A low-glycemic index diet combined with exercise reduces insulin resistance, postprandial hyperinsulinemia, and glucose-dependent insulinotropic polypeptide responses in obese, prediabetic humans

Nutrition and exercise: Cornerstones of health with emphasis on obesity and type 2 diabetes management-A narrative review

While a broad consensus exists that integrated nutrition and regular exercise are foundational for health maintenance and serve as a robust non-pharmacological strategy against cardiometabolic diseases, the nuanced interplay between these elements remains incompletely understood. Through multifaceted interactions, these factors profoundly influence primary metabolic organs, notably the skeletal muscle and adipose tissue. Despite the critical nature of this interactivity, a holistic understanding of the combined effects of physical activity and dietary practices is still emerging. This narrative review aims to elucidate the intertwined roles of nutrition and exercise. It provides a comprehensive overview of their synergistic dynamics and emphasizes the importance of a dual-focus approach in mitigating and managing cardiometabolic disorders, predominantly obesity and type 2 diabetes.

Understanding the Impact of Different Doses of Reducose® Mulberry Leaf Extract on Blood Glucose and Insulin Responses after Eating a Complex Meal: Results from a Double-Blind, Randomised, Crossover Trial

Non-communicable diseases (NCDs) are becoming an increasingly important health concern due to a rapidly ageing global population. The fastest growing NCD, type 2 diabetes mellitus (T2DM), is responsible for over 2 million deaths annually. Lifestyle changes, including dietary changes to low glycemic response (GR) foods, have been shown to reduce the risk of developing T2DM. The aim of this study was to investigate whether three different doses of Reducose®, a mulberry leaf extract, could lower the GR and insulinemic responses (IR) to a full meal challenge in healthy individuals. A double-blind, randomised, placebo-controlled, repeat-measure, crossover design trial was conducted by the Oxford Brookes Centre for Nutrition and Health; 37 healthy individuals completed the study. Participants consumed capsules containing either 200 mg, 225 mg, 250 mg Reducose® or placebo before a test meal consisting of 150 g white bread and egg mayo filler. Capillary blood samples were collected at 15-min intervals in the first hour and at 30-min intervals over the second and third hours to determine glucose and plasma insulin levels. The consumption of all three doses of Reducose® resulted in significantly lower blood glucose and plasma insulin levels compared to placebo. All three doses of Reducose® (200 mg, 225 mg, 250 mg) significantly lowered glucose iAUC 120 by 30% (p = 0.003), 33% (p = 0.001) and 32% (p = 0.002), respectively, compared with placebo. All three doses of Reducose® (200 mg, 225 mg, 250 mg) significantly lowered the plasma insulin iAUC 120 by 31% (p = 0.024), 34% (p = 0.004) and 38% (p < 0.001), respectively. The study demonstrates that the recommended dose (250 mg) and two lower doses (200 mg, 225 mg) of Reducose® can be used to help lower the GR and IR of a full meal containing carbohydrates, fats and proteins.

Associations of the glycaemic index and the glycaemic load with risk of type 2 diabetes in 127 594 people from 20 countries (PURE): a prospective cohort study

BACKGROUND

The association between the glycaemic index and the glycaemic load with type 2 diabetes incidence is controversial. We aimed to evaluate this association in an international cohort with diverse glycaemic index and glycaemic load diets.

METHODS

The PURE study is a prospective cohort study of 127 594 adults aged 35-70 years from 20 high-income, middle-income, and low-income countries. Diet was assessed at baseline using country-specific validated food frequency questionnaires. The glycaemic index and the glycaemic load were estimated on the basis of the intake of seven categories of carbohydrate-containing foods. Participants were categorised into quintiles of glycaemic index and glycaemic load. The primary outcome was incident type 2 diabetes. Multivariable Cox Frailty models with random intercepts for study centre were used to calculate hazard ratios (HRs).

FINDINGS

During a median follow-up of 11·8 years (IQR 9·0-13·0), 7326 (5·7%) incident cases of type 2 diabetes occurred. In multivariable adjusted analyses, a diet with a higher glycaemic index was significantly associated with a higher risk of diabetes (quintile 5 vs quintile 1; HR 1·15 [95% CI 1·03-1·29]). Participants in the highest quintile of the glycaemic load had a higher risk of incident type 2 diabetes compared with those in the lowest quintile (HR 1·21, 95% CI 1·06-1·37). The glycaemic index was more strongly associated with diabetes among individuals with a higher BMI (quintile 5 vs quintile 1; HR 1·23 [95% CI 1·08-1·41]) than those with a lower BMI (quintile 5 vs quintile 1; 1·10 [0·87-1·39]; p interaction=0·030).

INTERPRETATION

Diets with a high glycaemic index and a high glycaemic load were associated with a higher risk of incident type 2 diabetes in a multinational cohort spanning five continents. Our findings suggest that consuming low glycaemic index and low glycaemic load diets might prevent the development of type 2 diabetes.

FUNDING

Full funding sources are listed at the end of the Article.

Genetically predicted dietary macronutrient intakes and atrial fibrillation risk: a Mendelian randomization study

BACKGROUND AND AIM

Previous observational investigations have indicated a potential association between relative dietary macronutrient intakes and atrial fibrillation and flutter (AF) risk. In this study, we employed Mendelian Randomization (MR) to evaluate the presence of causality and to elucidate the specific causal relationship.

METHODS

We employed six, five, and three single nucleotide polymorphisms (SNPs) as instrumental variables for relative carbohydrate, protein, and fat intake, identified from a genome-wide association study that included 268,922 individuals of European descent. Furthermore, we acquired summary statistics for genome-wide association studies on AF from the FinnGen consortium, which involved 22,068 cases and 116,926 controls. To evaluate the causal estimates, we utilized the random effect inverse variance weighted method (IVW) and several other MR methods, including MR-Egger, weighted median, and MR-PRESSO, to confirm the robustness of our findings.

RESULTS

Our analysis indicates a convincing causal relationship between genetically predicted relative carbohydrate and protein intake and reduced AF risk. Inverse variance weighted analysis results for carbohydrates (OR = 0.29; 95% CI (0.14, 0.59); P < 0.001) and protein (OR = 0.47; 95% CI (0.26, 0.85); P = 0.01) support this association. Our MR analysis did not identify a significant causal relationship between relative fat intake and AF risk.

CONCLUSION

Our study provides evidence supporting a causal relationship between higher relative protein and carbohydrate intake and a lower risk of atrial fibrillation (AF).

Low Response to Aerobic Training in Metabolic Disease: Role of Skeletal Muscle

Aerobic exercise is established to increase cardiorespiratory fitness (CRF), which is linked to reduced morbidity and mortality. However, people with metabolic diseases such as type 1 and type 2 diabetes may be more likely to display blunted improvements in CRF with training. Here, we present evidence supporting the hypothesis that altered skeletal muscle signaling and remodeling may contribute to low CRF with metabolic disease.

The Health Effects of Low Glycemic Index and Low Glycemic Load Interventions on Prediabetes and Type 2 Diabetes Mellitus: A Literature Review of RCTs

Diets with a low glycemic index (GI) and a low glycemic load (GL) can improve glycemic control, blood lipids, blood pressure and BMI in prediabetes and type 2 diabetes (T2DM), but evidence regarding other aspects of cardiometabolic health is limited. We searched the literature for RCTs published from 2013 to 2023 and reviewed the evidence on low-GI/GL diets and their effects on different aspects of health in prediabetes and T2DM, aiming to build a report on all relevant outcomes included in the studies. We included 14 RCTs with 1055 participants, who were mostly middle-aged individuals with T2DM. Interventions were mostly low GI and lasted 1-36 months. Low-GI/GL foods and diets showed benefits in terms of short-term glycemic control, weight and adiposity. Longer-term trials would be necessary to determine whether these benefits persist over time and/or lead to lower CVD risk and mortality. Effects on lipid profile were inconsistent. Some studies also reported positive effects of low-GI/GL interventions on blood pressure, inflammatory biomarkers, renal function and gut microbiota composition. Future trials should focus on some of these novel outcome measures, which may provide important insights into the metabolic effects of low-GI diets on individuals with diabetes.

The effect of lyophilized dried cornelian cherry (Cornus mas L.) intake on anthropometric and biochemical parameters in women with insulin resistance: A randomized controlled trial

The aim of this study was to determine the effect on the anthropometric and biochemical parameters for women with insulin resistance when lyophilized dried cornelian cherry (Cornus mas L., CM) was added to medical nutrition therapy (MNT). The study was conducted with 84 women aged 18-45, who had been diagnosed with insulin resistance. Participants were randomized into four groups: MNT + 20 g lyophilized dried CM group (DCm, n = 22), MNT group (D, n = 21), only 20 g lyophilized dried CM group (Cm, n = 21), and the control group (C, n = 20). All participants were followed for 12 weeks. While pre- and post-intervention biochemical parameters were recorded from patient files, anthropometric measurements and food consumption records were taken every 15 days. Pre-intervention groups were homogeneously distributed. Post-intervention, among the groups, all anthropometric measurements were similar between the DCm and D, while the percentage of decrease in insulin resistance-related parameters was approximately two times greater in DCm than in D (p < .05). When the Cm and C were compared, it was found that all post-intervention anthropometric measurements were similar, but the percentage of decrease in fasting blood glucose, fasting insulin, and HOMA-IR (Homeostasis Model Assessment-Insulin Resistance) values were greater in C (p < .05). In this study, it was concluded that CM consumption resulted with a decrease in insulin resistance-related biochemical parameters independent of body weight change. Nevertheless, MNT has positive effects on women with insulin resistance, and adding lyophilized dried CM to MNT improves insulin resistance-related parameters and may be beneficial for preventing the development of diabetes.

