the past decade, concerning its clinical effectiveness and safety and its mechanisms of action in the treatment of obesity. These surgical procedures now emerge as the most effective therapeutic modality to induce long-term remission of type 2 diabetes. Recent research has shed light on the potential mechanisms leading to the profound improvement of glucose homeostasis following most bariatric surgery procedures. These mechanisms can be classified as weight loss dependent and independent, both playing sequential and then synergistic antidiabetes roles. Many groups, including our own, have contributed to our understanding of the relative roles of these mechanisms at differing time periods following these procedures. Here we summarize what we currently know about the mechanisms underlying the very rapid, weight loss-independent improvement in glucose homeostasis after bariatric surgery. Beyond its impact in the field of bariatric surgery, this new knowledge about the very rapid in vivo "reverse engineering" of type 2 diabetes actually provides unique insights into the intricate and complex mechanisms linking nutrition and obesity with the development of this disease.

Role of Serum Adiponectin and Vitamin D in Prediabetes and Diabetes Mellitus

OBJECTIVES

The roles of deficient or deranged insulin, adiponectin and 25 hydroxy vitamin D (25[OH]D) levels regulating food intake, energy metabolism, glucose and lipid metabolism and body weight have been reported in the pathogenesis of prediabetes and type 2 diabetes mellitus. However, their congruity in the etiology of diabetes mellitus is unknown. Thus, the aim of the study was to investigate the roles of these parameters together and to establish their interrelationship in patients with prediabetes and diabetes.

METHODS

The preliminary cross-sectional study included 77 persons with type 2 diabetes who were matched for age, sex and body mass index (BMI); 73 persons with prediabetes; and 52 healthy control subjects. Fasting serum levels of adiponectin, insulin and 25(OH)D were measured by commercially available immune assay kits, and routine biochemical parameters were analyzed in all study groups.

RESULTS

The results show statistically significant lower levels of serum adiponectin and serum 25(OH)D and higher serum insulin levels in persons with prediabetes or type 2 diabetes with respect to controls. The changes in the serum adiponectin or serum 25(OH)D in persons with prediabetes and type 2 diabetes were found to be inversely correlated with the serum levels of insulin. Moreover, multiple linear regression analysis, with 25(OH)D, insulin and homeostatic model assessment-insulin resistance (HOMA-IR) as the variables, revealed that serum adiponectin levels might be an independent risk factor for the progression of prediabetes and type 2 diabetes in subjects.

CONCLUSIONS

The association of these hormones might act as a significant predictor of progression of prediabetes to type 2 diabetes. Decreased serum adiponectin levels might be an independent risk factor for progression to prediabetes and type 2 diabetes, which may help in developing experimental models of the disease or in identifying biomarkers or disease-modifying drugs.

Influence of Amino Acids in Dairy Products on Glucose Homeostasis: The Clinical Evidence

Dairy products have been hypothesized to protect against type 2 diabetes because of their high content of whey proteins, rich in branched-chain amino acids (BCAAs) - leucine, isoleucine and valine - and lysine, which may decrease postprandial glucose responses and stimulate insulin secretion. Paradoxically, epidemiologic studies also show that higher levels of plasma BCAAs have been linked to insulin resistance and type 2 diabetes. Therefore, the objective was to review the recent clinical evidence concerning the intake of amino acids found in dairy proteins so as to determine their impact on glucose homeostasis in healthy persons and in those with prediabetes and type 2 diabetes. Clinical studies have reported that the major dairy amino acids, namely, leucine, isoleucine, glutamine, phenylalanine, proline and lysine, have beneficial effects on glucose homeostasis. Yet the reported doses of amino acids investigated are too elevated to be reached through adequate dairy product intake. The minor dairy amino acids, arginine and glycine, may improve glucose homeostasis by improving other risk factors for type 2 diabetes. Further, the combination of amino acids may also improve glucose-related outcomes, suggesting additive or synergistic effects. Nevertheless, additional long-term studies in individuals with prediabetes and type 2 diabetes are needed to ascertain the benefits for glucose homeostasis of amino acids found in dairy foods.

Molecular factors involved in the hypolipidemic- and insulin-sensitizing effects of a ginger (Zingiber officinale Roscoe) extract in rats fed a high-fat diet

