Trends in the high blood glucose and non-alcoholic fatty liver disease among Korean adolescents

Abstract

High blood glucose level and non-alcoholic fatty liver disease (NAFLD) in adolescents are long-term risk factors for cardiovascular diseases and poor prognosis. We investigated recent trends of high blood glucose levels and NAFLD among Korean adolescents aged 12–18 years. We conducted a cross-sectional analysis using data of 5,685 adolescents aged 12–18 years from the Korea National Health and Nutrition Examination Surveys (KNHANES), from 2007–2009 to 2016–2018. Linear trends in the prevalence of high blood glucose level, NAFLD, and associated factors were assessed using multivariable logistic regression analyses. During the study period, the odds ratios for high blood glucose level and NAFLD increased significantly in both sexes and in girls, respectively (p for trend <0.05). Over-consumption of total calories in boys and fat intake in boys and girls increased significantly (p for trend <0.05). In Korean adolescents, the prevalence of high blood glucose level and NAFLD has increased recently. Efforts to modify the associated factors and further research to determine the public health measures are warranted to prevent these metabolic abnormalities in adolescents.

AS IMPORTANT INDICATORS of altered glucose metabolism, impaired fasting glucose (IFG) and type 2 diabetes mellitus (T2DM) are rising problems in the adolescent population over the past three decades [1]. Patients with IFG are referred to as having pre-diabetes and are at risk for the future development of T2DM [2]. Data from the United States National Health and Nutrition Examination Survey (2005–2016) showed that the prevalence of adolescents with IFG was 11.1% [3]. In the United States, the incidence rate of T2DM increased by 7.1% annually among adolescents, from 9.0 cases per 100,000 per year in 2002–2003 to 12.5 cases per 100,000 per year in 2011–2012 [4]. High blood glucose level is a long-term risk factor for cardiovascular disease. It has a disrupting effect on young individuals during their most productive years and leads to increased healthcare costs [5].

Non-alcoholic fatty liver disease (NAFLD) is a chronic liver disease resulting from excessive fat accumulation in the liver. The prevalence of NAFLD among adolescents aged 12–17 years was 13% in the United States [6]. NAFLD in childhood and adolescence can cause progressive fibrosis and lead to end-stage liver disease [7]. Even in healthy adolescents, hepatic steatosis is associated with higher levels of fasting glucose, triglycerides, and insulin, regardless of body mass index (BMI) or total body fat mass [8]. In addition, NAFLD is associated with cardiometabolic risk factors [9]. Some studies showed a link between metabolic syndrome in the young and NAFLD [10], and the presence of NAFLD predicts the development of T2DM [11]. However, studies on frequency and trends in high blood glucose levels and NAFLD associated with insulin resistance in adolescents in Asian countries are insufficient. When compared to Caucasians, Asians are at a higher cardiovascular risk from diseases such as T2DM or insulin resistance at a given BMI [12]. The study that examined the trend of high blood glucose level, NAFLD, and associated factors among adolescents was minimal. Therefore, we investigated the recent trends of high blood glucose level, NAFLD, and associated factors among Korean adolescents aged 12–18 years using data from the Korea National Health and Nutrition Examination Survey (KNHANES), collected between 2007 and 2018.

Methods

We performed a cross-sectional study where we analyzed data on individuals who participated in the 4^th (2007–2009), 5^th (2010–2012), 6^th (2013–2015), and 7^th (2016–2018) KNHANES. The KNHANES is comprised of a health interview and nutrition and health examination surveys. It provides data on demographic characteristics, health behaviors, and health status collected through personal interviews, as well as data obtained from physical examinations along with blood sampling performed in mobile examination centers.

