Lifestyle intervention and adipokine levels in subjects at high risk for type 2 diabetes: the Study on Lifestyle intervention and Impaired glucose tolerance Maastricht (SLIM)

Effects of Exercise Training on Inflammatory and Cardiometabolic Risk Biomarkers in Patients With Type 2 Diabetes Mellitus: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

BACKGROUND

The interaction between type 2 diabetes mellitus (T2DM) and cardiometabolic morbidity and mortality stems from the progressive nature of inflammation underpinning both diseases. Exercise training is considered an effective treatment strategy for T2DM and cardiometabolic diseases.

OBJECTIVE

The current systematic review and meta-analysis investigated the effects of exercise training on inflammatory and cardiometabolic risk biomarkers in patients with T2DM.

DATA SOURCES

Electronic databases (PubMed/Medline, Embase, Cochrane Library, CINAHL, Google Scholar, Scopus, and Web of Science) were searched for randomized controlled trials (RCTs) from inception to January 2022. We used random effects models to estimate weighted mean differences with 95% confidence intervals.

STUDY SELECTION

Twenty-five RCTs were included (N = 1257 participants; mean age = 52 years). Included studies had moderate to good overall methodological quality (TESTEX = 9 (range 7-13).

RESULTS

Meta-analysis indicated that exercise training significantly increased adiponectin and decreased fasting insulin, homeostatic model assessment for insulin resistance, tumor necrosis factor-α, interleukin-6, and C-reactive protein (ps ≤ 0.05). Subgroup analysis by type of training indicated that aerobic exercise had the most consistent beneficial effects as compared to other types of exercise training; however, there was high heterogeneity among studies.

CONCLUSION

Different types of exercise training increase adiponectin levels and decrease pro-inflammatory cytokines such as TNF-α, IL-6, and CRP, as well as fasting insulin and insulin resistance markers in patients with T2DM. However, these effects were not beneficial for more commonly measured cardiometabolic risk factors (i.e., lipid profiles). Additional relevant clinical trials are required to confirm these results.

TRIAL REGISTRATION

This systematic review and meta-analysis was prospectively registered in the PROSPERO database (CRD42022307396).

Fitness Levels and Gender Are Related With the Response of Plasma Adipokines and Inflammatory Cytokines in Prepubertal Children

Background and Aim

Changes in adipokines have been related with the development of metabolic syndrome, frequently associated with obesity, and other risk factors. Fitness seems to promote a healthy cardiovascular status and could be a protector factor, just from childhood. Therefore, the present study aimed to evaluate the relationship between fitness levels with plasma adipokines and inflammatory biomarkers in prepubertal children.

Methods

One hundred and thirty-seven healthy normal-weight prepubertal children were recruited from local schools and divided after performing the fitness tests, into two groups according to fitness level—low cardiovascular fitness group (LF) and equal or higher cardiovascular fitness group (HF). Anthropometric variables, blood pressure (BP) and plasma insulin, and leptin, resistin, adiponectin, tumor necrosis factor-alpha, hepatic growth factor, interleukin (IL)-8, monocyte chemoattractant protein-1, nerve growth factor (NGF), and plasminogen activator inhibitor-1 (PAI-1) were measured fasting in both groups to be compared. Univariate analysis of variance, comparative analysis, binary logistic regression, stepwise linear regression, and principal component analysis were conducted to evaluate the association between fitness, BMI, gender, and the biochemical parameters.

Results

Girls and boys with HF presented lower waist circumference Z-score, BMI Z-score, systolic BP (only boys) as well as lower levels of leptin and NGF compared with their respective LF group. Regarding the association between variables, fitness showed an inverse relationship with BMI Z-score, leptin, PAI-1, HOMA-IR, resistin, IL-8, and NGF.

Conclusion

An adequate level of fitness seems to protect against risk factors related to low-grade inflammation and altered adipokines that are related to the onset of obesity just from the prepubertal stage.