Glyoxalase I is a novel target for the prevention of metabolic derangement

Obesity prevalence in the US has nearly tripled since 1975 and a parallel increase in prevalence of type 2 diabetes (T2D). Obesity promotes a myriad of metabolic derangements with insulin resistance (IR) being perhaps the most responsible for the development of T2D and other related diseases such as cardiovascular disease. The precarious nature of IR development is such that it provides a valuable target for the prevention of further disease development. However, the mechanisms driving IR are numerous and complex making the development of viable interventions difficult. The development of metabolic derangement in the context of obesity promotes accumulation of reactive metabolites such as the reactive alpha-dicarbonyl methylglyoxal (MG). MG accumulation has long been appreciated as a marker of disease progression in patients with T2D as well as the development of diabetic complications. However, recent evidence suggests that the accumulation of MG occurs with obesity prior to T2D onset and may be a primary driving factor for the development of IR and T2D. Further, emerging evidence also suggests that this accumulation of MG with obesity may be a result in a loss of MG detoxifying capacity of glyoxalase I. In this review, we will discuss the evidence that posits MG accumulation because of GLO1 attenuation is a novel target mechanism of the development of metabolic derangement. In addition, we will also explore the regulation of GLO1 and the strategies that have been investigated so far to target GLO1 regulation for the prevention and treatment of metabolic derangement.

The Association of Lifestyle Patterns with Prediabetes in Adults from Families at High Risk for Type 2 Diabetes in Europe: The Feel4Diabetes Study

The increasing prevalence of prediabetes globally does not bode well for the growing epidemic of type 2 diabetes (T2D) and its complications. Yet there is a lack of studies regarding lifestyle patterns (LPs) and their association with prediabetes. The present study aimed to examine the association of different LPs with the existence of prediabetes in adults from families at high risk for T2D in Europe. In total, 2759 adults (66.3% females) from six European countries were included in this cross-sectional analysis using data from the baseline assessment of the Feel4Diabetes study. Anthropometric, sociodemographic, dietary and behavioral data were assessed, and fasting blood glucose measurements were also obtained. LPs were derived via principal component analysis. Two LPs were derived, explaining 32% of the total variation. LP 1 was characterized by breakfast consumption, high consumption of fruits and berries, vegetables and nuts and seeds, and low consumption of salty snacks and soft drinks with sugar, while LP 2 was characterized by high consumption of salty and sweet snacks, soft drinks with sugar and juice with sugar and sedentary behavior. After adjusting for various confounders, LP 2 was positively associated with the existence of prediabetes (odds ratio = 1.02, 95% CI 1.01-1.04), while LP 1 was not significantly associated with prediabetes. Understanding LPs would provide necessary evidence for planning intervention and education strategies for prediabetes and T2D.

Healthful Plant-Based Dietary Pattern and Risk of Hepatocellular Carcinoma in a Multiethnic Population: A Cohort Study

BACKGROUND

Plant-based dietary patterns assessed by a priori indices are associated with various health outcomes, but have rarely been examined in relation to liver cancer.

OBJECTIVES

This study investigated the associations between plant-based diets and risk of hepatocellular carcinoma (HCC) and evaluated whether the associations vary by sex and race and ethnicity.

METHODS

Data were from a total of 170,321 African American, Japanese American, Latino, Native Hawaiian, and White adults aged 45-75 y who completed a food frequency questionnaire in the Multiethnic Cohort Study. Cox models with adjustment for potential confounders were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for HCC according to 3 plant-based diet scores: overall plant-based diet index (PDI), healthful plant-based diet index (hPDI), and unhealthful plant-based diet index (uPDI).

RESULTS

During a mean follow-up of 19.6 y, 722 incident HCC cases were identified. Multivariate-adjusted HR (95% CI) per 10-point increase was 0.82 (0.71-0.94) for PDI, 0.84 (0.74-0.96) for hPDI, and 1.08 (0.95-1.23) for uPDI. We found no significant differences by sex (all Pheterogeneity ≥ 0.53) or race and ethnicity (all Pheterogeneity ≥ 0.31).

CONCLUSION

Greater adherence to plant-based diets rich in healthy plant foods and low in less healthy plant foods is associated with a reduced risk of HCC in a multiethnic population.

Low glycaemic index or low glycaemic load diets for people with overweight or obesity

BACKGROUND

The prevalence of obesity is increasing worldwide, yet nutritional management remains contentious. It has been suggested that low glycaemic index (GI) or low glycaemic load (GL) diets may stimulate greater weight loss than higher GI/GL diets or other weight reduction diets. The previous version of this review, published in 2007, found mainly short-term intervention studies. Since then, randomised controlled trials (RCTs) with longer-term follow-up have become available, warranting an update of this review.

OBJECTIVES

To assess the effects of low glycaemic index or low glycaemic load diets on weight loss in people with overweight or obesity.

SEARCH METHODS

We searched CENTRAL, MEDLINE, one other database, and two clinical trials registers from their inception to 25 May 2022. We did not apply any language restrictions.

SELECTION CRITERIA

We included RCTs with a minimum duration of eight weeks comparing low GI/GL diets to higher GI/GL diets or any other diets in people with overweight or obesity.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. We conducted two main comparisons: low GI/GL diets versus higher GI/GL diets and low GI/GL diets versus any other diet. Our main outcomes included change in body weight and body mass index, adverse events, health-related quality of life, and mortality. We used GRADE to assess the certainty of the evidence for each outcome.

MAIN RESULTS

In this updated review, we included 10 studies (1210 participants); nine were newly-identified studies. We included only one study from the previous version of this review, following a revision of inclusion criteria. We listed five studies as 'awaiting classification' and one study as 'ongoing'. Of the 10 included studies, seven compared low GI/GL diets (233 participants) with higher GI/GL diets (222 participants) and three studies compared low GI/GL diets (379 participants) with any other diet (376 participants). One study included children (50 participants); one study included adults aged over 65 years (24 participants); the remaining studies included adults (1136 participants). The duration of the interventions varied from eight weeks to 18 months. All trials had an unclear or high risk of bias across several domains.  Low GI/GL diets versus higher GI/GL diets Low GI/GL diets probably result in little to no difference in change in body weight compared to higher GI/GL diets (mean difference (MD) -0.82 kg, 95% confidence interval (CI) -1.92 to 0.28; I2 = 52%; 7 studies, 403 participants; moderate-certainty evidence). Evidence from four studies reporting change in body mass index (BMI) indicated low GI/GL diets may result in little to no difference in change in BMI compared to higher GI/GL diets (MD -0.45 kg/m2, 95% CI -1.02 to 0.12; I2 = 22%; 186 participants; low-certainty evidence)at the end of the study periods. One study assessing participants' mood indicated that low GI/GL diets may improve mood compared to higher GI/GL diets, but the evidence is very uncertain (MD -3.5, 95% CI -9.33 to 2.33; 42 participants; very low-certainty evidence). Two studies assessing adverse events did not report any adverse events; we judged this outcome to have very low-certainty evidence. No studies reported on all-cause mortality.    For the secondary outcomes, low GI/GL diets may result in little to no difference in fat mass compared to higher GI/GL diets (MD -0.86 kg, 95% CI -1.52 to -0.20; I2 = 6%; 6 studies, 295 participants; low certainty-evidence). Similarly, low GI/GL diets may result in little to no difference in fasting blood glucose level compared to higher GI/GL diets (MD 0.12 mmol/L, 95% CI 0.03 to 0.21; I2 = 0%; 6 studies, 344 participants; low-certainty evidence).  Low GI/GL diets versus any other diet Low GI/GL diets probably result in little to no difference in change in body weight compared to other diets (MD -1.24 kg, 95% CI -2.82 to 0.34; I2 = 70%; 3 studies, 723 participants; moderate-certainty evidence). The evidence suggests that low GI/GL diets probably result in little to no difference in change in BMI compared to other diets (MD -0.30 kg in favour of low GI/GL diets, 95% CI -0.59 to -0.01; I2 = 0%; 2 studies, 650 participants; moderate-certainty evidence). Two adverse events were reported in one study: one was not related to the intervention, and the other, an eating disorder, may have been related to the intervention. Another study reported 11 adverse events, including hypoglycaemia following an oral glucose tolerance test. The same study reported seven serious adverse events, including kidney stones and diverticulitis. We judged this outcome to have low-certainty evidence. No studies reported on health-related quality of life or all-cause mortality. For the secondary outcomes, none of the studies reported on fat mass. Low GI/GL diets probably do not reduce fasting blood glucose level compared to other diets (MD 0.03 mmol/L, 95% CI -0.05 to 0.12; I2 = 0%; 3 studies, 732 participants; moderate-certainty evidence).  AUTHORS' CONCLUSIONS: The current evidence indicates there may be little to no difference for all main outcomes between low GI/GL diets versus higher GI/GL diets or any other diet. There is insufficient information to draw firm conclusions about the effect of low GI/GL diets on people with overweight or obesity. Most studies had a small sample size, with only a few participants in each comparison group. We rated the certainty of the evidence as moderate to very low. More well-designed and adequately-powered studies are needed. They should follow a standardised intervention protocol, adopt objective outcome measurement since blinding may be difficult to achieve, and make efforts to minimise loss to follow-up. Furthermore, studies in people from a wide range of ethnicities and with a wide range of dietary habits, as well as studies in low- and middle-income countries, are needed.

Low-Carbohydrate Diet Score and the Risk of Colorectal Cancer: Findings from the Singapore Chinese Health Study

BACKGROUND

Colorectal cancer is common cancer with a high mortality rate. Low-carbohydrate diet (LCD) score holistically evaluates the LCD pattern from carbohydrate, protein, and fat intake. Epidemiologic data of LCD-colorectal cancer association are sparse.

METHODS

We evaluated the associations between LCD (i.e., total, animal- and plant-based) and colorectal cancer risk in the Singapore Chinese Health Study, a population-based prospective cohort study including 61,321 Chinese in Singapore who were 45 to 74 years old at baseline. Cox proportional hazard regression model was used to determine the HRs and respective 95% confidence intervals (CI) for colorectal cancer associated with LCD after adjusting for potential confounders, including age, sex, BMI, physical activity, family history of colorectal cancer, etc.