Hypolipidemic and hypoglycemic properties of ginger in animal models have been reported. However, information related to the mechanisms and factors involved in the metabolic effects of ginger at a hepatic level are limited. The aim of the present study was to investigate molecular factors involved in the hypoglycemic and hypolipidemic effects of a hydroethanolic ginger extract (GE) in the liver of rats fed a high-fat diet (HFD). The study was conducted in male Wistar rats divided into the following 3 groups: (i) Rats fed a standard diet (3.5% fat), the control group; (ii) rats fed an HFD (33.5% fat); and (iii) rats fed an HFD treated with GE (250 mg·kg-1·day-1) for 5 weeks (HFD+GE). Plasma levels of glucose, insulin, lipid profile, leptin, and adiponectin were measured. Liver expression of glycerol phosphate acyltransferase (GPAT), cholesterol 7 alpha-hydroxylase, peroxisome proliferator-activated receptors (PPAR), PPARα and PPARγ, glucose transporter 2 (GLUT-2), liver X receptor, sterol regulatory element-binding protein (SREBP1c), connective tissue growth factor (CTGF), and collagen I was measured. Data were analyzed using a 1-way ANOVA, followed by a Newman-Keuls test if differences were noted. The study showed that GE improved lipid profile and attenuated the increase of plasma levels of glucose, insulin, and leptin in HFD rats. This effect was associated with a higher liver expression of PPARα, PPARγ, and GLUT-2 and an enhancement of plasma adiponectin levels. Furthermore, GE reduced liver expression of GPAT, SREBP1c, CTGF, and collagen I. The results suggest that GE might be considered as an alternative therapeutic strategy in the management of overweight and hepatic and metabolic-related alterations.

Vitamin D status is not related to insulin resistance in different phenotypes of moderate obesity

Low plasma 25-hydroxy-vitamin D (25OHD) and high levels of parathyroid hormone (PTH) are associated with obesity and could play a role in the occurrence of complications such as insulin resistance. The objective of the study was to evaluate whether the relationship between 25OHD status and phosphocalcic parameters differs between metabolically healthy obese (MHO) and insulin-resistant obese (IRO). This cross-sectional study included 158 consecutive adults (121 females) with obesity (body mass index (BMI) 35.15 ± 2.8 kg/m²), aged 43.21 ± 13.6 years. Serum 25OHD, calcemia, phosphatemia, PTH, plasma lipids, fasting plasma glucose, insulin levels, and body composition were measured. Participants were classified as MHO (n = 65) or IRO (n = 93) based on homeostatic model assessment insulin-resistance value. IRO patients had a higher BMI (p = 0.001), waist circumference (p = 0.03), and trunk fat mass (p = 0.007) than MHO patients. Mean HbA1c (p = 0.03), triglycerides (p = 0.02), and hsCRP (p = 0.04) plasmatic levels were increased in the IRO group. No between-group difference was found on 25OHD, PTH, calcium, or phosphorus plasmatic levels. Only age-predicted 25OHD levels were identified among IRO participants, whereas no factors were identified in MHO. No predictive factors of PTH plasmatic level were identified in the IRO and MHO groups. Although MHO and IRO patients have different metabolic profiles, we did not detect any difference regarding either 25OHD or PTH. Insulin resistance was not a predictive factor of vitamin D status. Our results confirm the absence of link between vitamin D status and insulin resistance in moderate obesity.

Inhibition of the gut enzyme intestinal alkaline phosphatase may explain how aspartame promotes glucose intolerance and obesity in mice

Diet soda consumption has not been associated with tangible weight loss. Aspartame (ASP) commonly substitutes sugar and one of its breakdown products is phenylalanine (PHE), a known inhibitor of intestinal alkaline phosphatase (IAP), a gut enzyme shown to prevent metabolic syndrome in mice. We hypothesized that ASP consumption might contribute to the development of metabolic syndrome based on PHE's inhibition of endogenous IAP. The design of the study was such that for the in vitro model, IAP was added to diet and regular soda, and IAP activity was measured. For the acute model, a closed bowel loop was created in mice. ASP or water was instilled into it and IAP activity was measured. For the chronic model, mice were fed chow or high-fat diet (HFD) with/without ASP in the drinking water for 18 weeks. The results were that for the in vitro study, IAP activity was lower (p < 0.05) in solutions containing ASP compared with controls. For the acute model, endogenous IAP activity was reduced by 50% in the ASP group compared with controls (0.2 ± 0.03 vs 0.4 ± 0.24) (p = 0.02). For the chronic model, mice in the HFD + ASP group gained more weight compared with the HFD + water group (48.1 ± 1.6 vs 42.4 ± 3.1, p = 0.0001). Significant difference in glucose intolerance between the HFD ± ASP groups (53 913 ± 4000.58 (mg·min)/dL vs 42 003.75 ± 5331.61 (mg·min)/dL, respectively, p = 0.02). Fasting glucose and serum tumor necrosis factor-alpha levels were significantly higher in the HFD + ASP group (1.23- and 0.87-fold increases, respectively, p = 0.006 and p = 0.01). In conclusion, endogenous IAP's protective effects in regard to the metabolic syndrome may be inhibited by PHE, a metabolite of ASP, perhaps explaining the lack of expected weight loss and metabolic improvements associated with diet drinks.

