Chan-Won Kim

Sleep duration and quality in relation to non-alcoholic fatty liver disease in middle-aged workers and their spouses

BACKGROUND & AIMS Although accumulated evidence implies that short sleep duration and poor sleep quality may lead to an altered metabolic milieu, potentially triggering the development of non-alcoholic fatty liver disease (NAFLD), no studies have explored this association. This study sought to examine whether short sleep duration or poor sleep quality is associated with NAFLD in the general population. METHODS We assessed sleep duration and quality using the Pittsburgh Sleep Quality Index in 69,463 middle-aged workers and their spouses and carried out biochemical and anthropometric measurements. The presence of fatty liver was determined using ultrasonographic findings. Logistic regression models were used to evaluate the association of sleep duration and quality with NAFLD, after adjusting for potential confounders. RESULTS After controlling for the relevant confounding factors (age, alcohol intake, smoking, physical activity, systolic blood pressure, education level, marital status, presence of job, sleep apnea, and loud snoring), the adjusted odds ratio (95% confidence interval) for NAFLD comparing sleep duration ≤5 h to the reference (>7h) was 1.28 (1.13-1.44) in men and 1.71 (1.38-2.13) in women. After further adjustments for BMI, this association was not significant in men (OR: 1.03, 95% CI: 0.90-1.19) but remained significant in women (OR: 1.59, 95% CI: 1.23-2.05). The multivariate-adjusted odds ratio comparing participants with poor sleep quality vs. participants with good sleep quality was 1.10 (95% CI 1.02-1.19) and 1.36 (95% CI 1.17-1.59) in men and women, respectively. CONCLUSIONS In the middle-aged, general population, short sleep duration, and poor sleep quality were significantly associated with an increased risk of NAFLD. Prospective studies are required to confirm this association.

Impact of BMI on the incidence of metabolic abnormalities in metabolically healthy men

Objectives:Although the existence of metabolically healthy obese (MHO) individuals has been recognized, little is known regarding metabolic health status in these subjects over time. Thus, we evaluated longitudinal changes in metabolic parameters among MHO subjects compared with metabolically healthy, normal-weight (MHNW) subjects.Methods:A cohort study was performed on 2599 Korean men, 30–59 years of age, with no evidence of fatty liver disease on ultrasound and no traits of metabolic syndrome at baseline. BMI was categorized based on criteria for Asian population. Study participants were followed annually or biennially between 2002 and 2009. At each visit, the fatty liver on ultrasound was assessed and metabolic abnormalities were measured. Parametric Cox models and a pooled logistic regression models were used to evaluate the relationships of BMI with incident metabolic abnormalities.Results:During 9647.1 person-years of follow-up, 1673 participants developed metabolic abnormalities. After adjusting for age, smoking, alcohol intake and exercise, higher baseline BMI categories predicted increased incidences of metabolic abnormalities in a dose-response manner. The hazard ratios (95% confidence intervals) for hypertriglyceridemia, prediabetes, pre-hypertension, low high-density lipoprotein-cholesterol, fatty liver, elevated high sensitivity-C reactive protein, elevated homeostasis model assessment of insulin resistance, any metabolic abnormality and metabolic syndrome among the MHO subjects compared with the MHNW subjects were 1.51 (1.23–1.85), 1.43 (1.19–1.72), 1.79 (1.45–2.22), 1.80 (1.30–2.49), 2.69 (2.19–3.31), 1.39 (1.16–1.67), 2.90 (2.31–3.62), 1.68 (1.45–1.93) and 1.84(1.02–3.30), respectively.Conclusion:In this study, MHO individuals showed higher incidences of metabolic abnormalities compared with MHNW individuals. This suggests that initially MHO individuals undergo adverse metabolic changes associated with obesity over time.