RESULTS

After an average of 19.5 years of follow-up, 2,520 participants developed colorectal cancer (1,608 colon cancer and 912 rectal cancer). Overall, the association between total or plant-based LCD scores with the risk of colorectal, colon, or rectal cancer was null (all Ptrend ≥ 0.28). The animal-based LCD was modestly associated with colon cancer risk (Ptrend = 0.02), but not with rectal cancer. Compared with the lowest quartile, HRs (95% CIs) of colon cancer for quartiles 2, 3, and 4 of animal-based LCD were 1.12 (0.98-1.29), 1.27 (1.10-1.46), and 1.14 (0.99-1.31), respectively.

CONCLUSIONS

A low-level carbohydrate diet with a high level of animal protein and fat was associated with a moderate increase in the risk of colon cancer among Chinese Singaporeans.

IMPACT

High consumption of animal protein/fat and low consumption of carbohydrates may increase colon cancer risk.

Effect of exercise training on insulin-stimulated glucose disposal: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND AND OBJECTIVE

The effect of exercise training on whole-body insulin sensitivity has not been systematically summarized. We aimed to summarize the data from randomized controlled trials evaluating the effect of exercise training on insulin action, in adults.

SUBJECTS

MEDLINE, EMBASE, and CENTRAL databases were searched until January 2021. Randomized controlled trials lasting ≥4 weeks, including adults, and evaluating the effect of exercise on insulin-stimulated glucose disposal measured using the hyperinsulinemic euglycemic clamp, were included.

METHODS

Three reviewers extracted summary data from published trials. The primary outcome was insulin-stimulated glucose disposal. Standardized weighted mean differences (SMD) in glucose disposal between intervention and control were compared. The PEDro scale was used to assess risk of bias.

RESULTS

We included 25 trials (36 interventions, N = 851). Exercise increased insulin-stimulated glucose disposal relative to control, SMD = 0.52 (95% confidence interval [CI]: 0.39, 0.65; p < 0.001; I2 = 47%) without significantly suppressing hepatic glucose production. In trials without isotopic tracers, exercise increased glucose disposal (SMD = 0.63; 95% CI: 0.48, 0.77; p < 0.001, I2 = 55%). In trials with isotopic tracers, exercise increased glucose disposal only when tracers were added to the exogenous glucose used for clamping (SMD = 0.34; 95% CI: 0.03, 0.66, p = 0.034. I2 = 0%). In a meta-regression model including aerobic exercise, weight change, and tracer technique, only percent weight change explained between trial heterogeneity (β = 0.069; 95% CI: 0.005, 0.013). The PEDro rating indicated relatively low risk of bias (5.8 ± 0.22).

CONCLUSIONS

Exercise training for at least four weeks significantly increases insulin-stimulated glucose disposal. Weight loss maximizes the effect and may be needed to improve hepatic insulin sensitivity. Differences in tracer methodology contribute to divergent outcomes and should be considered when assessing conclusions from research examining the effect of exercise on insulin action.

REGISTRATION

PROSPERO (CRD42019124381).

Carbohydrate quality indices and colorectal cancer risk: a case-control study

BACKGROUND

Colorectal cancer (CRC) is the fourth and third most common cancer in Iran and the world, respectively. Carbohydrates can lead to the proliferation of cancer cells, including CRC. The current study aimed to investigate the association between glycemic load (GL), insulin load (IL), glycemic index (GI), insulin index (II), low-carbohydrate diet score (LCDS), and carbohydrate quality index (CQI) with CRC odds.

METHODS

The present case-control study was performed on 71 CRC cases and 142 controls in the Hospital Cancer Organization and three general hospitals in Tehran, Iran. We calculated the dietary GI, GL, IL, II, CQI, and LCDS by a validated food frequency questionnaire.

RESULTS

The results indicated that people who were in the highest tertile of the GI had higher odds of CRC compared to the lower tertile (in the adjusted model: odds ratio (OR) = 3.89; 95% confidence interval (CI): 1.71-8.84). On the contrary, people who were in the highest tertile of the CQI and LCDS had significantly lower odds of CRC compared to the lower tertile (in the adjusted model: tertile (T) ₂-OR = 0.24; 95% CI: 0.11-0.53 and T₃-OR = 0.15; 95% CI: 0.06-0.39 for CQI and T₂-OR = 0.33; 95% CI: 0.13-0.79 and T₃-OR = 0.28; 95% CI: 0.10-0.82 for LCDS). Also, IL was positively associated with the odds of CRC after adjusting for confounding factors (T₂-OR = 2.46; CI: 1.08-5.61 and T₃- OR = 2.80; 95% CI: 1.07-7.31). Regarding the GL, only individuals who were in the second tertile had significantly higher odds of CRC compared to the first tertile (OR = 2.42; CI: 1.07-5.47).

CONCLUSION

According to the findings, it is recommended to use a diet with high-quality carbohydrates and low GI and GL to minimize the odds of developing CRC. People should also be encouraged to have a balanced carbohydrate intake.

The Effects of Exercise on Appetite-Regulating Hormone Concentrations over a 36-h Fast in Healthy Young Adults: A Randomized Crossover Study

Hunger and satiety are controlled by several physiological mechanisms, including pancreatic and gastrointestinal hormones. While the influence of exercise and fasting have been described individually, in relation to these hormones, there is a paucity of work showing the effects of the two modalities (fasting and exercise) combined. Twenty healthy adults (11 males, 9 females) completed both conditions of this study, each consisting of a 36-h water-only fast. One of the fasts began with treadmill exercise, and the differences between the conditions on various appetite hormones were measured every 12 h. The difference in the area under the curve between conditions for ghrelin was 211.8 ± 73.1 pg/mL (F = 8.40, p < 0.0105), and, for GLP-1, it was -1867.9 ± 850.4 pg/mL (F = 4.82, p < 0.0422). No significant differences were noted for areas under the curve between conditions for leptin, PP, PYY, insulin, or GIP. Initiating a fast with exercise lowers ghrelin concentrations and elevates GLP-1 concentrations. Given that ghrelin elicits feelings of hunger and GLP-1 signals feelings of satiety, adding exercise to the beginning of a fast may reduce some of the biological drive of hunger, which could make fasting more tolerable, leading to better adherence and more significant health outcomes.

Exercise in the Prevention and Treatment of Type 2 Diabetes

Type 2 diabetes is a systemic, multifactorial disease that is a leading cause of morbidity and mortality globally. Despite a rise in the number of available medications and treatments available for management, exercise remains a first-line prevention and intervention strategy due to established safety, efficacy, and tolerability in the general population. Herein we review the predisposing risk factors for, prevention, pathophysiology, and treatment of type 2 diabetes. We emphasize key cellular and molecular adaptive processes that provide insight into our evolving understanding of how, when, and what types of exercise may improve glycemic control. © 2023 American Physiological Society. Compr Physiol 13:1-27, 2023.

Dietary protein and the glycemic index handle insulin resistance within a nutritional program for avoiding weight regain after energy-restricted induced weight loss

Background and aim

The role of dietary protein and glycemic index on insulin resistance (based on TyG index) within a nutritional program for weight loss and weight maintenance was examined.

Methods

This study analyzed 744 adults with overweight/obesity within the DIOGenes project. Patients who lost at least 8% of their initial weight (0–8 weeks) after a low-calorie diet (LCD) were randomly assigned to one of five ad libitum diets designed for weight maintenance (8–34 weeks): high/low protein (HP/LP) and high/low glycemic index (HGI/LGI), plus a control. The complete nutritional program (0–34 weeks) included both LCD plus the randomized diets intervention. The TyG index was tested as marker of body mass composition and insulin resistance.

Results

In comparison with the LP/HGI diet, the HP/LGI diet induced a greater BMI loss (p < 0.05). ∆TyG was positively associated with resistance to BMI loss (β = 0.343, p = 0.042) during the weight maintenance stage. In patients who followed the HP/LGI diet, TyG (after LCD) correlated with greater BMI loss in the 8–34 weeks period (r = −0.256; p < 0.05) and during the 0–34 weeks intervention (r = −0.222, p < 0.05) periods. ΔTyG₁ value was associated with ΔBMI₂ (β = 0.932; p = 0.045) concerning the HP/LGI diet.

Conclusions

A HP/LGI diet is beneficial not only for weight maintenance after a LCD, but is also related to IR amelioration as assessed by TyG index changes. Registration Clinical Trials NCT00390637.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12986-022-00707-y.

Outcomes addressed in randomized controlled lifestyle intervention trials in community-dwelling older people with (sarcopenic) obesity-An evidence map

Obesity and sarcopenic obesity (SO) are characterized by excess body fat with or without low muscle mass affecting bio-psycho-social health, functioning, and subsequently quality of life in older adults. We mapped outcomes addressed in randomized controlled trials (RCTs) on lifestyle interventions in community-dwelling older people with (sarcopenic) obesity. Systematic searches in Medline, Embase, Cochrane Central, CINAHL, PsycInfo, Web of Science were conducted. Two reviewers independently performed screening and extracted data on outcomes, outcome domains, assessment methods, units, and measurement time. A bubble chart and heat maps were generated to visually display results. Fifty-four RCTs (7 in SO) reporting 464 outcomes in the outcome domains: physical function (n = 42), body composition/anthropometry (n = 120), biomarkers (n = 190), physiological (n = 30), psychological (n = 47), quality of life (n = 14), pain (n = 4), sleep (n = 2), medications (n = 3), and risk of adverse health events (n = 5) were included. Heterogeneity in terms of outcome definition, assessment methods, measurement units, and measurement times was found. Psychological and quality of life domains were investigated in a minority of studies. There is almost no information beyond 52 weeks. This evidence map is the first step of a harmonization process to improve comparability of RCTs in older people with (sarcopenic) obesity and facilitate the derivation of evidence-based clinical decisions.