A "healthy diet-optimal sleep" lifestyle pattern is inversely associated with liver stiffness and insulin resistance in patients with nonalcoholic fatty liver disease

Several lifestyle habits have been described as risk factors for nonalcoholic fatty liver disease (NAFLD). Given that both healthy and unhealthy habits tend to cluster, the aim of this study was to identify lifestyle patterns and explore their potential associations with clinical characteristics of individuals with NAFLD. One hundred and thirty-six consecutive patients with ultrasound-proven NAFLD were included. Diet and physical activity level were assessed through appropriate questionnaires. Habitual night sleep hours and duration of midday naps were recorded. Optimal sleep duration was defined as sleep hours ≥ 7 and ≤ 9 h/day. Lifestyle patterns were identified using principal component analysis. Eight components were derived explaining 67% of total variation of lifestyle characteristics. Lifestyle pattern 3, namely high consumption of low-fat dairy products, vegetables, fish, and optimal sleep duration was negatively associated with insulin resistance (β = -1.66, P = 0.008) and liver stiffness (β = -1.62, P = 0.05) after controlling for age, sex, body mass index, energy intake, smoking habits, adiponectin, and tumor necrosis factor-α. Lifestyle pattern 1, namely high consumption of full-fat dairy products, refined cereals, potatoes, red meat, and high television viewing time was positively associated with insulin resistance (β = 1.66, P = 0.005), although this association was weakened after adjusting for adiponectin and tumor necrosis factor-α. A "healthy diet-optimal sleep" lifestyle pattern was beneficially associated with insulin resistance and liver stiffness in NAFLD patients independent of body weight status and energy intake.

Glucocorticoid Antagonism Reduces Insulin Resistance and Associated Lipid Abnormalities in High-Fructose-Fed Mice

OBJECTIVES

High intake of dietary fructose causes perturbation in lipid metabolism and provokes lipid-induced insulin resistance. A rise in glucocorticoids (GCs) has recently been suggested to be involved in fructose-induced insulin resistance. The objective of the study was to investigate the effect of GC blockade on lipid abnormalities in insulin-resistant mice.

METHODS

Insulin resistance was induced in mice by administering a high-fructose diet (HFrD) for 60 days. Mifepristone (RU486), a GC antagonist, was administered to HFrD-fed mice for the last 18 days, and the intracellular and extracellular GC levels, the glucocorticoid receptor (GR) activation and the expression of GC-regulated genes involved in lipid metabolism were examined.

RESULTS

HFrD elevated the intracellular GC content in both liver and adipose tissue and enhanced the GR nuclear translocation. The plasma GC level remained unchanged. The levels of free fatty acids and triglycerides in plasma were elevated, accompanied by increased plasma insulin and glucose levels and decreased hepatic glycogen content. Treatment with RU486 reduced plasma lipid levels, tissue GC levels and the expression of GC-targeted genes involved in lipid accumulation, and it improved insulin sensitivity.

CONCLUSIONS

This study demonstrated that HFrD-induced lipid accumulation and insulin resistance are mediated by enhanced GC in liver and adipose tissue and that GC antagonism might reduce fructose-induced lipid abnormalities and insulin resistance.

Associations between heart rate variability, metabolic syndrome risk factors, and insulin resistance

The purpose of this study was to examine differences in heart rate variability (HRV) in metabolic syndrome (MetS) and to determine associations between HRV parameters, MetS risk factors, and insulin resistance (homeostasis model assessment for insulin resistance (HOMA-IR)). Participants (n = 220; aged 23-70 years) were assessed for MetS risk factors (waist circumference, blood pressure, fasting plasma glucose, triglycerides, and high-density lipoprotein cholesterol) and 5-min supine HRV (time and frequency domain and nonlinear). HRV was compared between those with 3 or more (MetS+) and those with 2 or fewer MetS risk factors (MetS-). Multiple linear regression models were built for each HRV parameter to investigate associations with MetS risk factors and HOMA-IR. Data with normal distribution are presented as means ± SD and those without as median [interquartile range]. In women, standard deviation of R-R intervals 38.0 [27.0] ms, 44.5 [29.3] ms; p = 0.020), low-frequency power (5.73 ± 1.06 ln ms(2), 6.13 ± 1.05 ln ms(2); p = 0.022), and the standard deviation of the length of the Poincaré plot (46.8 [31.6] ms, 58.4 [29.9] ms; p = 0.014) were lower and heart rate was higher (68 [13] beats/min, 64 [12] beats/min; p = 0. 018) in MetS+ compared with MetS-, with no differences in men. Waist circumference was most commonly associated with HRV, especially frequency domain parameters. HOMA-IR was associated with heart rate. In conclusion, MetS+ women had a less favourable HRV profile than MetS- women, but there were no differences in men. HOMA-IR was associated with heart rate, not HRV.

