Aerobic training effects on glucose tolerance in prediabetic and normoglycemic humans

Positive Effects of Physical Activity on Insulin Signaling

Physical activity is integral to metabolic health, particularly in addressing insulin resistance and related disorders such as type 2 diabetes mellitus (T2DM). Studies consistently demonstrate a strong association between physical activity levels and insulin sensitivity. Regular exercise interventions were shown to significantly improve glycemic control, highlighting exercise as a recommended therapeutic strategy for reducing insulin resistance. Physical inactivity is closely linked to islet cell insufficiency, exacerbating insulin resistance through various pathways including ER stress, mitochondrial dysfunction, oxidative stress, and inflammation. Conversely, physical training and exercise preserve and restore islet function, enhancing peripheral insulin sensitivity. Exercise interventions stimulate β-cell proliferation through increased circulating levels of growth factors, further emphasizing its role in maintaining pancreatic health and glucose metabolism. Furthermore, sedentary lifestyles contribute to elevated oxidative stress levels and ceramide production, impairing insulin signaling and glucose metabolism. Regular exercise induces anti-inflammatory responses, enhances antioxidant defenses, and promotes mitochondrial function, thereby improving insulin sensitivity and metabolic efficiency. Encouraging individuals to adopt active lifestyles and engage in regular exercise is crucial for preventing and managing insulin resistance and related metabolic disorders, ultimately promoting overall health and well-being.

Effects of qigong Training on Muscle Strengths, Flexibility, Cardiopulmonary Fitness, and Antioxidant/Oxidant Responses in Sedentary Middle-Aged and Elderly Type 2 Diabetes Mellitus Women: A Quasi-Experimental Design, Placebo-Controlled Study

Background: Qigong exercise training has been suggested to elicit beneficial effects on physical functioning, reduction of oxidative stress, and improved antioxidant capacity in women. However, regular exercise training may support the development of antioxidant defense mechanisms and beneficially modulate oxidant/antioxidant responses. Objective: To evaluate the effects of an 8-week qigong exercise training on exercise performance and oxidative stress responses in sedentary middle-aged and elderly women suffering from type 2 diabetic mellitus (T2DM). Method/design: Quasi-experimental design, placebo-controlled study. Setting: The Department of Physical Therapy, Faculty of Allied Health Science, Burapha University, Thailand. Participants: Thirty-six sedentary middle-aged and elderly women with T2DM. Intervention: Participants were allocated to qigong exercise (n = 20) or to the control group (CG, n = 20). Primary outcome measures: Muscle strengths, flexibility, VO2 max predicted, and walking intensity derived from the 6-minute walk test. Secondary outcome measures: Fasting plasma glucose, antioxidant/oxidant stress parameters, and body composition. Results: Leg strength and trunk flexibility were improved after qigong training and changes were significantly different compared with the CG (all p < 0.05). VO2 max predicted, 6-min walking distance, and walking intensity were all increased (p < 0.05), and oxidative stress markers were diminished after qigong training (p < 0.05). The antioxidant/oxidant balance was improved after qigong training (p < 0.05). Conclusion: The presented findings indicate that 8 weeks of qigong training significantly improved leg strength and trunk flexibility in middle-aged and elderly women with T2DM, partly associated with a more favorable antioxidant/oxidant balance. These effects may beneficially impact on health in this specific population. Clinical Trial Number: TCTR20221003001.

The influence of resistance exercise and aerobic exercise on type 2 diabetes: a meta-analysis

INTRODUCTION

Diabetes is a worldwide chronic disease. The incidence rate of this disease is high, and it is a common disease in clinics. At present, the incidence rate of diabetes patients is increasing year by year due to the increasing work pressure, the accelerated pace of life, the change of diet, the reduction of labor, and the acceleration of aging.

EVIDENCE ACQUISITION

The computer retrieves four databases to obtain random controlled trials on the influence of resistance exercise and aerobic exercise on type 2 diabetes. After a rigorous literature quality evaluation, data analysis was performed using RevMan 5.3 software.

EVIDENCE SYNTHESIS

Ten studies were ultimately included in this meta-analysis. 10 studies reported the HbA1c of the test group and the control group, which was no significant statistical significance (SMD: -0.01; 95% CI: -0.20,0.19; P=0.959) than the control group, HOMA-IR (SMD: 0.02; 95% CI: -0.65,0.69; P=0.954), SBP (SMD: 3.92; 95% CI: -0.92,8.75; P=0.112), DBP (SMD: 0.67; 95% CI: -3.66,5.01; P=0.761), HDL (SMD: -0.08; 95% CI: -2.79,2.64; P=0.955), TG (SMD: -7.51; 95% CI: -21.25,6.22; P=0.284) and TC (SMD: 9.10; 95% CI: -13.43,31.62; P=0.428).

CONCLUSIONS

The results of this study suggest that both resistance exercise and aerobic exercise may be effective on patients with type 2 diabetes, as evidenced by HbA1c, HOMA-IR, SBP, DBP, HDL, TG and TC. There is no significant difference in their impact on type 2 diabetes patients, and the above conclusions need to be verified by more high-quality studies.

Leptin-dependent differential remodeling of visceral and pericardial adipose tissue following chronic exercise and psychosocial stress

Obesity is driven by an imbalance between caloric intake and energy expenditure, causing excessive storage of triglycerides in adipose tissue at different sites around the body. Increased visceral adipose tissue (VAT) is associated with diabetes, while pericardial adipose tissue (PAT) is associated with cardiac pathology. Adipose tissue can expand either through cellular hypertrophy or hyperplasia, with the former correlating with decreased metabolic health in obesity. The aim of this study was to determine how VAT and PAT remodel in response to obesity, stress, and exercise. Here we have used the male obese Zucker rats, which carries two recessive fa alleles that result in the development of hyperphagia with reduced energy expenditure, resulting in morbid obesity and leptin resistance. At 9 weeks of age, a group of lean (Fa/Fa or Fa/fa) Zucker rats (LZR) and obese (fa/fa) Zucker rats (OZR) were treated with unpredictable chronic mild stress or exercise for 8 weeks. To determine the phenotype for PAT and VAT, tissue cellularity and gene expression were analyzed. Finally, leptin signaling was investigated further using cultured 3T3-derived adipocytes. Tissue cellularity was determined following hematoxylin and eosin (H&E) staining, while qPCR was used to examine gene expression. PAT adipocytes were significantly smaller than those from VAT and had a more beige-like appearance in both LZR and OZR. In the OZR group, VAT adipocyte cell size increased significantly compared with LZR, while PAT showed no difference. Exercise and stress resulted in a significant reduction in VAT cellularity in OZR, while PAT showed no change. This suggests that PAT cellularity does not remodel significantly compared with VAT. These data indicate that the extracellular matrix of PAT is able to remodel more readily than in VAT. In the LZR group, exercise increased insulin receptor substrate 1 (IRS1) in PAT but was decreased in the OZR group. In VAT, exercise decreased IRS1 in LZR, while increasing it in OZR. This suggests that in obesity, VAT is more responsive to exercise and subsequently becomes less insulin resistant compared with PAT. Stress increased PPAR-γ expression in the VAT but decreased it in the PAT in the OZR group. This suggests that in obesity, stress increases adipogenesis more significantly in the VAT compared with PAT. To understand the role of leptin signaling in adipose tissue remodeling mechanistically, JAK2 autophosphorylation was inhibited using 5 μM 1,2,3,4,5,6-hexabromocyclohexane (Hex) in cultured 3T3-derived adipocytes. Palmitate treatment was used to induce cellular hypertrophy. Hex blocked adipocyte hypertrophy in response to palmitate treatment but not the increase in lipid droplet size. These data suggest that leptin signaling is necessary for adipocyte cell remodeling, and its absence induces whitening. Taken together, our data suggest that leptin signaling is necessary for adipocyte remodeling in response to obesity, exercise, and psychosocial stress.