Nutrition and physical activity interventions for the general population with and without cardiometabolic risk: a scoping review

OBJECTIVE

The objective of this scoping review was to examine the research question: In the adults with or without cardiometabolic risk, what is the availability of literature examining interventions to improve or maintain nutrition and physical activity-related outcomes? Sub-topics included: (1) behaviour counseling or coaching from a dietitian/nutritionist or exercise practitioner, (2) mobile applications to improve nutrition and physical activity and (3) nutritional ergogenic aids.

DESIGN

The current study is a scoping review. A literature search of the Medline Complete, CINAHL Complete, Cochrane Database of Systematic Reviews and other databases was conducted to identify articles published in the English language from January 2005 until May 2020. Data were synthesised using bubble charts and heat maps.

SETTING

Out-patient, community and workplace.

PARTICIPANTS

Adults with or without cardiometabolic risk factors living in economically developed countries.

RESULTS

Searches resulted in 19 474 unique articles and 170 articles were included in this scoping review, including one guideline, thirty systematic reviews (SR), 134 randomised controlled trials and five non-randomised trials. Mobile applications (n 37) as well as ergogenic aids (n 87) have been addressed in several recent studies, including SR. While primary research has examined the effect of individual-level nutrition and physical activity counseling or coaching from a dietitian/nutritionist and/or exercise practitioner (n 48), interventions provided by these practitioners have not been recently synthesised in SR.

CONCLUSION

SR of behaviour counseling or coaching provided by a dietitian/nutritionist and/or exercise practitioner are needed and can inform practice for practitioners working with individuals who are healthy or have cardiometabolic risk.

A weight-loss Mediterranean diet/lifestyle intervention ameliorates inflammation and oxidative stress in patients with obstructive sleep apnea: results of the "MIMOSA" randomized clinical trial

PURPOSE

Inflammation and oxidative stress are implicated in obstructive sleep apnea (OSA) pathophysiology. We aimed at exploring whether the combination of a weight-loss Mediterranean diet/lifestyle intervention with OSA standard care, i.e., continuous positive airway pressure (CPAP) prescription, can lead to greater improvements in inflammation and oxidative stress, compared to standard care alone.

METHODS

This was a randomized controlled clinical trial in 187 adult, overweight patients with moderate-to-severe OSA. Participants were randomized to a standard care (SCG, n = 65), a Mediterranean diet (MDG, n = 62) or a Mediterranean lifestyle group (MLG, n = 60). All groups received OSA standard care. Intervention arms participated in a 6-month behavioral weight-loss intervention based on the Mediterranean diet, while the MLG also received counselling on physical activity and sleep habits.

RESULTS

Seven patients were excluded and 53/180 were lost to follow-up. In intention to treat analysis (n = 180), the SCG did not exhibit changes in any of the markers assessed. Post-intervention age-, sex-, baseline- and CPAP use-adjusted plasma high sensitivity C-reactive protein levels (mg/L) were lower in the MDG and the MLG compared to the SCG (mean difference - 1.33, P = 0.039 and - 1.68, P = 0.007, respectively). The MLG also exhibited lower urinary 8-iso prostaglandin F2a levels (ng/mg creatinine) compared to the SCG and the MDG (mean difference - 1.10, P < 0.0001 and - 0.80, P = 0.001, respectively). Adiponectin and oxidized guanine levels were not altered in any of the study groups. Results were similar in per protocol analysis (n = 127).

CONCLUSION

A weight-loss Mediterranean diet/lifestyle intervention on top of CPAP has anti-inflammatory and antioxidant benefits in OSA.

REGISTRATION

The trial was prospectively registered at ClinicalTrials.gov (NCT02515357) on August 4, 2015.

Effect of physical activity promotion on adiponectin, leptin and other inflammatory markers in prediabetes: a systematic review and meta-analysis of randomized controlled trials

AIMS

Inflammatory stage in prediabetes is associated with increase in level of adipokines and pro-inflammatory cytokines. Physical activity promotion considered as a first-line therapeutic strategy to treat prediabetes. We have conducted the systematic review and meta-analysis to strengthen the evidence on the impact of physical activity promotion on inflammatory markers in prediabetes.