We included data on adolescents aged 12–18 years who participated in the KNHANES within the period of 2007 to 2018 (n = 8,087). We excluded subjects with congenital heart diseases (n = 54), those who had an energy intake of <500 kcal/day or >8,000 kcal/day (n = 42), and those who had any missing variables (n = 2,306). Finally, data of 5,685 adolescents (3,028 boys and 2,657 girls) were considered for analyses. We excluded adolescents with an energy intake of >8,000 kcal/day, referring to another study [13]. The survey was approved by the Institutional Review Board of Korea Centers for Disease Control and Prevention. Our study adhered to the principles of the Declaration of Helsinki.

The participants’ height was measured to the nearest 0.1 cm on a stadiometer (SECA 225, Hamburg, Germany). Body weight was measured to the nearest 0.1 kg on a balance scale (GL-6000-20, Cas, Yangju, Korea) with the participants. Waist circumference (WC) was measured at the midpoint between the bottom of the subcostal region and the top of the iliac crest using a fiberglass tape. BMI was calculated by dividing the weight (kg) by square of the height (m).

Three blood pressure (BP) determinations were obtained by standard methods with the participant in a sitting position using a mercury sphygmomanometer. Blood samples were collected in the morning after subjects fasted for at least 8 hours. Fasting blood glucose was analyzed using a reaction between glucose and adenosine triphosphate catalyzed by the enzyme hexokinase. The concentrations of triglycerides (TG), total cholesterol (TC), and high-density lipoprotein cholesterol (HDL-C) were also measured using an enzymatic method. Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were measured by automated analyzer with enzymatic methods. The low-density lipoprotein cholesterol (LDL-C) concentration was estimated using the Friedewald formula [14].

The participants were classified as normal weight, BMI of <85^th percentile; or overweight and obese, BMI of ≥85^th percentile [15]. Central obesity was defined as WC of ≥90^th percentile for age and sex, based on the 2007 Korean Growth Charts [16] in children between 10 and 16 years: ≥90 cm for boys and ≥85 cm for girls as a Korean-specific criteria [17] in adolescents aged ≥16 years. We defined high blood glucose levels as fasting blood glucose levels of ≥100 mg/dL [18]. We defined NAFLD as ALT level of ≥40 IU/L [19] and a negative test for hepatitis B surface antigen.

The total energy intake was estimated based on the KNHANES nutrition survey using the 24-hour recall method. The survey on nutritional intake of the KNHANES included the type and amount of all food eaten the day before the survey was filled out. Nutrient intake was evaluated according to the Korean nutrient intake standards. The daily total calorie requirements were calculated by multiplying the standard weight by 35 kcal; the standard weight of boys was determined as height (m²) × 22, and that of girls was calculated as height (m²) × 21 [20]. An energy intake exceeding 120% of the total energy requirement was defined as overconsumption. Overconsumption of fat was defined as that exceeding 30% of the total energy intake. Low-frequency exercisers were described as those who exercised <2 days/week. Smokers were defined as having smoked more than one or two cigarettes per day for their whole life. The household income level was divided into the lowest quartile group and the second lowest to highest quartile group.

We combined data from the 2007 to 2018 KNHANES based on the raw data analysis guidelines of KNHANES. Moreover, based on the complex sample design, we conducted all analyses by assigning a dispersed stratification estimation, stratification variables, and weighted sample values. Continuous variables were analyzed in the general linear model and were presented as the mean and standard error. Categorical variables were presented as ratios and standard errors and were analyzed by the Chi-square test per period. Trend analysis of high blood glucose level, NAFLD, overconsumption of energy, and overconsumption of fat was conducted based on data from the period 2007–2009. Multivariable logistic regression analysis was performed to determine the odds ratio (OR) of the periods 2010–2012, 2013–2015, and 2016–2018 and their 95% confidence intervals (CI) to examine the trends. A p-value of <0.05 was considered statistically significant. All analyses were performed using SPSS ver. 21.0 (IBM Corp., Armonk, NY, USA).