Effect of resistance vs. aerobic exercise in pre-diabetes: an RCT

BACKGROUND

This study aimed to assess the different impacts of aerobic and resistance exercise intervention on pre-diabetes and its possible influencing factor (obesity) to identify which exercise intervention mode was better for pre-diabetes to control their blood glucose levels.

METHODS

Single-blind randomized controlled trial. Participants were recruited from Southwest Hospital between February 2016 and May 2017 and randomly divided into three groups using stratified randomization: aerobic exercise (A), resistance exercise (R), and control (C). The effects of each group were analyzed, and the relationship with obesity was investigated following a 12-week intervention.

RESULTS

Eighty participants were enrolled (9 were lost, and 1 was excluded). Finally, 26 participants were included in group A, 23 in group R, and 21 in group C. In groups A and R, FPG, OGTT 2-h PG, and HOMA2-IR decreased by 6.17% (P = 0.001) and 4.81% (P = 0.019), 20.39% (P < 0.001) and 16.50% (P < 0.001), and 8.34% (P = 0.026) and 18.31% (P = 0.001, superior to that in group A), respectively (all P < 0.001 compared with group C, with no significant differences between groups A and R). The ratio of reversal to euglycemia was 69.2% (P = 0.003 compared with group C) in group A and 43.5% (P = 0.213 compared with group C) in group R. The decreased ratio of GSP in group R was greater (65.2%, P = 0.008 compared with group C) compared with group A (38.5%, P = 0.355 compared with group C). Decreases in the parameters BMI (3.1 ± 3.2% P < 0.001, moderately positive correlation with the decreased FPG level, r = 0.498, P = 0.010, two-tailed) and waist circumference (3.1 ± 2.7% P < 0.001) were noted in group A, but no significant correlations were noted between other indicators in group R.

CONCLUSIONS

Both resistance and aerobic exercise can control and reverse IGR. Compared with aerobic exercise, resistance exercise may be superior in terms of GSP and IR improvement. Aerobic exercise decreases blood glucose levels through weight loss. However, the effect of resistance exercise might not be mediated via weight loss and obesity control.

TRIAL REGISTRATION

Chinese Clinical Trial Registry ChiCTR2000038304. Registered on September 17, 2020.

Effect of aerobic exercise and low-carbohydrate high-fat diet on glucose tolerance and android/gynoid fat in overweight/obese women: A randomized controlled trial

The study was designed to compare the effects of weight loss induced by a low-carbohydrate-high-fat diet or a normal diet, with and without exercise, on glucose tolerance measured as area under the curve (AUC), and android (A) and gynoid (G) fat distribution. The study was registered at clinicaltrials.gov; NCT04100356. In total, 57 women classified as overweight or obese (age 40 ± 3.5 years, body mass index 31.1 ± 2.6 kg/m²) were randomly assigned and completed a 10-week intervention using a low-carbohydrate high-fat diet or a normal diet, with or without aerobic interval exercise. An equal deficit of 700 kcal/day was prescribed, either restricting the diet only, or moderately restricting diet and including three 50-min high-intensity bicycle sessions per week. There were thus four groups: normal diet (NORM); low-carbohydrate-high-fat diet (LCHF); normal diet with exercise (NORM-EX); and low-carbohydrate-high-fat diet with exercise (LCHF-EX). Linear mixed models was used to assess differences between groups. With all groups pooled, the intervention resulted in a weight loss of 6.7 ± 2.5% (p < 0.001). The intervention did not result in differences between groups in AUC glucose, nor in fasting glucose or indicis for insulin resistance such as Homeostatic Model Assessment, Matsuda Insulin Sensitivity Index, insulinogenic index and disposition index. Post-intervention android fat was lower in LCHF than NORM (3,223 ± 727 vs. 2,533 ± 535 g, p = 0.041). LCHF reached a lower A/G ratio than NORM (0.94 ± 0.12 vs. 1.04 ± 0.09, p = 0.011) and LCHF-EX (0.94 ± 0.12 vs. 1.09 ± 0.09, p < 0.001) after the intervention. LCHF resulted in lower android fat mass compared to NORM and the lowest A/G ratio compared to the other matched groups, but with no accompanying improvement in AUC glucose. In conclusion, although all groups achieved improvements in glucose tolerance, no superior effect was observed with the LCHF diet, neither with nor without exercise.

The associations between health-related physical fitness and fasting blood glucose in war veterans: a population-based study

The main purpose of the study was to analyze the associations between health-related physical fitness and fasting blood glucose in war veterans. In this cross-sectional study, we recruited 764 men and women aged 45-75 years, who were part of the Homeland War between 1990 and 1995 (33.5% women). Health-related physical fitness included: (1) fat mass and fat-free mass (body composition), (2) push-ups in 30 s (muscular dynamic endurance of upper extremities), (3) sit-ups in 30 s (repetitive upper body strength), (4) chair-stands in 30 s (lower body strength), (5) sit-and-reach test (flexibility) and (6) the 2-min step test (cardiorespiratory function). Laboratory measurement of fasting blood glucose was performed according to standardized procedures in resting seated position after a 12-h overnight fast. Generalized estimating equations with multiple regression models were used to calculate the associations between health-related physical fitness and fasting blood glucose. In men, fasting blood glucose was significantly correlated with fat-free mass (β = - 0.25, p < 0.001), push-ups in 30 s (β = - 0.55, p < 0.001), chair-stands in 30 s (β = - 0.50, p < 0.001), sit-ups in 30 s (r = - 0.45, p < 0.001), the sit-and reach test (r = - 0.46, p < 0.001) and the 2-min step test (r = - 0.19, p < 0.001), while fat mass was positively correlated with fasting blood glucose (β = 0.14, p = 0.004). In women, fasting blood glucose was significantly correlated with fat mass (β = 0.20, p = 0.002), fat-free mass (β = - 0.15, p = 0.014), push-ups in 30 s (β = - 0.49, p < 0.001), chair-stands in 30 s (β = - 0.43, p < 0.001), sit-ups in 30 s (β = - 0.52, p < 0.001), the sit-and reach test (β = - 0.40, p < 0.001) and the 2-min step test (β = - 0.35, p < 0.001). This study shows that fasting blood glucose may be predicted by health-related physical fitness test in war veterans.