Maternal and postweaning folic acid supplementation interact to influence body weight, insulin resistance, and food intake regulatory gene expression in rat offspring in a sex-specific manner

Maternal intake of multivitamins or folic acid above the basal dietary requirement alters the growth and metabolic trajectory of rat offspring. We hypothesized that a modest increase in the folic acid content of maternal diets would alter the offspring's metabolic phenotype, and that these effects could be corrected by matching the folic acid content of the offspring's diet with that of the maternal diet. Female Sprague-Dawley rats were placed on a control or a 2.5× folic acid-supplemented diet prior to mating and during pregnancy and lactation. At weaning, pups from each maternal diet group were randomized to the control or to the 2.5× folic acid-supplemented diet for 25 weeks. Male pups from dams fed the folic acid-supplemented diet were 3.7% heavier than those from control-fed dams and had lower mRNA expression for leptin receptor Obrb isoform (Lepr) (11%) and Agouti-related protein (Agrp) (14%). In contrast, female pups from folic acid-supplemented dams were 5% lighter than those from control-fed dams and had lower proopiomelanocortin (Pomc) (42%), Lepr (32%), and Agrp (13%), but higher neuropeptide Y (Npy) (18%) mRNA expression. Folic acid supplementation ameliorated the alterations induced by maternal folic acid supplementation in male pups and led to the lowest insulin resistance, but the effects were smaller in female pups and led to the highest insulin resistance. In conclusion, maternal folic acid supplementation at 2.5× the control level was associated with alterations in body weight and hypothalamic gene expression in rat offspring in a sex-specific manner, and some of these effects were attenuated by postweaning folic acid supplementation.

Resveratrol prevents insulin resistance caused by short-term elevation of free fatty acids in vivo

Elevated levels of plasma free fatty acids (FFA), which are commonly found in obesity, induce insulin resistance. FFA activate protein kinases including the proinflammatory IκBα kinase β (IKKβ), leading to serine phosphorylation of insulin receptor substrate 1 (IRS-1) and impaired insulin signaling. To test whether resveratrol, a polyphenol found in red wine, prevents FFA-induced insulin resistance, we used a hyperinsulinemic-euglycemic clamp with a tracer to assess hepatic and peripheral insulin sensitivity in overnight-fasted Wistar rats infused for 7 h with saline, Intralipid plus 20 U·mL(-1) heparin (IH; triglyceride emulsion that elevates FFA levels in vivo; 5.5 μL·min(-1)) with or without resveratrol (3 mg·kg(-1)·h(-1)), or resveratrol alone. Infusion of IH significantly decreased glucose infusion rate (GIR; P < 0.05) and peripheral glucose utilization (P < 0.05) and increased endogenous glucose production (EGP; P < 0.05) during the clamp compared with saline infusion. Resveratrol co-infusion, however, completely prevented the effects induced by IH infusion: it prevented the decreases in GIR (P < 0.05 vs. IH), peripheral glucose utilization (P < 0.05 vs. IH), and insulin-induced suppression of EGP (P < 0.05 vs. IH). Resveratrol alone had no effect. Furthermore, IH infusion increased serine (307) phosphorylation of IRS-1 in soleus muscle (∼30-fold, P < 0.001), decreased total IRS-1 levels, and decreased IκBα content, consistent with activation of IKKβ. Importantly, all of these effects were abolished by resveratrol (P < 0.05 vs. IH). These results suggest that resveratrol prevents FFA-induced hepatic and peripheral insulin resistance and, therefore, may help mitigate the health consequences of obesity.

Cooking enhances beneficial effects of pea seed coat consumption on glucose tolerance, incretin, and pancreatic hormones in high-fat-diet-fed rats

Pulses, including dried peas, are nutrient- and fibre-rich foods that improve glucose control in diabetic subjects compared with other fibre sources. We hypothesized feeding cooked pea seed coats to insulin-resistant rats would improve glucose tolerance by modifying gut responses to glucose and reducing stress on pancreatic islets. Glucose intolerance induced in male Sprague-Dawley rats with high-fat diet (HFD; 10% cellulose as fibre) was followed by 3 weeks of HFD with fibre (10%) provided by cellulose, raw-pea seed coat (RP), or cooked-pea seed coat (CP). A fourth group consumed low-fat diet with 10% cellulose. Oral and intraperitoneal glucose tolerance tests (oGTT, ipGTT) were done. CP rats had 30% and 50% lower glucose and insulin responses in oGTT, respectively, compared with the HFD group (P < 0.05) but ipGTT was not different. Plasma islet and incretin hormone concentrations were measured. α- and β-cell areas in the pancreas and density of K- and L-cells in jejunum and ileum were quantified. Jejunal expression of hexose transporters was measured. CP feeding increased fasting glucagon-like peptide 1 and glucose-stimulated gastric inhibitory polypeptide responses (P < 0.05), but K- and L-cells densities were comparable to HFD, as was abundance of SGLT1 and GLUT2 mRNA. No significant difference in β-cell area between diet groups was observed. α-cell area was significantly smaller in CP compared with RP rats (P < 0.05). Overall, our results demonstrate that CP feeding can reverse adverse effects of HFD on glucose homeostasis and is associated with enhanced incretin secretion and reduced α-cell abundance.