Beyond bariatric surgery and weight loss medicaments. A systematic review of the current practice in obesity rehabilitative inpatient programs in adults and pediatrics

Background

Obesity treatment strategies mainly include outpatient lifestyle modification, drugs and bariatric surgery. Voluntary rehabilitative inpatient programs are gaining relevance as potential alternative settings of care that focus on weight loss and prevention of weight regain through a multidisciplinary approach, but their prevalence is still limited due to the high costs.

Aim

Considering the lack of evidence in this area, the objective of this study is to systematically review the currently available literature on non-pharmacological and non-surgical inpatient programs aimed at weight loss, to clarify the efficacy and the characteristics of these interventions.

Methods

Proper English language articles from 2000 to 2022 were searched on relevant databases. Quality assessment was performed by two different authors using ROB2 and robvis tools. Adult and pediatric studies were reviewed separately and their characteristics were systematically displayed.

Results

36 articles were included (20 on adults, 16 on children, and adolescents) for a total of 5,510 individuals. The multidisciplinary approach was mainly comprehensive of a low-calorie diet, scheduled physical activity, and psychological support based on behavioral treatment. Educational and cooking sessions were present at a lower rate. Globally, inpatient weight loss programs showed a consistent efficacy in reducing body weight and inducing beneficial effects on quality of life, psychological well-being, eating behavior, physical performance, and fatigue. Follow-up data were scarce, but with a high percentage of patients regaining weight after a short period.

Conclusion

Weight loss inpatient rehabilitation is a promising area that has evidence of all-rounded success in the amelioration of several aspects related to obesity. Nevertheless, it appears to be quite inconsistent in preserving these benefits after the intervention. This might slow the innovation process in this area and preclude further investments from national healthcare. Personalized and enriched programs could show greater impact when focusing on the behavioral and educational aspects, which are crucial points, in particular in pediatrics, for setting up a long-lasting lifestyle modification. More studies are therefore necessary to evaluate long-term efficacy based on the different work-up models.

Obesity Management in the Primary Prevention of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the most frequent primary hepatic malignancy and a leading cause of cancer-related death globally. HCC is associated with an indolent clinical presentation, resulting in frequent advanced stage diagnoses where surgical resection or transplant therapies are not an option and medical therapies are largely ineffective at improving survival. As such, there is a critical need to identify and enhance primary prevention strategies to mitigate HCC-related morbidity and mortality. Obesity is an independent risk factor for the onset and progression of HCC. Furthermore, obesity is a leading cause of nonalcoholic steatohepatitis (NASH), the fasting growing etiological factor of HCC. Herein, we review evolving clinical and mechanistic associations between obesity and hepatocarcinogenesis with an emphasis on the therapeutic efficacy of prevailing lifestyle/behavioral, medical, and surgical treatment strategies for weight reduction and NASH reversal.

The molecular signaling of exercise and obesity in the microbiota-gut-brain axis

Obesity is one of the major pandemics of the 21st century. Due to its multifactorial etiology, its treatment requires several actions, including dietary intervention and physical exercise. Excessive fat accumulation leads to several health problems involving alteration in the gut-microbiota-brain axis. This axis is characterized by multiple biological systems generating a network that allows bidirectional communication between intestinal bacteria and brain. This mutual communication maintains the homeostasis of the gastrointestinal, central nervous and microbial systems of animals. Moreover, this axis involves inflammatory, neural, and endocrine mechanisms, contributes to obesity pathogenesis. The axis also acts in appetite and satiety control and synthesizing hormones that participate in gastrointestinal functions. Exercise is a nonpharmacologic agent commonly used to prevent and treat obesity and other chronic degenerative diseases. Besides increasing energy expenditure, exercise induces the synthesis and liberation of several muscle-derived myokines and neuroendocrine peptides such as neuropeptide Y, peptide YY, ghrelin, and leptin, which act directly on the gut-microbiota-brain axis. Thus, exercise may serve as a rebalancing agent of the gut-microbiota-brain axis under the stimulus of chronic low-grade inflammation induced by obesity. So far, there is little evidence of modification of the gut-brain axis as a whole, and this narrative review aims to address the molecular pathways through which exercise may act in the context of disorders of the gut-brain axis due to obesity.

Consumption of “Diabetes Risk Reduction Diet” and Odds of Breast Cancer Among Women in a Middle Eastern Country

Background:

Given the role of insulin resistance in several cancers, we hypothesized that consumption of a diet that reduces insulin resistance might lower the risk of breast cancer.

Objective

The present study was designed to assess the association between consumption of “diabetes risk reduction diet” (DRRD) and odds of breast cancer among a large group of women in a Middle Eastern country.

Methods

This population-based case-control study enrolled 350 newly diagnosed cases of stage I-IV breast cancer and 700 age-matched apparently healthy individuals as controls. We collected dietary data via a validated 106-item Willett-format semi-quantitative dish-based food frequency questionnaire. A DRRD score was included based on 9 dietary factors (cereal fiber, coffee, nuts, whole fruits, ratio of polyunsaturated to saturated, trans fat, sugar-sweetened beverages, red and processed meat, and lower glycemic index). For food and nutrient items with a protective association with diabetes in earlier studies, participants were given the score as the quintile of that food item, but for food groups with unfavorable association with diabetes, we did vice versa. Total DRRD score ranged from 5 to 45.

Results

Mean age of cases and controls was 65.28 and 61.04 years. Mean BMI of patients with breast cancer and controls was 25.5 and 21.0. We found that individuals with the greatest adherence to the DRRD were 0.41 times less likely to have breast cancer than those with the lowest adherence (OR: 0.59; 95% CI: 0.38, 0.90, and P-trend = 0.002). Stratified analysis by menopausal status indicated a significant inverse relationship in postmenopausal women (OR: 0.57; 95% CI: 0.36–0.90), but not in premenopausal women (OR: 0.76; 95% CI: 0.19–2.96). Moreover, by BMI status, we found statistically significant inverse association between adherence to the DRRD and odds of breast cancer among normal-weight women (OR: 0.59; 95% CI: 0.36, 0.98) but not in overweight women (OR: 0.66; 95% CI: 0.31, 1.40). Conclusions: Significant inverse associations were found between adherence to DRRD and breast cancer, especially among postmenopausal and normal-weight women.

Effect of Dietary Glycemic Index on β-Cell Function in Prediabetes: A Randomized Controlled Feeding Study

The glycemic index (GI) reflects the relative ability of carbohydrates to raise blood glucose. We utilized a controlled feeding study to assess the impact of the dietary GI on β-cell function in adults with prediabetes (17F/18M, mean ± SEM: BMI 32.44 ± 0.94 kg/m², age 54.2 ± 1.57 years). Following a 2 week Control diet (GI = 55–58), participants were randomized to either a 4 week low GI (LGI: GI < 35, n = 17) or high GI (HGI: GI > 70, n = 18) diet (55% of energy from carbohydrate/30% fat/15% protein). The data from 4 h meal tolerance tests (MTTs) underwent mathematical modeling to assess insulin sensitivity, insulin secretion and β-cell function. Glucose concentrations during the MTT decreased on the LGI diet (p < 0.001) and trended to increase on the HGI diet (p = 0.14; LGI vs. HGI p < 0.001), with parallel changes in insulin and C-peptide concentrations. Total insulin secretion, adjusted for glucose and insulin sensitivity, increased on the LGI diet (p = 0.002), and trended lower on the HGI diet (p = 0.10; LGI vs. HGI p = 0.001). There was no significant diet effect on insulin sensitivity or other measures of β-cell function. Total insulin clearance increased on the LGI diet (p = 0.01; LGI vs. HGI p < 0.001). We conclude that short-term consumption of an LGI diet reduced glucose exposure and insulin secretion but had no impact on measures of β-cell function.

Differential Glycemic Effects of Low- versus High-Glycemic Index Mediterranean-Style Eating Patterns in Adults at Risk for Type 2 Diabetes: The MEDGI-Carb Randomized Controlled Trial

A Mediterranean-style healthy eating pattern (MED-HEP) supports metabolic health, but the utility of including low-glycemic index (GI) foods to minimize postprandial glucose excursions remain unclear. Therefore, we investigated the relative contribution of GI towards improvements in postprandial glycemia and glycemic variability after adopting a MED-HEP. We conducted a randomized, controlled dietary intervention, comparing high- versus low-GI diets in a multi-national (Italy, Sweden, and the United States) sample of adults at risk for type 2 diabetes. For 12 weeks, participants consumed either a low-GI or high-GI MED-HEP. We assessed postprandial plasma glucose and insulin responses to high- or low-GI meals, and daily glycemic variability via continuous glucose monitoring at baseline and post-intervention. One hundred sixty adults (86 females, 74 males; aged 55 ± 11 y, BMI 31 ± 3 kg/m2, mean ± SD) with ≥two metabolic syndrome traits completed the intervention. Postprandial insulin concentrations were greater after the high-GI versus the low-GI test meals at baseline (p = 0.004), but not post-intervention (p = 0.17). Postprandial glucose after the high-GI test meal increased post-intervention, being significantly higher than that after the low-GI test meal (35%, p < 0.001). Average daily glucose concentrations decreased in both groups post-intervention. Indices of 24-h glycemic variability were reduced in the low-GI group as compared to baseline and the high-GI intervention group. These findings suggest that low-GI foods may be an important feature within a MED-HEP.

Insulin resistance persists despite a metabolically healthy obesity phenotype

OBJECTIVE

Metabolically healthy obesity (MHO) is often defined as the absence of metabolic syndrome in the presence of obesity. However, phenotypic features of MHO are unclear. Insulin sensitivity in MHO was cross-sectionally compared with metabolically unhealthy obesity (MUO) and a reference group of young healthy participants without obesity.

METHODS

Sedentary adults (n = 96) undergoing anthropometric, blood chemistries, maximal aerobic capacity, and euglycemic-hyperinsulinemic clamp measurements were classified by BMI (<25 and ≥30 kg/m2 ). MUO was defined as having obesity with metabolic syndrome (≥2 additional risk factors). Data were analyzed using a linear mixed models approach.