The Effect of Traditional Aerobic Exercise and Sprint Interval Training on Insulin Resistance in Men With Prediabetes: A Randomised Controlled Trial

Introduction

Prediabetes is an intermediate stage with hyperglycaemia below the threshold of diabetes mellitus. Insulin resistance is a significant factor in its pathogenesis. Lifestyle modifications are suggested and found to be more beneficial in this stage. Moderate-intensity exercise for 30 to 45 minutes a day is routinely recommended but has low compliance, and lack of time is a significant deterrent. Sprint interval training (SIT) is an alternate exercise regimen with higher intensity and less time requirement. The present study compares the effect of a three-month intervention of traditional aerobic exercise and sprint interval training on insulin resistance in prediabetic men.

Methods

The study subjects were males aged 25 to 40 years with prediabetes as per the American Diabetes Association criteria of fasting and two-hour plasma glucose levels. The study is a parallel-group randomised trial with one arm (AE group) involved in the traditional aerobic exercise (brisk walking) for 30 minutes, five days a week. The other arm was the sprint interval training (SIT) group performing an ‘all-out’ run effort for one minute followed by a recovery rest period of one and a half minutes, completing one cycle of two and half minutes. Four such cycles were completed in each session. Thus, the exercise sessions were just 10 minutes daily, three days a week. The duration of the intervention was three months. One hundred and sixty participants were recruited after screening and randomly assigned in a 1:1 ratio to the two groups. The primary outcome measure was insulin resistance estimated by homeostasis model assessment -estimated insulin resistance (HOMA-IR). The secondary outcome measures were fasting plasma glucose and serum insulin, glycated haemoglobin, body mass index and waist-hip ratio.

Results

The mean age of the AE group was 30.7 ± 3.3 years, and the SIT group was 31 ± 3.4 years. Seventy-two men from the AE group and 74 from the SIT group completed the study. After the three-month AE and SIT exercise, the per-protocol analysis reflected a significant reduction in insulin resistance, i.e., HOMA-IR (3.6 ± 1.1 to 3 ± 1.2, p<0.0001) after traditional aerobic exercise. Similarly, the HOMA-IR was significantly reduced after sprint interval training (3.3 ± 1.2 to 2.5 ± 1, p<0.0001). The intention-to-treat analysis also found that the reductions in HOMA-IR after both exercise protocols were statistically significant. The change in insulin resistance compared for the SIT vs AE group was not statistically significant. Secondary outcome measures HbA1c, fasting glucose, fasting insulin, BMI, and waist-hip ratio showed significant improvement with AE and SIT. 

Conclusions

The sprint interval training similarly improved insulin resistance and other parameters compared to the traditional exercise group. SIT can be a time-efficient exercise protocol suggested as a part of lifestyle modification for men with prediabetes.

Residual Impact of Concurrent, Resistance, and High-Intensity Interval Training on Fasting Measures of Glucose Metabolism in Women With Insulin Resistance

We sought to assess the residual effects (post 72-h training cessation) on fasting plasma glucose (FPG) and fasting insulin (FI) after 12-weeks of high-intensity interval training (HIIT), resistance training (RT), or concurrent training (CT) in women with insulin resistance (IR). We also aimed to determine the training-induced, post-training residual impact of CT. A total of adult 45 women (age 38.5±9.2years) were included in the final analysis and were assigned to a control (CG; n=13, BMI 28.3±3.6kg/m2), HIIT [n=14, BMI 28.6±3.6kg/m2, three sessions/wk., 80-100% of the maximum heart rate (HRmax)], RT [n=8, BMI 29.4±5.5kg/m2, two sessions/wk., 8-10 points of the modified Borg, corresponding to 20 to 50% range of one maximum repetition test (1RM)], or CT group (n=10, BMI 29.1±3.0kg/m2, three sessions/wk., 80-100% of HRmax, and 8-10 Borg, or 20 to 50% range of 1RM, to each HIIT and RT compounds), with the latter including both HIIT and RT regimens. Training interventions lasted 12-weeks. The main outcomes were FPG and FI measured at pre- and 24-h and 72-h post-training (FPG24h, FI24h, and FPG72h, FI72h, respectively). Secondary endpoints were body composition/anthropometry and the adiposity markers waist circumference (WC) and tricípital skinfold (TSF). The residual effects 72-h post-training [delta (∆)] were significantly poorer (all p<0.01) in the CT group (∆FPG72h+6.6mg/dl, η 2: 0.76) than in the HIIT (∆FPG72h+1.2mg/dl, η 2: 0.07) and RT (∆FPG72h+1.0mg/dl, η 2: 0.05) groups. These findings reveal that HIIT reduces FPG and RT reduces FI 24-h post-training; both exercise interventions alone have remarkably better residual effects on FPG and FI (post-72h) than CT in women with insulin resistance.

Comparisons of different exercise interventions on glycemic control and insulin resistance in prediabetes: a network meta-analysis

BACKGROUND

In order to recommend the optimal type of exercise for type 2 diabetes prevention, different exercise interventions were compared with respect to their effects on glycemic control and insulin resistance.

METHODS

Studies on the curative effect of aerobic exercise training (AET), resistance training (RT), or control training (CT) on prediabetes were retrieved from the PubMed, Embase, SPORTDiscus, and Cochrane Library databases. Body mass index (BMI); homeostasis model assessment of insulin resistance index (HOMA-IR); and fasting blood glucose (FBG), glycated hemoglobin (HbA1c), and insulin levels were used as outcome indicators. The Q statistic was calculated to evaluate heterogeneity within studies. A fixed- or random-effects model was used for pooling data based on nonsignificant or significant heterogeneities. A consistency test was conducted using a node-splitting analysis.

RESULTS

A total of 13 eligible studies were included. The results of the direct meta-analysis indicated that AET or RT could significantly reduce the HbA1c level in prediabetic individuals compared to CT [AET vs. CT: standardized mean difference (SMD) = - 0.6739, 95% confidence interval (CI) = - 0.9424 to - 0.4055 to RT vs. CT: SMD = - 1.0014, 95% CI = - 1.3582 to - 0.6446]. The findings from the network meta-analysis showed that there were no statistical differences among the four comparisons for all the indicators except for lower HbA1c level (SMD = - 0.75, 95% CI = - 1.31 to - 0.19) and HOMA-IR (SMD = - 1.03, 95% CI = - 1.96 to - 0.10) in the AET group than in the CT group. In addition, prediabetic individuals in the AET + RT group showed greater control of BMI and insulin and FBG levels than those in the other groups, whereas AET was the most effective in controlling HbA1c and HOMA-IR levels in prediabetic individuals.

