Metformin modifies the exercise training effects on risk factors for cardiovascular disease in impaired glucose tolerant adults

Glucagon-Like Peptide-1 Receptor Agonists and Sodium Glucose Cotransporter-2 Inhibitors and Cardiorespiratory Fitness Interaction

INTRODUCTION

Cardiorespiratory fitness (CRF) is a stronger predictor of mortality than traditional risk factors and is a neglected vital sign of health. Enhanced fitness is a cornerstone in diabetes management and is most often delivered concurrently with pharmacological agents, which can have an opposing impact, as has been reported with metformin. Considering the rapid evolution of diabetes medications with improved cardiovascular outcomes, such as glucagon-like peptide-1 receptor agonists and sodium glucose cotransporter-2 inhibitors, it is of importance to consider the influence of these vis-a-vis effects on CRF.

MATERIALS AND METHODS

Combining the words glucagon-like peptide-1 receptor agonists and sodium glucose cotransporter-2 inhibitors with cardiorespiratory fitness, an online search was done using PubMed, Embase, Scopus, Web of Science, Scientific Electronic Library Online, and Cochrane.

RESULTS

There were only a few randomized controlled studies that included CRF, and the results were mostly neutral. A handful of smaller studies detected improved CRF using sodium glucose cotransporter-2 inhibitors in patients with congestive heart failure.

CONCLUSIONS

Since CRF is a superior prognosticator for cardiovascular outcomes and both medications can cause lean muscle mass loss, the current review highlights the paucity of relevant interactive analysis.

Understanding the variation in exercise responses to guide personalized physical activity prescriptions

Understanding the factors that contribute to exercise response variation is the first step in achieving the goal of developing personalized exercise prescriptions. This review discusses the key molecular and other mechanistic factors, both extrinsic and intrinsic, that influence exercise responses and health outcomes. Extrinsic characteristics include the timing and dose of exercise, circadian rhythms, sleep habits, dietary interactions, and medication use, whereas intrinsic factors such as sex, age, hormonal status, race/ethnicity, and genetics are also integral. The molecular transducers of exercise (i.e., genomic/epigenomic, proteomic/post-translational, transcriptomic, metabolic/metabolomic, and lipidomic elements) are considered with respect to variability in physiological and health outcomes. Finally, this review highlights the current challenges that impede our ability to develop effective personalized exercise prescriptions. The Molecular Transducers of Physical Activity Consortium (MoTrPAC) aims to fill significant gaps in the understanding of exercise response variability, yet further investigations are needed to address additional health outcomes across all populations.

The potential blunting effect of metformin and/or statin therapy on physical activity-induced associations with HbA1c in type 2 diabetes

Highlights Our analysis indicates a potential blunting effect of metformin and/or statin therapy on physical activity-induced associations with HbA1c. The benefit of daily physical activity on glycemic control in people with type 2 diabetes is potentially more apparent in those prescribed neither metformin nor statin therapy. As physical activity is rarely prescribed in isolation of other background medications used to manage type 2 diabetes, the results of this analysis may help to maximize interventions delivered through routine clinical care, while allowing for personalization in prescribed physical activity and pharmacotherapy.

Geroprotector drugs and exercise: friends or foes on healthy longevity?

Physical activity and several pharmacological approaches individually combat age-associated conditions and extend healthy longevity in model systems. It is tantalizing to extrapolate that combining geroprotector drugs with exercise could extend healthy longevity beyond any individual treatment. However, the current dogma suggests that taking leading geroprotector drugs on the same day as exercise may limit several health benefits. Here, we review leading candidate geroprotector drugs and their interactions with exercise and highlight salient gaps in knowledge that need to be addressed to identify if geroprotector drugs can have a harmonious relationship with exercise.

Effects of Aerobic Training and Semaglutide Treatment on Pancreatic β-Cell Secretory Function in Patients With Type 2 Diabetes

CONTEXT

Prior to this study, it is known that type 2 diabetes is linked to obesity and a sedentary lifestyle, leading to inadequate β-cell function and insulin resistance. Limited research has explored the metabolic effects of combining exercise training with antidiabetic medications, particularly focusing on insulin secretion in patients with type 2 diabetes and moderately preserved β-cell function.

OBJECTIVE

The effect of the interaction of semaglutide and physical training on pancreatic β-cell secretory function is unknown in patients with type 2 diabetes.

METHODS

Thirty-one patients with type 2 diabetes underwent 12 weeks of aerobic training alone or concurrent to treatment with semaglutide. Patients randomly allocated to concurrent semaglutide and training were treated with semaglutide for 20 weeks before the training and evaluated at inclusion and again before and after the training intervention. Patients randomized to training were evaluated before and after training. The primary outcome was a change in insulin secretory capacity with training, evaluated by a 2-stepped hyperglycemic (20 and 30 mM) clamp.

RESULTS

Training increased the incremental area under the curve for insulin from 21 to 27 nM × 2 hours (ratio 1.28, 95% CI 1.02-1.60) during clamp step 1 and from 40 to 64 nM × 2 hours (ratio 1.61, 95% CI 1.25-2.07) during step 2. Semaglutide treatment increased insulin secretion from 16 to 111 nM × 2 hours (ratio 7.10, 95% CI 3.68-13.71), and from 35 to 447 nM × 2 hours (ratio 12.74, 95% CI 5.65-28.71), correspondingly. Semaglutide and training increased insulin secretion from 130 to 171 nM × 2 hours (ratio 1.31, 95% CI 1.06-1.63), and from 525 to 697 nM × 2 hours (ratio 1.33, 95% CI 1.02-1.72), correspondingly. The median increase in total insulin secretion with the combination was 134 nM × 2 hours greater (95% CI 108-232) than with training.

CONCLUSION

The combination of aerobic training and semaglutide treatment synergistically improved β-cell secretory function. (ClinicalTrials.gov number, ID NCT04383197).

Efficacy of metformin targets on cardiometabolic health in the general population and non-diabetic individuals: a Mendelian randomization study

BACKGROUND

Metformin shows beneficial effects on cardiometabolic health in diabetic individuals. However, the beneficial effects in the general population, especially in non-diabetic individuals are unclear. We aim to estimate the effects of perturbation of seven metformin targets on cardiometabolic health using Mendelian randomization (MR).

METHODS

Genetic variants close to metformin-targeted genes associated with expression of the corresponding genes and glycated haemoglobin (HbA1c) level were used to proxy therapeutic effects of seven metformin-related drug targets. Eight cardiometabolic phenotypes under metformin trials were selected as outcomes (average N = 466,947). MR estimates representing the weighted average effects of the seven effects of metformin targets on the eight outcomes were generated. One-sample MR was applied to estimate the averaged and target-specific effects in 338,425 non-diabetic individuals in UK Biobank.

FINDINGS

Genetically proxied averaged effects of five metformin targets, equivalent to a 0.62% reduction of HbA1c level, was associated with 37.8% lower risk of coronary artery disease (CAD) (odds ratio [OR] = 0.62, 95% confidence interval [CI] = 0.46-0.84), lower levels of body mass index (BMI) (β = -0.22, 95% CI = -0.35 to -0.09), systolic blood pressure (SBP) (β = -0.19, 95% CI = -0.28 to -0.09) and diastolic blood pressure (DBP) levels (β = -0.29, 95% CI = -0.39 to -0.19). One-sample MR suggested that the seven metformin targets showed averaged and target-specific beneficial effects on BMI, SBP and DBP in non-diabetic individuals.

INTERPRETATION

This study showed that perturbation of seven metformin targets has beneficial effects on BMI and blood pressure in non-diabetic individuals. Clinical trials are needed to investigate whether similar effects can be achieved with metformin medications.

FUNDING

Funding information is provided in the Acknowledgements.

