Serum Fibroblast Growth Factor 21 Level After an Oral Fat Tolerance Test is Related to Postprandial Free Fatty Acid Level

Figures & data

Table 1 Comparison of Basic Characteristics of Participants in the Three Study Groups

Variable	NFT (n=52)	IFT (n=50)	HTG (n=56)	P
Age (years)	46.38±12.13	48.00±13.11	51.46±9.13	0.066
Male N (%)	24 (46)	29 (58)	27 (48)	0.442
BMI (kg/m^2)	24.30±4.17	26.51±3.84^#	28.29±4.15^##	<0.001
WC (cm)	82.50±11.06	89.86±10.73	95.34±10.08^##&&	<0.001
SBP (mmHg)	117.98±15.39	128.04±14.02	134.14±13.44^##&	<0.001
DBP (mmHg)	73.88±9.35	77.74±6.43^##	83.71±8.83^##&&	<0.001
TC (mmol/L)	4.59±0.98	4.78±0.81	5.28±0.97^##&	<0.001
TG (mmol/L)	0.96±0.48	1.36±0.73^#	2.70±0.84^##&&	<0.001
FFA (mmol/L)	0.50±0.30	0.83±0.47^##	1.15±0.45^##&&	<0.001
HDL-C (mmol/L)	1.37±0.28	1.25±0.32	1.22±0.28^#	0.029
LDL-C (mmol/L)	2.87±0.71	3.06±0.61	3.38±0.7^##	0.001
FBG (mmol/L)	5.12±0.48	5.20±0.48	5.42±0.48^#	0.005
FINS (uIU/mL)	7.92 (5.87–11.24)	10.00 (7.65–14.08)	13.28(9.82–16.08)^#&	<0.001
HOMA-IR	1.80 (1.32–2.76)	2.31(1.78,3.21)	3.12 (2.38–3.90)^##&	<0.001
FGF21 (pg/mL)	210.53 (159.78–365.13)	246.93 (179.56–344.43)	350.97 (220.65–539.77)^#&	0.001

Notes: Means ± SD for normally distributed variables or medians (interquartile range) for non–normally distributed variables. ^#P < 0.05 versus NFT group, ^##P < 0.001 versus NFT group, ^&P < 0.05 versus IFT group, ^&&P < 0.001 versus IFT group.

Abbreviations: NFT, normal fat tolerance group; IFT, impaired fat tolerance group; HTG, hypertriglyceridemia group; BMI, body mass index; DBP, diastolic blood pressure; FBG, fasting blood glucose; FFA, free fatty acid; FINS, fasting insulin; FGF21, fibroblast growth factor 21; HDL-C, high-density lipoprotein-cholesterol; HOMA-IR, homeostasis model assessment of insulin resistance; LDL-C, low-density lipoprotein-cholesterol; SBP, systolic blood pressure; TC, total cholesterol; TG, triglyceride; WC, waist circumference.

Figure 1 Relationship between fasting FFA, TG, and fasting LgFGF21. (A) Correlation between fasting FFA and LgFGF21. (B) Correlation between fasting TG and LgFGF21.

Abbreviations: FFA, free fatty acid; FGF21, fibroblast growth factor 21; TG, triglyceride.

Table 2 Comparison of Lipids Concentrations During the OFTT in the Three Groups

	0 h	2 h	4 h	6 h
TC (mmol/L)
NFT	4.59±0.98	4.53±0.97	4.50±0.93*	4.64±0.96
IFT	4.78±0.81	4.81±0.82	4.80±0.84	4.90±0.86*
HTG	5.28±0.97^##&	5.27±1.01^##&	5.42±1.06**^##&	5.58±1.03**^##
TG (mmol/L)
NFT	0.96±0.48	1.66±0.94**	1.65±0.98**	1.58±0.89**
IFT	1.36±0.73^#	2.44±0.75**^##	3.44±1.19**^##	2.91±1.25**^##
HTG	2.70±0.84^##&&	3.81±1.04**^##&&	5.06±1.27**^##&&	5.44±1.51**^##&&
FFA (mmol/L)
NFT	0.50±0.30	0.28±0.20**	0.77±0.30**	1.14±0.35**
IFT	0.83±0.47^##	0.69±0.61**^##	1.14±0.61**^##	1.31±0.59**
HTG	1.15±0.45^##&	0.99±0.35**^##&	1.36±0.41**^##&	1.48±0.41**^#
HDL (mmol/L)
NFT	1.37±0.28	1.38±0.29	1.31±0.27**	1.28±0.29**
IFT	1.25±0.32	1.25±0.31	1.19±0.31**	1.19±0.32**
HTG	1.22±0.28^#	1.21±0.26^#	1.16±0.25**^#	1.15±0.26**
LDL (mmol/L)
NFT	2.87±0.71	2.78±0.69**	2.74±0.66**	2.81±0.68*
IFT	3.06±0.61	3.02±0.62	2.95±0.60**	3.03±0.59
HTG	3.38±0.70^##&	3.30±0.71**^##	3.25±0.69**^##	3.31±0.69*^##

Notes: ^#P < 0.05 versus NFT group, ^##P < 0.001 versus NFT group, ^&P < 0.05 versus IFT group, ^&&P < 0.001 versus IFT group, *P < 0.05 versus 0 h in the same group, and **P < 0.001 versus 0 h in the same group.

Abbreviations: NFT, normal fat tolerance group; IFT, impaired fat tolerance group; HTG, hypertriglyceridemia group. FFA, free fatty acid; HDL-C, high-density lipoprotein-cholesterol; LDL-C, low-density lipoprotein-cholesterol; TC, total cholesterol; TG, triglyceride.

Figure 2 Changes in FFA and FGF21 levels after a high-fat diet in the three groups. (A) FFA. (B) FGF21.

Notes: FFA concentrations are shown as means; FGF21 levels are shown as medians, and statistical analysis was performed using logarithmic transformation. #P < 0.05 versus NFT group, ##P < 0.001 versus NFT group, ^&P < 0.05 versus IFT group, ^&&P < 0.001 versus IFT group, *P < 0.05 versus 0 h in the same group, and **P < 0.001 versus 0 h in the same group.

Abbreviations: NFT, normal fat tolerance group; IFT, impaired fat tolerance group; HTG, hypertriglyceridemia group. FFA, free fatty acid; FGF21, fibroblast growth factor 21.

Figure 3 Changes in other lipid levels after a high-fat diet in the three groups. (A) TG. (B) TC. (C) HDL-C. (D) LDL-C.

Notes: ^#P < 0.05 versus NFT group, ^##P < 0.001 versus NFT group, ^&P < 0.05 versus IFT group, ^&&P < 0.001 versus IFT group, *P < 0.05 versus 0 h in the same group, and **P < 0.001 versus 0 h in the same group.

Abbreviations: NFT, normal fat tolerance group; IFT, impaired fat tolerance group; HTG, hypertriglyceridemia group.

Table 3 Multiple Linear Regression Analysis of FGF21 iAUC

	B	B Standard Error	t	P value
Model 1
FFA iAUC	0.712	0.265	2.686	0.008
Model 2
FFA iAUC	0.788	0.265	2.972	0.003
Model 3
FFA iAUC	0.719	0.265	2.713	0.007

Notes: Model 1: without adjustment. Model 2: Based on Model 1, further adjusted for sex, age, SBP, DBP, and WC. Model 3: Based on Model 2, further adjusted for TC iAUC and HOMA-IR.