High L-Valine Concentrations Associate with Increased Oxidative Stress and Newly-Diagnosed Type 2 Diabetes Mellitus: A Cross-Sectional Study

Figures & data

Table 1 Multiple Linear Regression Analyses of the Relationship Between BCAAs and SOD(A) or MDA(B) in Different Glucose Metabolism Groups

A Independent Variable	Total (n=816)		NGM (n = 380)		Prediabetes (n = 334)		NDM (n = 102)
	β ± SE	P value	β ± SE	P value	β ± SE	P value	β ± SE	P value
Model 1
BCAAs	−0.028 ± 0.03	0.369	−0.012± 0.05	0.841	0.051 ± 0.059	0.388	−3.639 ± 1.152	0.001
L-Leu	−0.089 ± 0.074	0.232	−0.05 ± 0.123	0.684	−0.111 ± 0.136	0.415	−0.643 ± 0.249	0.040
L-Ile	−0.214 ± 0.141	0.129	−0.139 ± 0.216	0.520	−0.214 ± 0.260	0.411	−1.023 ± 0.512	0.048
L-Val	−0.009 ± 0.065	0.895	−0.017 ± 0.104	0.871	−0.087 ± 0.126	0.491	−0.437 ± 0.230	0.030
Model 2
BCAAs	0.014 ± 0.034	0.667	0.023 ± 0.052	0.213	0.101 ± 0.064	0.119	−3.312 ± 1.359	0.016
L-Leu	0.002 ± 0.079	0.992	0.064 ± 0.134	0.926	0.074 ± 0.126	0.921	−0.575± 0.270	0.076
L-Ile	0.059 ± 0.151	0.694	−0.038 ± 0.227	0.896	0.413 ± 0.281	0.142	−0.473 ± 0.292	0.102
L-Val	0.075 ± 0.070	0.285	0.064 ± 0.134	0.457	0.181 ± 0.136	0.147	−0.505 ± 0.262	0.036
B Independent variable	Total (n=816)		NGM (n = 380)		Prediabetes (n = 334)		NDM (n = 102)
	β ± SE	P value	β ± SE	P value	β ± SE	P value	β ± SE	P value
Model 1
BCAAs	0.028 ± 0.03	0.369	0.100 ± 0.033	0.001	0.045 ± 0.023	0.027	0.036 ± 0.024	0.381
L-Leu	0.089 ± 0.074	0.232	0.005 ± 0.007	0.440	0.005 ± 0.004	0.344	0.005 ± 0.004	0.286
L-Ile	0.214 ± 0.141	0.129	−0.009 ± 0.016	0.998	0.003 ± 0.004	0.702	0.019 ± 0.009	0.427
L-Val	0.020 ± 0.003	<0.001	0.023 ± 0.06	< 0.001	0.017 ± 0.006	< 0.001	0.017 ± 0.04	0.040
Model 2
BCAAs	0.004 ± 0.001	<0.001	0.008 ± 0.003	0.054	0.006 ± 0.002	0.010	−0.006 ± 0.002	0.295
L-Leu	0.014 ± 0.005	0.124	0.007 ± 0.120	0.926	0.008 ± 0.112	0.234	0.003 ± 0.007	0.698
L-Ile	0.007 ± 0.006	0.248	0.004 ± 0.013	0.770	0.008 ± 0.010	0.436	0.019 ± 0.010	0.325
L-Val	0.022 ± 0.004	<0.001	0.024 ± 0.006	0.001	0.020 ± 0.005	<0.001	0.024 ± 0.009	0.022

Notes: Model 1: adjusted for age, gender and body mass index; Model 2: adjusted for age, gender, body mass index, systolic blood pressure, diastolic blood pressure, fasting blood glucose, total cholesterol, Ln (triglyceride), high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, serum uric acid, smoking status and hypertension. The bold format serves as an emphasis note. Values were regression coefficient (β) ± standard error (SE). Definitions of NGM (normal glucose metabolism), prediabetes and T2DM (Type 2 diabetes) were in methods.

Abbreviations: BCAAs, branched-chain amino acids; SOD, superoxide dismutase.

Table 2 Characteristics of the Study Participants (n=816)

