Smoking and Diabetes as Predictive Factors of Accelerated Loss of Muscle Mass in Middle-Aged and Older Women: A Six-Year Retrospective Cohort Study

Associations of muscle mass and strength with new-onset diabetes among middle-aged and older adults: evidence from the China health and retirement longitudinal study (CHARLS)

BACKGROUND

The associations of muscle mass and strength with new-onset Type 2 diabetes mellitus (T2DM) remain controversial. We aimed to longitudinally evaluate muscle mass and strength in predicting T2DM among Chinese middle-aged and older adults.

METHODS

We enrolled 6033 participants aged ≥ 45 years from the China Health and Retirement Longitudinal Study (CHARLS), a cohort survey, between 2011 and 2012. The appendicular skeletal muscle mass (normalized by weight, ASM/BW%), relative hand grip strength (normalized by weight, HGS/BW), and five-repetition chair stand test (5CST). were all categorized into tertiles (lowest, middle, and highest groups) at baseline, respectively. Individuals were followed up until the occurrence of diabetes or the end of CHARLS 2018, whichever happened first. Cox proportional hazards models to calculate hazard ratios with 95% confidence intervals (CI) and mediation analysis were used.

RESULTS

During follow-up, 815 (13.5%) participants developed T2DM. After adjusting for covariates, lower ASW/BW% was not associated with a higher risk of diabetes. Compared with individuals in the highest tertile of HGS/BW, those in the lowest tertile had 1.296 (95%CI 1.073-1.567) higher risk of diabetes. Compared with individuals in the lowest tertile of 5CST, those in the highest tertile had 1.329 times (95%CI 1.106-1.596) higher risk of diabetes. By subgroup, both the lowest HGS/BW and highest 5CST were risk factors for diabetes among obesity. The mediation analysis revealed that the effect of HGS/BW on the risk of diabetes is mainly mediated by insulin resistance.

CONCLUSIONS

Lower muscle strength is associated with an increased risk of diabetes, especially in obese populations.

Tissue-specific mitochondrial toxicity of cigarette smoke concentrate: consequence to oxidative phosphorylation

Cigarette smoke exposure is a well-known risk factor for developing numerous chronic health conditions, including pulmonary disease and cardiometabolic disorders. However, the cellular mechanisms mediating the toxicity of cigarette smoke in extrapulmonary tissues are still poorly understood. Therefore, the purpose of this study was to characterize the acute dose-dependent toxicity of cigarette smoke on mitochondrial metabolism by determining the susceptibility and sensitivity of mitochondrial respiration from murine skeletal (gastrocnemius and soleus) and cardiac muscles, as well as the aorta to cigarette smoke concentrate (CSC). In all tissues, exposure to CSC inhibited tissue-specific respiration capacity, measured by high-resolution respirometry, according to a biphasic pattern. With a break point of 451 ± 235 μg/mL, the aorta was the least susceptible to CSC-induced mitochondrial respiration inhibition compared with the gastrocnemius (151 ± 109 μg/mL; P = 0.008, d = 2.3), soleus (211 ± 107 μg/mL; P = 0.112; d = 1.7), and heart (94 ± 51 μg/mL; P < 0.001; d = 2.6) suggesting an intrinsic resistance of the vascular smooth muscle mitochondria to cigarette smoke toxicity. In contrast, the cardiac muscle was the most susceptible and sensitive to the effects of CSC, demonstrating the greatest decline in tissue-specific respiration with increasing CSC concentration (P < 0.001, except the soleus). However, when normalized to citrate synthase activity to account for differences in mitochondrial content, cardiac fibers' sensitivity to cigarette smoke inhibition was no longer significantly different from both fast-twitch gastrocnemius and slow-twitch soleus muscle fibers, thus suggesting similar mitochondrial phenotypes. Collectively, these findings established the acute dose-dependent toxicity of cigarette smoke on oxidative phosphorylation in permeabilized tissues involved in the development of smoke-related cardiometabolic diseases.NEW & NOTEWORTHY Despite numerous investigations into the mechanisms underlying cigarette smoke-induced mitochondrial dysfunction, no studies have investigated the tissue-specific mitochondrial toxicity to cigarette smoke. We demonstrate that, while aorta is least sensitive and susceptible to cigarette smoke-induced toxicity, the degree of cigarette smoke-induced toxicity in striated muscle depends on the tissue-specific mitochondrial content. We conclude that while the mitochondrial content influences cigarette smoke-induced toxicity in striated muscles, aorta is intrinsically protected against cigarette smoke-induced mitochondrial toxicity.