RESULTS

Body weight was similar between MHO and MUO. Body fat (percentage) and high-density lipoprotein cholesterol were higher (p < 0.001), and systolic blood pressure, triglycerides, glucose, and insulin were lower in MHO versus MUO (p < 0.03, all). The MHO group also had lower high-density lipoprotein cholesterol and higher low-density lipoprotein cholesterol, diastolic blood pressure, and insulin compared with the reference. Both the MHO and MUO groups displayed impaired insulin sensitivity compared with the reference control (p < 0.001).

CONCLUSIONS

Participants with MHO had distinct clinical measures related to hypertension, lipid metabolism, and glycemic control compared with a healthy reference group. Peripheral insulin resistance in obesity independent of metabolic status portends increased risk for type 2 diabetes in the MHO patient population.

Lipids activate skeletal muscle mitochondrial fission and quality control networks to induce insulin resistance in humans

BACKGROUND AND AIMS

A diminution in skeletal muscle mitochondrial function due to ectopic lipid accumulation and excess nutrient intake is thought to contribute to insulin resistance and the development of type 2 diabetes. However, the functional integrity of mitochondria in insulin-resistant skeletal muscle remains highly controversial.

METHODS

19 healthy adults (age:28.4 ± 1.7 years; BMI:22.7 ± 0.3 kg/m²) received an overnight intravenous infusion of lipid (20% Intralipid) or saline followed by a hyperinsulinemic-euglycemic clamp to assess insulin sensitivity using a randomized crossover design. Skeletal muscle biopsies were obtained after the overnight lipid infusion to evaluate activation of mitochondrial dynamics proteins, ex-vivo mitochondrial membrane potential, ex-vivo oxidative phosphorylation and electron transfer capacity, and mitochondrial ultrastructure.

RESULTS

Overnight lipid infusion increased dynamin related protein 1 (DRP1) phosphorylation at serine 616 and PTEN-induced kinase 1 (PINK1) expression (P = 0.003 and P = 0.008, respectively) in skeletal muscle while reducing mitochondrial membrane potential (P = 0.042). The lipid infusion also increased mitochondrial-associated lipid droplet formation (P = 0.011), the number of dilated cristae, and the presence of autophagic vesicles without altering mitochondrial number or respiratory capacity. Additionally, lipid infusion suppressed peripheral glucose disposal (P = 0.004) and hepatic insulin sensitivity (P = 0.014).

CONCLUSIONS

These findings indicate that activation of mitochondrial fission and quality control occur early in the onset of insulin resistance in human skeletal muscle. Targeting mitochondrial dynamics and quality control represents a promising new pharmacological approach for treating insulin resistance and type 2 diabetes.

CLINICAL TRIAL REGISTRATION

NCT02697201, ClinicalTrials.gov.

Nutritional guidelines for the management of insulin resistance

Obesity and its related co-morbidities, namely type 2 diabetes (T2D), pose a significant global public health problem. Insulin resistance (IR) in muscle and liver is the core pathophysiologic defect that underlies obesity preceding and predicting the onset of T2D in susceptible humans. There is a broad population with IR that has no indication for prescription of medications, who still need medical consultation and specific advice in this respect. This prevalent need can be achieved by appropriate diet, exercise, and other behavioral therapies for lifestyle interventions. Despite a well-recognized role of IR in the progression to metabolic diseases, no specific nutritional recommendations exist to manage this condition, to the best of our knowledge. An international panel of experts reviewed and critically appraised the updated literature published about this topic. This review primarily examines the evidence for areas of consensus and ongoing uncertainty or controversy about diet and exercise approaches for IR. The aim of this article is to present the most common IR states, namely obesity and Polycystic Ovary Syndrome (PCOS), and provide nutritional advice to manage IR, hyperinsulinemia, and reactive hypoglycemia. These nutritional guidelines could prevent progression or worsening of IR with resultant beta-cell failure and, as a result, T2D.

Co-ingestion of NUTRALYS® pea protein and a high-carbohydrate beverage influences the glycaemic, insulinaemic, glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) responses: preliminary results of a randomised controlled trial

PURPOSE

Plant-based proteins may have the potential to improve glycaemic and gastrointestinal hormone responses to foods and beverages. The aim of this study was to investigate the effect of two doses of pea protein on postprandial glycaemic, insulinaemic, glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) response following a high-carbohydrate beverage intake in healthy individuals.

METHODS

In a single-blind, randomised, controlled, repeat measure, crossover design trial, thirty-one participants were randomly assigned to ingest 50 g glucose (Control), 50 g glucose with 25 g pea protein (Test 1) and 50 g glucose with 50 g pea protein (Test 2) on three separate days. Capillary blood samples (blood glucose and plasma insulin measurements) and venous blood samples (GIP and GLP-1 concentrations) were taken before each test and at fixed intervals for 180 min. The data were compared using repeated-measures ANOVA or the Friedman test.

RESULTS

Glucose incremental Area under the Curve (iAUC180) was significantly lower (p < 0.001) after Test 2 compared with Control (- 53%), after Test 1 compared with Control (- 31%) and after Test 2 compared with Test 1 (-32%). Insulin iAUC 180 was significantly higher (p < 0.001) for Test 1 (+ 28%) and Test 2 (+ 40%) compared with Control and for Test 2 (+ 17%) compared with Test 1 (p = 0.003). GIP and GLP-1 release showed no clear difference between Control and Pea protein drinks.

CONCLUSION

The consumption of pea protein reduced postprandial glycaemia and stimulated insulin release in healthy adults with a dose-response effect, supporting its role in regulating glycaemic and insulinaemic responses.

Low-carbohydrate diets and the risk of pancreatic cancer: a large prospective cohort study

Low-carbohydrate diets have become a popular approach for weight loss in recent years. However, whether low-carbohydrate diets are associated with the risk of pancreatic cancer remains to be elucidated. Hence, we examined the association of low-carbohydrate diets with the risk of pancreatic cancer in a US population. A population-based cohort of 95 962 individuals was identified. A low-carbohydrate-diet score was calculated to quantify adherence to this dietary pattern, with higher scores indicating greater adherence. Cox regression was used to calculate risk estimate for the association of the low-carbohydrate-diet score with the risk of pancreatic cancer. Subgroup analysis was used to identify the potential effect modifiers. After an average follow-up of 8.87 years (875856.9 person-years), we documented a total of 351 pancreatic cancer cases. In the fully adjusted model, the highest versus the lowest quartiles of the overall low-carbohydrate-diet score were found to be associated with a reduced risk of pancreatic cancer (hazard ratioquartile 4 versus 1: 0.61; 95% confidence interval: 0.45, 0.82; Ptrend < 0.001). Subgroup analysis found that the inverse association of low-carbohydrate diets with the risk of pancreatic cancer was more pronounced in individuals aged ≥65 years than in those aged <65 years (Pinteraction = 0.015). Similar results were obtained for animal and vegetable low-carbohydrate-diet scores. In conclusion, low-carbohydrate diets, regardless of the type of protein and fat, are associated with a lower risk of pancreatic cancer in the US population, suggesting that adherence to low-carbohydrate diets may be beneficial for pancreatic cancer prevention. Future studies should validate our findings in other populations.

Plant-Based and Animal-Based Low-Carbohydrate Diets and Risk of Hepatocellular Carcinoma Among US Men and Women

BACKGROUND AND AIMS

Little is known about the role of low-carbohydrate diets (LCDs) in the development of hepatocellular carcinoma (HCC). We prospectively evaluated the associations between plant-based and animal-based LCDs and risk of HCC in the Nurses' Health Study (NHS) and the Health Professionals Follow-up Study (HPFS).

APPROACH AND RESULTS

Dietary intake was assessed every 4 years using validated food frequency questionnaires. Cox proportional hazards regression models were used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs). HRs are shown for a 1-standard deviation (SD) increment with variables modeled as continuous. During 3,664,769 person-years of follow-up, there were 156 incident HCC cases. Although there were no associations between overall or animal-based LCD score and risk of HCC, plant-based LCD score was inversely associated with HCC risk (HR, 0.83; 95% CI, 0.70-0.98; P_trend  = 0.03). Carbohydrate intake, especially from refined grains (HR, 1.18; 95% CI, 1.00-1.39; P_trend  = 0.04), was positively, while plant fat (HR, 0.78; 95% CI, 0.65-0.95; P_trend  = 0.01) was inversely associated with HCC risk. Substituting 5% of energy from plant fat and protein for carbohydrate (HR, 0.74; 95% CI, 0.58-0.93; P_trend  = 0.01) or refined grains (HR, 0.70; 95% CI, 0.55-0.90; P_trend  = 0.006) was associated with lower HCC risk. In conclusion, a plant-based LCD and dietary restriction of carbohydrate from refined grains were associated with a lower risk of HCC. Substituting plant fat and protein for carbohydrate, particularly refined grains, may decrease HCC incidence.

CONCLUSIONS

Our findings support a potential benefit in emphasizing plant sources of fat and protein in the diet for HCC primary prevention; additional studies that carefully consider hepatitis B and C virus infections and chronic liver diseases are needed to confirm our findings.

Nutritional Strategies in Prediabetes: A Scoping Review of Recent Evidence

Nutritional therapy has been conventionally recommended for people with prediabetes as a method to delay or halt progression to type 2 diabetes. However, recommended nutritional strategies evolve over time. Hence, we performed a scoping review on recently reported nutritional interventions for individuals with prediabetes. Ovid MEDLINE, PubMed, Embase, Scopus, CINAHL and PsycINFO databases were searched to identify relevant research articles published within the past 10 years. Ninety-five articles involving a total of 11,211 participants were included in this review. Nutritional strategies were broadly classified into four groups: low calorie diet, low glycemic index diet, specific foods, and a combination of diet and exercise. The most frequently assessed outcomes were plasma glucose, serum insulin, serum lipid profile, body mass index and body weight. More than 50% of reported interventions resulted in significant improvements in these parameters. Nutritional interventions have demonstrated feasibility and practicality as an effective option for prediabetes management. However, the intervention variability demonstrates the challenges of a 'one-size-fits-all' approach. Investigations in genetically diverse populations and objective assessment of progression rate to diabetes are necessary to better comprehend the impact of these nutritional strategies in prediabetes.