Results

The anthropometric and cardiometabolic parameters from 2007 to 2018 are presented in Table 1. In boys, the mean fasting blood glucose level increased significantly from 89.2 mg/dL to 92.6 mg/dL in the 2007–2009 and 2016–2018 survey periods (p for trend <0.001). The mean levels of body weight, WC, TC, HDL-C, LDL-C, and systolic BP revealed rising patterns over 10 years. In girls, fasting blood glucose increased significantly from 87.7 mg/dL to 89.9 mg/dL in the 2007–2009 and 2016–2018 survey periods (p for trend <0.001). The body weight, BMI, TC, HDL-C, LDL-C, and systolic BP showed rising patterns over the 12-year period. The serum TG levels in girls showed a decreasing pattern.

Table 1 Anthropometric and cardiometabolic parameters in Korean adolescents from 2007 to 2018

	Boys (n = 3,028)					Girls (n = 2,657)
	2007–2009	2010–2012	2013–2015	2016–2018	p for trend	2007–2009	2010–2012	2013–2015	2016–2018	p for trend
N	884	845	671	628		776	710	614	557
Body weight (kg)	61.4 ± 0.6	61.3 ± 0.6	63.1 ± 0.6	62.8 ± 0.6	0.046	52.6 ± 0.4	53.6 ± 0.5	54.7 ± 0.5	54.3 ± 0.5	0.004
Height (cm)	169.3 ± 0.4	169.5 ± 0.4	169.8 ± 0.3	170.3 ± 0.4	0.22	159.7 ± 0.3	160.1 ± 0.3	160.0 ± 0.3	160.3 ± 0.3	0.38
BMI (kg/m2)	21.3 ± 0.2	21.2 ± 0.2	21.8 ± 0.2	21.5 ± 0.2	0.068	20.6 ± 0.1	20.9 ± 0.2	21.3 ± 0.2	21.1 ± 0.2	0.007
WC (cm)	73.1 ± 0.5	72.3 ± 0.1	74.1 ± 0.5	74.0 ± 0.5	0.011	68.5 ± 0.4	68.4 ± 0.4	69.4 ± 0.4	69.0 ± 0.4	0.27
TC (mg/dL)	152.1 ± 1.1	151.0 ± 1.2	150.2 ± 1.1	159.1 ± 1.2	<0.001	161.4 ± 1.2	162.1 ± 1.2	164.1 ± 1.2	169.6 ± 1.3	<0.001
TG (mg/dL)	89.4 ± 2.4	83.4 ± 2.2	88.9 ± 2.4	85.6 ± 2.5	0.22	90.6 ± 2.3	83.1 ± 2.3	82.1 ± 1.8	88.8 ± 2.3	0.008
HDL-C (mg/dL)	47.3 ± 0.4	48.4 ± 0.4	49.2 ± 0.4	49.3 ± 0.4	0.002	50.7 ± 0.5	52.6 ± 0.5	53.4 ± 0.5	53.3 ± 0.5	<0.001
LDL-C (mg/dL)	86.9 ± 1.1	85.9 ± 1.0	83.3 ± 1.0	92.7 ± 1.1	<0.001	92.6 ± 1.1	93.0 ± 1.1	94.3 ± 1.1	98.5 ± 1.1	<0.001
Systolic BP (mmHg)	109.4 ± 0.5	110.9 ± 0.5	111.8 ± 0.5	111.7 ± 0.4	0.002	103.0 ± 0.5	104.6 ± 0.5	105.6 ± 0.4	106.0 ± 0.5	<0.001
Diastolic BP (mmHg)	69.2 ± 0.5	68.4 ± 0.4	67.5 ± 0.4	68.4 ± 0.4	0.044	66.4 ± 0.5	66.9 ± 0.4	66.7 ± 0.4	67.2 ± 0.4	0.68
Fasting glucose (mg/dL)	89.2 ± 0.6	88.7 ± 0.3	92.1 ± 0.4	92.6 ± 0.5	<0.001	87.7 ± 0.3	88.3 ± 0.4	89.6 ± 0.4	89.9 ± 0.3	<0.001
AST (IU/L)	20.0 ± 0.5	20.1 ± 0.4	19.5 ± 0.3	20.8 ± 0.5	0.16	16.8 ± 0.2	16.4 ± 0.2	16.5 ± 0.2	17.3 ± 0.3	0.079
ALT (IU/L)	17.8 ± 0.6	17.9 ± 0.8	17.6 ± 0.6	19.6 ± 1.2	0.50	12.3 ± 0.3	11.7 ± 0.4	11.9 ± 0.4	13.2 ± 0.6	0.15