Overall and abdominal obesity and risks of all-cause and cause-specific mortality in Korean adults: a pooled analysis of three population-based prospective cohorts

BACKGROUND

Studies found a J-shaped association between body mass index (BMI) and mortality. However, it is unclear whether the association is driven by biases, particularly confounding by fat-free mass.

METHODS

We conducted an individual-level pooled analysis of three cohorts of Korean adults (aged ≥ 40 years; n = 153 248). Mortality was followed up through December 2019. Anthropometric data were directly measured at baseline. Fat and fat-free mass were predicted using validated prediction models. Using Cox proportional hazards models, we estimated the associations of BMI and waist circumference (WC) with all-cause and cause-specific mortality. To account for biases, we excluded participants aged ≥ 70 years, deaths that occurred within 5 years of follow-up and ever smokers, and adjusted for fat-free mass index (FFMI).

RESULTS

During the follow-up of up to 18 years, 6061 deaths were identified. We observed J-shaped association of BMI (nadir at 22-26) and monotonically positive association of WC with all-cause, cardiovascular, and cancer mortality among Korean adults without a history of cancer or cardiovascular disease. In the BMI analysis, excluding ever smokers and adjusting for FFMI attenuated the excess mortality in underweight participants and transformed the J-shaped association into a monotonically positive shape, suggesting an increased mortality at BMI > 22.0. Excluding participants aged ≥ 70 years and deaths that occurred within 5 years of follow-up did not change the results. In the WC analysis, the monotonic positive associations did not change after the control. Similar results were observed among participants with a history of cancer or cardiovascular disease.

CONCLUSIONS

Our data suggest that both overall and abdominal body fat are associated with increased mortality in Korean adults.

Lifestyle factors associated with muscle quality in community-dwelling older people with type 2 diabetes in Japan and Taiwan: a cross-sectional study

BACKGROUND

Type 2 diabetes mellitus (T2DM), common in older people, is an important reason for muscle loss in Japanese and Taiwanese populations. However, little is known about the association between lifestyle behaviours and muscle quality. We aimed to compare the lifestyle behaviours of Japanese and Taiwanese older adults with T2DM and to the identify lifestyle factors associated with muscle quality.

METHODS

This cross-sectional study was conducted among community-dwelling individuals with T2DM aged ≥65 years in Taiwan and Japan. Totally, 114 Japanese and 226 Taiwanese participants were enrolled in the study. Outcomes were measured by blood biochemical examinations, body composition analyses and structured self-reported questionnaires to assess lifestyle behaviours and muscle quality. Linear regression models were used to examine the relationship between lifestyle factors and muscle quality using SPSS version 27.0 with a statistical significance level of P < 0.05.

RESULTS

Japanese subjects were more likely to be smokers and alcohol consumers, and they were less likely to have well-balanced diets and engage in more physical activity as compared to Taiwanese subjects. The muscle quality in the Japanese subjects was significantly poorer than that in the Taiwanese subjects. Physical activity, dietary habits and smoking were associated with muscle quality, after adjusting for age, gender and body mass index.

CONCLUSIONS

Physical activity of insufficient intensity, unhealthy dietary habits and smoking could be risk factors for poor muscle quality. These findings can contribute to the development of effective strategies to improve muscle quality in community-dwelling older Asian people with T2DM.