CONCLUSION

AET, AET + RT, and RT exerted beneficial effects on insulin resistance and glycemic control in prediabetic patients. From the existing data, AET or AET + RT is preferentially recommended for these patients, although further studies may unveil RT as a promising therapy. Benefits from all types of exercise seem to occur in an intensity-dependent manner.

Comparing the effects of 12 months aerobic exercise and resistance training on glucose metabolism among prediabetes phenotype: A explorative randomized controlled trial

AIMS

The pathophysiology of each phenotype of prediabetes is unique that promotes different levels of diabetes and cardiovascular disease risks. Exercise guidelines for individuals with prediabetes including both aerobic and resistance training could improve metabolic control, but its effects on different prediabetes subtypes are unclear. The aim of this explorative randomized controlled trial was to evaluate the effects of aerobic training (AT) or resistance training (RT) on glucose metabolism and lipid profile by different prediabetes subtypes with.

METHODS

A randomized controlled trial in which 128 individuals with isolated impaired fasting glucose (i-IFG; n = 39), isolated impaired glucose tolerance (i-IGT; n = 29), combined glucose tolerance (CGI; n = 27) and isolated elevated HbA_1c (n = 33) were randomly assigned to the control group, AT group and RT group, respectively. Supervised exercise training, including AT and RT were completed at moderate intensity for 60 min per day, three non-consecutive days per week for 12 months. The primary outcome was improvement in glucose metabolism. Secondary outcomes included measure of lipid profile and if these effects were moderated by the prediabetes phenotype.

RESULTS

Of the initial 128 participants, 118 finished the study, but all participants were included in the intention-to-treat analyses. The improvement in 2 h postprandial plasma glucose (2 hPG) between group difference (AT vs. RT) at 12 months was 0.87 (95% CI, -1.59 to-0.16; p < 0.05). Compared with RT group, AT significantly decreased the 2hPG in participants with i-IGT at 12 months (-1.66, 95% CI -3.04 to -0.28; p < 0.05).

CONCLUSIONS

AT program conferred benefits in improving 2 h PG and HbA_1c compared with RT for prediabetes. These findings may moderate by prediabetes phenotype, and AT appeared more effective in i-IGT. A future trial with large sample size and long time follow up of prediabetes phenotype groups are needed.

Metrics of Diabetes Risk Are Only Minimally Improved by Exercise Training in Postmenopausal Breast Cancer Survivors

CONTEXT

Insulin resistance is a risk factor for breast cancer recurrence. How exercise training changes fasting and postglucose insulin resistance in breast cancer survivors is unknown.

OBJECTIVE

To evaluate exercise-induced changes in postglucose ingestion insulin concentrations, insulin resistance, and their associations with cancer-relevant biomarkers in breast cancer survivors.

SETTING

The University of Massachusetts Kinesiology Department.

PARTICIPANTS

15 postmenopausal breast cancer survivors not meeting the physical activity guidelines (150 min/week of exercise).

INTERVENTION

A supervised 12-week aerobic exercise program (60 min/day, 3-4 days/week).

MAIN OUTCOME MEASURES

Postglucose ingestion insulin was determined by peak insulin and area under the insulin curve (iAUC) during a 5-sample oral glucose tolerance test. Insulin sensitivity was estimated from the Matsuda composite insulin sensitivity index (C-ISI). Changes in fitness and body composition were determined from submaximal VO2peak and dual energy X-ray absorptiometry.

RESULTS

Participants averaged 156.8 ± 16.6 min/week of supervised exercise. Estimated VO2peak significantly increased (+2.8 ± 1.4 mL/kg/min, P < .05) and body weight significantly decreased (-1.1 ± 0.8 kg, P < .05) following the intervention. There were no differences in fasting insulin, iAUC, C-ISI, or peak insulin following the intervention. Insulin was only significantly lower 120 min following glucose consumption (68.8 ± 34.5 vs 56.2 ± 31.9 uU/mL, P < .05), and there was a significant interaction with past/present aromatase inhibitor (AI) use for peak insulin (-11.99 non-AI vs +13.91 AI uU/mL) and iAUC (-24.03 non-AI vs +32.73 AI uU/mL).

CONCLUSIONS

Exercise training had limited overall benefits on insulin concentrations following glucose ingestion in breast cancer survivors but was strongly influenced by AI use.

Two-year-supervised resistance training prevented diabetes incidence in people with prediabetes: A randomised control trial

AIM

The purpose of this study is to explore the long-term effects of aerobic training (AT), resistance training (RT), and combined training (AT + RT) on the prevention of T2D incidence in patients with prediabetes.

MATERIALS AND METHODS

In this randomised controlled trial, people with prediabetes (fasting glucose ≥5.6 and <7.0 mmol/L and/or 2-h glucose ≥7.8 and <11.1 mmol/L on the 75-g oral glucose tolerance test and/or haemoglobin A_1c ≥5.7% and <6.4%) were randomly assigned to the control group, AT group, RT group, or AT + RT group. Supervised exercise programmes, including AT, RT, and AT + RT, were completed for 60 minutes per day, three non-consecutive days per week for 24 months. The primary outcome was the incidence of T2D; secondary outcomes were blood glucose and lipid levels, including total cholesterol (TC) and standard 2-hour oral glucose tolerance (2hPG).

RESULTS

A total of 137 (80%) subjects with a mean age of 59 years (45 men, 92 women) entered the final analysis. After 24 months of intervention, the incidences of T2D adjusted by sex and age were significantly decreased by 74% (95% CI, 38-89), 65% (95% CI, 21-85), and 72% (95% CI, 36-87) in the AT + RT, RT, and AT groups compared with the control group (HR: AT + RT 0.26 [95% CI, 0.11-0.62], RT 0.35 [95% CI, 0.15-0.79], and AT 0.28 [95% CI, 0.13-0.64]). The cumulative T2D incidences were significantly lower in the AT + RT, RT, and AT groups than in the control group (21%, 26%, and 22% vs 69%). The blood glucose and lipid profiles improved more in the AT, RT, and AT + RT groups than in the control group.

CONCLUSION

RT and RT plus AT were as effective as isolated AT in preventing progression to T2D.

Glucose Tolerance is Linked to Postprandial Fuel Use Independent of Exercise Dose

PURPOSE

The optimal short-term exercise dose to improve glucose tolerance in relation to metabolic flexibility and/or insulin resistance is unknown. Therefore, we tested if short-term, work-matched continuous (CONT) versus interval (INT) exercise training improves glucose tolerance in part by reducing insulin resistance and increasing metabolic flexibility independent of clinically meaningful fat loss in adults with prediabetes.

