The contribution of cardiorespiratory fitness and visceral fat to risk factors in Japanese patients with impaired glucose tolerance and type 2 diabetes mellitus

Visceral fat and cardiorespiratory fitness with prevalence of pre-diabetes/diabetes mellitus among middle-aged and elderly Japanese people: WASEDA'S Health Study

The relationships between cardiorespiratory fitness (CRF) measurements not confounded by adiposity and the prevalence of pre-diabetes mellitus (pre-DM) and diabetes mellitus (DM) are not well known. Thus, we aimed to investigate the associations of visceral fat (VF) and CRF with the prevalence of pre-DM/DM among Japanese adults. The study included 970 individuals (327 women and 643 men) who were 40-87 years old and had complete health examinations, abdominal fat area, and fitness data from WASEDA'S Health Study during 2015-2018. The VF area was measured using magnetic resonance imaging. CRF was measured using a cycle ergometer and was defined as VO2peak divided by fat free mass. The pre-DM/DM was identified based on the questionnaire and fasting blood tests. The odds ratios (ORs) and 95% confidence intervals (CIs) for prevalence of pre-DM/DM were calculated. Seventy-three participants had pre-DM and 48 participants had DM. Compared to the low VF group, the high VF group had a higher prevalence of pre-DM/DM (OR: 1.87, 95% CI: 1.18-2.96), although no significant relationship was observed between CRF and pre-DM/DM prevalence (P for trend = 0.239). The sub-group analyses also revealed no significant relationship between CRF and pre-DM/DM prevalence in the low VF group (P for trend = 0.979), although CRF values were inversely related to the prevalence of pre-DM/DM in the high VF group (P for trend = 0.024). Although CRF was not independently related to the prevalence of pre-DM/DM after adjusting for adiposity, higher VF values were related to a higher prevalence of pre-DM/DM. In addition, CRF levels were inversely associated with the prevalence of pre-DM/DM only among high VF individuals.

Ectopic fat and aerobic fitness are key determinants of glucose homeostasis in nonobese Asians

BACKGROUND

The importance of ectopic fat deposition and physical fitness in the pathogenesis of insulin resistance and beta cell dysfunction in subjects from the nonobese Asians is not known.

MATERIALS AND METHODS

We conducted a cross-sectional study and measured insulin sensitivity (M value; 4-hour hyperinsulinaemic-euglycaemic clamp), insulin secretion rate (3-hour mixed meal tolerance test with oral minimal modelling), percent body fat, visceral adipose tissue, intramyocellular and intrahepatic lipid contents (magnetic resonance imaging and spectroscopy), cardiorespiratory fitness (VO₂ max; graded exercise test) and habitual physical activity (short International Physical Activity Questionnaire) in 60 healthy nonobese Asian subjects (BMI = 21.9 ± 1.7 kg/m² , age = 41.8 ± 13.4 years).

RESULTS

M was inversely associated with percent body fat (r = -0.460, P < 0.001), visceral fat (r = -0.623, P < 0.001) and liver fat (r = -0.601, P < 0.001), whereas insulin secretion correlated positively with these adiposity indices (percent body fat: r = 0.303, P = 0.018; visceral fat: r = 0.409, P = 0.010; hepatic fat: r = 0.393, P = 0.002). VO₂ max correlated negatively with insulin secretion rate (r = -0.420, P < 0.001) and positively with M (r = 0.658, P < 0.001). The amount of vigorous physical activity was positively associated with VO₂ max (r = 0.682, P < 0.001). Multiple stepwise linear regression analyses indicated that VO₂ max, age, and IHTG or VAT were independent determinants of insulin sensitivity and secretion (adjusted R²  = 69% and 33%, respectively, P < 0.001).

CONCLUSIONS

Increased ectopic fat deposition is associated with reduced insulin sensitivity and increased insulin secretion in healthy nonobese Asians. Poor cardiorespiratory fitness, likely due to inadequate participation in vigorous exercise, is strongly related to suboptimal metabolic function. Interventions to encourage engagement in physical activity may thus be important for improving metabolic health in nonobese Asians.

Association Between Visceral Fat Accumulation and Exercise Tolerance in Non-Obese Subjects Without Diabetes

Background

We examined the associations between visceral fat accumulation, presence of the components of metabolic syndrome (MetS), and exercise tolerance in non-obese subjects without diabetes.

