Characteristics of the study population
The clinical characteristics of the 110 pregnant women at 20–29 weeks’ gestation were presented in Table 1. A total of 43 women with GDM (age, 30.98±4.63 years) and 67 women without GDM (age, 29.10±3.63 years) were included. Women with GDM were older and had higher pre-BMI than the non-GDMs. Subjects in the GDM group had higher glucose levels in all three time points during OGTT. There were also significant differences in SBP and DBP between the two groups.
Table 1
Characteristics of the study population
|
GDM (n=43)
|
Non-GDM (n=67)
|
P
|
Age (years)
|
30.98±4.63
|
29.10±3.63
|
0.02
|
Pre-weight (kg)
|
70.93±11.70
|
55.25±8.04
|
<0.001
|
Pre-BMI (kg/m2)
|
27.69±4.76
|
21.33±3.01
|
<0.001
|
Gestational age (days)
|
180.86±13.67
|
171.78±6.69
|
<0.001
|
SBP (mmHg)
|
120.40±14.90
|
106±11.95
|
<0.001
|
DBP (mmHg)
|
75.4±9.89
|
67.75±8.48
|
<0.001
|
HbA1c (%)
|
5.37±0.55
|
4.77±0.36
|
<0.001
|
Fasting glucose (mmol/L)
|
5.53±1.00
|
4.07±0.40
|
<0.001
|
1-h glucose (mmol/L)
|
11.64±1.91
|
7.37±1.31
|
<0.001
|
2-h glucose (mmol/L)
|
9.43±1.78
|
6.06±1.08
|
<0.001
|
Continuous variables with a normal distribution or approximate normal distribution were represented as mean±standard deviation; Comparisons between the non-gestational diabetes mellitus (non-GDM) and the GDM groups were performed using student’s t-test. The statistically significant difference was defined as P < 0.05.
BMI, body mass index; SBP, systolic blood pressure; DBP, diastolic blood pressure; HbA1c, hemoglobin A1c; OGTT, oral glucose tolerance test; 1-h glucose, one-hour glucose at OGTT; 2-h glucose, two-hour glucose at OGTT.
Comparison of serum amino acid concentrations during an oral glucose tolerance test between women with gestational diabetes mellitus (GDM) and women without GDM (non-GDM)
We examined the amino acid concentrations in each group (Table 2). There was no significant difference between the GDM group and non-GDM group in fasting status. After a 75-g OGTT, amino acids levels differed between the GDM group and non-GDM group. All of the 1-h amino acids in the GDM group, including Val, Leu, Ile and Tyr, Phe, were higher than those in the non-GDM group. Moreover, except for Phe, amino acids at 2-h showed similar results as those at 1-h.
Table 2
Comparisons of serum amino acid concentrations in the non-gestational diabetes mellitus (non-GDM) and GDM during an oral glucose tolerance test (OGTT)
Amino acids (µmol/L)
|
GDM (n=43)
|
Non-GDM (n=67)
|
P
|
0-Val
|
199.62±33.15
|
201.8±24.69
|
0.694
|
1-h Val
|
200.32±32.33
|
170.14±22.74
|
<0.001
|
2-h Val
|
166.65±27.86
|
151.31±20.92
|
0.001
|
0-Leu
|
119.91±20.64
|
120.70±14.02
|
0.810
|
1-h Leu
|
118.30±22.33
|
92.52±12.12
|
<0.001
|
2-h Leu
|
89.56±16.21
|
77.91±11.76
|
<0.001
|
0-Ile
|
60.93±9.91
|
59.04±7.81
|
0.266
|
1-h Ile
|
62.04±14.53
|
42.37±6.85
|
<0.001
|
2-h Ile
|
45.04±10.64
|
33.10±6.25
|
<0.001
|
0-Tyr
|
42.16±7.40
|
44.22±6.42
|
0.125
|
1-h Tyr
|
46.73±8.16
|
35.85±5.89
|
<0.001
|
2-h Tyr
|
38.52±7.60
|
29.42±5.34
|
<0.001
|
0-Phe
|
91.39±19.29
|
91.17±12.96
|
0.947
|
1-h Phe
|
87.72±14.20
|
80.30±12.20
|
0.004
|
2-h Phe
|
78.53±14.16
|
74.53±11.37
|
0.105
|
Values were expressed as mean ± standard deviation. Comparisons between the non-gestational diabetes mellitus (non-GDM) and GDM groups were performed using student’s t-test. The statistically significant difference was defined as P < 0.05.