METHODS

Subjects (age = 60.9 ± 1.4 yr, body mass index = 33.5 ± 1.1 kg·m) were screened for prediabetes using the American Diabetes Association criteria (75 g oral glucose tolerance test [OGTT] and/or HbA1c) and were randomized to 60 min·d of supervised CONT (n = 17, 70% HRpeak) or work-matched INT (n = 14; 90% HRpeak for 3 min and 50% HRpeak for 3 min) exercise for 12 bouts. Fitness (V˙O2peak) and body composition were assessed pre- and postintervention. A 180-min 75-g OGTT was performed, and glucose, insulin, and free fatty acids were collected to calculate glucose tolerance (tAUC180min) and whole-body as well as adipose tissue insulin resistance pre- and postintervention. RER (indirect calorimetry) was also measured at 0, 60, 120, and 180 min of the OGTT to assess fasting and postprandial metabolic flexibility.

RESULTS

CONT and INT training improved V˙O2peak (L·min; P = 0.001) and glucose tolerance (P = 0.01) and reduced fasting RER (P = 0.006), as well as whole-body and adipose insulin resistance (both P = 0.02) with no effect on body fat (P = 0.18). Increased postprandial RER was correlated with reduced glucose tAUC180min (r = -0.38, P = 0.05) and increased 180-min RER related to decreased whole-body insulin resistance (r = -0.42, P = 0.03).

CONCLUSION

Independent of exercise dose and fat loss, short-term training improves glucose tolerance in relation to enhanced postprandial fuel use.

Bitter gourd reduces elevated fasting plasma glucose levels in an intervention study among prediabetics in Tanzania

ETHNOPHARMACOLOGICAL RELEVANCE

Impaired glucose tolerance and diabetes mellitus have become major health issues even in non-industrialized countries. As access to clinical management is often poor, dietary interventions and alternative medicines are required. For bitter gourd, Momordica charantia L., antidiabetic properties have been claimed.

AIM OF THE STUDY

The main objective of the intervention study was to assess antidiabetic effects of daily bitter gourd consumption of 2.5g powder over the course of eight weeks among prediabetic individuals.

MATERIALS AND METHODS

In a randomized placebo-controlled single blinded clinical trial, 52 individuals with prediabetes were studied after consuming a bitter gourd or a cucumber juice. For reducing the impact of between subject differences in the study population, a crossover design was chosen with eight weeks for each study period and four weeks washout in between. Fasting plasma glucose was chosen as the primary outcome variable.

RESULTS

Comparing the different exposures, the CROS analysis (t=-2.23, p=0.031, r=0.326) revealed a significant difference in the change of FPG of 0.31mmol/L (5.6mg/dL) with a trend (R²=0,42387). The number of 44 finally complete data sets achieved a power of 0.82, with a medium-to-large effect size (Cohen's d 0.62). The effect was also proven by a general linear mixed model (estimate 0.31; SE: 0.12; p: 0.01; 95%CI: 0.08; 0.54). Not all participants responded, but the higher the initial blood glucose levels were, the more pronounced the effect was. No serious adverse effects were observed.

CONCLUSIONS

Bitter gourd supplementation appeared to have benefits in lowering elevated fasting plasma glucose in prediabetes. The findings should be replicated in other intervention studies to further investigate glucose lowering effects and the opportunity to use bitter gourd for dietary self-management, especially in places where access to professional medical care is not easily assured.

The effect of low volume sprint interval training in patients with non-alcoholic fatty liver disease

OBJECTIVES

Exercise is an important part of disease management in patients with non-alcoholic fatty liver disease (NAFLD), but adherence to current exercise recommendations is poor. Novel low-volume sprint interval training (SIT) protocols with total training time commitments of ≤30 min per week have been shown to improve cardiometabolic risk and functional capacity in healthy sedentary participants, but the efficacy of such protocols in the management of NAFLD remains unknown. The aim of the present study was to examine whether a low-volume SIT protocol can be used to improve liver function, insulin resistance, body composition, physical fitness, cognitive function and general well-being in patients with NAFLD.

METHODS

In the present study, 7 men and 2 women with NAFLD (age: 45 ± 8 y, BMI: 28.7 ± 4.1 kg·m^-2) completed a 6-week control period followed by 6 weeks of twice-weekly SIT sessions (5-10 × 6-s 'all-out' cycle sprints). Body composition, blood pressure, liver function, metabolic function, functional capacity, cognitive function and quality of life were assessed at baseline, following the control period, and following the SIT intervention.

RESULTS

Walking speed during the walk test (+12%), estimated V̇O₂max (+8%), verbal fluency (+44%), and blood platelet count (+12%; all p < 0.05) significantly increased during the control period. These measures remained significantly raised compared to baseline following the SIT intervention, but did not significantly change any further compared to the post-control time-point. Diastolic blood pressure decreased from 87 ± 10 to 77 ± 8 mm Hg from the end of the control period to the end of the SIT intervention (p < 0.05).

CONCLUSION

This study does not support the use of 6 weeks of a low volume SIT protocol involving twice-weekly sessions with 5-10 × 6-s 'all-out' cycle sprints as an intervention for NAFLD disease management.

The impact of structured physical activity on glycaemic control in diabetes prevention programmes: A systematic review

Background:

Seven landmark randomised controlled trials, with some that began as early as the 1990s, observed the prediabetic state, namely, impaired glucose tolerance and impaired fasting glucose conditions, against the impact of lifestyle interventions such as physical activity, to prevent or delay the onset of type 2 diabetes mellitus. In addition to the landmark trials, this systematic review examines 14 studies that retained a focus on prediabetic individuals and measured the efficacy of physical activity on improving glucose tolerance.

Results:

Type, duration and intensity of structured physical activity can have unique benefits to prediabetic individuals. It is posited that diabetes prevention programmes must target prediabetic individuals as belonging to a high-risk group, separate and distinct from those identified with overall risk factors. While the transition from prediabetes to type 2 diabetes mellitus is not completely deterministic, the conversion rate is phenomenally higher among those with impaired glucose tolerance than those with normal glucose levels.

Conclusion:

Tenets of health behaviour models do support inferences that prediabetic individuals are potentially more inclined to weighing the risks and benefits of progressive illnesses and would therefore be more receptive to active participation in interventions. More research is required to develop evidence-based diabetes prevention programmes linked to structured physical activity intervention.

Glycemic Variability and Its Association With Demographics and Lifestyles in a General Adult Population

OBJECTIVE

The objective was to investigate glycemic variability indices in relation to demographic factors and common environmental lifestyles in a general adult population.

METHODS

The A Estrada Glycation and Inflammation Study is a cross-sectional study covering 1516 participants selected by sampling of the population aged 18 years and over. A subsample of 622 individuals participated in the Glycation project, which included continuous glucose monitoring procedures. Five glycemic variability indices were analyzed, that is, SD, MAGE, MAG, CONGA1, and MODD.