Characterisation of body size phenotypes in a middle-aged Maltese population

Obesity is increasingly recognised as being a heterogeneous disease. Some obese individuals may present a metabolically healthy profile (metabolically healthy obese (MHO)), while some normal weight individuals exhibit an adverse cardiometabolic phenotype (metabolically unhealthy normal weight individuals (MUHNW)). The objectives of the present study were to examine the prevalence and associated characteristics of the different body composition phenotypes within a Maltese cohort. This was a cross-sectional analysis involving 521 individuals aged 41 ± 5 years. The metabolically unhealthy state was defined as the presence of ≥2 metabolic syndrome components (NCEP-ATPIII parameters), while individuals with ≤1 cardiometabolic abnormalities were classified as metabolically healthy. Overall, 70 % of the studied population was overweight or obese and 30⋅7 % had ≥2 cardiometabolic abnormalities. The prevalence of MHO and MUHNW was 10⋅7 and 2⋅1 %, respectively. Individuals with the healthy phenotype were more likely to consume alcohol, participate in regular physical activity and less likely to be smokers. While the MHO phenotype had similar values for waist, hip and neck circumferences, waist-hip ratio and insulin resistance when compared with MUHNW individuals, there was a lower proportion of MHO subjects having a high fasting plasma glucose, hypertriglyceridaemia or low HDL-C when compared with the unhealthy lean individuals. A high prevalence of the metabolically unhealthy phenotype was observed in this relatively young population which may result in significant future cardiovascular disease burden if timely assessment and management of modifiable risk factors are not implemented. Furthermore, the present study suggests that the MHO phenotype is not totally benign as previously thought.

Prevalence of Sarcopenia and Its Association With Diabetes: A Meta-Analysis of Community-Dwelling Asian Population

Purpose: Sarcopenia is a major disease affecting mortality and quality of life in the elderly population. We performed a meta-analysis of studies on the community-dwelling population to investigate the prevalence of sarcopenia and its association with diabetes.

Methods: Databases were searched for studies published up to February 3, 2021, reporting the prevalence of sarcopenia in patients with and without diabetes. Data extraction and quality assessment were performed according to the Newcastle-Ottawa scale.

Results: Six articles were included in the systematic review. All the patients were Asian, aged ≥60 years (women 53.4%), and the diabetic and non-diabetic population was 1,537 and 5,485, respectively. In all six studies, the Asian Working Group for Sarcopenia criteria were used to diagnose sarcopenia. The prevalence of sarcopenia was 15.9% in diabetics and 10.8% in non-diabetics. Diabetics showed a significantly higher risk of sarcopenia than non-diabetics (pooled OR = 1.518, 95% CI = 1.110 to 2.076, Z-value = 2.611, p = 0.009).

Conclusion: Among the Asian community-dwelling geriatric population, the prevalence of sarcopenia was significantly higher in diabetics than in non-diabetics. These results suggest that strategies for the management of sarcopenia are required in Asian elderly patients, especially with diabetes.

Mediation effect of the duration of diabetes mellitus on the decrease in bioimpedance phase angles in ethnically Korean people: A multicenter clinical study

AIMS/INTRODUCTION

We carried out a multicenter clinical study to investigate whether the decrease in segmental phase angles (PhA values) observed using bioelectrical impedance is useful in screening for diabetes mellitus and monitoring disease progression.

MATERIALS AND METHODS

The segmental PhA values of the four limbs were acquired using multifrequency bioimpedance at 5, 50 and 250 kHz in three clinics. Differences in PhA values between the diabetes and control groups were analyzed using the two-sample t-test and analysis of variance (anova). Changes in PhA values with increasing durations of diabetes were analyzed using a moderated mediation model and multivariate linear regression analysis. We recruited 217 participants aged ≥40 years (diabetes 158, controls 59, men 106, women 111, A-clinic 71, B-clinic 70 and C-clinic 76).

RESULTS

PhA values at 50 kHz were significantly decreased in people with diabetes (PhA of the right arm in men: t-value -4.0, P < 0.001; PhA of the right leg in women: t-value -4.6 P < 0.001), and the difference was partially attributable to the duration of diabetes, as well as aging. Specifically, the mediation effect of the duration of diabetes on the decrease in PhA values was 29.8% in the left arm of men, 53.3% in the right arm of women, and 36.3% in the left arm of both sexes.

CONCLUSIONS

Phase angle values at 50 kHz decreased in people with diabetes, and the changes were exacerbated as the disease duration increased. Thus, bioimpedance PhA values represent a non-invasive tool for monitoring the progression of diabetes mellitus.

