Table 1 Summary characteristics of included studies.
First author, year | Location | Study design | Language | Sample source (outpatient/inpatient) | Sample size (n) | Vitamin D assay | Mean vitamin D concentrations (nmol/L) | Male (%) | Mean age (years) | Mean BMI (kg/m2) | Mean diabetes duration (years) | Mean HbA1c (%) | ||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
DFU | Non-DFU | Total | DFU | Non-DFU | DFU | Non-DFU | ||||||||||
Afarideh et al. 201622 | Iran | Cross-sectional | English | Out | Out | 60 | 30 | 30 | ELISA | 42 | 40 | 58.3 | 56.8 | 27.7 | #N/A | 8.2 |
Atoum et al. 202323 | Jordan | Cross-sectional | English | Out | Out | 486 | 95 | 391 | N | 49.5 | 60.25 | 56.0 | 59.1 | 31.7 | #N/A | 8.5 |
Bao et al. 201924 | China | N | Chinese | N | N | 110 | 50 | 60 | ELISA | 38.23 | 40.08 | 55.5 | 47.9 | 28.5 | 8.0 | 8.0 |
Chen et al. 202325 | China | N | English | N | N | 160 | 80 | 80 | CLIA | 44 | 55.05 | 49.4 | 63.5 | 24.7 | #N/A | #N/A |
Dai et al. 202026 | China | N | English | In | In | 51 | 21 | 30 | RIA | 28.03 | 44.33 | 56.9 | 60.4 | 24.8 | 10.4 | 8.5 |
Darlington et al. 201927 | India | Cross-sectional | English | Out | Out | 176 | 88 | 88 | ELISA | 57.98 | 73.98 | #N/A | 57.3 | 24.4 | #N/A | 9.5 |
Deng et al. 201528 | China | N | Chinese | In | In | 120 | 60 | 60 | ECL | 45.1 | 52.2 | 52.5 | 62.7 | #N/A | 13.0 | 8.9 |
Feldkamp et al. 201829 | Germany | N | English | Out/in | Out/in | 207 | 104 | 103 | RIA | 29.5 | 47.5 | #N/A | 69.8 | #N/A | 17.2 | #N/A |
Gupta et al. 201630 | India | N | English | Out | Out | 100 | 50 | 50 | RIA | 35.63 | 53.2 | 63.0 | 52.1 | 23.7 | 4.5 | 9.9 |
Hong et al. 201731 | China | N | Chinese | N | N | 70 | 30 | 40 | ELISA | 38 | 40 | #N/A | 42.0 | 28.8 | 8.0 | 8.0 |
Ignatovich et al. 201432 | Belarus | N | Russian | N | N | 40 | 22 | 18 | N | 24.62 | 43.87 | 45.0 | #N/A | #N/A | #N/A | #N/A |
Kota et al. 201333 | India | N | English | N | N | 200 | 100 | 100 | RIA | 40.25 | 49.5 | 64.0 | 53.4 | #N/A | #N/A | 10.6 |
Li et al. 202134 | China | Case–Control | Chinese | In | In | 47 | 26 | 21 | CL | 44.15 | 59.48 | 61.7 | 55.0 | 23.3 | 5.3 | 10.5 |
Li et al. 202335 | China | N | Chinese | N | N | 120 | 60 | 60 | CLIA | 40 | 50.05 | 60.0 | 63.3 | 24.5 | #N/A | #N/A |
Lu et al. 201936 | China | Case–Control | Chinese | In | In | 120 | 60 | 60 | CL | 45.63 | 61.28 | #N/A | 61.5 | #N/A | 10.4 | 8.9 |
Luo et al. 201937 | China | N | Chinese | Out | Out | 80 | 40 | 40 | ECL | 24.45 | 35.78 | 58.8 | 55.0 | 24.6 | 4.7 | 8.2 |
Najafipour et al. 201938 | Iran | N | English | N | N | 70 | 35 | 35 | CLIA | 42.15 | 59.75 | 62.9 | 59.2 | 28.4 | 12.0 | 8.4 |