Mens Sana in Corpore Sano: Does the Glycemic Index Have a Role to Play?

Although diet interventions are mostly related to metabolic disorders, nowadays they are used in a wide variety of pathologies. From diabetes and obesity to cardiovascular diseases, to cancer or neurological disorders and stroke, nutritional recommendations are applied to almost all diseases. Among such disorders, metabolic disturbances and brain function and/or diseases have recently been shown to be linked. Indeed, numerous neurological functions are often associated with perturbations of whole-body energy homeostasis. In this regard, specific diets are used in various neurological conditions, such as epilepsy, stroke, or seizure recovery. In addition, Alzheimer’s disease and Autism Spectrum Disorders are also considered to be putatively improved by diet interventions. Glycemic index diets are a novel developed indicator expected to anticipate the changes in blood glucose induced by specific foods and how they can affect various physiological functions. Several results have provided indications of the efficiency of low-glycemic index diets in weight management and insulin sensitivity, but also cognitive function, epilepsy treatment, stroke, and neurodegenerative diseases. Overall, studies involving the glycemic index can provide new insights into the relationship between energy homeostasis regulation and brain function or related disorders. Therefore, in this review, we will summarize the main evidence on glycemic index involvement in brain mechanisms of energy homeostasis regulation.

[Reactive hypoglycemia - an interdisciplinary approach of the disease of XXI Century]

Reactive hypoglycemia is characterized by low blood glucose level in non-diabetic patients. It manifests as a syndrome of adrenergic and neuroglycopenic symptoms in the postprandial period, and their resolution occurs after consuming carbohydrates. The etiology of reactive hypoglycemia is not fully understood. It may occur in patients after gastrointestinal surgery due to too fast gastric emptying. Decreases in postprandial glucose are also observed in people with a pre-diabetes condition in which insulin secretion is disturbed. Hypoglycaemia can also be seen in patients with insulin resistance and hyperinsulinism. The aim of this study was to summarize existing knowledge about reactive hypoglycemia - etiology, diagnostic model and treatment.

Low-glycemic index diets as an intervention for diabetes: a systematic review and meta-analysis

BACKGROUND

Low-glycemic index (GI) diets are thought to reduce postprandial glycemia, resulting in more stable blood glucose concentrations.

OBJECTIVE

We hypothesized that low-GI diets would be superior to other diet types in lowering measures of blood glucose control in people with type 1 or type 2 diabetes, or impaired glucose tolerance.

METHODS

We searched PubMed, the Cochrane Library, EMBASE, and clinical trials registries for published and unpublished studies up until 1 March, 2019. We included 54 randomized controlled trials in adults or children with impaired glucose tolerance, type 1 diabetes, or type 2 diabetes. Continuous data were synthesized using a random effects, inverse variance model, and presented as standardized mean differences with 95% CIs.

RESULTS

Low-GI diets were effective at reducing glycated hemoglobin (HbA1c), fasting glucose, BMI, total cholesterol, and LDL, but had no effect on fasting insulin, HOMA-IR, HDL, triglycerides, or insulin requirements. The reduction in fasting glucose and HbA1c was inversely correlated with body weight. The greatest reduction in fasting blood glucose was seen in the studies of the longest duration.

CONCLUSIONS

Low-GI diets may be useful for glycemic control and may reduce body weight in people with prediabetes or diabetes.

Dietary Glycemic Index and Load and the Risk of Type 2 Diabetes: Assessment of Causal Relations

While dietary factors are important modifiable risk factors for type 2 diabetes (T2D), the causal role of carbohydrate quality in nutrition remains controversial. Dietary glycemic index (GI) and glycemic load (GL) have been examined in relation to the risk of T2D in multiple prospective cohort studies. Previous meta-analyses indicate significant relations but consideration of causality has been minimal. Here, the results of our recent meta-analyses of prospective cohort studies of 4 to 26-y follow-up are interpreted in the context of the nine Bradford-Hill criteria for causality, that is: (1) Strength of Association, (2) Consistency, (3) Specificity, (4) Temporality, (5) Biological Gradient, (6) Plausibility, (7) Experimental evidence, (8) Analogy, and (9) Coherence. These criteria necessitated referral to a body of literature wider than prospective cohort studies alone, especially in criteria 6 to 9. In this analysis, all nine of the Hill's criteria were met for GI and GL indicating that we can be confident of a role for GI and GL as causal factors contributing to incident T2D. In addition, neither dietary fiber nor cereal fiber nor wholegrain were found to be reliable or effective surrogate measures of GI or GL. Finally, our cost-benefit analysis suggests food and nutrition advice favors lower GI or GL and would produce significant potential cost savings in national healthcare budgets. The high confidence in causal associations for incident T2D is sufficient to consider inclusion of GI and GL in food and nutrient-based recommendations.

Exercise training promotes a GDF15-associated reduction in fat mass in older adults with obesity

Obesity is a major risk factor for metabolic disease. Growth differentiation factor 15 (GDF15) has shown promise as a weight loss agent for obesity in animal studies. In healthy lean humans, fasting plasma GDF15 increases after acute exercise. However, the role of GDF15 in human obesity and the response of plasma GDF15 to exercise training in patients with obesity is unknown. Here, 24 sedentary volunteers with obesity [age: 65 ± 1 yr; body mass index (BMI): 35.3 ± 0.9 kg/m²] participated in a supervised 12-wk aerobic exercise intervention: 1 h/day, 5 days/wk at ~85% maximum heart rate with controlled isocaloric diet. As a result, plasma GDF15 was significantly increased (PRE: 644.1 ± 42.6 pg/ml, POST: 704.4 ± 47.2 pg/ml, P < 0.01) after the exercise intervention. Inconsistent with animal models, ΔGDF15 was not correlated with change in weight, BMI, or resting energy expenditure. However, ΔGDF15 was correlated with a reduction in total fat mass (P < 0.05), abdominal fat mass (P < 0.05), and android fat mass (P ≤ 0.05). Participants with a positive GDF15 response to exercise had increased total fat oxidation (PRE: 0.25 ± 0.05 mg·kg^-1·min^-1, POST: 0.43 ± 0.07 mg·kg^-1·min^-1, P ≤ 0.05), metabolic flexibility [PRE: -0.01 ± 0.01 delta respiratory quotient (RQ), POST: 0.06 ± 0.01 delta RQ, P < 0.001], and insulin sensitivity (PRE: 0.33 ± 0.01 QUICKI index, POST: 0.34 ± 0.01 QUICKI index, P < 0.01), suggesting a link between GDF15 and fat mass loss as well as exercise-induced metabolic improvement in humans with obesity. We conclude that the exercise-induced increase in plasma GDF15 and the association with reduced fat mass may indicate a role for GDF15 as a therapeutic target for human obesity.

Effectiveness of Low Glycemic Index Diet Consultations Through a Diet Glycemic Assessment App Tool on Maternal and Neonatal Insulin Resistance: A Randomized Controlled Trial

Background

Low glycemic index (LGI) diet has shown to be effective in reducing maternal and neonatal complications in high-risk pregnancies.

Objective

This trial aimed to examine the effectiveness of individualized LGI diet consultations based on the accurate diet glycemic load (GL) assessment tool on maternal and neonatal insulin resistance levels and diet behavior changes in overweight and obese pregnant women.

Methods

Overweight and obese pregnant women were recruited before 16 weeks of gestation and randomized to the LGI diet arm or the control arm. All participants received standard dietary education according to the Chinese Dietary Guide for Pregnant Women. In the intervention arm, additional individualized dietary GL assessments were performed using an app and instructions of lowering diet glycemic index (GI) to achieve LGI diet were provided by a clinical dietitian at early, middle, and late gestation. Primary outcomes were serum insulin at late gestation, incidence of gestational diabetes mellitus (GDM) for mothers, and cord blood C-peptide level of neonates.

Results

In total, 400 subjects were randomized and received different interventions. There were no significant differences in maternal serum insulin levels (13.2 [9.3−13.2] uU/mL vs 12.4 [10.5−12.4] uU/mL), incidence of GDM (45 [22.5%] vs 43 [21.5%]), or cord blood C-peptide levels (mean 0.9ng/mL [SD 0.7] vs mean 0.8ng/mL [SD 0.6]) in the intervention group compared with the controls. The diet GI at late gestation was similar (mean 63.2 [SD 10.4] vs mean 64.3 [SD 10.4]), whereas greater diet fiber intake was observed in the intervention group (mean 11.6 grams [SD 8.0] vs mean 9.0 grams [SD 5.6]; P=.006). Adherence measurements did not significantly differ between 2 groups.

Conclusions

Individualized LGI diet consultations for overweight and obese pregnant women failed to make a significant difference in maternal or neonatal insulin resistance compared with the standard gestational diet consultation.

Trial Registration

ClinicalTrials.gov NCT01628835; http://clinicaltrials.gov/ct2/show/NCT01628835 (Archived by WebCite at http://www.webcitation.org/77LHgWP0k)

Functional high-intensity exercise training ameliorates insulin resistance and cardiometabolic risk factors in type 2 diabetes

NEW FINDINGS

What is the central question of this study? Does short-duration, high-intensity exercise training that combines functional aerobic and resistance exercises into training sessions lasting 8-20 min benefit individuals with type 2 diabetes? What is the main finding and its importance? Functional high-intensity training improves insulin sensitivity and reduces cardiometabolic risk in individuals with type 2 diabetes. This type of exercise training may be an effective exercise mode for managing type 2 diabetes. The increase in insulin sensitivity addresses a key defect in type 2 diabetes.