Ferulic acid exerts its antidiabetic effect by modulating insulin-signalling molecules in the liver of high-fat diet and fructose-induced type-2 diabetic adult male rat

Ferulic acid (FA) is a phenolic phytochemical known for its antidiabetic property The present study is designed to evaluate the mechanism behind its antidiabetic property in high-fat and fructose-induced type 2 diabetic adult male rats. Animals were divided into 5 groups: (i) control, (ii) diabetic control, (iii) diabetic animals treated with FA (50 mg/(kg body weight · day)(-1), orally) for 30 days, (iv) diabetic animals treated with metformin (50 mg/(kg body weight · day)(-1), orally) for 30 days, and (v) control rats treated with FA. FA treatment to diabetic animals restored blood glucose, serum insulin, glucose tolerance, and insulin tolerance to normal range. Hepatic glycogen concentration, activity of glycogen synthase, and glucokinase were significantly decreased, whereas activity of glycogen phosphorylase and enzymes of gluconeogenesis (phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G6Pase)) were increased in diabetic animals and FA restored these to normal levels similar to that of metformin. FA improved the insulin signalling molecules and reduced the negative regulators of insulin signalling. The messenger RNA of gluconeogenic enzyme genes (PEPCK and G6Pase) and the interaction between forkhead transcription factor-O1 and promoters of gluconeogenic enzyme genes (PEPCK and G6Pase) was reduced significantly by ferulic acid. It is concluded from the present study that FA treatment to type 2 diabetic rats improves insulin sensitivity and hepatic glycogenesis but inhibits gluconeogenesis and negative regulators of insulin signalling to maintain normal glucose homeostasis.

Molecular mechanisms linking diabetes to the accelerated development of atherosclerosis

Diabetes mellitus is a major independent risk factor for the development of cardiovascular disease, and both type 1 and type 2 diabetes have been shown to accelerate the development of atherosclerosis, the underlying cause of most myocardial infarctions. Despite the profound clinical importance of vascular disease in patients with diabetes mellitus, our understanding of the relative contributions of insulin resistance and hyperglycemia to atherogenesis is not complete. Furthermore, the molecular and cellular pathways that are involved in disease progression are not clear. In this review, we summarize our current understanding of the potential mechanisms that link diabetes to atherosclerosis and indicate existing gaps in our knowledge.

Diabetic dyslipidemia: from evolving pathophysiological insight to emerging therapeutic targets

Diabetic dyslipidemia is characterized by hepatic very low density lipoprotein (VLDL) and intestinal chylomicron overproduction, reduced high density lipoprotein cholesterol (HDL-C) level, increased propensity of small dense LDL (sdLDL) and increased postprandial lipemia. This dyslipidemic profile is also strongly linked to other features of the metabolic syndrome. Diabetic dyslipidemia is a well-recognized risk factor for atherosclerotic cardiovascular diseases. Currently, statins remain the first line therapy primarily through reducing the atherogenic LDL. Clinical trials on other lipid modifying agents were met with variable success in selective patient populations. Emerging new insights into the pathophysiology of lipid metabolism, in general, and diabetic dyslipidemia, in particular, have opened up potentially novel therapeutic strategies to further reduce the risk associated with diabetic dyslipidemia and insulin resistant state.

Vitamin E and vitamin C do not reduce insulin sensitivity but inhibit mitochondrial protein expression in exercising obese rats

Controversy exists as to whether supplementation with the antioxidants vitamin E and vitamin C blocks adaptation to exercise. Exercise is a first-line means to treat obesity and its complications. While diet-induced obesity alters mitochondrial function and induces insulin resistance (IR), no data exist as to whether supplementation with vitamin E and vitamin C modify responses to exercise in pre-existing obesity. We tested the hypothesis that dietary supplementation with vitamin E (0.4 g α-tocopherol acetate/kg) and vitamin C (0.5 g/kg) blocks exercise-induced improvements on IR and mitochondrial content in obese rats maintained on a high-fat (45% fat energy (en)) diet. Diet-induced obese, sedentary rats had a 2-fold higher homeostasis model assessment of insulin resistance and larger insulin area under the curve following glucose tolerances test than rats fed a low-fat (10% fat en) diet. Exercising (12 weeks at 5 times per week in a motorized wheel) of obese rats normalized IR indices, an effect not modified by vitamin E and vitamin C. Vitamin E and vitamin C supplementation with exercise elevated mtDNA content in adipose and skeletal muscle to a greater extent (20%) than exercise alone in a depot-specific manner. On the other hand, vitamin C and vitamin E decreased exercise-induced increases in mitochondrial protein content for complex I (40%) and nicotinamide nucleotide transhydrogenase (35%) in a muscle-dependent manner. These data indicate that vitamin E and vitamin C supplementation in obese rodents does not modify exercise-induced improvements in insulin sensitivity but that changes in mitochondrial biogenesis and mitochondrial protein expression may be modified by antioxidant supplementation.