RESULTS

Participants had a mean age of 48 years, 62% were females, and 12% had been previously diagnosed with diabetes. In the population without diabetes, index distributions were not normal but skewed to the right. Distributional regression models that adjusted for age, gender, BMI, alcohol intake, smoking status, and physical activity confirmed that all indices were positively and independently associated with fasting glucose levels and negatively with heavy drinking. SD, MAGE, and CONGA1 were positively associated with aging, and MAG was negatively associated with BMI. None of the GVI studied were influenced by physical activity. Age-group-specific reference values are given for the indices.

CONCLUSIONS

This study yielded age-specific reference values for glucose variability indices in a general adult population. Significant increases were observed with aging. Heavy drinking of more than 140 g/week was associated with significant decreases in variability indices. No differences were found between males and females. These normative ranges provide a guide for clinical care, and may offer an alternative treatment target among persons with diabetes.

Glucose and Lipid Dysmetabolism in a Rat Model of Prediabetes Induced by a High-Sucrose Diet

Glucotoxicity and lipotoxicity are key features of type 2 diabetes mellitus, but their molecular nature during the early stages of the disease remains to be elucidated. We aimed to characterize glucose and lipid metabolism in insulin-target organs (liver, skeletal muscle, and white adipose tissue) in a rat model treated with a high-sucrose (HSu) diet. Two groups of 16-week-old male Wistar rats underwent a 9-week protocol: HSu diet (n = 10)-received 35% of sucrose in drinking water; Control (n = 12)-received vehicle (water). Body weight, food, and beverage consumption were monitored and glucose, insulin, and lipid profiles were measured. Serum and liver triglyceride concentrations, as well as the expression of genes and proteins involved in lipid biosynthesis were assessed. The insulin-stimulated glucose uptake and isoproterenol-stimulated lipolysis were also measured in freshly isolated adipocytes. Even in the absence of obesity, this rat model already presented the main features of prediabetes, with fasting normoglycemia but reduced glucose tolerance, postprandial hyperglycemia, compensatory hyperinsulinemia, as well as decreased insulin sensitivity (resistance) and hypertriglyceridemia. In addition, impaired hepatic function, including altered gluconeogenic and lipogenic pathways, as well as increased expression of acetyl-coenzyme A carboxylase 1 and fatty acid synthase in the liver, were observed, suggesting that liver glucose and lipid dysmetabolism may play a major role at this stage of the disease.

Effects of Weight Loss with and without Exercise on Regional Body Fat Distribution in Postmenopausal Women

BACKGROUND/AIMS

The purpose was to determine whether lifestyle interventions have different effects on regional fat in women with normal glucose tolerance vs. impaired glucose tolerance (NGT vs. IGT).

METHODS

Changes in glucose metabolism (2-h oral glucose-tolerance tests), android to gynoid fat mass ratio (dual energy X-ray absorptiometry [DXA]), visceral to subcutaneous abdominal fat area ratio (CT), and abdominal to gluteal subcutaneous fat cell weight (FCW; adipose tissue biopsies) were determined in 60 overweight postmenopausal women (45-80 years) following 6 months of weight loss alone (WL; n = 28) or with aerobic exercise (AEX + WL; n = 32).

RESULTS

The interventions led to ∼8% decrease in weight, but only the AEX + WL group improved fitness (↑11% in VO2max) and reduced the android-to-gynoid fat mass ratio (↓5%; p < 0.05). Both NGT and IGT groups reduced visceral and subcutaneous abdominal fat areas and abdominal and gluteal FCWs, which related to improvements in homeostatic model assessment (r = 0.34-0.42) and 2-h glucose (r = 0.34-0.35), respectively (p < 0.05). The decline in FCW was 2× greater in women with IGT following WL (p < 0.05). The ratios of abdominal-to-gluteal FCW did not change following either intervention.

CONCLUSIONS

The mechanisms by which WL with and without exercise impact regional fat loss should be explored as reductions in abdominal fat area and subcutaneous FCW appear to influence glucose metabolism. This is a work of the U.S. Government and is not subject to copyright protection in the United States. Foreign copyrights may apply. Published by S. Karger AG, Basel.

A comparison of the health benefits of reduced-exertion high-intensity interval training (REHIT) and moderate-intensity walking in type 2 diabetes patients

Reduced-exertion high-intensity interval training (REHIT) is a genuinely time-efficient intervention that can improve aerobic capacity and insulin sensitivity in sedentary individuals. The present study compared the effects of REHIT and moderate-intensity walking on health markers in patients with type 2 diabetes (T2D) in a counter-balanced crossover study. Sixteen men with T2D (mean ± SD age: 55 ± 5 years, body mass index: 30.6 ± 2.8 kg·m^-2, maximal aerobic capacity: 27 ± 4 mL·kg^-1·min^-1) completed 8 weeks of REHIT (three 10-min low-intensity cycling sessions/week with two "all-out" 10-20-s sprints) and 8 weeks of moderate-intensity walking (five 30-min sessions/week at an intensity corresponding to 40%-55% of heart-rate reserve), with a 2-month wash-out period between interventions. Before and after each intervention, participants underwent an incremental fitness test, an oral glucose tolerance test (OGTT), a whole-body dual-energy X-ray absorptiometry scan, and continuous glucose monitoring. REHIT was associated with a significantly larger increase in maximal aerobic capacity compared with walking (7% vs. 1%; time × intervention interaction effect: p < 0.05). Both REHIT and walking decreased resting mean arterial pressure (-4%; main effect of time: p < 0.05) and plasma fructosamine (-5%; main effect of time: p < 0.05). Neither intervention significantly improved OGTT-derived measures of insulin sensitivity, glycaemic control measured using continuous glucose monitors, blood lipid profile, or body composition. We conclude that REHIT is superior to a 5-fold larger volume of moderate-intensity walking in improving aerobic fitness, but similar to walking REHIT is not an effective intervention for improving insulin sensitivity or glycaemic control in T2D patients in the short term.

Exercise Training and Insulin Resistance: A Current Review

There is a general perception that increased physical activity will improve glucose homeostasis in all individuals. While this is an attractive concept, this conclusion may be overly simplistic and even misleading. The topic was reviewed extensively over 30 years ago and it was concluded that acute exercise enhances glucose uptake. However, in some cases the chronic influence of interventions utilizing exercise may have little effect on glucose metabolism. Moreover, insulin resistance often returns to near baseline levels within a couple of days following cessation of the exercise bout; leaving the overall effectiveness of the intervention in question. Since improving glucose homeostasis should be the focal endpoint of any intervention designed to mitigate the overwhelming degree of insulin resistance in individuals at risk for metabolic disease, it is essential to evaluate the key components of a successful approach.