Methods

Seventy-four non-obese, non-diabetic Japanese men were enrolled. The subjects were divided into the following two groups: non-obese subjects without any MetS risk factors (n = 38, Group A) and non-obese subjects with one or two MetS risk factors (n = 36, Group B). Anthropometric and metabolic parameters were measured. The response of heart rate (HR) and blood pressure (BP), and exercise tolerance were also evaluated with a cardiopulmonary exercise test using a bicycle ergometer.

Results

The body mass index, abdominal circumference, visceral fat area, and homeostasis model assessment-insulin resistance, were significantly higher, while levels of anaerobic threshold and maximal oxygen uptake were significantly lower in Group B than in Group A. The levels of resting HR, resting BP, and BP at maximal exercise were significantly higher in Group B than in Group A. There were no significant differences in the HR at maximal exercise as well as the HR and BP after exercise between the two groups. The visceral fat area was significantly and negatively correlated with exercise tolerance. Multivariate linear regression analyses demonstrated that visceral fat area, but not abdominal circumference, was significantly and independently associated with maximal oxygen uptake.

Conclusions

These data suggest that the visceral fat area is a significant determinant for exercise tolerance even in non-obese subjects without diabetes.

Study on Cardiopulmonary Function, Maximal Oxygen Uptake, and Obesity Index according to Smoking Status in Middle-Aged and Older Office Workers

Objectives

To investigate the effect of smoking upon cardiopulmonary function, maximal oxygen uptake, and obesity index, in middle-aged and older workers to propose guidelines on healthcare for these age groups.

Methods

This study analyzed medical data from 2,753 white-collar workers aged 50 years or older from workplaces located in Seoul, South Korea. Blood pressure (BP), resting heart rate, maximal oxygen uptake (VO₂max), and body mass index (BMI) of each subject were measured. The collected data were analyzed using SPSS 21.0.

Results

In the smoking group BP and resting heart rate were significantly higher than in the non-smoking and smoking-cessation groups (p < 0.05). In addition, VO₂max was lower in the smoking group compared to the other 2 groups. BP closely correlated with resting heart rate, abdominal fat ratio, and BMI. BMI was the highest in the group that stopped smoking and, BMI and abdominal fat ratio negatively correlated with VO₂max.

Conclusion

Smoking increases the risk of cardiopulmonary disease but obesity may be caused by stopping smoking. Therefore, healthcare guidelines on smoking cessation should also include nutritional advice.

Waist circumference and cardiorespiratory fitness are independently associated with glucose tolerance and insulin resistance in obese women

The purpose of this study was to determine the independent associations between physical activity (PA), cardiorespiratory fitness (CRF), abdominal obesity and insulin action in obese women. We studied 141 abdominally obese women (waist circumference (WC): 106.4 ± 10.2 cm). PA duration (min/day) and intensity (counts/min) were obtained by accelerometry. CRF was measured using a treadmill. WC was measured at the iliac crest; abdominal adiposity was measured by magnetic resonance imaging. Glucose and insulin measures were obtained during a 75-g, 2-h glucose tolerance test. The homeostasis model of assessment iHOMA2-IS was used to estimate insulin sensitivity. PA duration and intensity were not associated with glucose or insulin metabolism (p > 0.05). However, moderate-to-vigorous PA (MVPA) duration was associated with fasting insulin and iHOMA2-IS (p < 0.01). CRF was associated with fasting insulin and iHOMA2-IS (r = 0.27, p ≤ 0.01), whereas WC was associated with fasting insulin (r = 0.50, p < 0.01) and iHOMA2-IS (r = -0.52, p ≤ 0.01). Following adjustment for CRF, MVPA, and age, WC remained associated with fasting glucose, insulin, 2-h glucose and iHOMA2-IS (r = -0.44, p ≤ 0.01). CRF was associated with fasting glucose as well as 1- and 2-h glucose (r = 0.24, p < 0.01) after adjusting for WC, MVPA, and age. MVPA was not associated with glucose or insulin measures after control for CRF and WC (p > 0.05). Mediation analysis revealed that CRF and WC combined mediated the relationship between MVPA and both glucose tolerance and insulin resistance (p < 0.05). In conclusion, among abdominally obese women, WC and CRF are independently associated with measures of glucose tolerance and insulin resistance and mediate the association between MVPA and insulin resistance.

The leptin to adiponectin ratio is a good biomarker for the prevalence of metabolic syndrome, dependent on visceral fat accumulation and endurance fitness in obese patients with diabetes mellitus

BACKGROUND

We investigated the contribution of adiponectin or leptin on the prevalence of metabolic syndrome (MS), while also taking cardiorespiratory fitness and visceral fat accumulation into account regarding diabetes patients.