Effects of a brief high-fat diet and acute exercise on the mTORC1 and IKK/NF-κB pathways in rat skeletal muscle

One exercise session can improve subsequent insulin-stimulated glucose uptake by skeletal muscle in healthy and insulin-resistant individuals. Our first aim was to determine whether a brief (2 weeks) high-fat diet (HFD) that caused muscle insulin resistance would activate the mammalian target of rapamycin complex 1 (mTORC1) and/or inhibitor of κB kinase/nuclear factor κB (IKK/NF-κB) pathways, which are potentially linked to induction of insulin resistance. Our second aim was to determine whether acute exercise that improved insulin-stimulated glucose uptake by muscles would attenuate activation of these pathways. We compared HFD-fed rats with rats fed a low-fat diet (LFD). Some animals from each diet group were sedentary and others were studied 3 h postexercise, when insulin-stimulated glucose uptake was increased. The results did not provide evidence that brief HFD activated either the mTORC1 (including phosphorylation of mTOR(Ser2448), TSC2(Ser939), p70S6K(Thr412), and RPS6(Ser235/236)) or the IKK/NF-κB (including abundance of IκBα or phosphorylation of NF-κB(Ser536), IKKα/β(Ser177/181), and IκB(Ser32)) pathway in insulin-resistant muscles. Exercise did not oppose the activation of either pathway, as evidenced by no attenuation of phosphorylation of key proteins in the IKK/NF-κB pathway (NF-κB(Ser536), IKKα/β(Ser177/181), and IκB(Ser32)), unaltered IκBα abundance, and no attenuation of phosphorylation of key proteins in the mTORC1 pathway (mTOR(Ser2448), TSC2(Ser939), and RPS6(Ser235/236)). Instead, exercise induced greater phosphorylation of 2 proteins of the mTORC1 pathway (PRAS40(Thr246) and p70S6K(Thr412)) in insulin-stimulated muscles, regardless of diet. Insulin resistance induced by a brief HFD was not attributable to greater activation of the mTORC1 or the IKK/NF-κB pathway in muscle, and exercise-induced improvement in insulin sensitivity was not attributable to attenuated activation of these pathways in muscle.

Improved glucose tolerance in insulin-resistant rats after pea hull feeding is associated with changes in lipid metabolism-targeted transcriptome

Understanding of the mechanisms by which pulse grain fractions elicit beneficial effects on glucose tolerance is incomplete. An untargeted metabolomic analysis of serum from insulin-resistant rats was carried out to identify potential metabolic pathways affected by feeding rats the hull fraction of dried peas for 4 weeks. From this, we hypothesized that transcription of hepatic genes involved in lipid metabolism would be altered. cDNA was prepared from total RNA extracted from livers of rats fed a high-fat diet (HFD) or HFD + pea hulls (PH) diet. The liver lipid transcriptome of each cDNA sample was characterized using a PCR-based array of 84 genes. The activity of peroxisome-proliferator-activated receptor alpha (PPAR-α) was measured in hepatocyte nuclei. The predominant findings of the metabolomic analysis revealed a significant increase in the intermediaries of β-oxidation: C16-OH and C16:1 acylcarnitines (>50%, p < 0.05) and 3-hydroxybutyrate (100%, p < 0.05) in the PH group compared with the HFD group. mRNA of hadha, a gene involved in β-oxidation, was significantly reduced by 53% (p < 0.005) in the PH group compared with the HFD group, but no differences in PPAR-α activity were detected. 3-Hydroxybutyrate concentrations were associated with insulin sensitivity and reduced demand for insulin. The results indicate that feeding PH alters lipid metabolism in liver, which may contribute to improved glucose tolerance in insulin-resistant rats.

Macrophages inhibit insulin signalling in adipocytes: role of inducible nitric oxide synthase and nitric oxide

OBJECTIVES

The interaction of immune cells with adipocytes within the adipose tissues in obese persons with diabetes mellitus may play a role in insulin resistance. We examined in vitro whether nitric oxide (NO) and inducible nitric oxide synthase (iNOS) play a role in impaired insulin signalling in adipocytes exposed to activated macrophages.

METHODS

We used a co-culture system in which Raw264.7 macrophages were plated over differentiated, low passage 3T3-L1 cells (dif3T3) at a cell density ratio of 1:2. Inflammation was induced by a challenge with bacterial lipopolysaccharide.