Personalized metabolomics for predicting glucose tolerance changes in sedentary women after high-intensity interval training

High-intensity interval training (HIIT) offers a practical approach for enhancing cardiorespiratory fitness, however its role in improving glucose regulation among sedentary yet normoglycemic women remains unclear. Herein, multi-segment injection capillary electrophoresis-mass spectrometry is used as a high-throughput platform in metabolomics to assess dynamic responses of overweight/obese women (BMI > 25, n = 11) to standardized oral glucose tolerance tests (OGTTs) performed before and after a 6-week HIIT intervention. Various statistical methods were used to classify plasma metabolic signatures associated with post-prandial glucose and/or training status when using a repeated measures/cross-over study design. Branched-chain/aromatic amino acids and other intermediates of urea cycle and carnitine metabolism decreased over time in plasma after oral glucose loading. Adaptive exercise-induced changes to plasma thiol redox and orthinine status were measured for trained subjects while at rest in a fasting state. A multi-linear regression model was developed to predict changes in glucose tolerance based on a panel of plasma metabolites measured for naïve subjects in their untrained state. Since treatment outcomes to physical activity are variable between-subjects, prognostic markers offer a novel approach to screen for potential negative responders while designing lifestyle modifications that maximize the salutary benefits of exercise for diabetes prevention on an individual level.

Tennis for physical health: acute age- and gender-based physiological responses to cardio tennis

This study described physiological and perceptual responses to Cardio tennis for "younger" and "older" adult populations of both sexes for health-related outcomes. Thirty-one active participants, each with prior recreational tennis experience (∼2 years) (8 younger and 8 older males, and 7 younger and 8 older females) performed preliminary testing and a 50-minute instructor-led Cardio tennis session. Cardio tennis is a conditioning-based tennis program comprised of warm-up movements, drill-based exercises (set movement and hitting games), and competitive play scenarios. Participants performed the 20-m shuttle run test to determine maximal heart rate (HR) during preliminary testing. Before, after, and 30-minute post Cardio tennis session, HR, blood pressure (BP), rate pressure product (RPP), and capillary blood lactate and glucose were determined. Furthermore, HR and pedometer-derived step counts were measured throughout, while the session was filmed and coded for technical skill. After the session, ratings of perceived exertion, enjoyment, and challenge were obtained. Heart rate, systolic BP, and RPP were significantly increased by Cardio tennis (p ≤ 0.05), though returned to pre-exercise levels after 30 minutes (p > 0.05). Heart rate and BP did not differ between groups pre- or 30-minute postexercise (p > 0.05); however, these were lower in younger males during and higher in younger females postsession (p ≤ 0.05). Lactate and glucose concentrations were increased in all groups (p ≤ 0.05), with lactate being highest in male groups (p ≤ 0.05), without differences in glucose between groups (p > 0.05). Stroke and step counts were not different between groups (p > 0.05). Ratings of perceived exertion and perceived challenge were lowest in the younger male group compared with all other groups (p ≤ 0.05). Cardio tennis presents as an effective stimulus to invoke sufficient cardiovascular and metabolic load to benefit health and fitness, though age- and sex-based responses should be considered in prescription.

Only minor additional metabolic health benefits of high as opposed to moderate dose physical exercise in young, moderately overweight men

OBJECTIVE

The dose-response effects of exercise training on insulin sensitivity, metabolic risk, and quality of life were examined.

METHODS

Sixty-one healthy, sedentary (VO₂max: 35 ± 5 ml/kg/min), moderately overweight (BMI: 27.9 ± 1.8), young (age: 29 ± 6 years) men were randomized to sedentary living (sedentary control group; n = 18), moderate (moderate dose training group [MOD]: 300 kcal/day, n = 21), or high (high dose training group [HIGH]: 600 kcal/day, n = 22) dose physical exercise for 11 weeks.

RESULTS

The return rate for post-intervention testing was 82-94% across groups. Weekly exercise amounted to 2,004 ± 24 and 3,774 ± 68 kcal, respectively, in MOD and HIGH. Cardiorespiratory fitness increased (P < 0.001) 18 ± 3% in MOD and 17 ± 3% in HIGH, and fat percentage decreased (P < 0.001) similarly in both exercise groups (MOD: 32 ± 1 to 29 ± 1%; HIGH: 30 ± 1 to 27 ± 1%). Peripheral insulin sensitivity increased (P < 0.01) (MOD: 28 ± 7%; HIGH: 36 ± 8%) and the homeostasis model assessment of insulin resistance decreased (P < 0.05) (MOD: -17 ± 7%; HIGH: -18 ± 10%). The number of subjects meeting the criteria of the metabolic syndrome decreased by 78% in MOD (P < 0.01) and by 80% in HIGH (P < 0.05). General health assessed by questionnaire increased similarly in MOD (P < 0.05) and HIGH (P < 0.01).

CONCLUSIONS

Only minor additional health benefits were found when exercising ∼3,800 as opposed to ∼2,000 kcal/week in young moderately overweight men. This finding may have important public health implications.

Comparison of glucose tolerance tests to detect the insulin sensitizing effects of a bout of continuous exercise

The aim of the present study was to determine which of the available glucose tolerance tests (oral (OGTT) vs. intravenous (IVGTT)) could more readily detect the insulin sensitizing effects of a bout of continuous exercise. Ten healthy moderately fit young men (V̇O2peak of 45.4 ± 1.8 mL·kg(-1)·min(-1); age 27.5 ± 2.7 yr) underwent 4 OGTT and 4 IVGTT on different days following a standardized dinner and overnight fast. One test was performed immediately after 55 min of cycle-ergometer exercise at 60% V̇O2peak. Insulin sensitivity index was determined during a 50 min IVGTT according to Tura (CISI) and from a 120 min OGTT using the Matsuda composite index (MISI). After exercise, MISI improved 29 ± 10% without reaching statistical significance (p = 0.182) due to its low reproducibility (coefficient of variation 16 ± 3%; intra-class reliability 0.846). However, CISI significantly improved (50 ± 4%; p < 0.001) after exercise showing better reproducibility (coefficient of variation 13 ± 4%; intra-class reliability 0.955). Power calculation revealed that 6 participants were required for detecting the effects of exercise on insulin sensitivity when using IVGTT, whereas 54 were needed when using OGTT. The superior response of CISI compared with MISI suggests the preferential use of IVGTT to assess the effects of exercise on insulin sensitivity when using a glucose tolerance test.