METHODS

Studies were identified using electronic search and manual search techniques by choosing keywords for prediabetes, physical activity and inflammatory marker. Randomized controlled trials on individuals diagnosed with prediabetes and provided intervention in the form of physical activity were included in this review. Adiponectin, leptin, C-reactive protein, interleukin-6 and tumour necrosis factor-α were the considered outcome measures.

RESULTS

Our search retrieved 1,688 citations, 31 full-text articles assessed for eligibility of inclusion. Nine studies satisfied the pre-specified criteria for inclusion. Meta-analysis found that physical activity with or without dietary or lifestyle modification reduces level of leptin (MD-2.11 ng/mL, 95% CI -3.81 - -0.42) and interleukin-6 (MD -0.15 pg/mL, 95% CI -0.25--0.04). It has no effect on level of adiponectin (MD 0.26 µg/mL, 95% CI -0.42- 0.93), C-reactive protein (MD -0.05 mg/L, 95% CI -0.33-0.23) and tumour necrosis factor-α (MD 0.67 pg/mL, 95% CI -2.56-3.89).

CONCLUSIONS

This review suggests that physical activity promotion with dietary and lifestyle modification may reduce the level of leptin and interleukin-6 but are uncertain if there is any effect on levels of adiponectin, C-reactive protein and tumour necrosis factor-α in the individuals with prediabetes.

Combined Fluoxetine and Metformin Treatment Potentiates Antidepressant Efficacy Increasing IGF2 Expression in the Dorsal Hippocampus

An increasing number of studies show that selective serotonin reuptake inhibitors (SSRIs) exert their therapeutic action, at least in part, by amplifying the influence of the living environment on mood. As a consequence, when administered in a favorable environment, SSRIs lead to a reduction of symptoms, but in stressful conditions, they show limited efficacy. Therefore, novel therapeutic approaches able to neutralize the influence of the stressful environment on treatment are needed. The aim of our study was to test whether, in a mouse model of depression, the combined administration of SSRI fluoxetine and metformin, a drug able to improve the metabolic profile, counteracts the limited efficacy of fluoxetine alone when administered in stressful conditions. Indeed, metabolic alterations are associated to both the onset of major depression and the antidepressant efficacy. To this goal, adult C57BL/6 male mice were exposed to stress for 6 weeks; the first two weeks was aimed at generating a mouse model of depression. During the remaining 4 weeks, mice received one of the following treatments: vehicle, fluoxetine, metformin, or a combination of fluoxetine and metformin. We measured liking- and wanting-type anhedonia as behavioral phenotypes of depression and assessed the expression levels of selected genes involved in major depressive disorder and antidepressant response in the dorsal and ventral hippocampus, which are differently involved in the depressive symptomatology. The combined treatment was more effective than fluoxetine alone in ameliorating the depressive phenotype after one week of treatment. This was associated to an increase in IGF2 mRNA expression and enhanced long-term potentiation, specifically in the dorsal hippocampus, at the end of treatment. Overall, the present results show that, when administered in stressful conditions, the combined fluoxetine and metformin treatment may represent a more effective approach than fluoxetine alone in a short term. Finally, our findings highlight the relevance of polypharmacological strategy as effective interventions to increase the efficacy of the antidepressant drugs currently available.

Exercise Increases Adiponectin and Reduces Leptin Levels in Prediabetic and Diabetic Individuals: Systematic Review and Meta-Analysis of Randomized Controlled Trials

