Fig 1.
Flowchart of the meta-analysis.
Table 1.
Methodological quality of studies included in the final analysis based on the AHRQ for assessing the quality of cross-sectional study.
Table 2.
Methodological quality of studies included in the final analysis based on the NOS for assessing the quality of case-control study.
Table 3.
Characteristics of included studies.
Fig 2.
Duration of diabetes and risk of DPN.
The summary mean difference was calculated using a random-effects model. The mean difference and 95% CI for each study and the final combined results are displayed numerically on the left and graphically as a forest plot on the right. A and B are based on univariate analysis and multivariate analysis data, respectively. The sensitivity analysis results are shown in C.
Fig 3.
The summary mean difference was calculated using a random-effects model. The mean difference and 95% CI for each study and the final combined results are displayed numerically on the left and graphically as a forest plot on the right. A and B are based on univariate analysis and multivariate analysis data for cross-sectional studies, respectively. C showed significant differences in age in the case-control studies. The sensitivity analysis results are shown in D.
Fig 4.
The summary mean difference was calculated using a random-effects model. The mean difference and 95% CI for each study and the final combined results are displayed numerically on the left and graphically as a forest plot on the right. A and B are based on univariate analysis and multivariate analysis data, respectively. The sensitivity analysis results are shown in C.
Fig 5.
The summary odds ratio was calculated using a fixed-effects model. The odds ratio and 95% CI for each study and the final combined results are displayed numerically on the left and graphically as a forest plot on the right. A and B are based on univariate analysis and multivariate analysis data, respectively.
Fig 6.
The summary odds ratio was calculated using a random-effects model. The odds ratio and 95% CI for each study and the final combined results are displayed numerically on the left and graphically as a forest plot on the right. A and B are based on univariate analysis and multivariate analysis data, respectively.
Fig 7.
The summary mean difference was calculated using a random-effects model. The mean difference and 95% CI for each study and the final combined results are displayed numerically on the left and graphically as a forest plot on the right. A and B are based on univariate analysis and multivariate analysis data, respectively. A subgroup analysis was conducted on the basis of ethnicity; the results are shown in C. The sensitivity analysis results are shown in D.
Fig 8.
The summary mean difference was calculated using a random-effects model. The mean difference and 95% CI for each study and the final combined results are displayed numerically on the left and graphically as a forest plot on the right. A and B are based on univariate analysis and multivariate analysis data, respectively.
Fig 9.
The summary mean difference was calculated using a random-effects model. The mean difference and 95% CI for each study and the final combined results are displayed numerically on the left and graphically as a forest plot on the right.