METHODS

Japanese male patients (n = 77) with either impaired glucose tolerance (IGT) or type 2 diabetes mellitus were divided into three tertiles according to their adipocytokine levels. A logistic regression analysis was performed after adjusting for age to investigate the association between the adipocytokine levels and the prevalence of MS based on World Health Organization (WHO) criteria.

RESULTS

The visceral fat area (VFA) and maximal oxygen uptake ([Formula: see text] O(2)max) were found to be significantly different within the tertiles regarding the leptin and adiponectin levels and the adiponectin-to-leptin (A/L) ratio. The low tertile of leptin showed a significantly lower odds ratio (OR) for prevalence of MS than that in the high group. Both the low and the medium tertiles of adiponectin showed a significantly higher OR for prevalence of SM than that of the high group. Especially, the low tertile of A/L ratio had about an eight times higher prevalence of MS than the high tertile, and the difference was significant. However, when both the VFA and/or [Formula: see text] O(2)max were added to the logistic regression model as adjusting factors, all of these significant differences disappeared.

CONCLUSION

The A/L ratio is suggested to be a good biomarker for the prevalence of MS in comparison to the adiponectin and leptin levels alone. However, these relationships are dependent on abdominal fat accumulation and/or cardiorespiratory fitness levels.

Association between Relative Hypogonadism and Metabolic Syndrome in Newly Diagnosed Adult Male Patients with Impaired Glucose Tolerance or Type 2 Diabetes Mellitus

Sex steroid hormones are known to be important regulators of the lipid and glucose metabolism. Lower levels of testosterone (T) or sex hormone-binding globulin (SHBG) have been reported in men with type 2 diabetes. On the other hand, the relationship between relative hypogonadism and metabolic syndrome has not yet to be thoroughly studied. Ninety-eight Japanese adult (age 20-64) male patients with impaired glucose tolerance (IGT) or type 2 diabetes mellitus were divided into either an metabolic syndrome group (n = 42) or a non- metabolic syndrome (n = 56) group according to the definition of metabolic syndrome from WHO, or into three tertiles according to their sex hormone index level. The metabolic syndrome group had a significantly lower T/estradiol (E(2)) and SHBG level (p < 0.01). The age and subcutaneous fat surface area (SFA) were significantly different within the tertiles in SHBG and T/E(2). Logistic regression analyses were performed to investigate the association between the sex steroid hormone index level and the incidence of metabolic syndrome. Regarding the highest tertiles as a criterion, lower SHBG, T/E(2) or free T/E(2) had a higher odds ratio of prevalence of metabolic syndrome even after adjusting for age and SFA. Relative hypogonadism was strongly associated with the prevalence of metabolic syndrome in Japanese adult men who were newly diagnosed to have IGT or type 2 diabetes.

Effect of a prolonged altitude expedition on glucose tolerance and abdominal fatness

In the present study, we investigated the effect of a long-term mountain expedition on glucose tolerance and insulin action. Twelve registered mountaineers ages 31 years (SD = 1.1) participated in a 25-day expedition at a 2,200-3,800-m altitude with an average duration of 8 hr per day. Arterial oxygen saturation (SaO2) was substantially reduced during hiking. Glucose tolerance and insulin responses were measured prior to and twice during the expedition period. Maximal oxygen consumption increased from 43.0 +/- 2.7 to 49.1 +/- 2.2 mL/kg/min. Percentage of body fat decreased from 19.4 +/- 6.8% to 16.9 +/- 5.9%. The area under the curves for insulin and glucose during the oral glucose tolerance test were also reduced in Days 3 and 25. The present study demonstrated that altitude hiking activity is an effective lifestyle intervention to improve insulin action.

Visceral fat is a strong predictor of insulin resistance regardless of cardiorespiratory fitness in non-diabetic people

Abdominal adiposity and low cardiorespiratory fitness are associated with insulin resistance in people with impaired glucose tolerance and type 2 diabetes. However, little is known about which factor precedes insulin resistance in people with impaired glucose tolerance and type 2 diabetes, and which is the stronger predictor of insulin resistance in non-diabetic people. The purpose of this study was to examine the relationship between insulin resistance and cardiorespiratory fitness, visceral fat, and subcutaneous fat in non-diabetic people. Subjects included 87 men and 77 women aged 30-72 y (mean+/-SD, 51.3+/-12.3 y). Cardiorespiratory fitness was assessed by measuring the maximal oxygen uptake (VO2max) in a progressive continuous test to exhaustion on a cycle ergometer. The visceral and subcutaneous fat areas were measured by magnetic resonance imaging. The homeostasis model assessment of insulin resistance (HOMA-R) was calculated from the fasting concentrations of glucose and insulin. Stepwise multiple linear regression analysis revealed that visceral and subcutaneous fat were significant correlates of HOMA-R, explaining 24% and 6% of the variance, respectively, whereas sex, age, and VO2max were not significant independent determinants. Abdominal fat deposition rather than cardiorespiratory fitness is a significant predictor of insulin resistance in non-diabetic people; visceral fat is the most important factor.