It is speculated that lifestyle interventions known to improve diabetic metabolic state may exert their effects via adipokines. The aim of this systematic review and meta-analysis was to evaluate the chronic effects of physical exercise on adiponectin and leptin levels in adult prediabetic and diabetic individuals. PubMed, Embase, Scopus, The Cochrane Library, clinicaltrials.gov, and WHO Clinical Trials Registry were searched for randomized controlled trials. Pooled effects of interventions were assessed as mean difference (MD) with random effects model. Sensitivity analysis was conducted to test data robustness and subgroup analysis for study heterogeneity. Twenty-two trials with 2996 individuals were included in the meta-analysis. Physical exercise increased levels of adiponectin (MD: 0.42 µg/mL; 95% confidence interval (CI), 0.23, 0.60, p < 0.00001, n = 19 trials) and reduced leptin levels (MD: −1.89 ng/mL; 95% CI, −2.64, −1.14, p < 0.00001, n = 14 trials). These results were robust and remained significant after sensitivity analysis. Study heterogeneity was generally high. As for physical exercise modalities, aerobic exercise, but not other modalities, increased adiponectin and reduced leptin levels. In conclusion, physical exercise and, specifically, aerobic exercise, leads to higher adiponectin and lower leptin levels in prediabetic and diabetic adults. However, cautious interpretation of current findings is warranted.

Diet, physical activity or both for prevention or delay of type 2 diabetes mellitus and its associated complications in people at increased risk of developing type 2 diabetes mellitus

BACKGROUND

The projected rise in the incidence of type 2 diabetes mellitus (T2DM) could develop into a substantial health problem worldwide. Whether diet, physical activity or both can prevent or delay T2DM and its associated complications in at-risk people is unknown.

OBJECTIVES

To assess the effects of diet, physical activity or both on the prevention or delay of T2DM and its associated complications in people at increased risk of developing T2DM.

SEARCH METHODS

This is an update of the Cochrane Review published in 2008. We searched the CENTRAL, MEDLINE, Embase, ClinicalTrials.gov, ICTRP Search Portal and reference lists of systematic reviews, articles and health technology assessment reports. The date of the last search of all databases was January 2017. We continuously used a MEDLINE email alert service to identify newly published studies using the same search strategy as described for MEDLINE up to September 2017.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) with a duration of two years or more.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methodology for data collection and analysis. We assessed the overall quality of the evidence using GRADE.

MAIN RESULTS

We included 12 RCTs randomising 5238 people. One trial contributed 41% of all participants. The duration of the interventions varied from two to six years. We judged none of the included trials at low risk of bias for all 'Risk of bias' domains.Eleven trials compared diet plus physical activity with standard or no treatment. Nine RCTs included participants with impaired glucose tolerance (IGT), one RCT included participants with IGT, impaired fasting blood glucose (IFG) or both, and one RCT included people with fasting glucose levels between 5.3 to 6.9 mmol/L. A total of 12 deaths occurred in 2049 participants in the diet plus physical activity groups compared with 10 in 2050 participants in the comparator groups (RR 1.12, 95% CI 0.50 to 2.50; 95% prediction interval 0.44 to 2.88; 4099 participants, 10 trials; very low-quality evidence). The definition of T2DM incidence varied among the included trials. Altogether 315 of 2122 diet plus physical activity participants (14.8%) developed T2DM compared with 614 of 2389 comparator participants (25.7%) (RR 0.57, 95% CI 0.50 to 0.64; 95% prediction interval 0.50 to 0.65; 4511 participants, 11 trials; moderate-quality evidence). Two trials reported serious adverse events. In one trial no adverse events occurred. In the other trial one of 51 diet plus physical activity participants compared with none of 51 comparator participants experienced a serious adverse event (low-quality evidence). Cardiovascular mortality was rarely reported (four of 1626 diet plus physical activity participants and four of 1637 comparator participants (the RR ranged between 0.94 and 3.16; 3263 participants, 7 trials; very low-quality evidence). Only one trial reported that no non-fatal myocardial infarction or non-fatal stroke had occurred (low-quality evidence). Two trials reported that none of the participants had experienced hypoglycaemia. One trial investigated health-related quality of life in 2144 participants and noted that a minimal important difference between intervention groups was not reached (very low-quality evidence). Three trials evaluated costs of the interventions in 2755 participants. The largest trial of these reported an analysis of costs from the health system perspective and society perspective reflecting USD 31,500 and USD 51,600 per quality-adjusted life year (QALY) with diet plus physical activity, respectively (low-quality evidence). There were no data on blindness or end-stage renal disease.One trial compared a diet-only intervention with a physical-activity intervention or standard treatment. The participants had IGT. Three of 130 participants in the diet group compared with none of the 141 participants in the physical activity group died (very low-quality evidence). None of the participants died because of cardiovascular disease (very low-quality evidence). Altogether 57 of 130 diet participants (43.8%) compared with 58 of 141 physical activity participants (41.1%) group developed T2DM (very low-quality evidence). No adverse events were recorded (very low-quality evidence). There were no data on non-fatal myocardial infarction, non-fatal stroke, blindness, end-stage renal disease, health-related quality of life or socioeconomic effects.Two trials compared physical activity with standard treatment in 397 participants. One trial included participants with IGT, the other trial included participants with IGT, IFG or both. One trial reported that none of the 141 physical activity participants compared with three of 133 control participants died. The other trial reported that three of 84 physical activity participants and one of 39 control participants died (very low-quality evidence). In one trial T2DM developed in 58 of 141 physical activity participants (41.1%) compared with 90 of 133 control participants (67.7%). In the other trial 10 of 84 physical activity participants (11.9%) compared with seven of 39 control participants (18%) developed T2DM (very low-quality evidence). Serious adverse events were rarely reported (one trial noted no events, one trial described events in three of 66 physical activity participants compared with one of 39 control participants - very low-quality evidence). Only one trial reported on cardiovascular mortality (none of 274 participants died - very low-quality evidence). Non-fatal myocardial infarction or stroke were rarely observed in the one trial randomising 123 participants (very low-quality evidence). One trial reported that none of the participants in the trial experienced hypoglycaemia. One trial investigating health-related quality of life in 123 participants showed no substantial differences between intervention groups (very low-quality evidence). There were no data on blindness or socioeconomic effects.