ABSTRACT

Functional high-intensity training (F-HIT) is a novel fitness paradigm that integrates simultaneous aerobic and resistance training in sets of constantly varied movements, based on real-world situational exercises, performed at high-intensity in workouts that range from ∼8 to 20 min per session. We hypothesized that F-HIT would be an effective exercise mode for reducing insulin resistance in type 2 diabetes (T2D). We recruited 13 overweight/obese adults (5 males, 8 females; 53 ± 7 years; BMI 34.5 ± 3.6 kg m^-2 , means ± SD) with T2D to participate in a 6-week (3 days week^-1 ) supervised F-HIT programme. An oral glucose tolerance test was used to derive measures of insulin sensitivity. F-HIT significantly reduced fat mass (43.8 ± 83.8 vs. 41.6 ± 7.9 kg; P < 0.01), diastolic blood pressure (80.2 ± 7.1 vs. 74.5 ± 5.8; P < 0.01), blood lipids (triglyceride and VLDL, both P < 0.05) and metabolic syndrome z-score (6.4 ± 4.5 vs. -0.2 ± 5.2 AU; P < 0.001), and increased basal fat oxidation (0.08 ± 0.03 vs. 0.10 ± 0.04 g min^-1 ; P = 0.05), and high molecular mass adiponectin (214.4 ± 88.9 vs. 288.8 ± 127.4 ng mL^-1 ; P < 0.01). Importantly, F-HIT also increased insulin sensitivity (0.037 ± 0.010 vs. 0.042 ± 0.010 AU; P < 0.05). Increases in high molecular mass adiponectin and basal fat oxidation correlated with the change in insulin sensitivity (ρ, 0.75, P < 0.05 and ρ, 0.81, P < 0.01, respectively). Compliance with the training programme was >95% and no injuries or adverse events were reported. These data suggest that F-HIT may be an effective exercise mode for managing T2D. The increase in insulin sensitivity addresses a key defect in T2D and is consistent with improvements observed after more traditional aerobic exercise programmes in overweight/obese adults with T2D.

Exercise training remodels human skeletal muscle mitochondrial fission and fusion machinery towards a pro-elongation phenotype

AIMS

Mitochondria exist as a morphologically plastic network driven by cellular bioenergetic demand. Induction of fusion and fission machinery allows the organelle to regulate quality control and substrate flux. Physiological stressors promote fragmentation of the mitochondrial network, a process implicated in the onset of metabolic disease, including type 2 diabetes and obesity. It is well-known that exercise training improves skeletal muscle mitochondrial volume, number, and density. However, the effect of exercise training on muscle mitochondrial dynamics remains unclear.

METHODS

Ten sedentary adults (65.8 ± 4.6 years; 34.3 ± 2.4 kg/m² ) underwent 12 weeks of supervised aerobic exercise training (5 day/wk, 85% of HR_MAX ). Body composition, cardio-metabolic testing, hyperinsulinaemic-euglycaemic clamps, and skeletal muscle biopsies were performed before and after training. MFN1, MFN2, OPA1, OMA1, FIS1, Parkin, PGC-1α, and HSC70 protein expression was assessed via Western blot.

RESULTS

Exercise training led to improvements in insulin sensitivity, aerobic capacity, and fat oxidation (all P < 0.01), as well as reductions in body weight, BMI, fat mass and fasting glucose (all P < 0.001). When normalized for changes in mitochondrial content, exercise reduced skeletal muscle FIS1 and Parkin (P < 0.05), while having no significant effect on MFN1, MFN2, OPA1, and OMA1 expression. Exercise also improved the ratio of fusion to fission proteins (P < 0.05), which positively correlated with improvements in glucose disposal (r²  = 0.59, P < 0.05).

CONCLUSIONS

Exercise training alters the expression of mitochondrial fusion and fission proteins, promoting a more fused, tubular network. These changes may contribute to the improvements in insulin sensitivity and substrate utilization that are observed after exercise training.

Skeletal muscle Nur77 and NOR1 insulin responsiveness is blunted in obesity and type 2 diabetes but improved after exercise training

Obesity and type 2 diabetes (T2DM) are characterized by a blunted metabolic response to insulin, and strongly manifests in skeletal muscle insulin resistance. The orphan nuclear receptors, Nur77 and NOR1, regulate insulin-stimulated nutrient metabolism where Nur77 and NOR1 gene expression is increased with acute aerobic exercise and acute insulin stimulation. Whether Nur77 or NOR1 are associated with the insulin-sensitizing effects of chronic aerobic exercise training has yet to be elucidated. Fourteen lean healthy controls (LHC), 12 obese (OB), and 10 T2DM individuals (T2DM) underwent hyperinsulinemic-euglycemic clamps with skeletal muscle biopsies. Muscle was analyzed for Nur77 and NOR1 gene and protein expression at basal and insulin-stimulated conditions. Furthermore, a subcohort of 18 participants (OB, n = 12; T2DM, n = 6) underwent a 12-week aerobic exercise intervention (85% HRmax , 60 min/day, 5 days/week). In response to insulin infusion, LHC increased protein expression of Nur77 (8.7 ± 3.2-fold) and NOR1 (3.6 ± 1.1-fold), whereas OB and T2DM remained unaffected. Clamp-derived glucose disposal rates correlated with Nur77 (r2  = 0.14) and NOR1 (r2  = 0.12) protein expression responses to insulin, whereas age (Nur77: r2  = 0.22; NOR1: r2  = 0.25) and BMI (Nur77: r2  = 0.22; NOR1: r2  = 0.42) showed inverse correlations, corroborating preclinical data. In the intervention cohort, exercise improved Nur77 protein expression in response to insulin (PRE: -1.2 ± 0.3%, POST: 6.2 ± 1.5%). Also, insulin treatment of primary human skeletal muscle cells increased Nur77 and NOR1 protein. These findings highlight the multifactorial nature of insulin resistance in human obesity and T2DM. Understanding the regulation of Nur77 and NOR1 in skeletal muscle and other insulin-sensitive tissues will create opportunities to advance therapies for T2DM.

Exercise-induced improvements in glucose effectiveness are blunted by a high glycemic diet in adults with prediabetes

AIMS

Glucose effectiveness (GE) refers to the ability of glucose to influence its own metabolism through insulin-independent mechanisms. Diminished GE is a predictor of progression to type 2 diabetes. Exercise training improves GE, however, little is known about how dietary interventions, such as manipulating the glycemic index of diets, interact with exercise-induced improvements in GE in at-risk populations.

METHODS

We enrolled 33 adults with obesity and pre-diabetes (17 males, 65.7 ± 4.3 years, 34.9 ± 4.2 kg m^-2) into a 12-week exercise training program (1 h day^-1 and 5 day week^-1 at ~ 85% of maximum heart rate) while being randomized to concurrently receive either a low (EX-LOG: 40 ± 0.3 au) or high (EX-HIG: 80 ± 0.6 au) glycemic index diet. A 75-g oral-glucose-tolerance test (OGTT) was performed before and after the intervention and GE was calculated using the Nagasaka equation. Insulin resistance was estimated using a hyperinsulinemic-euglycemic clamp and cardiorespiratory fitness using a VO_2max test.

RESULTS

Both EX-LOG and EX-HIG groups had similar improvements in weight (8.6 ± 5.1 kg, P < 0.001), VO_2max (6 ± 3.5 mL kg^-1 min^-1, P < 0.001) and clamp-measured peripheral insulin resistance (1.7 ± 0.9 mg kg^-1 min^-1, P < 0.001), relative to baseline data. GE in EX-LOG and EX-HIG was similar at baseline (1.9 ± 0.38 vs. 1.85 ± 0.3 mg dL^-1 min^-1, respectively; P > 0.05) and increased by ~ 20% post-intervention in the EX-LOG arm (∆GE: 0.07-0.57 mg dL^-1 min^-1, P < 0.05). Plasma free fatty acid (FFA) concentrations also decreased only in the EX-LOG arm (∆FFA: 0.13 ± 0.23 mmol L^-1, P < 0.05).

CONCLUSIONS

Our data suggest that a high glycemic index diet may suppress exercise-induced enhancement of GE, and this may be mediated through plasma FFAs.

Low glycaemic index diets as an intervention for obesity: a systematic review and meta-analysis

OBJECTIVES

Low glycaemic index (GI) diets may aid in weight loss by reducing postprandial blood glucose excursions, leading to more stable blood glucose concentrations and therefore a reduction in hunger. To test this hypothesis, we conducted a systematic review and meta-analysis of randomized controlled trials comparing low GI diets with other diet types.

METHODS

We included 101 studies involving 109 study arms and 8,527 participants. We meta-analysed the studies using a random-effects model and conducted subgroup analyses and meta-regression based on control diet, blood glucose control, baseline BMI and dietary GI.

RESULTS

Low GI diets resulted in small but significant improvements in body weight, BMI, LDL and total cholesterol overall, although no individual control diet was significantly different from low GI diets. Studies in people with normal blood glucose who achieved a difference in GI of 20 points or more resulted in a larger reduction in body weight (SMD = -0.26; 95% CIs [-0.43, -0.09]), and total cholesterol (SMD = -0.24; 95% CIs [-0.42, -0.05]) than studies that only achieved a smaller reduction in GI.

CONCLUSIONS

Low GI diets, especially diets achieving a substantial decrease in GI, were moderately effective in lowering body weight. However, efforts should be made to increase compliance with low GI diets, in order for them to be effective in people with overweight and obesity.

Low-Carbohydrate Diet Score and Macronutrient Intake in Relation to Survival After Colorectal Cancer Diagnosis

Background

A low-carbohydrate diet may improve cancer survival, but relevant clinical evidence remains limited.

Methods

We followed 1542 stages I to III colorectal cancer (CRC) patients who completed a validated food frequency questionnaire between 6 months and 4 years after diagnosis. We calculated overall, animal-, and plant-rich, low-carbohydrate diet scores and examined their associations with CRC-specific and overall mortality using Cox proportional hazards regression after adjusting for potential predictors for cancer survival. We also assessed the intake and changes of macronutrients after diagnosis. Statistical tests were two-sided.