Relationship of sitting time and physical activity with non-alcoholic fatty liver disease

BACKGROUND & AIMS The goal of this study was to examine the association of sitting time and physical activity level with non-alcoholic fatty liver disease (NAFLD) in Korean men and women and to explore whether any observed associations were mediated by adiposity. METHODS A cross-sectional study was performed on 139,056 Koreans, who underwent a health examination between March 2011 and December 2013. Physical activity level and sitting time were assessed using the validated Korean version of the international Physical Activity Questionnaire Short Form. The presence of fatty liver was determined using ultrasonographic findings. Poisson regression models with robust variance were used to evaluate the association of sitting time and physical activity level with NAFLD. RESULTS Of the 139,056 subjects, 39,257 had NAFLD. In a multivariable-adjusted model, both prolonged sitting time and decreased physical activity level were independently associated with increasing prevalence of NAFLD. The prevalence ratios (95% CIs) for NAFLD comparing 5-9 and ⩾10 h/day sitting time to <5h/day were 1.04 (1.02-1.07) and 1.09 (1.06-1.11), respectively (p for trend <0.001). These associations were still observed in subjects with BMI <23 kg/m(2). The prevalence ratios (95% CIs) for NAFLD comparing minimally active and health-enhancing physically active groups to the inactive group were 0.94 (0.92-0.95) and 0.80 (0.78-0.82), respectively (p for trend <0.001). CONCLUSIONS Prolonged sitting time and decreased physical activity level were positively associated with the prevalence of NAFLD in a large sample of middle-aged Koreans, supporting the importance of reducing time spent sitting in addition to promoting physical activity.

A1C and Coronary Artery Calcification in Nondiabetic Men and Women

Objective—This study aimed to examine the association between glycohemoglobin (A1C) and coronary artery calcification (CAC) in nondiabetic men and women without overt cardiovascular disease or diabetes mellitus after accounting for fasting glucose and traditional cardiovascular disease risk factors. Approach and Results—A cross-sectional study was performed in 25 564 Korean adults (41.4±7.0 years) with no diabetes mellitus (fasting glucose, ≥7.0 mmol/L or a history of diabetes mellitus) and no clinically evident cardiovascular disease, who underwent a health checkup, including a cardiac computed tomography estimation of CAC scores and measurements of cardiovascular risk factors. The presence of CAC was defined as a CAC score >0; CAC was observed in 12.0% of men and 4.9% of women. Age-adjusted odds ratios (95% confidence interval) for CAC comparing A1C of 5.5% to 5.6%, 5.7% to 5.9%, and 6.0% to 6.4% with A1C <5.5% were 1.12 (0.99–1.28), 1.44 (1.27–1.63), and 1.63 (1.39–1.90) in men and 1.76 (0.96–3.25), 1.86 (1.05–3.29), and 3.09 (1.68–5.70) in women, respectively. After adjusting for potential confounders, the odds ratios (95% confidence interval) comparing A1C of 5.5% to 5.6%, 5.7% to 5.9%, and 6.0% to 6.4% with A1C of <5.5% were 1.04 (0.91–1.19), 1.21 (1.07–1.38), and 1.25 (1.05–1.48) in men and 1.75 (0.94–3.29), 1.59 (0.88–2.87), and 2.48 (1.29–4.74) in women, respectively. These associations persisted in subjects without any metabolic abnormalities, including fasting glucose ≥100 mg/dL. Conclusions—A higher A1C level was found to have a modest and independent association with the subclinical coronary atherosclerosis, even in metabolically healthy individuals.

Weekend catch-up sleep is associated with decreased risk of being overweight among fifth-grade students with short sleep duration

Previous studies have reported a relationship between short sleep duration and childhood overweight. Although school‐aged children tend to compensate for weekday sleep deficit by increasing weekend sleep duration, the association between weekend catch‐up sleep and childhood overweight remains unclear. This study aimed to examine the relationship between weekend catch‐up sleep and being overweight in children. A total of 936 school children (48.2% boys) aged 10 or 11 years participated in this school‐based cohort study. Anthropometric measurements including height and body weight were carried out. We obtained data on sleep patterns, lifestyle and parent characteristics using questionnaires. The main outcome measure was childhood overweight. After adjusting for the relevant confounding variables (age, sex, breakfast eating, screen time and parental obesity), longer sleep on weekdays and weekends was associated with decreased odds of childhood overweight (OR: 0.68; 95% CI: 0.54–0.86; OR: 0.64; 95% CI: 0.53–0.77, respectively). Participants with increased catch‐up sleep duration during weekends also had decreased odds of being overweight (OR: 0.67; 95% CI: 0.53–0.85). There was an interaction between weekday sleep duration and weekend catch‐up sleep in relation to childhood overweight, and this effect of weekend catch‐up sleep on being overweight was stronger as the participants slept less on weekdays (P = 0.024). These results indicate that weekend catch‐up sleep is independently associated with decreased risk of being overweight in fifth‐grade students, and this effect can be varied by the weekday sleep duration. A prospective study is required to confirm this observation.