AUTHORS' CONCLUSIONS

There is no firm evidence that diet alone or physical activity alone compared to standard treatment influences the risk of T2DM and especially its associated complications in people at increased risk of developing T2DM. However, diet plus physical activity reduces or delays the incidence of T2DM in people with IGT. Data are lacking for the effect of diet plus physical activity for people with intermediate hyperglycaemia defined by other glycaemic variables. Most RCTs did not investigate patient-important outcomes.

Prevention of Type 2 Diabetes with the Chinese Herbal Medicine Tianqi Capsule: A Systematic Review and Meta-Analysis

INTRODUCTION

Prevention of the rapid growth in incidence of type 2 diabetes (T2DM) is a big challenge for clinicians. In China, many trials have indicated that Tianqi capsule, which contains several Chinese herbal medicines as part of a large healing system called traditional Chinese medicine, could decrease the incidence of T2DM. The review assessed the effectiveness of Tianqi capsule in prevention of T2DM.

METHODS

Seven electronic databases were searched to identify eligible trials published from the inception of the databases up until May 1, 2017. Randomized controlled trials (RCTs) of Tianqi capsule for impaired glucose tolerance (IGT) were included. Data extraction and quality assessment were performed according to the Cochrane review standards. A random or a fixed effect model was used to analyze outcomes which were expressed as risk ratios (RRs) or mean differences (MD), and I ² statistics were used to assess heterogeneity.

RESULTS

Six trials were identified that included 1027 subjects. Meta-analysis showed that subjects who received Tianqi capsule plus lifestyle modification (LM) were less likely to progress to T2DM compared to controls (RR 0.55, 95% CI 0.44-0.68). Subjects who received Tianqi capsule plus LM were more likely to have glucose return to normal compared to controls (RR 0.69; 95% CI 0.62-0.78); and they had reduced fasting plasma glucose (FBG) (MD - 0.35; 95% CI - 0.55 to - 0.16) and 2-h plasma glucose (2 h PG) (MD - 1.04; 95% CI - 1.75 to - 0.32). There was no statistical difference between the two groups for IGT stabilized incidence (RR 0.89; 95% CI 0.71-1.12). No obvious adverse events occurred.