RESULTS

Significantly (p<0.001) enhanced iNOS expression and NO synthesis was observed in activated co-cultures. In the co-cultures as compared with Raw264.7 cells alone, iNOS protein was induced up to 11-fold above background, and NO release was significantly (p<0.001) increased up to 2.8-fold. Co-culturing dif3T3 and Raw264.7 cells as compared to dif3T3 alone reduced insulin-induced Akt phosphorylation by 50% and AS160 phosphorylation by 42%. This was correlated with reduced glucose consumption when dif3T3 was exposed to 1,3-morpholinosydnonimine. Adiponectin, GLUT4 and AS160 mRNA were reduced by 4-fold, 5-fold and 2-fold, respectively, in co-cultures as compared to dif3T3 alone. On the contrary, GLUT1 mRNA levels were increased by 2-fold in co-cultures as compared to dif3T3. NG-monomethyl-L-arginine abolished NO production with modest reversal of Akt/AS160 phosphorylation.

CONCLUSIONS

This study demonstrated a potential association between iNOS/NO-mediated inflammation and insulin resistance.

Effect of a low-starch/low-dairy diet on fat oxidation in overweight and obese women with polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) affects between 4%-18% of reproductive-aged women and is associated with increased risk of obesity and obesity-related disease. PCOS is associated with hyperinsulinemia, which is known to impair fat oxidation. Research shows that carbohydrates from dairy and starch-based foods cause greater postprandial insulin secretion than carbohydrates from nonstarchy vegetables and fruits. The purpose of this study was to determine whether an ad libitum 8-week low-starch/low-dairy diet would improve fasting and postprandial fat oxidation after a high saturated fat liquid meal (HSFLM) in overweight and obese women with PCOS. Prospective 8-week dietary intervention using a low-starch/low-dairy diet in 10 women (body mass index ≥25 kg/m(2) and ≤45 kg/m(2)) with PCOS. Indirect calorimetry was used at fasting and for 5 h following consumption of the HSFLM to determine respiratory exchange ratio (RER), macronutrient oxidation, and energy expenditure (EE) at week 0 and week 8. Participants had a reduction in body weight (-8.1 ± 1.8 kg, p < 0.05) and fasting insulin (-19.5 ± 8.9 μg/mL, p < 0.05) after dietary intervention; however, these were not significantly correlated with improved fat oxidation. There was a reduction in fasting RER, and fasting and postprandial carbohydrate oxidation, and an increase in fasting and postprandial fat oxidation after adjusting for body weight. There was also significant difference in incremental area under the curve from pre- to post-diet for fat (0.06 ± 0.00 g/kg per 5 h; p < 0.001) and carbohydrate oxidation (-0.29 ± 0.06 g/kg per 5 h; p < 0.001), but not for RER or EE. In conclusion, an 8-week low-starch/low-dairy diet increased fat oxidation in overweight and obese women with PCOS.

Role of O-GlcNAcylation in nutritional sensing, insulin resistance and in mediating the benefits of exercise

The purpose of this review is to highlight the role of O-linked β-N-acetylglucosamine (O-GlcNAc) protein modification in metabolic disease states and to summarize current knowledge of how exercise affects this important post-translational signalling pathway. O-GlcNAc modification is an intracellular tool capable of integrating energy supply with demand. The accumulation of excess energy associated with obesity and insulin resistance is mediated, in part, by the hexosamine biosynthetic pathway (HBP), which results in the O-GlcNAcylation of a myriad of proteins, thereby affecting their respective function, stability, and localization. Insulin resistance is related to the excessive O-GlcNAcylation of key metabolic proteins causing a chronic blunting of insulin signalling pathways and precipitating the accompanying pathologies, such as heart and kidney disease. Lifestyle modifications such as diet and exercise also modify the pathway. Exercise is a front-line and cost-effective therapeutic approach for insulin resistance, and recent work shows that the intervention can alter O-GlcNAc gene expression, signalling, and protein modification. However, there is currently no consensus on the effect of frequency, intensity, type, and duration of exercise on O-GlcNAc modification, the HBP, and its related enzymes. On one end of the spectrum, mild, prolonged swim training reduces O-GlcNAcylation, while on the other end, higher intensity treadmill running increases cardiac protein O-GlcNAc modification. Clearly, a balance between acute and chronic stress of exercise is needed to reap the benefits of the intervention on O-GlcNAc signalling.

Effects of high-intensity interval exercise versus continuous moderate-intensity exercise on postprandial glycemic control assessed by continuous glucose monitoring in obese adults