Insulin sensitivity and metabolic flexibility following exercise training among different obese insulin-resistant phenotypes

Impaired fasting glucose (IFG) blunts the reversal of impaired glucose tolerance (IGT) after exercise training. Metabolic inflexibility has been implicated in the etiology of insulin resistance; however, the efficacy of exercise on peripheral and hepatic insulin sensitivity or substrate utilization in adults with IFG, IGT, or IFG + IGT is unknown. Twenty-four older (66.7 ± 0.8 yr) obese (34.2 ± 0.9 kg/m(2)) adults were categorized as IFG (n = 8), IGT (n = 8), or IFG + IGT (n = 8) according to a 75-g oral glucose tolerance test (OGTT). Subjects underwent 12-wk of exercise (60 min/day for 5 days/wk at ∼85% HRmax) and were instructed to maintain a eucaloric diet. A euglycemic hyperinsulinemic clamp (40 mU·m(2)·min(-1)) with [6,6-(2)H]glucose was used to determine peripheral and hepatic insulin sensitivity. Nonoxidative glucose disposal and metabolic flexibility [insulin-stimulated respiratory quotient (RQ) minus fasting RQ] were also assessed. Glucose incremental area under the curve (iAUCOGTT) was calculated from the OGTT. Exercise increased clamp-derived peripheral and hepatic insulin sensitivity more in adults with IFG or IGT alone than with IFG + IGT (P < 0.05). Exercise reduced glucose iAUCOGTT in IGT only (P < 0.05), and the decrease in glucose iAUCOGTT was inversely correlated with the increase in peripheral but not hepatic insulin sensitivity (P < 0.01). Increased clamp-derived peripheral insulin sensitivity was also correlated with enhanced metabolic flexibility, reduced fasting RQ, and higher nonoxidative glucose disposal (P < 0.05). Adults with IFG + IGT had smaller gains in clamp-derived peripheral insulin sensitivity and metabolic flexibility, which was related to blunted improvements in postprandial glucose. Additional work is required to assess the molecular mechanism(s) by which chronic hyperglycemia modifies insulin sensitivity following exercise training.

Effect of adiposity on insulin action after acute and chronic resistance exercise in non-diabetic women

PURPOSE

Obesity may attenuate metabolic health improvements following lifestyle interventions. However, the effect of adiposity on insulin action following resistance exercise in young non-diabetic women is unknown. The purpose of this study was to test the hypothesis that adiposity attenuates improvements in insulin sensitivity and glucose-stimulated insulin secretion (INS0-60/GLC0-60) after both acute resistance exercise (ARE) and progressive training (PRT).

METHODS

Twenty-six young non-diabetic women (21.2 ± 0.7 years) were randomly assigned to control (C; n = 7; BF 40.1 ± 2.1 %) or exercise groups: normal body fat (NBF; n = 8; BF 29.9 ± 2.3 %) and high body fat (HBF; n = 12; BF 48.2 ± 1.4 %). Acute whole-body exercises were performed at 60 % of 1-RM for three sets of 8-12 repetitions, and PRT was performed 3 days/week for 7 weeks. A 75 g OGTT was conducted before and after ARE and PRT to estimate insulin sensitivity (Matsuda index) and INS0-60/GLC0-60. Insulin area under the curve (AUC) was calculated using the trapezoidal model.

RESULTS

ARE had no statistical effect on insulin action across groups. Strength and fat-free mass (via DXA) increased after PRT in both NBF and HBF (p < 0.05), but only HBF women decreased BF (p < 0.01). HBF women were less insulin sensitive at baseline compared to NBF women (p < 0.05). Insulin sensitivity increased 95 % and INS0-60/GLC0-60 decreased 32 % following PRT in NBF, but not HBF or C (p < 0.05). After training, enhanced insulin sensitivity was inversely related to decreased INS0-60/GLC0-60 (r = -0.71, p < 0.001), fasting insulin (r = -0.71, p < 0.001), and insulin AUC (r = -0.85, p < 0.001).

CONCLUSION

Seven weeks of PRT increases insulin sensitivity and reduces glucose-stimulated insulin secretion in NBF, but not HBF women. Obesity attenuates exercise-induced improvements in glucose regulation in young non-diabetic women.

Fasting hyperglycaemia blunts the reversal of impaired glucose tolerance after exercise training in obese older adults

AIM

Lifestyle modification, consisting of exercise and weight loss, delays the progression from prediabetes to type 2 diabetes (T2D). However, no study has determined the efficacy of exercise training on glucose metabolism in the different prediabetes subtypes.

METHODS

Seventy-six older (65.1 ± 0.6 years) obese adults with impaired fasting glucose (IFG; n = 12), impaired glucose tolerance (IGT; n = 9) and combined glucose intolerance (IFG + IGT = CGI; n = 22) were compared with normal glucose tolerant (NGT; n = 15) and T2D (n = 18) groups after 12 weeks of exercise training (60 min/day for 5 days/week at ~85% HR(max)). An oral glucose tolerance test was used to assess glucose levels. Insulin sensitivity (IS; euglycaemic hyperinsulinaemic clamp at 40 mU/m(2)/min), β-cell function (glucose-stimulated insulin secretion corrected for IS), body composition (hydrostatic weighing/computed tomography scan) and cardiovascular fitness (treadmill VO(2) max) were also assessed.

RESULTS

Exercise training reduced weight and increased cardiovascular fitness (p < 0.05). Exercise training lowered fasting glucose levels in IFG, CGI and T2D (p < 0.05) and 2-h glucose levels in IGT, CGI and T2D (p < 0.05). However, 2-h glucose levels were not normalized in adults with CGI compared with IGT (p < 0.05). β-Cell function improved similarly across groups (p < 0.05). Although not statistically significant, IS increased approximately 40% in IFG and IGT, but only 17% in CGI.

CONCLUSION

The magnitude of improvement in glucose metabolism after 12 weeks of exercise training is not uniform across the prediabetes subtypes. Given the high risk of progressing to T2D, adults with CGI may require more aggressive therapies to prevent diabetes.

Exercise training improves fasting glucose control

Purpose

Numerous studies have measured changes in fasting blood glucose (FBG) levels in response to physical activity (PA) interventions. While studies involving clinical populations such as type 2 diabetics typically report significant reductions, most others report no change in FBG. This study investigated changes in FBG in apparently healthy adults following a PA intervention.

Methods

We measured fingertip samples for FBG pre and post a 40-day PA program in 575 insufficiently active adults. The PA goal was at least 30 minutes of moderate exercise daily, and there was 73% compliance.

Results

A PA questionnaire showed the average level of activity was 69 ± 46 min/wk preintervention, and this increased to 635 ± 458 min/wk postintervention. When the change in FBG was regressed against baseline FBG levels, there was a significant negative relationship (y = 2.623 − 0.471 × x; r = 0.472; P < 0.0001). The regression line showed, on average, subjects with low pre-study glucose levels had increased FBG while those with high levels had reductions in FBG.

Conclusion

It appears that the body’s response to PA training is to upregulate glucose control, which is reflected in tighter FBG levels around a physiological set point (5.6 mmol/L, in the present study). Regulation of blood glucose is a complex neuroendocrine process with numerous organs involved, but it was not possible in the present study to determine which of these regulatory steps are involved in exercise-induced changes of FBG.