CONCLUSION

In patients with IGT, Tianqi capsule reduced the risk of progression to T2DM and increased the possibility of regression toward normoglycemia. As a result of the limited number of RCTs and the methodological drawbacks of the included studies, the results should be interpreted with caution.

Clinical use of adiponectin as a marker of metabolic dysregulation

Adiponectin concentrations exhibit strong cross-sectional relationships with obesity, inflammation, and diabetes. Adiponectin concentrations have been extensively evaluated as epidemiologic markers of diabetes and cardiovascular disease risk. In the present review we will provide an overview of these epidemiologic relationships as the backdrop for an evaluation of the clinical applications of adiponectin measurements. These include using adiponectin as an indicator of need for preventive or therapeutic intervention, as a predictor of response to therapy, and as a marker of therapeutic effectiveness. These efforts are laying the groundwork for the transition of adiponectin measurements from the laboratory to the clinic.

Diabetes self-management and leptin in Mexican Americans with type 2 diabetes: the Starr County border health initiative

PURPOSE

The purpose of the study was to (1) characterize leptin in Mexican Americans with poorly controlled type 2 diabetes, (2) examine relationships among leptin and indicators of diabetes status (body mass index and A1C), and (3) explore the effects of a culturally tailored diabetes self-management education intervention on leptin.

METHODS

In Starr County, an impoverished Texas-Mexico border community, 252 Mexican Americans with type 2 diabetes were recruited to test a diabetes self-management education intervention culturally tailored in terms of language, dietary recommendations, social emphasis, family participation, and incorporation of cultural health beliefs. Groups of 8 participants were randomized to experimental or wait-listed control conditions. Outcomes were measured at 3, 6, and 12 months; by 12 months, 109 had complete leptin data.

RESULTS

Most participants were women and, on average, 55 years of age, diagnosed with diabetes for 8 years, obese, and in poor glycemic control. Three variables-body mass index, sex, A1C-explained 36% of the variance in baseline leptin; there were no intervention effects on leptin. Sex, time, and gender × time interaction effects on leptin were statistically significant; greater increases in leptin over time occurred in women compared to men. In women, fasting blood glucose changes from baseline to 12 months significantly predicted leptin changes from baseline to 12 months; in men, body mass index changes predicted leptin change.

CONCLUSIONS

With increasing obesity rates, further research is warranted to determine if leptin is a useful intervention target in type 2 diabetes.

Efficacy of lifestyle interventions in reducing diabetes incidence in patients with impaired glucose tolerance: a systematic review of randomized controlled trials

OBJECTIVE

Every year over 3.8 million people are dying of diabetes and its complications. Lifestyle intervention was suggested to have beneficial effects in preventing and reducing diabetes incidence. Interventions in patients with impaired glucose tolerance (IGT), who belong to a high risk group in developing diabetes, are supposed to be especially effective. According to the evidence hierarchy, a 1a level of evidence is missing and therefore a systematic review verifying the efficacy of lifestyle intervention is needed.

MATERIALS/METHODS

Systematic review: The electronic database PubMed, Embase, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, and Health Technology Assessment database were searched. Main inclusion criteria were randomized controlled trials, impaired glucose tolerance, lifestyle intervention with control group and observation time >6 months. Outcome measures were all diabetes events, as defined by the authors of each study, all-cause mortality, diabetes mortality, and quality adjusted life years (QALY). Two independent reviewers abstracted the studies by title, abstract and full-text analysis. Furthermore the reporting quality of each study was assessed by using the CONSORT criteria (Consolidated Standards of Reporting Trials) and the methodological quality by SIGN 50 instrument (Scottish Intercollegiate Guidelines Network methodology checklist for randomized controlled trials). The primary outcome measure was diabetes incidence. Secondary outcome measures were overall mortality, disease-specific mortality, quality adjusted life years (QALY), and clinical parameters; body mass index (BMI), weight change, blood pressure, blood parameter, smoking, alcohol consumption.