The effect of SGLT-2 inhibitors on cardiorespiratory fitness capacity: A systematic review and meta-analysis

Objective: The study aimed to evaluate the effect of sodium-glucose transporter 2 (SGLT-2) inhibitors on various parameters of exercise capacity and provide an evidence-based basis for type 2 diabetes mellitus (T2DM) combined with heart failure (HF) patients or HF patients without T2DM who use SGLT-2 inhibitors to improve cardiorespiratory fitness (CRF). Methods: According to the participant, intervention, comparison, and outcome (PICO) elements, the effects of SGLT-2 inhibitor administration on VO₂ or VO₂peak were researched in this study. Weighted mean difference (WMD) and 95% confidence intervals (CIs) were calculated (random-effects model). Heterogeneity was assessed by the I² test. Results: Six studies were included according to the eligibility criteria: four were RCTs, and two were non-RCTs. Compared with the control group, the merge results of RCTs showed that SGLT-2 inhibitors could significantly increase the VO₂peak (WMD, 2.02 ml kg^-1 min^-1, 95% CI: 0.68-3.37, and p = 0.03; I² = 0% and p = 0.40) and VAT (WMD, 1.57 ml kg^-1 min^-1, 95% CI: 0.06-3.07, and p = 0.04; I² = 0% and p = 0.52) of the obese population, patients with T2DM, and chronic HF patients with or without T2DM. Subgroup analysis showed that SGLT-2 inhibitors improved the VO₂peak in non-HF patients (WMD, 3.57 ml kg^-1 min^-1, 95% CI: 0.87-6.26, and p = 0.009; I² = 4% and p = 0.31) more than in HF patients (WMD, 1.46 ml kg^-1 min^-1, 95% CI: -0.13-3.04, and p = 0.07; I² = 0% and p = 0.81). Moreover, the merge of single-arm studies also indicated that empagliflozin could improve VO₂peak (MD, 1.11 ml kg^-1 min^-1, 95% CI: 0.93-1.30, and p = 0.827, Δ p = 0.000 and I² = 0%) of T2DM patients with chronic HF. Conclusion: Despite the limited number of studies and samples involved, the meta-analysis preliminarily demonstrated that SGLT-2 inhibitors could improve some parameters of exercise capacity (VO₂peak, VAT) in chronic HF patients with or without T2DM and obese individuals, which had a positive effect on promoting cardiopulmonary fitness to help these populations improve their prognosis. Systematic Review Registration: [https://www.crd.york.ac.uk/prospero/#recordDetails], identifier [CRD42020202788].

Key signalling pathways underlying the aetiology of polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is a common endocrine condition characterised by a range of reproductive, endocrine, metabolic and psychological abnormalities. Reports estimate that around 10% of women of reproductive age are affected by PCOS, representing a significant prevalence worldwide, which poses a high economic health burden. As the origin of PCOS remains largely unknown, there is neither a cure nor mechanism-based treatments leaving patient management suboptimal and focused solely on symptomatic treatment. However, if the underlying mechanisms underpinning the development of PCOS were uncovered then this would pave the way for the development of new interventions for PCOS. Recently, there have been significant advances in our understanding of the underlying pathways likely involved in PCOS pathogenesis. Key insights include the potential involvement of androgens, insulin, anti-Müllerian hormone and transforming growth factor beta in the development of PCOS. This review will summarise the significant scientific discoveries on these factors that have enhanced our knowledge of the mechanisms involved in the development of PCOS and discuss the impact these insights may have in shaping the future development of effective strategies for women with PCOS.

Antioxidant and Antihyperglycemic Effects of Ephedra foeminea Aqueous Extract in Streptozotocin-Induced Diabetic Rats

Background: Ephedra foeminea is known in Jordan as Alanda and traditionally. It is used to treat respiratory symptoms such as asthma and skin rashes as an infusion in boiling water. The purpose of this study was to determine the antidiabetic property of Ephedra foeminea aqueous extract in streptozotocin-induced diabetic rats. Methods: The aqueous extract of Ephedra foeminea plant was used to determine the potential of its efficacy in the treatment of diabetes, and this extract was tested on diabetic rats as a model. The chemical composition of Ephedra foeminea aqueous extract was determined using liquid chromatography–mass spectrometry (LC-MS). Antioxidant activity was assessed using two classical assays (ABTS and DPPH). Results: The most abundant compounds in the Ephedra foeminea extract were limonene (6.3%), kaempferol (6.2%), stearic acid (5.9%), β-sitosterol (5.5%), thiamine (4.1%), riboflavin (3.1%), naringenin (2.8%), kaempferol-3-rhamnoside (2.3%), quercetin (2.2%), and ferulic acid (2.0%). The antioxidant activity of Ephedra foeminea aqueous extract was remarkable, as evidenced by radical scavenging capacities of 12.28 mg Trolox/g in ABTS and 72.8 mg GAE/g in DPPH. In comparison to control, induced diabetic rats treated with Ephedra foeminea extract showed significant improvement in blood glucose levels, lipid profile, liver, and kidney functions. Interleukin 1 and glutathione peroxidase levels in the spleen, pancreas, kidney, and liver of induced diabetic rats treated with Ephedra foeminea extract were significantly lower than in untreated diabetic rats. Conclusions: Ephedra foeminea aqueous extract appears to protect diabetic rats against oxidative stress and improve blood parameters. In addition, it has antioxidant properties that might be very beneficial medicinally.

Effects of chronic metformin treatment on training adaptations in men and women with hyperglycemia: A prospective study

OBJECTIVE

This study aimed to determine whether chronic metformin use interferes with the improvements in insulin resistance (IR) and cardiorespiratory fitness with aerobic training in people with hyperglycemia and metabolic syndrome (MetS).

METHODS

A total of 63 middle-aged (53 [7] years) individuals with MetS and obesity (BMI = 32.8 [4.5] kg/m² ) completed 16 weeks of supervised high-intensity interval training (3 d/wk, 43 min/session). Participants were either taking metformin (EXER+MET; n = 29) or were free of any pharmacological treatment for their MetS factors (EXER; n = 34). Groups were similar in their initial cardiorespiratory fitness (maximal oxygen uptake [VO_2MAX ]), age, percentage of women, BMI, and MetS factors (z score). The effects of exercise training on IR (homeostatic model assessment of insulin resistance [HOMA-IR]), MetS z score, VO_2MAX , maximal fat oxidation during exercise, and maximal aerobic power output were measured.

RESULTS

Fasting insulin and HOMA-IR decreased similarly in both groups with training (EXER+MET: -4.3% and -10.6%; EXER: -5.3% and -14.5%; p value for time = 0.005). However, metformin use reduced VO_2MAX improvements by half (i.e., EXER+MET: 12.7%; EXER: 25.3%; p value for time × group = 0.012). Maximal fat oxidation during exercise increased similarly in both groups (EXER+MET: 20.7%; EXER: 25.3%; p value for time = 0.040). VO_2MAX gains were not associated with HOMA-IR reductions (EXER+MET: r = -0.098; p = 0.580; EXER: r = -0.255; p = 0.182).

CONCLUSIONS

Metformin use was associated with attenuated VO_2MAX improvements but did not affect fasting IR reductions with aerobic training in individuals with hyperglycemia and high cardiovascular risk (i.e., MetS).