BMI, body mass index; WC, waist circumference; TC, total cholesterol; TG, triglycerides; HDL-C, high-density lipoprotein cholesterol; LDL-C, low-density lipoprotein cholesterol; BP, blood pressure; AST, aspartate aminotransferase; ALT, alanine aminotransferase.

Data are presented as mean ± standard error.

Table 2 shows the patterns of lifestyle factors in Korean adolescents. Although the carbohydrate intake was decreased significantly, total energy, protein, and fat intakes revealed pertinent escalating trends both in boys and girls. In boys, the rate of overconsumption of total energy and fat intake increased significantly from 25.6% to 34.9% and from 16.2% to 22.1%, respectively (p for trend <0.05). In girls, the rate of overconsumption of total energy and fat increased significantly from 21.1% to 25.4% and from 14.9% to 23.5%, respectively (p for trend <0.05). Even though the smoking prevalence decreased in boys, the ambivalent trends of low-frequency exercise, obesity, and abdominal obesity were statistically insignificant.

Table 2 Patterns of lifestyle factors in Korean adolescents from 2007 to 2018

	Boys (n = 3,028)					Girls (n = 2,657)
	2007–2009	2010–2012	2013–2015	2016–2018	p for trend	2007–2009	2010–2012	2013–2015	2016–2018	p for trend
Total calorie (kcal)	2,170.4 ± 36.8	2,491.8 ± 42.1	2,556.9 ± 50.1	2,448.2 ± 43.7	<0.001	1,766.3 ± 33.6	1,912.8 ± 34.0	1,881.2 ± 34.9	1,851.5 ± 36.9	0.016
Protein (%)	14.3 ± 0.2	14.7 ± 0.2	14.3 ± 0.2	14.9 ± 0.2	0.029	13.9 ± 0.2	14.3 ± 0.2	14.2 ± 0.2	14.6 ± 0.2	0.067
Fat (%)	22.1 ± 0.4	23.1 ± 0.4	24.6 ± 0.4	24.1 ± 0.4	<0.001	21.9 ± 0.4	23.1 ± 0.5	23.8 ± 0.4	24.4 ± 0.5	<0.001
Carbohydrate (%)	63.4 ± 0.5	62.2 ± 0.5	59.4 ± 0.5	59.6 ± 0.5	<0.001	64.4 ± 0.5	62.9 ± 0.5	60.9 ± 0.5	60.0 ± 0.6	<0.001
Overconsumption of energy intake	25.6 (1.7)	36.0 (2.0)	38.1 (2.1)	34.9 (2.1)	<0.001	21.1 (2.1)	29.1 (2.1)	25.9 (2.0)	25.4 (2.1)	0.044
Overconsumption of fat intake	16.2 (1.7)	17.3 (1.6)	24.9 (1.9)	22.1 (1.8)	0.001	14.9 (1.7)	21.1 (2.0)	21.7 (2.0)	23.5 (2.1)	0.009
Low frequency of exercise	62.7 (1.9)	61.8 (2.2)	67.0 (2.1)	63.7 (2.3)	0.36	89.2 (1.3)	89.2 (1.5)	87.3 (1.3)	88.6 (1.4)	0.75
Smoking	21.5 (1.8)	25.8 (2.0)	24.7 (2.0)	15.5 (1.8)	0.001	9.5 (1.4)	10.9 (1.5)	10.5 (1.5)	6.1 (1.2)	0.077
Alcohol drinker	1.5 (0.5)	1.5 (0.5)	3.1 (0.8)	1.3 (0.5)	0.13	0.6 (0.3)	0.6 (0.4)	2.8 (0.8)	0.9 (0.5)	0.007
Income (lowest)	14.5 (1.6)	14.5 (1.6)	9.5 (1.5)	11.1 (1.5)	0.07	12.5 (1.7)	14.7 (2.2)	13.0 (1.6)	12.1 (1.8)	0.75
Obesity	8.4 (1.4)	8.0 (1.1)	10.4 (1.3)	11.9 (1.4)	0.75	17.7 (1.7)	19.2 (1.8)	19.2 (1.8)	21.2 (1.9)	0.52
Abdominal obesity	6.5 (1.1)	4.4 (0.9)	11.7 (1.4)	13.7 (1.6)	0.14	9.6 (1.3)	11.5 (1.5)	11.5 (1.5)	13.2 (1.6)	0.30