RESULTS

7 trials which included 25 relevant publications were identified. Kappa Cohens for title-analysis were К=0.77, (CI=0.71-0.83), abstract-analysis К=0.81 (CI=0.64-0.92) and full-text analysis К=0.78 (CI=0.57-0.98). Overall 5663 patients were analyzed with primary follow-up time: India (3y), Japan (4y), Sweden (5y), Da Qing (6y), SIM (3y), DPP (5y), DPS (4y) and drop-out rate ranges from 5% to 28%. Diabetes incidence ranges from 3% to 46% in the intervention group and 9.3% to 67.7% in the control group. The India study reported ARR=16%, RRR=29% (p=0.018), Japan: ARR=6.3%, RRR=65% (p<0.001), Sweden: ARR=4%, RRR=25% (p=not significant), Da Qing: ARR=22%, RRR=32% (p<0.05), SLIM: ARR=20%, RRR=53% (p=0.025), DPP: ARR=15%, RRR=58% (significant, no p-value reported), and DPS: ARR=12%, RRR=52% (significant, no p-value reported). Mortality and morbidity were only analyzed in Da Qing study which showed no statistical differences (overall mortality: HRR 0.96, CI 0.65-1.41, CVD-mortality: HRR 0.83; CI 0.48-1.40, CVD event: HRR 0.98; CI 0.71-1.37).

CONCLUSION

Under consideration of heterogeneity in lifestyle interventions and follow up time of the included studies, this systematic review illustrated that lifestyle intervention can have a beneficial effect on the incidence of diabetes in patients with impaired glucose tolerance. However, several studies found the effect of lifestyle intervention decreased after intervention was terminated. No long-term benefit in mortality and morbidity was found. Development of standardized lifestyle intervention program is strongly needed and further long-term intervention trials using this program are crucial in evidencing the long-term efficacy.

Resistance Exercise Did Not Alter Intramuscular Adipose Tissue but Reduced Retinol-binding Protein-4 Concentration in Individuals with Type 2 Diabetes Mellitus

Lipid accumulation in muscle is associated with diminished insulin sensitivity. It was hypothesized that resistance exercise decreases muscular adipose tissue and reduces the level of retinol-binding protein-4 (RBP4), which is linked to adipose tissue and insulin sensitivity in diabetics. Forty-four women with type 2 diabetes were randomly assigned to three groups for a period of 12 weeks: control (asked to maintain a sedentary lifestyle); resistance exercise (elastic band exercise at moderate intensity five times per week); and aerobic exercise (walking for 60 min at moderate intensity five times per week). Subcutaneous (SCAT), subfascial (SFAT) and intramuscular (IMAT) adipose tissues at mid-thigh level were assessed using computed tomography, and RBP4 level and insulin sensitivity (fractional disappearance rate of insulin, kITT) were assessed before and after intervention. Changes in SCAT, SFAT, IMAT, RBP4 and kITT were similar among the three groups. Within-group analysis revealed that body mass index and waist circumference decreased significantly in both exercise groups, but RBP4 decreased significantly only with resistance exercise. Resistance exercise did not alter muscular adipose tissue or improve insulin sensitivity.

Subcutaneous and visceral adipose tissue: structural and functional differences

Obesity is a heterogeneous disorder. Obese individuals vary in their body fat distribution, their metabolic profile and degree of associated cardiovascular and metabolic risk. Abdominal obesity carries greater risk of developing diabetes and future cardiovascular events than peripheral or gluteofemoral obesity. There are differences between adipose tissue present in subcutaneous areas (SCAT) and visceral adipose tissue (VAT) present in the abdominal cavity. These include anatomical, cellular, molecular, physiological, clinical and prognostic differences. Anatomically, VAT is present mainly in the mesentery and omentum, and drains directly through the portal circulaion to the liver. VAT compared with SCAT is more cellular, vascular, innervated and contains a larger number of inflammatory and immune cells, lesser preadipocyte differentiating capacity and a greater percentage of large adipocytes. There are more glucocorticoid and androgen receptors in VAT than in SCAT. VAT adipocytes are more metabolically active, more sensitive to lipolysis and more insulin-resistant than SCAT adipocytes. VAT has a greater capacity to generate free fatty acids and to uptake glucose than SCAT and is more sensitive to adrenergic stimulation, while SCAT is more avid in absorption of circulating free fatty acids and triglycerides. VAT carries a greater prediction of mortality than SCAT.