Metformin for diabetes prevention: update of the evidence base

We have conducted a narrative review based on a structured search strategy, focusing on the effects of metformin on the progression of non-diabetic hyperglycemia to clinical type 2 diabetes mellitus. The principal trials that demonstrated a significantly lower incidence of diabetes in at-risk populations randomized to metformin (mostly with impaired glucose tolerance [IGT]) were published mainly from 1999 to 2012. Metformin reduced the 3-year risk of diabetes by -31% in the randomized phase of the Diabetes Prevention Program (DPP), vs. -58% for intensive lifestyle intervention (ILI). Metformin was most effective in younger, heavier subjects. Diminishing but still significant reductions in diabetes risk for subjects originally randomized to these groups were present in the trial's epidemiological follow-up, the DPP Outcomes Study (DPPOS) at 10 years (-18 and -34%, respectively), 15 years (-18 and -27%), and 22 years (-18 and -25%). Long-term weight loss was also seen in both groups, with better maintenance under metformin. Subgroup analyses from the DPP/DPPOS have shed important light on the actions of metformin, including a greater effect in women with prior gestational diabetes, and a reduction in coronary artery calcium in men that might suggest a cardioprotective effect. Improvements in long-term clinical outcomes with metformin in people with non-diabetic hyperglycemia ("prediabetes") have yet to be demonstrated, but cardiovascular and microvascular benefits were seen for those in the DPPOS who did not vs. did develop diabetes. Multiple health economic analyses suggest that either metformin or ILI is cost-effective in a community setting. Long-term diabetes prevention with metformin is feasible and is supported in influential guidelines for selected groups of subjects. Future research will demonstrate whether intervention with metformin in people with non-diabetic hyperglycemia will improve long-term clinical outcomes.

Exercise-Pharmacology Interactions: Metformin, Statins, and Healthspan

There is an increased focus on treatments to extend the healthspan. There is solid evidence that exercise extends the healthspan, but other treatments, such as metformin and statins, are also gaining traction. If metformin and statins will be used to prolong healthspan, we must understand their effects in those free of disease and in combination with exercise.

An Ethanolic Extract of Artemisia dracunculus L. Enhances the Metabolic Benefits of Exercise in Diet-induced Obese Mice

PURPOSE

The purpose of this study was to determine the effect of an ethanolic extract of Artemisia dracunculus L. (5011) combined with exercise on in vivo glucose and fat metabolism in diet-induced obese male mice.

METHODS

After 8 wk of high-fat diet (HFD) feeding, 52 mice were randomly allocated to a voluntary wheel running group (HFD Ex), a 5011 + HFD sedentary group (5011 Sed), a 5011 + HFD Ex (5011 Ex), or an HFD sedentary group (HFD Sed) for 4 wk. Real-time energy expenditure and substrate utilization were measured by indirect calorimetry. A stable isotope glucose tolerance test was performed before and after the 4-wk wheel running period to determine changes in endogenous glucose production and glucose disposal. We also performed an analysis of genes and proteins associated with the early response to exercise and exercise adaptations in skeletal muscle and liver.

RESULTS

When compared with HFD Ex mice, 5011 Ex mice had increased fat oxidation during speed- and distance-matched wheel running bouts. Both HFD Ex and 5011 Ex mice had reduced endogenous glucose during the glucose tolerance test, whereas only the 5011 Sed and the 5011 Ex mice had improved glucose disposal after the 4-wk experimental period when compared with HFD Sed and HFD Ex mice. 5011 Ex mice had increased Pgc1-α and Tfam expression in skeletal muscle when compared with HFD Ex mice, whereas Pdk4 expression was reduced in the liver of HFD Ex and 5011 Ex mice.

CONCLUSIONS

Our study demonstrates that 5011, an ethanolic extract of A. dracunculus L., with a history of medicinal use, enhances the metabolic benefits of exercise to improve in vivo fat and glucose metabolism.

Cardiovascular Safety and Benefits of Noninsulin Antihyperglycemic Drugs for the Treatment of Type 2 Diabetes Mellitus-Part 1

Cardiovascular disease (CVD) is a major contributor to the morbidity and mortality associated with type 2 diabetes mellitus (T2DM). With T2DM growing in pandemic proportions, there will be profound healthcare implications of CVD in person with diabetes. The ideal drugs to improve outcomes in T2DM are those having antiglycemic efficacy in addition to cardiovascular (CV) safety, which has to be determined in appropriately designed CV outcome trials as mandated by regulatory agencies. Available evidence is largely supportive of metformin's CV safety and potential CVD risk reduction effects, whereas sulfonylureas are either CV risk neutral or are associated with variable CVD risk. Pioglitazone was also associated with improved CVD risk in patients with diabetes. The more recent antihyperglycemic medications have shown promise with regards to CVD risk reduction in T2DM patients at a high CV risk. Glucagon-like peptide-1 receptor agonists, a type of incretin-based therapy, were associated with better CV outcomes and mortality in T2DM patients, leading to the Food and Drug Administration approval of liraglutide to reduce CVD risk in high-risk T2DM patients. Ongoing and planned randomized controlled trials of the newer drugs should clarify the possibility of class effects, and of CVD risk reduction benefits in low-moderate CV risk patients. While metformin remains the first-line antiglycemic therapy in T2DM, glucagon-like peptide-1 receptor agonists should be appropriately prescribed in T2DM patients with baseline CVD or in those at a high CVD risk to improve CV outcomes. Dipeptidyl peptidase-4 inhibitors and sodium-glucose cotransporter-2 inhibitors are discussed in the second part of this review.

Effect of Metformin on Circulating Levels of Inflammatory Markers in Patients With Type 2 Diabetes: A Systematic Review and Meta-analysis of Randomized Controlled Trials

BACKGROUND

Emerging evidence indicates that metformin has anti-inflammatory effect; however, the results differ concerning randomized controlled trails of the effect of metformin on inflammatory markers in type 2 diabetes (T2D) patients.

OBJECTIVE

This study reassessed the data on the effect of metformin treatment on inflammatory markers in T2D patients through a systematic review and meta-analysis.

METHODS

A systematic search was performed in the PubMed, ISI Web of Science, EMBASE, Cochrane Library and Scopus databases to collect relevant published data up to September 2020. Data of each study was combined using random-effects model. Subgroup analysis was performed based on subgroups of the treatment duration, dose and target population.

RESULTS

Thirteen RCTs including 1776 participants with T2D were analyzed. Although CRP levels significantly decreased [SMD: -0.76 mg/L; 95% CI (-1.48, -0.049); P = 0.036] in patients with T2D following metformin treatment, circulating levels of TNF-α [SMD: -0.17 pg/mL; 95% CI (-0.55, 0.20); P = 0.37] and IL-6 [SMD: -0.06 pg/mL; 95% CI (-0.38, 0.25); P = 0.69] were insignificant after metformin treatment. Compared to treatment duration of less than 24 weeks, longer treatment duration (more than 24 weeks) was associated with reduced level of CRP.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

Based on available evidence from RCTs in this meta-analysis, metformin decreased CRP level. However, strategies for the treatment of inflammation should focus on metformin in patients with T2D.

CONCLUSION

The present study evidences that therapy with metformin can reduce CRP level significantly in T2D patients compared to other inflammatory markers.

Metformin May Contribute to Inter-individual Variability for Glycemic Responses to Exercise

Metformin and exercise independently improve glycemic control. Metformin traditionally is considered to reduce hepatic glucose production, while exercise training is thought to stimulate skeletal muscle glucose disposal. Collectively, combining treatments would lead to the anticipation for additive glucose regulatory effects. Herein, we discuss recent literature suggesting that metformin may inhibit, enhance or have no effect on exercise mediated benefits toward glucose regulation, with particular emphasis on insulin sensitivity. Importantly, we address issues surrounding the impact of metformin on exercise induced glycemic benefit across multiple insulin sensitive tissues (e.g., skeletal muscle, liver, adipose, vasculature, and the brain) in effort to illuminate potential sources of inter-individual glycemic variation. Therefore, the review identifies gaps in knowledge that require attention in order to optimize medical approaches that improve care of people with elevated blood glucose levels and are at risk of cardiovascular disease.

Effects of Metformin on Left Ventricular Size and Function in Hypertensive Patients with Type 2 Diabetes Mellitus: Results of a Randomized, Controlled, Multicenter, Phase IV Trial

Background

Metformin is the most widely used oral antihyperglycemic agent for patients with type 2 diabetes mellitus (T2DM). Despite the possible benefits of metformin on diabetes mellitus (DM) and heart failure (HF), acute or unstable HF remains a precaution for its use.

Objective

The aim of the present prospective randomized controlled trial was to assess whether metformin treatment has beneficial effects on patients with T2DM with hypertension without overt HF.

