Characteristics of studies identifying significant risk factor for patients with diabetes
| First author | Year | Types of diabetes | Sample size | Country | Study design | Variables (n) | |
| Assessed | Significant | ||||||
| Bennett 31 | 2012 | T1DM and T2DM | 1 792 826 | USA | Retrospective cohort study | 11 | 7 |
| Caughey 32 | 2017 | T1DM and T2DM | 848 | Australia | Retrospective cohort study | 9 | 3 |
| Chen16 | 2012 | T1DM and T2DM | 30 139 | USA | Retrospective cohort study | 37 | 16 |
| Chen33 | 2017 | T1DM and T2DM | 115 221 | USA | Retrospective cohort study | 29 | 12 |
| Chin34 | 1998 | T1DM and T2DM | 1376 | USA | Retrospective cohort study | 4 | 0 |
| Collins35 | 2017 | T2DM | 63 237 | USA | Retrospective cohort study—development of risk prediction model | 15 | 14 |
| Eby36 | 2015 | T2DM | 52 070 | USA | Retrospective cohort study | 39 | 14 |
| Emons37 | 2016 | T1DM and T2DM | 4476 | USA | Retrospective cohort study | 20 | 12 |
| Enomoto14 | 2017 | T2DM | 1 080 580 | USA | Case–control study | 21 | 15 |
| Jiang38 | 2005 | T1DM and T2DM | 130 751 | USA | Retrospective cohort study | 3 | 0 |
| Karunakaran39 | 2018 | T1DM and T2DM | 17 284 | USA | Retrospective cohort study—development of risk prediction model | 48 | 27 |
| Lin40 | 2015 | T2DM | 161 174 | USA | Retrospective cohort study | 15 | Not reported* |
| Lipska41 | 2014 | T1DM and T2DM | 33 952 331 | USA | Retrospective cohort study—12-year trend analysis | 24 | Not reported* |
| McCoy43 | 2017 | T1DM and T2DM | 342 186 | USA | Retrospective cohort study | 10 | 7 |
| McCoy42 | 2018 | T1DM and T2DM | 11 161 | USA | Retrospective cohort study | 27 | 8 |
| Nishino44 | 2015 | T1DM and T2DM | 174 932 | UK | Retrospective cohort study | 26 | 13 |
| Raval45 | 2015 | T2DM | 202 496 | USA | Retrospective cohort study | 21 | 10 |
| Robbins15 | 2006 | T1DM and T2DM | 88 776 | USA | Retrospective cohort study | 11 | 5 |
| Rubin10 | 2016 | T1DM and T2DM | 17 248 | USA | Retrospective cohort study—development of risk prediction model | 46 | 10 |
| Rubin9 | 2018 | T1DM and T2DM | 42 800 | USA | Retrospective cohort study—development of risk prediction model | 15 | 7 |
| Sonmez30 | 2017 | T1DM and T2DM | 102 694 | USA | Case–control study | 3 | 3 |
| Takahashi46 | 2015 | T2DM | 5731 | USA | Retrospective cohort study | 4 | 0 |
| Wei47 | 2013 | T2DM | 1949 | USA | Retrospective cohort study | 7 | 2 |
The variables are significant in multivariable analysis.
*These studies were only included in the systematic review, as statistical significance was not formally evaluated and they did not provide sufficient information to be included in the meta-analysis.
T1DM, type 1 diabetes mellitus; T2DM, type 2 diabetes mellitus.