Val, valine; Leu, leucine; Ile, isoleucine; Tyr, tyrosine; Phe, phenylalanine; 0, fasting; 1-h, one- hour at OGTT; 2-h, two-hour at OGTT
The Amino Acid Changes during the oral glucose tolerance test (OGTT)
The amino acid changes during the OGTT in the GDM group and non-GDM group were illustrated in Figures 1–3. Compared with the baseline levels, all the amino acids at 2-h significantly reduced after the OGTT in both groups(Fig. 1A,B). We also described the percent changes and significance of changes in both groups(Fig. 2A,B) and specific results were available in Table S1. In the GDMs, compared to baseline, Val, Leu, Ile and Phe at 1-h didn’t show any difference and reduced significantly at 2-h ranging from 12.75%-25.30%. Tyr primarily increased by 12.56% at 1-h and lowed by 7.59% at 2-h. In the non-GDMs, compared to baseline, all the amino acids initially decreased small during 1-h and became more pronounced during 2-h. On the other hand, our results revealed that the percent change in Ile was 43.90% in the non-GDM group which was largest among the amino acids. Similarly, the largest percent change was also Ile in the GDM group. Furthermore, we compared the percent changes in the two groups (Fig. 3) and specific results were seen in Table S2. Pronounced differences were observed after glucose ingestion between the two groups. Val, Leu, Ile and Phe showed a delayed decrease in the GDMs compared to the non-GDMs; within the first hour there was no significant decrease in Val, Leu, Ile and Phe in the GDMs. At 2-h, the GDMs displayed smaller decrease in all five amino acids compared with the non-GDMs.
The odds ratio (OR) for the association of amino acids with gestational diabetes mellitus (GDM)
Logistic regression model was used to analyze the risks of amino acids levels (fasting and 2-h change of amino acids) for GDM (Table 3). In the cruel model, the risks of fasting BCAAs (Val, Leu, and Ile) and fasting AAAs (Tyr and Phe) for GDM were insignificant. We further discovered that 2-h change of BCAAs and AAAs for GDM were evidently significant. These significant associations remained the same or became slightly attenuated after adjustment for age and gestational age. By contrast, the associations were moderately attenuated after further adjusting for pre-BMI. The OR of 2-h change of Val, Ile, Tyr for GDM still exsited while 2-h response of Leu, Phe disappeared.
Table 3
The cruel and adjusted logistic regression model of amino acids with gestational diabetes mellitus
|
Fasting
|
|
|
2h-change
|
|
|
Beta(95% C.I.)
|
Beta(95% C.I.)
|
Beta(95% C.I.)
|
Beta(95% C.I.)
|
Beta(95% C.I.)
|
Beta(95% C.I.)
|
Model 1
|
Model 2
|
Model 3
|
Model 1
|
Model 2
|
Model.3
|
Val
|
0.997 (0.984,1.011)
|
1.001 (0.985,1.017)
|
0.991 (0.971,1.010)
|
1.061 (1.031,1.092)***
|
1.060 (1.027,1.093)***
|
1.035 (1.001,1.070)*
|
Leu
|
0.997 (0.975,1.020)
|
1.002 (0.974,1.030)
|
0.985 (0.952,1.018)
|
1.070 (1.034,1.106)***
|
1.071 (1.029,1.115)**
|
1.040 (0.996,1.085)
|
Ile
|
1.026 (0.981,1.073)
|
1.019 (0.966,1.075)
|
0.970 (0.906,1.038)
|
1.149 (1.084,1.218)***
|
1.157 (1.082,1.238)***
|
1.108 (1.028,1.194)**
|
Tyr
|
0.955 (0.901,1.013)
|
0.952 (0.891,1.018)
|
0.942 (0.867,1.024)
|
1.445 (1.255,1.665)***
|
1.423 (1.227,1.650)***
|
1.302 (1.118,1.516)**
|
Phe
|
1.001 (0.977,1.026)
|
1.000 (0.972,1.028)
|
0.990 (0.957,1.024)
|
1.044 (1.001,1.089)**
|
1.044 (0.996,1.095)
|
1.017 (0.964,1.073)
|
Results are based on analyses of the study population (43 women with gestational diabetes mellitus (GDM) and 67 women without GDM(non-GDM)).
Values represent regression coefficients from the logistic regression analyses and their 95% confidence intervals (C.I.) for the risk of GDM
The statistically significant difference was defined as P < 0.05. *P < 0.05, **P < 0.01, ***P < 0.001.
2-h changes which were calculated as Concentration at 2-h − Concentration at fasting.
Model 1: unadjusted. Model 2: adjusted for age and gestational age. Model 3: adjusted for age, gestational age and pre-BMI.