Methods

A total of 164 patients (92 males, 72 females; median age 66 years) were included in this study. Patients with T2DM with a history of hypertension were randomized 1:1 to treatment for 1 year with either metformin (metformin-treated group) or other hypoglycemic agents (control group). The primary endpoints were changes in brain natriuretic peptide (BNP) levels, left ventricular (LV) mass index, and indicators of LV diastolic function. We also evaluated changes in both clinical findings and blood laboratory examination data.

Results

We observed no significant changes between baseline and 1-year post-treatment in LV mass index, BNP levels, or E/e′ (early diastolic transmitral flow velocity/early diastolic mitral annular velocity; an indicator of LV diastolic function) in either the metformin-treated (n = 83) or the control (n = 81) groups. The metformin-treated group had a significant reduction of body mass index (BMI) and low-density lipoprotein cholesterol (LDL-C), but the control group did not. We determined that renal function, including serum creatinine and estimated glomerular filtration rate, deteriorated significantly in the control group but not in the metformin-treated group.

Conclusion

LV mass and diastolic function were not affected after 1 year of metformin treatment in patients with T2DM. However, we observed benefits in terms of reductions in both BMI and LDL-C levels and preservation of renal function.

Trial Registration

UMIN000006504. Registered 7 October 2011.

Optimizing the Interaction of Exercise Volume and Metformin to Induce a Clinically Significant Reduction in Metabolic Syndrome Severity: A Randomised Trial

Insulin resistance is a central mediating factor of the metabolic syndrome (MetS), with exercise training and metformin proven antidotes to insulin resistance. However, when the two therapies are combined there is conflicting data regarding whether metformin blunts or improves exercise training-induced adaptations. The volume of exercise (duration, intensity, and frequency) on the interaction of exercise training and metformin has yet to be investigated. The aim of this study is therefore to explore the impact of a combination of different exercise volumes and metformin on MetS severity. This is a secondary analysis of data from one of the sites of the ‘Exercise in Prevention of Metabolic Syndrome’ (EX-MET) study. Ninety-nine adults with MetS were randomized into a 16-week exercise program completing either: (i) moderate-intensity continuous training (MICT) at 60–70% of peak heart rate (HRpeak) for 30 min/session (n = 34, 150 min/week); (ii) high-volume high-intensity interval training (HIIT) consisting of 4 × 4 min bouts at 85–95% HRpeak, interspersed with 3 min of active recovery at 50–70% HRpeak (n = 34, 38 min/session, 114 min/week); or (iii) low volume HIIT, 1 × 4 min bout of HIIT at 85–95% HRpeak (n = 31, 17 min/session, 51 min/week). Metformin intake was monitored and recorded throughout the trial. MetS severity was calculated as z-scores derived from MetS risk factors assessed at pre- and post-intervention. Sixty-five participants had complete pre- and post-intervention data for MetS z-score, of which 18 participants (28%) were taking metformin. Over the 16-week intervention, a similar proportion of participants clinically improved MetS severity (Δ ≥ −0.87) with metformin (8/18, 44%) or without metformin (23/47, 49%) (p = 0.75). While there were no between-group differences (p = 0.24), in those who did not take metformin low-volume HIIT had more likely responders (10/15, 67%) compared to MICT (6/16, 38%) and high-volume HIIT (7/16, 44%). In those taking metformin, there was a lower proportion of participants who clinically improved MetS severity following high-volume HIIT (1/6, 17%) compared to MICT (2/4, 50%) and low-volume HIIT (5/8, 63%), but with no between-group difference (p = 0.23). Moreover, in those who performed high-volume HIIT, there was a statistically significantly higher proportion (p = 0.03) of likely non-responders with improved MetS severity in participants taking metformin (4/6, 67%) compared to those not taking metformin (3/16, 19%). In individuals with MetS, the effect of high volume HIIT on MetS severity may be blunted in those taking metformin. These findings need to be confirmed in a larger study.

Combined effect of canagliflozin and exercise training on high-fat diet-fed mice

Sodium-glucose cotransporter 2 inhibitors (SGLT2is) have been reported to improve obesity, diabetes, and nonalcoholic fatty liver disease (NAFLD) in addition to exercise training, whereas the combined effects remain to be elucidated fully. We investigated the effect of the combination of the SGLT2i canagliflozin (CAN) and exercise training in high-fat diet-induced obese mice. High-fat diet-fed mice were housed in normal cages (sedentary; Sed) or wheel cages (WCR) with or without CAN (0.03% of diet) for 4 wk. The effects on obesity, glucose metabolism, and hepatic steatosis were evaluated in four groups (Control/Sed, Control/WCR, CAN/Sed, and CAN/WCR). Numerically additive improvements were found in body weight, body fat mass, blood glucose, glucose intolerance, insulin resistance, and the fatty liver of the CAN/WCR group, whereas CAN increased food intake and reduced running distance. Exercise training alone, CAN alone, or both did not change the weight of skeletal muscle, but microarray analysis showed that each resulted in a characteristic change of gene expression in gastrocnemius muscle. In particular, in the CAN/WCR group, there was acceleration of the angiogenesis pathway and suppression of the adipogenesis pathway compared with the CAN/Sed group. In conclusion, the combination of an SGLT2i and exercise training improves obesity, insulin resistance, and NAFLD in an additive manner. Changes of gene expression in skeletal muscle may contribute, at least in part, to the improvement of obesity and insulin sensitivity.

Effects of metformin on blood lipid profiles in nondiabetic adults: a meta-analysis of randomized controlled trials

PURPOSE

To evaluate the effects of metformin on serum lipid profiles in nondiabetic adults through a comprehensive meta-analysis.

METHODS

In the present meta-analysis, randomized and controlled trials were collected by searching PubMed, Embase, and Cochrane Libraries from inception to April 2019. Compared with placebos, the effects of metformin treatment on lipid profiles in nondiabetic adults were evaluated.

RESULTS

Forty-seven studies from 45 articles including 5731 participants were enrolled. Pooled results showed that metformin had significant effects on total cholesterol (mean change -6.57 mg/dl; 95% CI -9.66, -3.47; P = 0.000) and LDL-c (mean change -4.69 mg/dl; 95% CI -7.38, -2.00; P = 0.001), but insignificant effects on HDL-c (mean change -4.33 mg/dl; 95% CI -9.62, 0.96; P = 0.109) and triglyceride (mean change -0.85 mg/dl; 95% CI -0.36, 2.06; P = 0.169). Significant heterogeneities were found for all lipid profiles (HDL-c = 85.5%; LDL-c = 59.9%; total cholesterol = 75.3% and triglyceride = 67.1%). Different from the pooled data, in a subgroup analysis, the effect of metformin on triglyceride in patients with polycystic ovarian syndrome (PCOS) was significant with a mean reduction of 8.15 mg/dl. In addition, sensitivity analysis showed that the pooled effects of metformin on serum lipid profiles were stable. Publication bias derived from funnel plots or Begg's tests (P = 0.933, 0.860, 0.904, and 0.567 for HDL-c, LDL-c, total cholesterol, and triglyceride, respectively) was not significant.

CONCLUSION

This meta-analysis revealed that metformin could reduce total cholesterol and LDL-c in nondiabetic adults. In addition, metformin might exert a triglyceride-lowering effect in nondiabetics with PCOS status.

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

INTRODUCTION

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

METHODS

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

RESULTS

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

CONCLUSION

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

Metformin one in a Million Efficient Medicines for Rheumatoid Arthritis Complications: Inflammation, Osteoblastogenesis, Cardiovascular Disease, Malignancies

BACKGROUND

Rheumatoid arthritis is a widespread autoimmune disease and inflammation and bone destruction are two main issues in rheumatoid arthritis.

OBJECTIVE

To discussing metformin effects on rheumatoid arthritis complications.