The purpose of this study was to examine the impact of acute high-intensity interval training (HIIT) compared with continuous moderate-intensity (CMI) exercise on postprandial hyperglycemia in overweight or obese adults. Ten inactive, overweight or obese adults (41 ± 11 yrs, BMI = 36 ± 7 kg/m(2)) performed an acute bout of HIIT (10 × 1 min at approximately 90% peak heart rate (HRpeak) with 1-min recovery periods) or matched work CMI (30 min at approximately 65% HRpeak) in a randomized, counterbalanced fashion. Exercise was performed 2 h after breakfast, and glucose control was assessed by continuous glucose monitoring under standardized dietary conditions over 24 h. Postprandial glucose (PPG) responses to lunch, dinner, and the following day's breakfast were analyzed and compared with a no-exercise control day. Exercise did not affect the PPG responses to lunch, but performing both HIIT and CMI in the morning significantly reduced the PPG incremental area under the curve (AUC) following dinner when compared with control (HIIT = 110 ± 35, CMI = 125 ± 34, control = 162 ± 46 mmol/L × 2 h, p < 0.05). The PPG AUC (HIIT = 125 ± 53, CMI = 186 ± 55, control = 194 ± 96 mmol/L × 2 h) and the PPG spike (HIIT = Δ2.1 ± 0.9, CMI = Δ3.0 ± 0.9, control = Δ3.0 ± 1.5 mmol/l) following breakfast on the following day were significantly lower following HIIT compared with both CMI and control (p < 0.05). Absolute AUC and absolute glucose spikes were not different between HIIT, CMI, or control for any meal (p > 0.05 for all). We conclude that a single session of HIIT has greater and more lasting effects on reducing incremental PPG when compared with CMI.

Effect of atorvastatin on pancreatic Beta-cell function and insulin resistance in type 2 diabetes mellitus patients: a randomized pilot study

OBJECTIVE

Statins are commonly used for the management of dyslipidemia in type 2 diabetes mellitus patients. We hypothesized that atorvastatin could modulate the beta-cell function by altering the levels of proapoptotic and antiapoptotic lipoproteins and could also have an effect on insulin resistance. The aim of the present pilot study was to assess the effect of atorvastatin 10 mg on pancreatic beta-cell function and insulin resistance in patients with hyperlipidemia and type 2 diabetes by using the homeostasis model assessment-2 (HOMA2) index.

METHODS

Fifty-one type 2 diabetes patients receiving oral antidiabetes drugs, not taking statins, with baseline low-density lipoprotein cholesterol between 2.6 mmol/L and 4.1 mmol/L were included. Forty-three patients (21 in placebo group and 22 in atorvastatin group) completed the study and were taken up for final analysis. Fasting blood samples were obtained at baseline and at 12 weeks to determine levels of blood glucose, lipid profile, insulin, C-peptide and glycosylated hemoglobin (A1C).

RESULTS

Atorvastatin nonsignificantly increased fasting serum insulin (+14.29%, p=0.18), accompanied by marginal nonsignificant increases in fasting plasma glucose and A1C. There was a decrease in HOMA2 percent beta-cell function (-2.9%, p=0.72) and increase in HOMA2 insulin resistance (+14%, p=0.16) in the atorvastatin group as compared with baseline, but the difference was not statistically significant.

CONCLUSIONS

Atorvastatin in the dose used failed to produce significant change in pancreatic beta-cell function and insulin resistance in type 2 diabetes patients as assessed by the HOMA2 index. The possible explanations include absence of lipotoxicity at prevailing levels of dyslipidemia at baseline or inadequacy of statin dose used in the study. (Clinical Trials Registry-India: CTRI/2008/091/000099).

The independent and combined effects of exercise training and reducing sedentary behavior on cardiometabolic risk factors

This pilot study examined if the combination of exercise training and reducing sedentary time (ST) results in greater changes to health markers than either intervention alone. Fifty-seven overweight/obese participants (19 males/39 females) (mean ± SD; age, 43.6 ± 9.9 years; body mass index (BMI), 35.1 ± 4.6 kg·m(-2)) completed the 12-week study and were randomly assigned to (i) EX: exercise 5 days·week(-1) for 40 min·session(-1) at moderate intensity; (ii) rST: reduce ST and increase nonexercise physical activity; (iii) EX-rST: combination of EX and rST; and (iv) CON: maintain behavior. Fasting lipids, blood pressure (BP), peak oxygen uptake, BMI, and 2-h oral glucose tolerance tests were completed pre- and post-intervention. EX and EX-rST increased peak oxygen uptake by ∼10% and decreased systolic BP (both p < 0.001). BMI decreased by -3.3% (95% confidence interval: -4.6% to -1.9%) for EX-rST and -2.2% (-3.5% to 0.0%) for EX. EX-rST significantly increased composite insulin-sensitivity index by 17.8% (2.8% to 32.8%) and decreased insulin area under the curve by 19.4% (-31.4% to -7.3%). No other groups improved in insulin action variables. rST group decreased ST by 7% (∼50 min·day(-1)); however, BP was the only health-related outcome that improved. EX and EX-rST improved peak oxygen uptake and BMI, providing further evidence that moderate-intensity exercise is beneficial. The within-group analysis provides preliminary evidence that exercising and reducing ST may result in improvements in metabolic biomarkers that are not seen with exercise alone, though between-group differences did not reach statistical significance. Future studies, with larger samples, should examine health-related outcomes resulting from greater reductions in ST over longer intervention periods.