Diet quality and a traditional dietary pattern predict lean mass in Australian women: Longitudinal data from the Geelong Osteoporosis Study

Low muscle mass is associated with reduced independence and increased risk for falls and fractures. Identification of modifiable risk factors for low muscle mass is thus imperative. This study aimed to examine the longitudinal relationship between both diet quality and patterns and lean mass in Australian women. Data from n = 494 participants of the Geelong Osteoporosis Study's 10- and 15-year women's follow-ups were used (conducted in 2004-08 and 2011-14, respectively), and participants were aged 21-89 years. Self-reported lifestyle and demographics were collected, and food frequency questionnaire data informed the dietary exposure variables: the Australian Recommended Food Score (ARFS); the Dietary Inflammatory Index (DII); and a posteriori dietary patterns. The outcome, Skeletal Muscle Index (SMI), was calculated from DXA-derived appendicular lean mass (ALM) relative to height (ALM kg/m2). Analyses employed Generalised Estimating Equations. A higher ARFS score positively predicted SMI over 5-years, and adjustments for age and physical activity did not attenuate this relationship (B:0.044, (95%CI 0.004, 0.084) kg/m2). Following adjustment, both an anti-inflammatory diet (B:-0.034, (95%CI -0.070, -0.002) kg/m2) and a 'traditional' dietary pattern predicted higher SMI (B:0.081, (95%CI 0.004, 0.158) kg/m2). No other associations were observed. Our study reinforces the importance of diet quality for healthy, aging muscle mass. Furthermore, a less inflammatory diet and a diet comprising a wide variety of plant and animal foods may be conducive to maintenance of muscle mass in women. Further studies investigating diet quality's impact on various muscle health measures over longer time periods are warranted.

Longitudinal Observation of Muscle Mass over 10 Years According to Serum Calcium Levels and Calcium Intake among Korean Adults Aged 50 and Older: The Korean Genome and Epidemiology Study

The aim of this study was to investigate the longitudinal change in muscle mass over 10 years according to serum calcium levels and calcium intake. A total of 1497 men and 1845 women aged 50 years and older were included. Significant muscle loss (SML) was defined as a 5% or greater loss from baseline, while time-dependent development of SML was assessed according to quartiles for corrected calcium level and daily calcium intake using Cox regression models. The incidence of SML was 6.7 and 7.7 per 100-person-years among men and women, respectively. Groups with the lowest corrected calcium levels had more prominent SML than those with higher calcium levels, regardless of sex. The relationship between SML and calcium intake was significant only among women. The hazard ratio for SML per 1 mmol/L increase in corrected calcium level was 0.236 and 0.237 for men and women, respectively. In conclusion, low serum calcium levels may predict SML among adults aged ≥ 50 years, while low calcium intake may be a predictor for muscle loss among women. Therefore, encouraging dietary calcium intake among middle-aged and older adults for preservation of muscle mass should be considered.

The relationships between sarcopenic skeletal muscle loss during ageing and macronutrient metabolism, obesity and onset of diabetes

Skeletal muscle is integral to the metabolism and utilisation of macronutrients; however, substantial muscle loss and morphological changes occur with ageing. These are associated with loss of muscle function and accelerate rapidly from the age of 60 years, leading to the conditions of sarcopenia and frailty. As the relationship between muscle ageing and macronutrient metabolism and utilisation has seen limited research to date, this review focuses on the interactions between skeletal muscle changes during ageing, metabolism and utilisation of fat, carbohydrates and overall energy expenditure.Skeletal muscle contributes less to resting energy expenditure during ageing, potentially contributing to onset of obesity from middle age. Age-related changes to skeletal muscle lead to glucose dysregulation, with consequent reduction in glycaemic control, increased insulin resistance and ultimately onset of type-2 diabetes. Recent studies indicate that high total fat and SFA intake are detrimental to skeletal muscle, while higher intakes of PUFA are protective. Age-associated changes in skeletal muscle may also reduce total fatty acid utilisation.In conclusion, further research is needed to understand the relationships between macronutrient metabolism and utilisation and age-related changes to skeletal muscle. No dietary recommendations exist specifically for skeletal muscle health during ageing, but we advise individuals to follow healthy eating guidelines, by consuming sufficient protein, fruit and vegetables, and limited SFA and to maintain physically active lifestyles. Clinicians responsible for managing type-2 diabetes need to be aware of growing evidence relating age-related skeletal muscle changes to diabetes onset and progression.