METHODS

We conducted a narrative literature search including clinical trials, experimental studies on laboratory animals and cell lines. Our search covered Medline, PubMed and Google Scholar databases from 1999 until 2018. We used the terms" Metformin; Rheumatoid arthritis; Cardiovascular disease; Cancer; Osteoblastogenesis.

DISCUSSION

Inflammatory pro-cytokines such as Interlukin-6 play important roles in T. helper 17 cell lineage differentiation. Interlukin-6 and Tumor Necrosis Factor-α activate Janus kinase receptors signal through signaling transducer and activator of transcription signaling pathway which plays important role in inflammation, bone destruction and cancer in rheumatoid arthritis patients. Interlukin-6 and Tumor Necrosis Factor-α synergistically activate signaling transducer and activator of transcription and Nuclear Factor-kβ pathways and both cytokines increase the chance of cancer development in rheumatoid arthritis patients. Metformin is AMPK activators that can suppress mTOR, STAT3 and HIF-1 so AMPK activation plays important role in suppressing inflammation and osteoclastogenesis and decreasing cancer.

CONCLUSION

Metformin effect on AMPK and mTOR pathways gives the capability to change Treg/Th17 balance and decrease Th17 differentiation and inflammation, osteoclastogenesis and cancers in RA patients. Metformin can be useful in protecting bones especially in first stages of RA and it can decrease inflammation, CVD and cancer in RA patients so Metformin beside DAMARs can be useful in increasing RA patients' life quality with less harm and cost.

The combination of exercise training and sodium-glucose cotransporter-2 inhibition improves glucose tolerance and exercise capacity in a rodent model of type 2 diabetes

PURPOSE

Exercise is recommended in addition to pharmacotherapies for the management of type 2 diabetes, but metformin and exercise training may have non-additive or even inhibitory effects on exercise-induced improvements in glycemic control and exercise capacity. The objectives of this report were to determine if co-treatment with a sodium-glucose cotransporter-2 inhibitor and exercise could (1) further improve glycemic control when compared to either monotherapy and (2) not worsen exercise capacity when compared to exercise alone.

METHODS

A rodent model of type 2 diabetes (30 mg/kg streptozotocin and high-fat feeding in male Sprague-Dawley rats) was used to assess 12 weeks of co-treatment with a sodium-glucose cotransporter 2 inhibitor (SGLT2i) and exercise (EX; treadmill running) on glycemic control and exercise capacity. Animals were randomized to the following conditions (n = 7-10/group): vehicle (0.5% methyl cellulose) sedentary (VEH SED), VEH EX, canagliflozin (3 mg kg^-1 d^-1) SED (SGLT2i SED), or SGLT2i EX.

RESULTS

Both EX and SGLT2i independently improved indices of glycemic control. The combination of SGLT2i and EX further improved glucose tolerance (glucose area under the curve 1109 ± 51 vs 1427 ± 82 mmol/ L 120 min^-1 for SGLT2i EX vs. SGLT2i SED, respectively; p < 0.05) and insulin responses (insulin area under the curve 24,524 ± 4126 vs. 41,208 ± 2714 pmol L^-1 120 min^-1 for SGLT2i EX vs. VEH EX, respectively; p < 0.05) during an oral glucose tolerance test. Only the combination of SGLT2i EX lowered body weight compared to VEH SED (p < 0.01). SGLT2i caused several metabolic adaptations including increased ketone production and a greater reliance on fat as a source of energy during normal cage activity. Interestingly, animals that were given the SGLT2i and underwent exercise training (SGLT2i EX) had better submaximal exercise capacity than EX alone, as indicated by distance run prior to fatigue (882 ± 183 vs.433 ± 33 m for SGLT2i EX and VEH EX, respectively; p < 0.01), and this was accompanied by a greater reliance on fat as an energy source during exercise (p < 0.01).

CONCLUSIONS

If these findings with the combination of SGLT2i and exercise translate to humans, they will have important clinical health implications.

Effect of intensive lifestyle modification & metformin on cardiovascular risk in prediabetes: A pilot randomized control trial

Background & objectives:

Prediabetes is associated with increased prevalence of cardiovascular disease (CVD). In participants with prediabetes, the effects of exercise and metformin were evaluated on high-sensitivity C-reactive protein (hsCRP) and carotid intima-media thickness (CIMT), surrogate markers of atherosclerosis and CVD compared with standard care.

Methods:

In a pilot randomized control trial, the participants were randomized in to three arms: standard care (STD), intensive lifestyle modification (ILSM) or ILSM and metformin (ILSM+Met) and followed up for six months. Monitoring of ILSM was done by a trained healthcare facilitator. hsCRP, CIMT and other relevant parameters were measured before and after intervention.

Results:

A total of 103 participants were randomized into three arms and followed up for six months. At six months, there was a reduction from baseline in weight and fasting blood sugar (FBS) (P<0.01) in all three arms and a reduction in haemoglobin A_1c (P=0.03) only in the ILSM+Met arm. The differences in hsCRP over six months within the STD, ILSM and ILSM+Met arms were −0.12 (95% confidence interval, −1.81, 2.08), −0.58 (−2.64, 0.43) and −0.11 (−1.84, 1.56), respectively. There was no difference in hsCRP, CIMT (right) or CIMT (left) between the three arms at six months.

Interpretation & conclusions:

There was a reduction in weight and FBS from baseline in all three arms. There was, however, no difference seen in hsCRP and CIMT in the two intervention arms compared to standard care. Larger studies with long-term follow up need to be done to detect differences in risk markers for CVD in prediabetes.

Effect of PPARγ agonist on aerobic exercise capacity in relation to body fat distribution in men with type 2 diabetes mellitus and coronary artery disease: a 1-yr randomized study

Targeting metabolic determinants of exercise performance with pharmacological agents that would mimic/potentiate the effects of exercise represents an attractive clinical alternative to counterbalance the poor exercise capacity in patients with type 2 diabetes mellitus (T2DM). We examined the effect of 1-yr treatment with the insulin sensitizer peroxisome proliferator-activated receptor (PPAR)γ agonist rosiglitazone on aerobic exercise capacity and body fat composition/distribution in men with T2DM and stable coronary artery disease (CAD). One-hundred four men (age: 64 ± 7 yr; body mass index: 30.0 ± 4.4 kg/m²) with T2DM and CAD were randomized to receive rosiglitazone or placebo for 1 yr. Aerobic exercise capacity (exercise duration) was assessed with a maximal treadmill test, and body composition/distribution were assessed by dual-energy X-ray absorptiometry/computed tomography scans. At 1 yr, patients with T2DM under PPARγ agonist treatment showed a reduction in aerobic exercise capacity compared with the control group (exercise duration change, -31 ± 8 versus 7 ± 11 s, P = 0.009). Significant increases in body fat mass (3.1 ± 0.4 kg, 12%), abdominal and mid-thigh subcutaneous adipose tissue (AT) levels, and mid-thigh skeletal muscle fat were found (all P < 0.01), whereas no effect on visceral AT levels was observed (P > 0.05) under treatment. Subcutaneous fat mass gained under PPARγ agonist was the strongest predictor of the worsening in aerobic exercise capacity (P > 0.0001); no association was found with skeletal muscle fat infiltration nor visceral AT. Treatment with the insulin sensitizer PPARγ agonist rosiglitazone in patients with T2DM and CAD is associated with a worsening in aerobic exercise capacity, which seems to be mainly attributable to weight gain and subcutaneous fat mass expansion.