Ethnic difference in inter-East Asian subjects with normal glucose tolerance and impaired glucose regulation: a systematic review and meta-analysis focusing on fasting serum insulin

AIMS

To investigate ethnic difference by focusing on fasting serum insulin (FSI) in inter-East Asian subjects with normal glucose tolerance (NGT) and impaired glucose regulation (IGR).

METHODS

Data sources included MEDLINE and EMBASE between 2001 and 2007. We conducted a search for articles containing mean or geometric mean values of FSI in East Asian subjects with NGT, IGR, or type 2 diabetes (T2DM). The Monte Carlo method was used for simulation of the mean and standard deviation of individual measures in each ethnic group; calculation of the median ratio and 95% confidence interval of individual measures between ethnic groups.

RESULTS

Twenty-two articles fully met our pre-determined criteria and were included in the meta-analysis. Results of the meta-analysis revealed that FSI level is significantly lower in Japanese subjects with NGT, IGR, or T2DM than in Korean and Chinese subjects.

CONCLUSIONS

Ethnic difference in FSI level between East Asians was observed in not only T2DM patients but also subjects with NGT or IGR. The lower FSI level in Japanese subjects was accompanied by lower triglyceride level. These results suggest that ethnic difference in dietary habit was one of the most influential factors for the ethnic difference in FSI.

Comparison of ventilatory threshold and exercise habits between Japanese men with and without metabolic syndrome

OBJECTIVE

We compared the levels of ventilatory threshold (VT) and exercise habits in subjects with metabolic syndrome with those in age, sex-matched subjects without metabolic syndrome.

METHODS

We used data of 155 Japanese men (47.1+/-9.2 years) with metabolic syndrome; the diagnosis was given by the definition and the diagnostic standard for metabolic syndrome in Japan. The influence of metabolic syndrome on oxygen uptake, work rate and heart rate at VT, and exercise habits were evaluated.

RESULTS

Oxygen uptake and work rate at VT in subjects with metabolic syndrome were significantly lower than those in subjects without metabolic syndrome even after adjusting for body mass index (BMI). The number of subjects with exercise habits was significantly lower in metabolic syndrome. The subjects with exercise habits were significantly older than that in subjects without exercise habits. Furthermore, oxygen uptake and work rate at VT were significantly higher in subjects with exercise habits than those in subjects without exercise habits.

CONCLUSION

Lower level of VT was characteristic in subjects with metabolic syndrome. Promotion of exercise habits is necessary for preventing and improving metabolic syndrome in Japanese men.

Cardiorespiratory fitness attenuates metabolic risk independent of abdominal subcutaneous and visceral fat in men

OBJECTIVE

Moderate to high levels of cardiorespiratory fitness (CRF) are associated with a lower risk of the metabolic syndrome and all-cause mortality. Unknown is whether CRF attenuates health risk for a given level of abdominal visceral fat, subcutaneous fat, and/or waist circumference.

RESEARCH DESIGN AND METHODS

The sample studied comprised 297 apparently healthy men with available computed tomography or magnetic resonance imaging scans of the abdomen, metabolic data, and maximal treadmill exercise test results. Men were categorized into low-CRF (20%, n = 56), moderate-CRF (40%, n = 94), and high-CRF (40%, n = 147) groups based on age and exercise test results. All analyses were adjusted for age.

RESULTS

For a given level of waist circumference, visceral fat, or subcutaneous fat, the high-CRF group had lower triglyceride levels (P < 0.05) and higher HDL cholesterol levels than the low- or moderate-CRF groups. There was a significant group interaction (P < 0.01) for blood pressure, indicating that the increase in blood pressure per unit increase in visceral fat or waist circumference was greater in men in the low-CRF group compared with the high-CRF group. The relative risks of having the metabolic syndrome were 1.8 (95% CI 1.0-3.1) and 1.6 (0.9-2.7) times higher in the low- and moderate-CRF groups, respectively, compared with the high-CRF group after adjusting for age, visceral fat, and subcutaneous fat (P for trend = 0.06).

CONCLUSIONS

High levels of CRF are associated with a substantial reduction in health risk for a given level of visceral and subcutaneous fat.