	NGM (n = 380)	Prediabetes (n = 334)	NDM (n = 102)	P value
Male (%)	123 (32.4)	121 (36.2)	35 (34.7)	0.096
Age (years)	57.56 ± 5.79	59.38 ± 5.79	60.08 ± 6.21	< 0.001
Smoking (%)	58 (15.2)	57 (17.1)	18 (17.3)	0.577
Hypertension (%)	75 (19.6)	124 (37.1)	36 (35.6)	0.033
WC (cm)	81.26 ± 8.88	84.22 ± 9.58	87.24 ± 13.97	< 0.001
BMI (kg/m2)	23.87 ± 2.90	24.70 ± 3.05	26.18 ± 4.21	< 0.001
SBP (mmHg)	141.46 ± 20.11	139.42 ± 19.31	139.93 ± 19.64	0.597
DBP (mmHg)	84.75 ± 13.94	83.81 ± 13.31	84.27 ± 13.19	0.073
TC (mmol/L)	5.11 ± 0.82	5.26 ± 0.85	5.27 ± 0.99	0.008
TG (mmol/L)	1.55 (0.50, 8.22)	1.79 (0.58, 7.43)	1.85 (0.83, 12.5)	< 0.001
HDL-C (mmol/L)	1.47 ± 0.65	1.33 ± 0.38	1.29 ± 0.30	< 0.001
LDL-C (mmol/L)	2.68 ± 0.68	2.87 ± 0.71	2.85 ± 0.79	< 0.001
SUA (mmol/L)	271.09 ± 76.87	293.68 ± 78.21	295.94 ± 78.04	< 0.001
BUN (mmol/L)	5.11 ± 1.39	5.07 ± 1.21	4.95 ± 1.33	0.282
Serum creatinine (mg/dL)	0.79 ± 0.17	0.78 ± 0.16	0.79 ± 0.18	0.656
eGFR (mL/min per 1.73 m^2)	90.51 ± 13.76	91.03 ± 13.25	90.20 ± 14.77	0.540
HbA1c (%)	5.32 (4.3,5.6)	6.04 (5.0,6.4)	7.14 (6.0,11.8)	< 0.001
FPG (mmol/L)	5.06 ± 0.31	5.62 ± 0.57	7.35 ± 2.42	< 0.001
BCAAs
L-Leu (μg/mL)	25.57 ± 5.13	26.64 ± 5.43	27.74 ± 5.11	< 0.001
L-Ile (μg/mL)	12.68± 2.97	13.22± 2.91	13.67± 2.51	< 0.001
L-Val (μg/mL)	30.75± 12.12	31.48± 5.81	32.47± 5.57	< 0.001
MDA (nmol/L)	0.86 ± 0.71	0.83 ± 0.47	0.95 ± 0.43	0.023
SOD (u/mL)	59.53± 12.12	56.39 ± 13.46	56.98± 12.39	0.040

Notes: Data were presented as means (±SD) or median with range (minimum, maximum) as appropriate, and categorical variables are expressed as number (%). Comparisons between the three groups were made using ANOVA or Fisher’s exact test, as appropriate. P values testing the overall difference among different glucose metabolism groups. International system of units (SI) conversion: serum creatinine, 1mg/dl=88.41umol/L.

Abbreviations: NGM, normal glucose metabolism; NDM, newly diagnosed diabetes; WC, waist circumference; BMI, body mass index; SBP, systolic blood pressure; DBP, diastolic blood pressure; HDL-C, high density lipoprotein cholesterol; LDL-C, low density lipoprotein cholesterol; FPG, fasting plasma glucose; HbA1c, hemoglobin A1c; TG, triglycerides; TC, total cholesterol; SUA, serum uric acid; BUN, urea nitrogen; e-GFR, estimated glomerular filtration rate; L-Leu, L-leucine; L-Ile, L-isoleucine; L-Val, L-valine; FPG, fasting plasma glucose; HbA1c, glycated hemoglobin; BCAAs, branched-chain amino acids; SOD, superoxide dismutase; MDA, malondialdehyde.

Table 3 Comparison of Clinical Parameters According to the Level of L-Val Quartiles (n=816)