Long-term exercise training in overweight adolescents improves plasma peptide YY and resistin

The objective of this study was to investigate the effect of long-term exercise training on concentrations of five hormones related to appetite and insulin resistance in overweight adolescents. In addition, we were interested in the relationships of these hormones with each other and with anthropometric and/or cardiovascular disease marker changes. Participants were >or=the 85th percentile for BMI for age and sex and participated in an 8-month supervised aerobic training program. Anthropometrics, cardiovascular fitness assessment, and fasting blood samples were taken pre- and post-training. Glucose, insulin, total cholesterol (TC), high-density lipoprotein (HDL) cholesterol, low-density lipoprotein (LDL) cholesterol, triglycerides, leptin, active ghrelin, total peptide YY (PYY), adiponectin, and resistin concentrations were measured. The participants increased their time to exhaustion on an incremental treadmill test and decreased both percent body fat and blood triglyceride concentrations. Total PYY concentration increased and resistin concentration decreased after long-term exercise training, which are favorable outcomes. Leptin concentrations were related to weight, percent body fat, waist circumference, and triglyceride concentrations pre- and post-training. The changes in resistin concentrations were related to the changes in triglyceride concentrations. We conclude that long-term exercise training has beneficial effects for overweight adolescents with respect to PYY and resistin, hormones related to appetite and insulin sensitivity.

Exercise test and glucose homeostasis in rats treated with alloxan during the neonatal period or fed a high calorie diet

BACKGROUND

Animal models appear well-suited for studies into the role of exercise in the prevention of non-insulin-dependent diabetes mellitus (NIDDM). The aim of the present study was to analyze glucose homeostasis and blood lactate during an exercise swimming test in rats treated with alloxan during the neonatal period and/or fed a high calorie diet from weaning onwards.

METHODS

Rats were injected with alloxan (200 mg/kg, i.p.) or vehicle (citrate buffer) at 6 days of age. After weaning, rats were divided into four groups and fed either a balanced diet or a high-caloric diet as follows: C, control group (vehicle + normal diet); A, alloxan-treated rats fed the normal diet; H, vehicle-treated rats fed the high-caloric diet; and HA, alloxan-treated rats fed the high-caloric diet.

RESULTS

Fasting serum glucose levels were higher in groups A and AH compared with the control group. The Homeostatic Model Assessment index varied in the groups as follows: H>A>HA = C. There were no differences in free fatty acids or blood lactate concentrations during the swim test.

CONCLUSIONS

Alloxan-treated rats fed a normal or high-caloric diet have the potential to be used in studies analyzing the role physical exercise plays in the prevention of NIDDM.

Intricacies of fat

One of the most exciting cell biology fields of study concerns the physiology and pathology of fat. The basic assumptions once held concerning the function of adipose tissue have been shown to be oversimplified or sometimes completely wrong. Fat does more than store excess energy; it is actually the largest endocrine organ in the body, and it may be one of the most active. Adipocytes release hormones and other molecules that act on nearby tissues and travel through the vasculature to distant sites, such as the brain, skeletal muscle, and liver. Under conditions of normal weight, those signals help the body to suppress hunger, utilize glucose, and decrease the risk of cardiovascular disease. However, under conditions of obesity, the hormones (or the proteins that bind the hormones) become abnormal and can result in states of chronic inflammation leading to diabetes and heart disease. In addition, excessive fat can lead to the accumulation of lipid droplets in nonfat cells, including skeletal and cardiac muscle. Although some lipid droplets are used as an immediate source of energy for cells, large numbers of stored droplets can cause cellular damage and cell death. The purposes of this article are to review the normal and deviant signals released by fat cells, to draw a link between those signals and chronic diseases such as diabetes, and to discuss the role of exercise in reversing some of the deviant signaling perpetrated by excess fat.