Table 3

Association between the peak intensity of the four metabolites and the odds of diabetic retinopathy

MetabolitesNCases (%)CrudeAdjusted*
OR (95% CI)P valueOR (95% CI)P value
Phenylacetylglutamine
 Per IQR4.45 (2.10 to 9.43)<0.0014.64 (1.98 to 10.88)<0.001
 Quartiles
 Q1233 (13)1.00 (1.00 to 1.00)Ref.1.00 (1.00 to 1.00)Ref.
 Q22313 (57)8.67 (2.00 to 37.58)0.00412.05 (2.34 to 61.98)0.003
 Q32313 (57)8.67 (2.00 to 37.58)0.00411.78 (2.27 to 61.00)0.003
 Q42317 (74)18.89 (4.09 to 87.17)<0.00123.01 (3.98 to 133.20)<0.001
 P for trend<0.0010.001
Linoleic acid
 Per IQR0.26 (0.14 to 0.49)<0.0010.22 (0.11 to 0.45)<0.001
 Quartiles
 Q12319 (83)1.00 (1.00 to 1.00)Ref.1.00 (1.00 to 1.00)Ref.
 Q22315 (65)0.40 (0.10 to 1.57)0.1860.30 (0.07 to 1.42)0.129
 Q3239 (39)0.14 (0.04 to 0.53)0.0040.11 (0.02 to 0.54)0.006
 Q4233 (13)0.03 (0.01 to 0.16)<0.0010.02 (0.00 to 0.14)<0.001
 P for trend<0.001<0.001
Nicotinuric acid
 Per IQR2.32 (1.42 to 3.78)0.0012.50 (1.47 to 4.25)0.001
 Quartiles
 Q1237 (30)1.00 (1.00 to 1.00)Ref.1.00 (1.00 to 1.00)Ref.
 Q22310 (44)1.76 (0.52 to 5.91)0.3611.45 (0.39 to 5.41)0.578
 Q32311 (48)2.10 (0.63 to 7.01)0.2301.68 (0.48 to 5.84)0.415
 Q42318 (78)8.23 (2.18 to 31.13)0.00213.02 (2.79 to 60.71)0.001
 P for trend0.0020.002
Ornithine
 Per IQR1.71 (1.09 to 2.69)0.0201.80 (1.12 to 2.89)0.015
 Quartiles
 Q12310 (44)1.00 (1.00 to 1.00)Ref.1.00 (1.00 to 1.00)Ref.
 Q2239 (39)0.84 (0.26 to 2.71)0.7650.74 (0.21 to 2.61)0.643
 Q32310 (44)1.00 (0.31 to 3.21)1.0001.04 (0.30 to 3.64)0.948
 Q42317 (74)3.68 (1.06 to 12.77)0.0404.46 (1.14 to 17.39)0.031
 P for trend0.0430.028
  • In the present study, the T2DM duration for each participant was obtained mainly by the self-report and highly correlated to age. Furthermore, it might be inaccurate since many people may be suffering from unnoticed T2DM for a long time. So, to avoid collinearity and overfitting, it was not included in the multiple generalized linear regression models, although it was not comparable between the cases and controls.

  • *Adjusted for age, smoking habits and therapy history.

  • Q1, the first quartile; Q2, the second quartile; Q3, the third quartile; Q4, the fourth quartile; Ref., reference; T2DM, type 2 diabetes mellitus.