Data are presented as the mean ± standard error or percentage (standard error).

Fig. 1 presents the trends of high blood glucose levels and NAFLD prevalence in boys and girls, respectively. Although the trend of NAFLD prevalence in boys was not statistically significant from 2007 to 2018, the prevalence of high blood glucose levels increased significantly from 6.5% to 13.7% (p for trend <0.001). Conversely, in girls, even though the trends in the prevalence of high blood glucose levels were not statistically significant, the prevalence of NAFLD increased significantly from 0.2% to 2.6% during the period (p for trend = 0.012).

Fig. 1

Trends in the prevalence of high blood glucose level and non-alcoholic fatty liver disease (NAFLD) among adolescents from 2007 to 2018. a: Prevalence of high blood glucose level in boys, b: Prevalence of high blood glucose level in girls, c: Prevalence of NAFLD in boys, d: Prevalence of NAFLD in girls.

Multivariable logistic regression analyses of the ORs for the prevalence of high blood glucose level and NAFLD and the rate of overconsumption of total calories and fat in each survey period during the past 12 years are presented in Table 3. In boys, the ORs of high blood glucose levels increased significantly from 2.03 (95% CI: 1.30–3.17) to 2.30 (1.48–3.59) in the 2013–2015 and 2016–2018 survey periods (p for trend <0.001). The ORs of the overconsumption of total calories in the 2010–2012, 2013–2015, and 2016–2018 surveys showed a significant increase in all periods compared to those in the 2007–2009 period (p for trend <0.001). The ORs of the overconsumption of fat in the 2013–2015 and 2016–2018 surveys significantly increased compared to those in the 2007–2009 period (p for trend = 0.001).

Table 3 Results of multivariable analysis for high blood glucose level, NAFLD, and overconsumption of total energy and fat intake in Korean adolescents from 2007 to 2018

	Survey period	Boys			Girls
		OR (95% CI)	p-value	p for trend	OR (95% CI)	p-value	p for trend
High blood glucose level	2007–2009	1 (reference)		<0.001	1 (reference)		0.044
	2010–2012	0.68 (0.39–1.17)	0.16		1.22 (0.66–2.23)	0.53
	2013–2015	2.03 (1.30–3.17)	0.002		1.77 (0.98–3.19)	0.06
	2016–2018	2.30 (1.48–3.59)	<0.001		1.63 (0.90–2.93)	0.10
NAFLD	2007–2009	1 (reference)		0.137	1 (reference)		0.002
	2010–2012	1.39 (0.79–2.42)	0.25		6.26 (1.15–34.00)	0.03
	2013–2015	1.26 (0.71–2.25)	0.43		7.25 (1.38–38.21)	0.02
	2016–2018	1.60 (0.92–2.77)	0.096		12.23 (2.56–58.62)	<0.01
Overconsumption of total energy intake	2007–2009	1 (reference)		<0.001	1 (reference)		0.19
	2010–2012	1.64 (1.28–2.08)	<0.001		1.61 (1.18–2.18)	<0.01
	2013–2015	1.79 (1.40–2.30)	<0.001		1.32 (0.97–1.80)	0.08
	2016–2018	1.58 (1.23–2.02)	<0.001		1.33 (0.96–1.83)	0.09
Overconsumption of fat intake	2007–2009	1 (reference)		0.001	1 (reference)		0.004
	2010–2012	1.09 (0.78–1.52)	0.60		1.53 (1.07–2.19)	0.02
	2013–2015	1.73 (1.25–2.41)	0.001		1.50 (1.05–2.15)	0.03
	2016–2018	1.51 (1.09–2.11)	0.015		1.71 (1.21–2.42)	<0.01