Characteristics	L-Val (μg/mL)
	I	II	III	IV	P-value
	(<27.26, n=203)	(27.26–31.12, n=205)	(31.12–35.25, n=204)	(≥35.25 n=204)	Unadjusted	Model 1	Model 2	Model 3
L-Val (μg/mL)	24.04± 2.52	29.21 ±1.19	32.83± 1.09	38.91 ± 3.63	<0.001	<0.001	<0.001	<0.001
Male, n (%)	51 (25.1)	72 (35.1)	78 (38.2)	73 (35.2)	0.027	–
Age (years)	58.15 ± 6.49	58.86 ± 5.82	59.43 ± 5.67	58.84 ± 6.25	0.111	–
Current smoking, n (%)	23 (11.3)	31 (15.1)	43 (38.2)	37 (18.1)	0.0407	–
Hypertension, n (%)	52 (25.6)	54 (26.1)	70 (34.3)	64 (31.4)	0.166	–
WC (cm)	81.43 ± 9.88	83.77 ± 9.97	85.39 ± 9.66	84.32 ± 10.00	<0.001	<0.001
BMI (kg/m^2)	23.95 ± 3.18	24.27 ± 3.24	24.98 ± 3.43	24.91 ± 3.73	<0.001	<0.001
SBP (mmHg)	140.05 ± 19.16	141.44±20.37	137.98± 19.91	142.73 ± 21.87	0.987	–
DBP (mmHg)	85.25 ± 13.23	84.93 ± 14.17	82.68 ± 16.07	83.69 ± 14.01	0.482	–
FPG (mmol/L)	5.34 ± 0.73	5.50 ± 0.96	5.55 ± 1.01	5.82 ± 1.67	<0.001		<0.001
HbA1c (%)	5.50 (5.1, 7.4)	5.50 (5.1, 8.6)	5.86 (5.1, 11.2)	5.90 (5.1, 11.8)	0.002		<0.001
TC (mmol/L)	5.23 ± 0.97	5.13 ± 0.83	5.25 ± 0.88	5.11 ± 0.74	0.334	–
TG (mmol/L)	1.48 (0.60,7.40)	1.60 (0.50, 6.40)	1.80 (0.62,12.50)	1.89 (0.58,8.22)	<0.001			0.008
LDL-C (mmol/L)	2.83 ± 0.78	2.73 ± 0.66	2.81 ± 0.69	2.74 ± 0.69	0.438	–
HDL-C (mmol/L)	1.45 ± 0.44	1.38 ± 0.41	1.29 ± 0.48	1.34 ± 0.65	0.020			0.167
SUA (mmol/L)	270.12 ± 74.17	282.46 ± 81.99	291.58 ± 81.93	299.06 ± 86.56	<0.001	<0.001	0.052	0.096
BUN (mmol/L)	5.11 ± 1.32	5.02 ± 1.31	5.26 ± 1.21	5.23 ± 1.39	0.106
Serum creatinine (μmol/L)	69.01 ± 13.93	70.52 ± 15.59	69.82 ± 13.19	71.16 ± 16.72	0.278	–
eGFR (ml/min/1.73 m^2)	90.88 ± 21.32	91.95 ± 13.14	90.09 ± 14.56	90.79 ± 13.72	0.634	–
SOD (u/mL)	58.26 ± 12.6	60.12 ± 11.87	57.64± 12.76	57.19 ± 13.0	0.553	–
MDA (nmol/L)	0.72± 0.52	0.85 ± 0.47	0.88 ± 0.49	1.01 ± 0.83	<0.001	<0.001	<0.001	<0.001
NDM	14 (6.9)	22 (10.7)	26 (12.7)	40 (19.6)	<0.001

Notes: Data were presented as means (±SD) and categorical variables are expressed as number (%). Means and proportions were compared by ANCOVA, and categorical variables were compared by the chi-square test respectively. P values testing the overall difference among L-Val quartiles. Model 1: adjusting for age, gender, SBP, DBP, LnTG, HDL-C, FPG and smoking status. Model 2: adjusting for age, gender, BMI, SBP, DBP, LnTG, HDL-C and smoking status. Model 3: adjusting for age, gender, SBP, DBP, HOMA-IR and smoking status. TG which is not normal distribution were analyzed by logarithmic transformation. Definitions of T2DM, NDM and L-Val quartiles were in methods.

Abbreviations: L-Val, L-valine; T2DM, type 2 diabetes mellitus; NDM, newly diagnosed diabetes mellitus; WC, waist circumference; BMI, body mass index; SBP, systolic blood pressure; DBP, diastolic blood pressure; HDL-C, high density lipoprotein cholesterol; LDL-C, low density lipoprotein cholesterol; FPG, fasting plasma glucose; HbA1c, hemoglobin A1c; TG, triglycerides; TC, total cholesterol; SUA, serum uric acid; eGFR, estimated glomerular filtration rate; SOD, superoxide dismutase; MDA, malondialdehyde; HOMA-IR, homeostasis model assessment of insulin resistance.

Figure 1 Association between L-Val, MDA and HOMA-IR.

Table 4 Multiple Logistic Regression Analyses of the Relationship Between L-Val, MDA and NDM

Independent Variable	Model 1		Model 2		Model 3
	OR (95% CI)	P-value	OR (95% CI)	P-value	OR (95% CI)	P-value
L-Val (μg/mL)	1.08 (1.04–1.11)	<0.001	1.08 (1.03–1.12)	0.001	1.06 (1.02–1.10)	0.005
L-Val
I	1		1		1
II	1.62 (0.81–3.27)	0.175	1.47 (0.79–3.26)	0.297	1.62 (0.77–3.44)	0.205
III	1.97 (0.998–3.89)	0.051	1.35 (0.71–3.05)	0.415	1.25 (0.59–2.64)	0.562
IV	2.61 (1.47–4.61)	0.001	2.37 (1.20–4.69)	0.013	2.25 (1.11–4.57)	0.024

Notes: Model 1: un-adjusting. Model 2: adjusting for age, gender BMI and MDA. Model 2: adjusting for age, gender, BMI, MDA, SBP, DBP, TC, TG, HDL-C, LDL-C, eGFR and smoking status. Definitions of T2DM were in statistical analysis. Classifying patients into four sub-groups on the basis of the level of L-Val quartiles.

Abbreviations: CI, confidence interval; L-Val, L-valine; MDA, malondialdehyde; T2DM, type 2 diabetes.