Personalized Moderate-Intensity Exercise Training Combined with High-Intensity Interval Training Enhances Training Responsiveness

This study sought to determine if personalized moderate-intensity continuous exercise training (MICT) combined with high-intensity interval training (HIIT) was more effective at improving comprehensive training responsiveness than MICT alone. Apparently healthy, but physically inactive men and women (n = 54) were randomized to a non-exercise control group or one of two 13-week exercise training groups: (1) a personalized MICT + HIIT aerobic and resistance training program based on the American Council on Exercise guidelines, or (2) a standardized MICT aerobic and resistance training program designed according to current American College of Sports Medicine guidelines. Mean changes in maximal oxygen uptake (VO_2max) and Metabolic (MetS) z-score in the personalized MICT + HIIT group were more favorable (p < 0.05) when compared to both the standardized MICT and control groups. Additionally, on the individual level, there were positive improvements in VO_2max (Δ > 4.9%) and MetS z-score (Δ ≤ -0.48) in 100% (16/16) of participants in the personalized MICT + HIIT group. In the present study, a personalized exercise prescription combining MICT + HIIT in conjunction with resistance training elicited greater improvements in VO_2max, MetS z-score reductions, and diminished inter-individual variation in VO_2max and cardiometabolic training responses when compared to standardized MICT.

Influence of Sodium Glucose Cotransporter 2 Inhibition on Physiological Adaptation to Endurance Exercise Training

CONTEXT

The combination of two beneficial antidiabetes interventions, regular exercise and pharmaceuticals, is intuitively appealing. However, metformin, the most commonly prescribed diabetes medication, attenuates the favorable physiological adaptations to exercise; in turn, exercise may impede the action of metformin.

OBJECTIVE

We sought to determine the influence of an alternative diabetes treatment, sodium glucose cotransporter 2 (SGLT2) inhibition, on the response to endurance exercise training.

DESIGN, PARTICIPANTS, AND INTERVENTION

In a randomized, double-blind, repeated measures parallel design, 30 sedentary overweight and obese men and women were assigned to 12 weeks of supervised endurance exercise training, with daily ingestion of either a placebo or SGLT2 inhibitor (dapagliflozin: ≤10 mg/day).

OUTCOME MEASUREMENTS AND RESULTS

Endurance exercise training favorably modified body mass, body composition (dual-energy x-ray absorptiometry), peak oxygen uptake (graded exercise with indirect calorimetry), responses to standardized submaximal exercise (indirect calorimetry, heart rate, and blood lactate), and skeletal muscle (vastus lateralis) citrate synthase activity (main effects of exercise training, all P < 0.05); SGLT2 inhibition did not influence any of these physiological adaptations (exercise training × treatment interaction, all P > 0.05). However, after endurance exercise training, fasting blood glucose was greater with SGLT2 inhibition, and increased insulin sensitivity (oral glucose tolerance test/Matsuda index) was abrogated with SGLT2 inhibition (exercise training × treatment interaction, P < 0.01).

CONCLUSION

The efficacy of combining two beneficial antidiabetes interventions, regular endurance exercise and SGLT2 inhibition, was not supported. SGLT2 inhibition blunted endurance exercise training-induced improvements in insulin sensitivity, independent of effects on aerobic fitness or body composition.

Fibre Intake Is Independently Associated with Increased Circulating Interleukin-22 in Individuals with Metabolic Syndrome

The positive effects of dietary fibre on gut barrier function and inflammation have not been completely elucidated. Mice studies show gut barrier disruption and diet-induced insulin resistance can be alleviated by cytokine interleukin-22 (IL-22). However, little is known about IL-22 in humans and its association with gut-beneficial nutrients like fibre. We investigated whether fibre intake was associated with circulating levels of IL-22 in 48 participants with metabolic syndrome (MetS). Bivariate analysis was used to explore associations between circulating IL-22, fibre intake, MetS factors, body composition, and cardiorespiratory fitness (peak oxygen uptake, V ˙ O2peak). Hierarchical multiple regression (HMR) was used to test the independent association of fibre intake with circulating IL-22, adjusting for variables correlated with IL-22. Circulating IL-22 was positively associated with fibre intake (rs = 0.393, p < 0.006). The HMR-adjusted model explained 40% of circulating IL-22 variability, and fibre intake significantly improved the prediction model by 8.4% (p < 0.022). Participants with fibre intake above median intake of 21.5 g/day had a significantly higher circulating IL-22 than the lower intake group (308.3 ± 454.4 vs. 69.0 ± 106.4 pg/mL, p < 0.019). Fibre intake is independently associated with increased circulating IL-22 in individuals with MetS. Findings warrant further investigations to evaluate whether changes in dietary fibre intake alter circulating IL-22, and its effects on health outcomes.

Reduced Exertion High-Intensity Interval Training is More Effective at Improving Cardiorespiratory Fitness and Cardiometabolic Health than Traditional Moderate-Intensity Continuous Training

This study sought to determine the effectiveness of an 8 wk reduced-exertion high-intensity interval training (REHIT) at improving cardiorespiratory fitness (CRF) and positively modifying cardiometabolic health in the workplace environment. Participants (n = 32) were randomized to two groups: (1) One group (n = 16) was prescribed an 8 wk REHIT program, and (2) one group (n = 16) was prescribed moderate-intensity continuous training (MICT). Cardiometabolic risk factors and CRF were measured at baseline and 8 wks. After 8 wks, changes in CRF (REHIT, 12%; MICT, 7%), systolic blood pressure (REHIT, −5%; MICT, −2%), waist circumference (REHIT, −1.4%; MICT, −0.3%), and metabolic syndrome (MetS) severity (MetS z-score: REHIT, −62%; MICT, 27%) were more favorable (p < 0.05) in the REHIT group relative to the MICT group. Interestingly, there was a significantly greater proportion of participants in the REHIT group (75%, 9/12) who had a favorable change in the MetS z-score (Δ > −0.60) relative to the MICT group (47%, 7/15). The main finding of the present study is that 8 wks REHIT elicited more potent and time-efficient improvements in CRF and cardiometabolic health when compared to traditional MICT. This study provides critical evidence for implementation of the sprint interval training (SIT) paradigm from the scientific literature into a real-world workplace setting.

Effects of the combination of metformin and exercise on glycated hemoglobin, functional capacity, lipid profile, quality of life, and body weight

Objective

To evaluate the impact of the combination of metformin and exercise on changes in glycated hemoglobin (HbA_1c), functional capacity, the lipid profile, quality of life, and weight.

Methods

Data from a 12-week cardiovascular rehabilitation program (2014–2016) were retrospectively evaluated. Metformin exposure was determined through recorded prescriptions, and average minutes of exercise per week were computed from exercise logs. The primary outcomes were changes in HbA_1c and functional capacity (6-minute walk test [6MWT]) over 12 weeks. The secondary outcomes were changes in the lipid profile, quality of life, and weight. Directed acyclic graphs were used to identify potential confounders, accounted for with multiple linear regression.

Results

The cohort comprised 403 patients (85 metformin users, 318 non-users). The average amount of exercise was 102.7±48.7 minutes/week among metformin users and 107.7±58.1 minutes/week among non-users. Although changes in HbA_1c were similar for both groups, the coefficient for the metformin–exercise interaction indicated significantly greater improvements in the 6MWT among metformin users. There were no between-group differences in any secondary outcomes.

Conclusions

The combination of metformin and exercise led to greater gains in functional capacity than exercise alone. This combination did not appear to influence the effects of either treatment on other outcomes.

Changes in Metabolic Syndrome Severity Following Individualized Versus Standardized Exercise Prescription: A Feasibility Study

This study sought to investigate the efficacy of standardized versus individualized exercise intensity prescription on metabolic syndrome (MetS) severity following a 12-week exercise intervention. A total of 38 experimental participants (47.8 ± 12.2 yr, 170.7 ± 8.0 cm, 82.6 ± 18.7 kg, 26.9 ± 6.7 mL·k⁻¹·min⁻¹) were randomized to one of two exercise interventions (exercise intensity prescribed using heart rate reserve or ventilatory threshold). Following the 12-week intervention, MetS z-score was significantly improved for the standardized (−2.0 ± 3.1 to −2.8 ± 2.8 [p = 0.01]) and individualized (−3.3 ± 2.3 to −3.9 ± 2.2 [p = 0.04]) groups. When separating participants based on prevalence of MetS at baseline and MetS z-score responsiveness, there were six and three participants in the standardized and individualized groups, respectively, with three or more MetS risk factors. Of the six participants in the standardized group, 83% (5/6) of the participants were considered responders, whereas 100% (3/3) of the individualized participants were responders. Furthermore, only 17% (1/6) of the participants with MetS at baseline in the standardized group no longer had symptoms of MetS following the intervention. In the individualized group, 67% (2/3) of participants with baseline MetS were not considered to have MetS at week 12. These findings suggest that an individualized approach to the exercise intensity prescription may ameliorate the severity of MetS.