NAFLD, non-alcoholic fatty liver disease; OR, odds ratio; CI, confidence interval.

The results were calculated by multivariable logistic regression analysis after adjustment for age, alcohol consumption, smoking status, income, and exercise.

In girls, the ORs of high blood glucose levels showed a tendency to increase over the study period (p for trend = 0.044). The ORs of NAFLD prevalence during the 2010–2012, 2013–2015, and 2016–2018 survey periods were 6.26 (95% CI: 1.15–34.00), 7.25 (1.38–38.21), and 12.23 (2.56–58.62), respectively, which displayed a significant increase as compared to those during the 2007–2009 period (p for trend = 0.002). The ORs of the overconsumption of fat in the 2010–2012, 2013–2015, and 2016–2018 surveys showed a significant increase compared to those in the 2007–2009 period (p for trend = 0.004) and exhibited an increasing trend during the 12 years of study period.

Discussion

In this study, we investigated recent trends in the prevalence of high blood glucose levels and NAFLD among Korean adolescents aged 12–18 years over the last 12 years. During the study period, the ORs for high blood glucose levels and NAFLD prevalence significantly increased in boys, with a similar trend for the ORs of NAFLD prevalence in girls. As contributing lifestyle factors, overconsumption of total energy in boys and overconsumption of fat both in boys and girls showed significant escalating patterns.

In a study of American teenagers, the prevalence of fasting glucose levels ≥100 mg/dL was 11.1% from 1999 to 2002 [20] and the prevalence of prediabetes was 18% from 2005–2016 [3]. In a study using KNHANES data, the prevalence of high fasting glucose in boys and girls in 2005 was 3.3% and 2.9%, respectively [21]. Our study showed that the prevalence of high blood glucose levels in 2007–2009 was 6.5% and 3.9% in boys and girls, respectively, and that in 2016–2018 was 13.7% and 6.1%, respectively, all of which were higher than that in 2005. In another study, the prevalence of high blood glucose levels in boys was higher than that in girls, and the difference was almost twice as high in recent years [22].

As increased hepatic fat is associated with insulin resistance which is one of the basic compensatory mechanisms, increased insulin secretion leads to hyperinsulinemia [23]. Hyperinsulinemia also plays a major role in the formation of fatty liver in childhood obesity, and the degree of fatty changes, inflammation, and fibrosis can be predicted by elevated insulin levels in the blood [24]. In addition, intracellular lipid accumulation may have deleterious effects on the liver. Such toxic effects are presumed to occur through insufficient mitochondrial and peroxisomal β-oxidation [25]. The goal of the treatment for NAFLD is to lower excess adiposity to improve dyslipidemia, insulin resistance, high blood glucose level, and central adiposity [26]. Therefore, it is necessary to manage NAFLD in adolescents to prevent impaired glucose metabolism.