Age at menarche and non-alcoholic fatty liver disease

BACKGROUND & AIMS The goal of this study was to examine the association between age at menarche and non-alcoholic fatty liver disease (NAFLD) in Korean women and to explore whether any observed associations were mediated by adult adiposity. METHODS A cross-sectional study was performed for 95,183 Korean women, aged 30 or older, who underwent a regular health screening examination between March 2011 and April 2013. Information regarding age at menarche was collected using standardized, self-administered questionnaires. The presence of fatty liver was determined using ultrasonographic findings. Poisson regression models with robust variance were used to evaluate the association between age at menarche and NAFLD. RESULTS Of the 76,415 women evaluated in this study, 9601 had NAFLD. Age at menarche was inversely associated with the prevalence of NAFLD. In a multivariable-adjusted model, the prevalence ratios (95% CIs) for NAFLD comparing menarche at <12, 12, 14, 15, and 16-18 years to menarche at 13 years were 1.31 (1.18-1.45), 1.05 (0.97-1.13), 0.93 (0.87-0.99), 0.87 (0.82-0.93), and 0.78 (0.73-0.84), respectively (p for trend <0.001). Adjusting for adult BMI or percent fat mass (%) substantially reduced these associations; however, they remained statistically significant. The association between age at menarche and NAFLD was modified by age. CONCLUSIONS We identified an inverse association between age at menarche and NAFLD in a large sample of middle-aged women. This association was partially mediated by adiposity. The findings of this study suggest that obesity prevention strategies are needed in women who undergo early menarche to reduce the risk of NAFLD.

Relationship Between Low Relative Muscle Mass and Coronary Artery Calcification in Healthy Adults

Objective—Sarcopenia or low muscle mass is related to cardiovascular risk factors; however, the association between low muscle mass and subclinical atherosclerosis has been largely unexplored. We investigated whether muscle mass is related to coronary artery calcification (CAC) in a large sample of middle-aged asymptomatic adults. Approach and Results—We performed a cross-sectional study of 31 108 asymptomatic adults without cancer, diabetes mellitus, or known cardiovascular disease who underwent a health checkup examination including cardiac tomography estimation of CAC scores between 2012 and 2013. Skeletal muscle mass index (SMI) [SMI (%)=total skeletal muscle mass (kg)/body weight (kg)×100] was estimated using a bioelectrical impedance analyzer. We assessed the relationship between SMI and CAC scores using both multivariate-adjusted Tobit models and multinomial logistic regression models. Of the 31 108 subjects, 3374 subjects (10.9%) had a CAC score 1 to 100, and 628 subjects (2.0%) had a CAC score >100. SMI was inversely associated with CAC score ratios. Specifically, in a multivariable-adjusted model adjusting for potential confounders, CAC score ratios (95% confidence intervals) of SMI for quartiles 1, 2, and 3 compared with quartile 4 were 2.27 (1.70–3.05), 1.46 (1.15–1.85), and 1.24 (0.98–1.55), respectively (P for trend <0.001). Adjusting for insulin resistance reduced the magnitude of the associations, but they remained statistically significant. Conclusions—Relative muscle mass was negatively associated with the prevalence of coronary calcification, supporting low muscle mass as an independent risk factor of coronary heart disease.