The Effect of Detraining after a Period of Training on Cardiometabolic Health in Previously Sedentary Individuals

The purpose of this study was to quantify the time-magnitude changes in cardiometabolic health outcomes that occur with cessation of regular exercise training. All participants (n = 22) performed baseline testing, completed a 13-week exercise program, and completed post-program testing. Upon completion of the 13-week exercise program, participants were randomized to one of the following two treatment groups: (1) the treatment group that continued their exercise for 4 weeks (TRAIN); or (2) the treatment group that discontinued exercise (DETRAIN). Changes from baseline to 13 weeks in both the TRAIN and DETRAIN treatment groups for maximal oxygen consumption (VO₂max), body fat percentage, mean arterial pressure, high-density lipoprotein (HDL) cholesterol, and triglycerides were significantly favourable (p < 0.05). VO₂max, body fat percentage, and favourable cardiometabolic health adaptations continued to improve (p < 0.05) with an additional one month of exercise training. Upon cessation of exercise, all measures of VO₂max and body fat percentage, along with mean arterial pressure, HDL cholesterol, and triglycerides significantly worsened (p < 0.05) in the DETRAIN treatment group. Favourable training adaptations were further enhanced with an additional month of continued exercise training, and cessation of regular exercise rapidly abolished all training adaptations within one month. These novel findings underscore the importance of sustained and uninterrupted exercise training.

Can reducing sitting time in the university setting improve the cardiometabolic health of college students?

PURPOSE

The high prevalence of metabolic syndrome (MetS), prediabetes, and increased risk of cardiovascular diseases linked with prolonged sitting has created a need to identify options to limit sedentary behaviors. A potentially simple approach to achieve this goal in the university setting is to provide students the option to stand during courses rather than sit. The purpose of the present study was to examine the effects of standing in the college classroom setting on cardiometabolic risk factors in a cohort of college students.

PATIENTS AND METHODS

Healthy college students (n=21) who attended at least two courses per week (a minimum of 5 hours) in a specified university building with standing desks participated in a 7-week intervention that was divided into three phases: 3 weeks of standing, 1 week of washout (sitting), and 3 weeks of sitting. The participants (mean ± SD: age, height, weight, body mass index, and waist-to-hip ratio were 22.7±6.4 years, 174.3±10.0 cm, 70.6±14.3 kg, 23.0±3.0 kg/m2, and 0.76±0.05, respectively) were randomly assigned to the phase of intervention of which they should start (sitting or standing), and all participants engaged in sitting during the washout phase. Cardiometabolic risk factors and metabolic equivalents (METs) were measured at baseline and weekly throughout the intervention.

RESULTS

Paired t-tests revealed significant differences (P<0.05) in all cardiometabolic risk factors between the 3 weeks of sitting and 3 weeks of standing time blocks. Moreover, MetS z-score was significantly improved (P<0.05) during the 3 weeks of standing (-5.91±2.70) vs 3 weeks of sitting (-5.25±2.69). The METs were significantly higher (P<0.05) during standing (1.47±0.09) than during sitting (1.02±0.07). Although there was considerable interindividual variability in the ∆ MetS z-score response, there was a 100% (21/21) incidence of a favorable change (ie, responders) in MetS z-score response.

CONCLUSION

A standing desk in the classroom paradigm was found to significantly improve cardiometabolic health throughout a short 3 weeks time span. Increasing standing time in the classroom, and therefore lessening weekly sedentary behavior, could be a potential wide-scale, effective strategy for primordial prevention of cardiometabolic diseases.

Effect of metformin on glycaemic control in patients with type 1 diabetes: A meta-analysis of randomized controlled trials

BACKGROUND

For type 1 diabetes (T1D) patients, adding metformin to insulin therapies is thought to improve blood glucose levels, but current evidence does not support this clinical benefit. Additional data from large clinical trials are now available; therefore, we conducted a meta-analysis of studies on assessing the efficacy and adverse effects of metformin.

METHODS

We searched the MEDLINE, EMBASE, and Cochrane Library databases for data from randomized controlled trials. We performed statistical analyses by using Review Manager 5.2.

RESULTS

Thirteen randomized controlled trials that compared metformin versus placebo met our inclusion criteria and were included in the study. The final meta-analysis included a total of 1183 participants with T1D. Metformin was associated with reductions in BMI (-1.14, 95% CI -2.05 to -0.24, P = .01), insulin requirements (-0.47, 95% CI -0.70 to -0.23, P = .0001), total cholesterol (-0.23, 95% CI -0.34 to -0.12, P < .0001), and low-density lipoprotein cholesterol (-0.20, 95% CI -0.29 to -0.11, P < .0001) in T1D patients. No clear evidence indicated that metformin improved HbA1c, triglyceride, or high-density lipoprotein cholesterol levels. A safety analysis showed that metformin slightly increased the risk of severe hypoglycaemia (1.23, 95% CI 1.00 to 1.52, P = .05) and mainly gastrointestinal adverse events (2.67, 95% CI 2.06 to 3.45, P < .00001). No evidence showed that metformin increased diabetic ketoacidosis events.

CONCLUSIONS

Compared with placebo, metformin was not associated with glycaemic control in T1D patients. Although it exhibited other benefits, such as lower BMI and reduced insulin requirements, total cholesterol, and low-density lipoprotein cholesterol, negative outcomes, such as gastrointestinal adverse effects and severe hypoglycaemia, should also be considered in the use of metformin for T1D patients.

Timing of Exercise Affects Glycemic Control in Type 2 Diabetes Patients Treated with Metformin

OBJECTIVE

The purpose of the study was to examine the acute effects of the timing of exercise on the glycemic control during and after exercise in T2D.

METHODS

This study included 26 T2D patients (14 women and 12 men) who were treated with metformin. All patients were tested on four occasions: metformin administration alone (Metf), high-intensity interval training (HIIT) performed at 30 minutes (EX30), 60 minutes (EX60), and 90 minutes (EX90) postbreakfast, respectively. Glucose, insulin, and superoxide dismutase (SOD) activity were examined.

RESULTS

Glucose decreased significantly after the exercise in EX30, EX60, and EX90. Compared with Metf, the decline in glucose immediately after the exercise was larger in EX30 (-2.58 mmol/L; 95% CI, -3.36 to -1.79 mmol/L; p < 0.001), EX60 (-2.13 mmol/L; 95% CI, -2.91 to -1.34 mmol/L; p < 0.001), and EX90 (-1.87 mmol/L; 95% CI, -2.65 to -1.08 mmol/L; p < 0.001), respectively. Compared with Metf, the decrease in insulin was larger in EX30 and EX60 (both p < 0.001).

CONCLUSIONS

Timing of exercise is a factor to consider when prescribing exercise for T2D patients treated with metformin. This trial is registered with ChiCTR-IOR-16008469 on 13 May 2016.

Influence of endurance training on skeletal muscle mitophagy regulatory proteins in type 2 diabetic men

BACKGROUND

Mitophagy is a form of autophagy for the elimination of mitochondria. Mitochondrial content and function are reduced in the skeletal muscle of patients with type 2 diabetes mellitus (T2DM). Physical training has been shown to restore mitochondrial capacity in T2DM patients, but the role of mitophagy has not been examined in this context. This study analyzes the impact of a 3-month endurance training on important skeletal muscle mitophagy regulatory proteins and oxidative phosphorylation (OXPHOS) complexes in T2DM patients.