Results

Although no association was found for overall and animal-rich low-carbohydrate diet score, plant-rich, low-carbohydrate diet, which emphasizes plant sources of fat and protein with moderate consumption of animal products, was associated with lower CRC-specific mortality (hazard ratio [HR] comparing extreme quartiles = 0.37, 95% confidence interval [CI] = 0.25 to 0.57, P_trend < .001). Carbohydrate intake was associated with higher CRC-specific mortality, and this association was restricted to carbohydrate consumed from refined starches and sugars (HR per one-SD increment = 1.36, 95% CI = 1.14 to 1.62, P_trend < .001). In contrast, replacing carbohydrate with plant fat and protein was associated with lower CRC-specific mortality, with the HR per one-SD increment of 0.81 (95% CI = 0.69 to 0.95, P_trend = .01) for plant fat and 0.77 (95% CI = 0.62 to 0.95, P_trend = .02) for plant protein. Similar results were obtained for overall mortality and when changes in macronutrient intake after diagnosis were assessed.

Conclusion

Plant-rich, low-carbohydrate diet score was associated with lower mortality in patients with nonmetastatic CRC. Substituting plant fat and protein for carbohydrate, particularly that from refined starches and sugars, may improve patients’ survival.

Dicarbonyl Stress and Glyoxalase-1 in Skeletal Muscle: Implications for Insulin Resistance and Type 2 Diabetes

Glyoxalase-1 (GLO1) is a ubiquitously expressed cytosolic protein which plays a role in the natural maintenance of cellular health and is abundantly expressed in human skeletal muscle. A consequence of reduced GLO1 protein expression is cellular dicarbonyl stress, which is elevated in obesity, insulin resistance and type 2 diabetes (T2DM). Both in vitro and pre-clinical models suggest dicarbonyl stress per se induces insulin resistance and is prevented by GLO1 overexpression, implicating a potential role for GLO1 therapy in insulin resistance and type 2 diabetes (T2DM). Recent work has identified the therapeutic potential of novel natural agents as a GLO1 inducer, which resulted in improved whole-body metabolism in obese adults. Given skeletal muscle is a major contributor to whole-body glucose, lipid, and protein metabolism, such GLO1 inducers may act, in part, through mechanisms in skeletal muscle. Currently, investigations examining the specificity of dicarbonyl stress and GLO1 biology in human skeletal muscle are lacking. Recent work from our lab indicates that dysregulation of GLO1 in skeletal muscle may underlie human insulin resistance and that exercise training may impart therapeutic benefits. This minireview will summarize the existing human literature examining skeletal muscle GLO1 and highlight the emerging therapeutic concepts for GLO1 gain-of-function in conditions such as insulin resistance and cardiometabolic disease.

Effect of pasta in the context of low-glycaemic index dietary patterns on body weight and markers of adiposity: a systematic review and meta-analysis of randomised controlled trials in adults

OBJECTIVE

Carbohydrate staples such as pasta have been implicated in the obesity epidemic. It is unclear whether pasta contributes to weight gain or like other low-glycaemic index (GI) foods contributes to weight loss. We synthesised the evidence of the effect of pasta on measures of adiposity.

DESIGN

Systematic review and meta-analysis using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach.

DATA SOURCES

MEDLINE, Embase, CINAHL and the Cochrane Library were searched through 7 February 2017.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

We included randomised controlled trials ≥3 weeks assessing the effect of pasta alone or in the context of low-GI dietary patterns on measures of global (body weight, body mass index (BMI), body fat) and regional (waist circumference (WC), waist-to-hip ratio (WHR), sagittal abdominal diameter (SAD)) adiposity in adults.

DATA EXTRACTION AND SYNTHESIS

Two independent reviewers extracted data and assessed risk of bias. Data were pooled using the generic inverse-variance method and expressed as mean differences (MDs) with 95% CIs. Heterogeneity was assessed (Cochran Q statistic) and quantified (I2 statistic). GRADE assessed the certainty of the evidence.

RESULTS

We identified no trial comparisons of the effect of pasta alone and 32 trial comparisons (n=2448 participants) of the effect of pasta in the context of low-GI dietary patterns. Pasta in the context of low-GI dietary patterns significantly reduced body weight (MD=-0.63 kg; 95% CI -0.84 to -0.42 kg) and BMI (MD=-0.26 kg/m2; 95% CI -0.36 to -0.16 kg/m2) compared with higher-GI dietary patterns. There was no effect on other measures of adiposity. The certainty of the evidence was graded as moderate for body weight, BMI, WHR and SAD and low for WC and body fat.

CONCLUSIONS

Pasta in the context of low-GI dietary patterns does not adversely affect adiposity and even reduces body weight and BMI compared with higher-GI dietary patterns. Future trials should assess the effect of pasta in the context of other 'healthy' dietary patterns.

TRIAL REGISTRATION NUMBER

NCT02961088; Results.

High-intensity interval training improves insulin sensitivity in older individuals

AIM

Metabolic health may deteriorate with age as a result of altered body composition and decreased physical activity. Endurance exercise is known to counter these changes delaying or even preventing onset of metabolic diseases. High-intensity interval training (HIIT) is a time efficient alternative to regular endurance exercise, and the aim of this study was to investigate the metabolic benefit of HIIT in older subjects.

METHODS

Twenty-two sedentary male (n = 11) and female (n = 11) subjects aged 63 ± 1 years performed HIIT training three times/week for 6 weeks on a bicycle ergometer. Each HIIT session consisted of five 1-minute intervals interspersed with 1½-minute rest. Prior to the first and after the last HIIT session whole-body insulin sensitivity, measured by a hyperinsulinaemic-euglycaemic clamp, plasma lipid levels, HbA1c, glycaemic parameters, body composition and maximal oxygen uptake were assessed. Muscle biopsies were obtained wherefrom content of glycogen and proteins involved in muscle glucose handling were determined.

RESULTS

Insulin sensitivity (P = .011) and maximal oxygen uptake increased (P < .05) in both genders, while plasma cholesterol (P < .05), low-density lipoprotein (P < .05), visceral fat mass (P < .05) and per cent body fat (P < .05) decreased after 6 weeks of HIIT. HbA1c decreased only in males (P = .001). Muscle glycogen content increased in both genders (P = .001) and in line GLUT4 (P < .05), glycogen synthase (P = .001) and hexokinase II (P < .05) content all increased.

CONCLUSION

Six weeks of HIIT significantly improves metabolic health in older males and females by reducing age-related risk factors for cardiometabolic disease.

Circulating soluble RAGE isoforms are attenuated in obese, impaired-glucose-tolerant individuals and are associated with the development of type 2 diabetes

The soluble receptor for advanced glycation end products (sRAGE) may be protective against inflammation associated with obesity and type 2 diabetes (T2DM). The aim of this study was to determine the distribution of sRAGE isoforms and whether sRAGE isoforms are associated with risk of T2DM development in subjects spanning the glucose tolerance continuum. In this retrospective analysis, circulating total sRAGE and endogenous secretory RAGE (esRAGE) were quantified via ELISA, and cleaved RAGE (cRAGE) was calculated in 274 individuals stratified by glucose tolerance status (GTS) and obesity. Group differences were probed by ANOVA, and multivariate ordinal logistic regression was used to test the association between sRAGE isoform concentrations and the proportional odds of developing diabetes, vs. normal glucose tolerance (NGT) or impaired glucose tolerance (IGT). When stratified by GTS, total sRAGE, cRAGE, and esRAGE were all lower with IGT and T2DM, while the ratio of cRAGE to esRAGE (cRAGE:esRAGE) was only lower (P < 0.01) with T2DM compared with NGT. When stratified by GTS and obesity, cRAGE:esRAGE was higher with obesity and lower with IGT (P < 0.0001) compared with lean, NGT. In ordinal logistic regression models, greater total sRAGE (odds ratio, 0.91; P < 0.01) and cRAGE (odds ratio, 0.84; P < 0.01) were associated with lower proportional odds of developing T2DM. Reduced values of sRAGE isoforms observed with both obesity and IGT are independently associated with greater proportional odds of developing T2DM. The mechanisms by which each respective isoform contributes to obesity and insulin resistance may reveal novel treatment strategies for diabetes.

Dicarbonyl stress and glyoxalase enzyme system regulation in human skeletal muscle

Skeletal muscle insulin resistance is a hallmark of Type 2 diabetes (T2DM) and may be exacerbated by protein modifications by methylglyoxal (MG), known as dicarbonyl stress. The glyoxalase enzyme system composed of glyoxalase 1/2 (GLO1/GLO2) is the natural defense against dicarbonyl stress, yet its protein expression, activity, and regulation remain largely unexplored in skeletal muscle. Therefore, this study investigated dicarbonyl stress and the glyoxalase enzyme system in the skeletal muscle of subjects with T2DM (age: 56 ± 5 yr.; BMI: 32 ± 2 kg/m²) compared with lean healthy control subjects (LHC; age: 27 ± 1 yr.; BMI: 22 ± 1 kg/m²). Skeletal muscle biopsies obtained from the vastus lateralis at basal and insulin-stimulated states of the hyperinsulinemic (40 mU·m^-2·min^-1)-euglycemic (5 mM) clamp were analyzed for proteins related to dicarbonyl stress and glyoxalase biology. At baseline, T2DM had increased carbonyl stress and lower GLO1 protein expression (-78.8%), which inversely correlated with BMI, percent body fat, and HOMA-IR, while positively correlating with clamp-derived glucose disposal rates. T2DM also had lower NRF2 protein expression (-31.6%), which is a positive regulator of GLO1, while Keap1 protein expression, a negative regulator of GLO1, was elevated (207%). Additionally, insulin stimulation during the clamp had a differential effect on NRF2, Keap1, and MG-modified protein expression. These data suggest that dicarbonyl stress and the glyoxalase enzyme system are dysregulated in T2DM skeletal muscle and may underlie skeletal muscle insulin resistance. Whether these phenotypic differences contribute to the development of T2DM warrants further investigation.