Menopausal stages and non-alcoholic fatty liver disease in middle-aged women

OBJECTIVES There is no established evidence regarding the influence of the menopausal transition period on non-alcoholic fatty liver disease (NAFLD). The goal of this study was to examine the association between menopausal stages and the prevalence of NAFLD in middle-aged Korean women. METHODS This study was a cross-sectional analysis of 1559 women aged 44-56 years, who underwent a comprehensive health screening examination in the Kangbuk Samsung Hospital Total Healthcare Centers during 2012 and 2013. Information regarding menopause status was collected using a standardized, self-administered questionnaire. The presence of fatty liver was determined using ultrasonography. Menopausal stages were defined according to the criteria of the Stages of Reproductive Aging Workshop (STRAW+10) as follows: early menopausal transition was defined as a persistent difference in consecutive menstrual cycle length of seven or more days; late menopausal transition was defined as having an interval of amenorrhea of 60 days or more; post-menopause was defined as the absence of menstrual periods for 12 or more months since the last period; pre-menopause was defined as having a regular menstrual cycle and not meeting the above criteria. Odds ratios and 95% confidence intervals for NAFLD were estimated by menopausal stages. RESULTS Of the 1559 women, 334 had NAFLD. A higher prevalence of NAFLD was observed across menopausal stages (p for trend <0.05). After adjusting for age, center, BMI, smoking status, alcohol intake, physical activity, educational level, parity and age at menarche, the odds ratios (95% CIs) for NAFLD comparing early transition, late transition, and post-menopause to pre-menopause were 1.07 (0.68-1.67), 1.87 (1.23-2.85), and 1.67 (1.01-2.78), respectively. CONCLUSIONS This study performed in middle-aged Korean women suggests that there is an increased prevalence of NAFLD in the late menopausal transition as well as post-menopausal stages, independent of a variety of potential confounders. The findings of this study suggest that early intervention strategies implemented before women begin to experience the menopausal transition are needed to reduce the risk of NAFLD.

Weight change as a predictor of incidence and remission of insulin resistance.

Objective The objective of this study was to assess the longitudinal relationship of weight change on incidence and remission of insulin resistance (IR). Methods We performed a cohort study in apparently healthy Korean men, 30 to 59 years of age, who underwent a health checkup and were followed annually or biennially between 2002 and 2009. The computer model of homeostasis model assessment, HOMA2-IR, was obtained at each visit, and IR was defined as HOMA2-IR ≥75th percentile. Results For IR development, 1,755 of the 6,612 IR-free participants at baseline developed IR (rate 5.1 per 100 person-years) during 34,294.8 person-years of follow-up. The hazard ratios (95% confidence intervals) for incident IR with weight changes of <−0.9 kg, 0.6–2.1 kg and ≥2.2 kg from visit 1 to visit 2 (average 1.8 years) compared to weight change of −0.9–0.5 kg (reference) were 0.78 (0.68–0.90), 1.19 (1.04–1.35) and 1.26 (1.11–1.44), respectively. This association persisted in normal-weight individuals or those without any metabolic syndrome traits and remained significant after introducing weight categories and confounders as time-dependent exposures (P-trend <0.001). For IR remission, 903 of 1,696 IR participants had no IR (remission rate 10.3 per 100 person-years) during 8,777.4 person-years of follow-up. IR remission decreased with increasing quartiles of weight change (P-trend <0.001) and this association persisted in normal-weight individuals. Conclusions Weight gain was associated with increased IR development and decreased IR remission regardless of baseline BMI status. Preventing weight gain, even in healthy and normal-weight individuals, is an important strategy for reducing IR and its associated consequences.

Effects of short-term chromium supplementation on insulin sensitivity and body composition in overweight children: randomized, double-blind, placebo-controlled study ☆

Excessive body weight is inversely associated with insulin sensitivity in children and adults. Chromium supplementation produces modest improvement in insulin sensitivity in adults. The aim of this study was to examine the beneficial effects of chromium supplementation on insulin sensitivity and body composition in overweight children simultaneously modifying lifestyle. Twenty-five overweight children aged 9-12 years were randomized to receive either 400 μg of chromium chloride or placebo in double-blind fashion, during a 6-week lifestyle modification regimen that included nutritional education and 3×90 min of aerobic physical activity weekly. Insulin sensitivity was demonstrated using homeostasis model assessment-insulin resistance and quantitative insulin sensitivity check index (QUICKI). Changes in body mass index (BMI; kg/m(2)), BMI Z-score, waist circumference, body composition and fasting plasma glucose were measured. Although no significant benefit of chromium supplementation over placebo was evident for BMI, BMI Z-score and fasting insulin level, children who received chromium chloride demonstrated more positive changes versus the placebo group in HOMA (-1.84±1.07 vs. 0.05±0.42, P=.05), QUICKI (0.02±0.01 vs. -0.002±0.01, P=.05), lean body mass (2.43±0.68 kg vs. 1.36±1.61 kg, P=.02) and percentage body fat (-3.32±1.29% vs. 0.65±1.05%, P=.04). The desirable effects of chromium supplementation on insulin sensitivity and body composition were more apparent in pre-pubertal children. These results suggest that short-term chromium supplementation can improve insulin sensitivity and body composition in overweight children.