Priyanto et al. 202339 | Indonesia | Cross-sectional | English | Outpatient | Outpatient | 81 | 41 | 40 | CLIA | 21.91 | 40.71 | 39.5 | 56.0 | 26.6 | 7.4 | 8.1 |
Shen et al. 201540 | China | Cross-sectional | Chinese | Out/in | Out/in | 53 | 21 | 32 | RIA | 41.75 | 73 | 52.8 | 57.3 | 30.3 | 7.1 | 8.9 |
Tang et al. 20224 | China | N | English | In | In | 1721 | 547 | 1174 | ECLIA | 36.74 | 46.09 | 49.2 | 66.3 | 24.3 | #N/A | 8.0 |
Tang et al. 202341 | China | N | English | In | In | 256 | 156 | 100 | CLIA | 29.17 | 40.83 | 55.5 | 55.3 | #N/A | 7.5 | 9.0 |
Tiwari et al. 201342 | India | N | English | N | N | 289 | 125 | 164 | RIA | 40.25 | 50.75 | 65.1 | 52.1 | 24.4 | 6.1 | 9.6 |
Tiwari et al. 201443 | India | N | English | Out | Out | 219 | 112 | 107 | RIA | 40.2 | 49.4 | 67.6 | 52.8 | 24.0 | 6.6 | 9.4 |
Tiwari et al. 202244 | India | N | English | In | In | 173 | 100 | 73 | RIA | 40.25 | 49.4 | #N/A | 52.9 | 24.0 | 6.6 | 9.4 |
Todorova et al. 202245 | Bulgaria | Cross-sectional | English | N | N | 136 | 73 | 63 | ECLIA | 29.71 | 39.22 | 63.2 | 58.1 | 30.9 | #N/A | 8.4 |
Tong et al. 202346 | China | N | Chinese | N | N | 210 | 160 | 50 | ELISA | 24.8 | 37.73 | 55.7 | 60.0 | #N/A | #N/A | 8.7 |
Tsitsou et al. 202347 | Greece | Cross-sectional | English | Out | Out | 68 | 33 | 35 | LC–MS/MS | 44.75 | 49.5 | 75.0 | 64.1 | 29.7 | 15.7 | 6.9 |
Wang et al. 2022a48 | China | N | English | In | In | 429 | 242 | 187 | ECLIA | 28.28 | 37.78 | 64.3 | 62.3 | 24.9 | 14.8 | 8.7 |
Wang et al. 2022b49 | China | N | English | In | In | 339 | 204 | 135 | N | 30.49 | 38.14 | 62.8 | 67.2 | 24.5 | 17.2 | 8.5 |
Wang et al. 2022c50 | China | N | Chinese | N | N | 160 | 80 | 80 | CL | 47.18 | 56.03 | 74.4 | 64.9 | 25.0 | 11.4 | 9.9 |
Wu et al. 201551 | China | N | Chinese | N | N | 48 | 24 | 24 | ELISA | 25.8 | 31.7 | 58.3 | 55.5 | #N/A | 8.9 | 8.9 |
Xiao et al. 202021 | China | Cross-sectional | English | In | In | 4284 | 245 | 4039 | CL | 36.96 | 40.97 | 52.6 | #N/A | #N/A | #N/A | #N/A |
Yoho et al. 200952 | USA | N | English | N | N | 26 | 13 | 13 | N | 35.2 | 43.45 | 73.1 | 63.6 | #N/A | #N/A | #N/A |
Zhang et al. 201353 | China | N | Chinese | In | In | 85 | 41 | 44 | ELISA | 26.56 | 32.23 | 70.6 | 56.5 | 24.5 | 12.6 | 8.9 |
Zhang et al. 202254 | China | N | Chinese | In | In | 180 | 120 | 60 | ECL | 24.55 | 37.55 | 64.4 | 55.4 | 24.4 | #N/A | 8.6 |
Zubair et al. 201355 | India | Prospective cohort | English | In | In | 324 | 162 | 162 | RIA | 20.56 | 74.68 | 63.3 | 46.7 | 24.4 | #N/A | 8.8 |