METHODS

Muscle biopsies were obtained from eight overweight/obese T2DM men (61±10 years) at T1 (6 weeks pre-training), T2 (1 week pre-training), and T3 (3 to 4 days post-training). Protein contents were determined by Western blotting.

RESULTS

The training increased mitochondrial complex II significantly (T2-T3: +29%, p = 0.037). The protein contents of mitophagy regulatory proteins (phosphorylated form of forkhead box O3A (pFOXO3A), mitochondrial E3 ubiquitin protein ligase-1 (MUL1), Bcl-2/adenovirus E1B 19-kD interacting protein-3 (BNIP3), microtubule-associated protein 1 light chain-3B (the ratio LC3B-II/LC3B-I was determined)) did not differ significantly between T1, T2, and T3.

CONCLUSIONS

The results imply that training-induced changes in OXPHOS subunits (significant increase in complex II) are not accompanied by changes in mitophagy regulatory proteins in T2DM men. Future studies should elucidate whether acute exercise might affect mitophagic processes in T2DM patients (and whether a transient regulation of mitophagy regulatory proteins is evident) to fully clarify the role of physical activity and mitophagy for mitochondrial health in this particular patient group.

Effects of metformin on blood pressure in nondiabetic patients: a meta-analysis of randomized controlled trials

OBJECTIVE

To evaluate the effects of metformin on systolic blood pressure (SBP) and diastolic blood pressure (DBP) in nondiabetic patients.

METHODS

In this meta-analysis, we systematically searched PubMed, Embase, and the Cochrane Library through March 2016, and randomized controlled trials assessing the effects of metformin treatment compared with placebo were included. Random-effects models were used to estimate pooled mean differences in SBP and DBP.

RESULTS

Twenty-eight studies from 26 articles consisting of 4113 participants were included. Pooled results showed that metformin had a significant effect on SBP (mean difference -1.98 mmHg; 95% confidence interval -3.61, -0.35; P = 0.02), but not on DBP (mean difference -0.67 mmHg; 95% confidence interval -1.74, 0.41; P = 0.22). In subgroup analysis, we found that the effect of metformin on SBP was significant in patients with impaired glucose tolerance or obesity (BMI ≥30 kg/m), with a mean reduction of 5.03 and 3.00 mmHg, respectively. Significant heterogeneity was found for both SBP (I = 60.0%) and DBP (I = 45.4%). A sensitivity analysis indicated that the pooled effects of metformin on SBP and DBP were robust to systematically dropping each trial. Furthermore, no evidence of significant publication bias from funnel plots or Egger's tests (P = 0.51 and 0.21 for SBP and DBP, respectively) was found.

CONCLUSION

This meta-analysis suggested that metformin could effectively lower SBP in nondiabetic patients, especially in those with impaired glucose tolerance or obesity.

Metformin: a review of its potential indications

Metformin is the most commonly prescribed drug for type 2 diabetes mellitus. In recent years, in addition to glucose lowering, several studies have presented evidence suggesting some potential role for metformin, such as antitumor effect, antiaging effect, cardiovascular protective effect, neuroprotective effect or an optional treatment for polycystic ovary syndrome. This paper will critically review the role of metformin to provide reference for doctors and researchers.

Metformin effects on the heart and the cardiovascular system: A review of experimental and clinical data

BACKGROUND

Metformin, the eldest and most widely used glucose lowering drug, is likely to be effective also on cardiac and vascular disease prevention. Nonetheless, uncertainty still exists with regard to its effects on the cardiovascular system as a whole and specifically on the myocardium, both at the organ and cellular levels.

METHODS

We reviewed the available data on the cardiac and vascular effects of metformin, encompassing both in vitro, either tissue or isolated organ, and in vivo studies in experimental animals and humans, as well as the evidence generated by major clinical trials.

RESULTS

At the cellular level metformin's produces both AMP-activated kinase (AMPK) dependent and independent effects. At the systemic level, possibly also through other pathways, this drug improves endothelial function, protects from oxidative stress and inflammation, and from the negative effects of angiotensin II. On the myocardium it attenuates ischemia-reperfusion injury and prevents adverse remodeling induced by humoral and hemodynamic factors. The effects on myocardial cell metabolism and contractile function being not evident at rest or in more advanced stages of cardiac dysfunction, could be relevant during transient ischemia, during an acute increase in workload and in the early stages of diabetic/hypertensive cardiomyopathy as confirmed by few small clinical trials and some observational studies. The overall evidence emerging from both clinical trials and real world registry is in favor of a protective effect of metformin with respect to both coronary events and progression to heart failure.

CONCLUSIONS

Given this potential, its efficacy and its safety (and also its low cost) metformin remains the central pillar of the therapy of diabetes.

Exercise training and metformin, but not exercise training alone, decreases insulin production and increases insulin clearance in adults with prediabetes

Adding metformin to exercise does not augment the effect of training alone to boost whole body insulin sensitivity and lower circulating insulin concentrations. Although lower insulin concentrations (lower supply) following lifestyle and/or pharmacological interventions are primarily attributed to reductions in insulin secretion that match increases in peripheral insulin sensitivity (lower demand), it is unclear whether exercise and/or metformin exert direct effects on insulin production, extraction, or clearance. Thirty-six middle-aged, obese, sedentary adults with prediabetes were randomized to placebo (P), metformin (M), exercise and placebo (E+P), or exercise and metformin (E+M) for 12 wk. Fasting plasma proinsulin (an indicator of insulin production), C-peptide, insulin, and glucose were collected before and after the intervention. Peripheral insulin sensitivity (euglycemic clamp), hepatic insulin extraction, insulin clearance, body weight, and cardiorespiratory fitness were also measured. Fasting proinsulin was unchanged following P (19.4 ± 10.1 vs. 22.6 ± 15.0 pmol/l), E+P (15.1 ± 7.4 vs. 15.5 ± 7.4 pmol/l), or M (24.8 ± 18.9 vs. 16.7 ± 20.3 pmol/l) but was significantly reduced after E+M (18.6 ± 11.9 vs. 13.9 ± 6.7 pmol/l; P = 0.04). Insulin clearance was significantly greater following M (384.6 ± 19.4 vs. 477.4 ± 49.9; P = 0.03) and E+M (400.1 ± 32.0 vs. 482.9 ± 33.9; P = 0.02) but was unchanged in P or E+P. In this study, metformin combined with exercise training reduced circulating proinsulin, and both groups taking metformin increased insulin clearance. This suggests that adding metformin to exercise may augment or attenuate training effects depending on the outcome or organ system being assessed.NEW & NOTEWORTHY Exercise is increasingly viewed as medication, creating a need to understand its interactions with other common medications. Research suggests metformin, a widely prescribed diabetes medication, may diminish the benefits of exercise when used in combination. In this study, however, metformin combined with exercise training, but not exercise alone, lowered proinsulin concentrations and increased insulin clearance in adults with prediabetes. This may directly influence personalized prescriptions of lifestyle and/or pharmacology to reduce diabetes risk.

Resistance training to improve type 2 diabetes: working toward a prescription for the future

The prevalence of type 2 diabetes (T2D) is rapidly increasing, and effective strategies to manage and prevent this disease are urgently needed. Resistance training (RT) promotes health benefits through increased skeletal muscle mass and qualitative adaptations, such as enhanced glucose transport and mitochondrial oxidative capacity. In particular, mitochondrial adaptations triggered by RT provide evidence for this type of exercise as a feasible lifestyle recommendation to combat T2D, a disease typically characterized by altered muscle mitochondrial function. Recently, the synergistic and antagonistic effects of combined training and Metformin use have come into question and warrant more in-depth prospective investigations. In the future, clinical intervention studies should elucidate the mechanisms driving RT-mitigated mitochondrial adaptations in muscle and their link to improvements in glycemic control, cholesterol metabolism and other cardiovascular disease risk factors in individuals with T2D.