Our study showed that the prevalence of NAFLD in 2007–2009 was 3.8% and 0.2% in boys and girls, respectively, and that in 2016–2018 was 6.5% and 2.6%, respectively. The prevalence trends were only significantly different in girls, but the prevalence was higher in boys than in girls. The prevalence of NAFLD in children was 9% to 37% [27]. The wide range exists because of the cutoffs of the concentrations of liver enzymes which define NAFLD in adolescents. In this population, it is difficult to assess NAFLD accurately due to a lack of simple and non-invasive diagnostic tests [28]. The gold standard for diagnosing NAFLD and its severity is liver biopsy, but this is neither feasible nor ethical for use in healthy adolescents [29]. One study conducted in adolescents with obesity estimated the sensitivity and specificity for the prediction of NAFLD with serum ALT level of ≥40 IU/L to be 41% and 89%, respectively. Therefore, in our study, we classified NAFLD according to this definition [30]. However, using ALT may under-estimate NAFLD prevalence in adolescents with obesity, and over-estimate prevalence in adolescents with normal weight.

In our study, rates of overconsumption of total energy increased significantly in adolescents during the 2016–2018 survey period as compared to that in the 2007–2009 period. The rate of overconsumption of fat also increased significantly during the same period. Our results suggest that the increasing trend in high blood glucose levels and NAFLD could be attributed to the trends of increasing total energy and fat intake. Eating habits can also affect high blood glucose levels and NAFLD, and thus patient education regarding healthy eating habits is necessary [31].

This study has several limitations. First, high blood glucose level was defined based on a single test, and we could not exclude some errors because of the extreme daily fluctuations. Second, even though we used the most common definition of NAFLD in adolescents, it could be inconsistent with the biopsy findings. Third, because the health status and lifestyle of participants were based on self-reported questionnaires, the data could be subjected to recall bias. Also, the 24-hour recall method for calculating calorie intake was not an overall average because of the stark daily variations. In addition, although we might have considered some of the factors that influenced the study outcomes, all confounding variables were not likely accounted for. Despite these shortcomings, our study demonstrates that the prevalence of high blood glucose level and NAFLD as important metabolic disturbances in adolescents, have increased in recent years.

Conclusion

The prevalence of high blood glucose levels and NAFLD in Korean adolescents has increased significantly in recent years, which is accompanied by overconsumption of total energy and fat. To prevent an increase in the prevalence of high blood glucose level and NAFLD in adolescents, it is necessary to manage factors that affect these diseases. Further research to determine the public health measures and clinical collaborations is required for combating these metabolic diseases in adolescents.

Abbreviations

IFG, Impaired fasting glucose; T2DM, type 2 diabetes mellitus; NAFLD, non-alcoholic fatty liver disease; BMI, body mass index; KNHANES, Korea National Health and Nutrition Examination Survey; WC, waist circumference; BP, blood pressure; TG, triglycerides; TC, total cholesterol; HDL-C, high-density lipoprotein cholesterol; AST, aspartate aminotransferase; ALT, alanine aminotransferase; LDL-C, low-density lipoprotein cholesterol; OR, odds ratio; CI, confidence interval

Acknowledgments

None.

Disclosure

The authors have no conflict of interest to disclose.

Funding

This study was supported by the Korean Ministry of Education, Science, and Technology (grant no. 2017030666).

Authors’ Contributions

Y.H. acquired data, wrote the original draft manuscript, and contributed to the statistical analysis. H.S.P. acquired data, wrote the original draft manuscript, discussed the results, and reviewed/commented on the manuscript. G.E.N. discussed the results and reviewed/commented on the manuscript. J.L commented on the manuscript. All authors were responsible for study concept and design, analysis, interpretation of data, and critical revision of the manuscript for intellectual content. All authors agreed to accept equal responsibility for the accuracy and content of the paper. All authors approved the final manuscript as submitted and agree to be accountable for all aspects of the work.

Data Availability Statement

All data underlying the authors’ findings in this study are freely available in Korea Centers for Disease Control and Prevention. If interested in requesting these data, please visit the following link for more information: https://knhanes.cdc.go.kr/knhanes/main.do

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