Table 1.
The characteristics of included randomized control trials in this meta-analysis.
| Authors (years) | Years | Country | Sample size intervention | Sample size placebo | Mean age | BMI | Disease duration | Follow-up duration | Intervention | Study population |
|---|---|---|---|---|---|---|---|---|---|---|
| Barale et al. (2021) [50] | 2021 | Italy | 14 | 16 | 71.5 | 29.8 | NR | 12 weeks; 24 weeks; 36 weeks; 48 weeks | 5000 IU/day | T2DM |
| Cojic et al. (2021) [51] | 2021 | Serbia | 65 | 65 | 60 | 30 | 4 | 12 weeks; 24 weeks | 50,000 IU/week | T2DM |
| Mozaffari et al. (2021) [52] | 2021 | Iran | 40 | 40 | NR | NR | NR | 12 weeks | 50,000 IU/week | T2DM |
| Safarpour et al. (2020) [53] | 2020 | Iran | 42 | 43 | 48.3 | 31.37 | NR | 8 weeks | 50,000 IU/week | T2DM |
| Angellotti et al. (2018) [54] | 2018 | United States | 61 | 59 | 60.2 | 30.9 | NR | 16 weeks; 24 weeks; 36 weeks; 48 weeks | 4000 IU/day | Patients with well-controlled Type 2 diabetes (metformin or lifestyle) |
| Khan et al. (2018) [17] | 2018 | Pakistan | 70 | 70 | 54.8 | NR | >10 | 12 weeks | 50,000 IU/week | Patients with Type 2 diabetes with vitamin D deficiency |
| Safarpour et al. (2018) [55] | 2018 | Iran | 42 | 43 | 50.36 | 30.43 | 5.5 | 8 weeks | 50,000 IU/week | T2DM |
| Sosale et al. (2017) [56] | 2017 | India | 29 | 31 | 53 | 25.9 | 7 | 24 weeks | 60,000 IU/week | Type 2 diabetes and dyslipidemia, had A1c below 9%, and low vitamin D levels (<30 ng/mL) |
| Upreti et al. (2018) [23] | 2018 | India | 30 | 30 | 48.3 | 24.56 | NR | 24 weeks | 60,000 IU/week | Patients with coexisting Type 2 diabetes mellitus and hypovitaminosis D |
| Angellotti et al. (2019) [57] | 2019 | United States | 66 | 61 | 60.1 | 30.7 | NR | 24 weeks; 48 weeks | 4000 IU/day | Patients with well-controlled Type 2 diabetes (metformin or lifestyle) |
| Esfandiari et al. (2018) [58] | 2018 | Iran | 25 | 25 | 39.7 | NR | NR | 8 weeks | 50,000 IU/week | T2DM |
| Omidian et al. (2019) [59] | 2019 | Iran | 32 | 34 | 49.7 | 27.3 | NR | 12 weeks | 4000 IU/day | T2DM |
| Omidian et al. (2019) [21] | 2019 | Iran | 23 | 23 | 51.3 | 26.8 | 5.8 | 12 weeks | 4000 IU/day | T2DM |
| Talari et al. (2019) [60] | 2019 | Iran | 30 | 31 | 67.3 | 29.2 | 24 weeks | 50,000 IU/week | T2DM | |
| Cojic et al. (2020) [61] | 2020 | Montenegro | 50 | 68 | 60 | 29.34 | 12 weeks; 24 weeks | 50,000 IU/week | T2DM+metformin | |
| El Hajj et al. (2020) [24] | 2020 | Lebanon | 45 | 43 | 66.9 | 22.6 | 8.7 | 24 weeks | 30,000 IU/week | T2DM |
| Mirzavandi et al. (2020) [62] | 2020 | Iran | 25 | 25 | 45.56 | 31 | 7 | 8 weeks | 200,000 IU/once | T2DM |
| Jorde and Figenschau (2009) [63] | 2009 | Norway | 16 | 16 | 56.25 | 32.1 | 24 weeks | 40,000 IU/week | T2DM | |
| Eftekhari et al. (2011) [64] | 2011 | Iran | 35 | 35 | 53.8 | 28.3 | 12 weeks; 10 weeks | 5000 IU/day | T2DM | |
| Heshmat et al. (2012) [65] | 2012 | Iran | 21 | 21 | 56.2 | 27.7 | 6.7 | 12 weeks | 300,000 IU/once | T2DM+metformin+glibenclamide |
| Nasri et al. (2014) [66] | 2014 | Iran | 30 | 30 | 55.1 | 12 weeks | 50,000 IU/week | T2DM | ||
| Jehle et al. (2014) [20] | 2014 | Switzerland | 29 | 26 | 66.9 | 28.9 | 12.7 | 12 weeks; 24,weeks | 300,000 IU/once | T2DM+metformin+sulfonylureas+pioglitazone+GLP-1 receptor signaling+insulin |
| Park et al. (2014) [67] | 2014 | Korea | 11 | 13 | 73.27 | 24.08 | 12 weeks | 1200 IU/day | T2DM | |
| Ryu et al. (2014) [68] | 2014 | Korea | 64 | 65 | 54.8 | 25 | 5.7 | 24 weeks | 1000 IU/day | T2DM+meglitinide+metformin+alpha-glucosidase inhibitor+sulfonylurea+pioglitazone |
| Rad et al. (2014) [69] | 2014 | Iran | 28 | 30 | 50.03 | 27.94 | 5.89 | 8 weeks | 4000 IU/day | T2DM+metformin+glibenclamide |
| Al-Zahrani et al. (2014) [70] | 2014 | Saudi | 91 | 92 | 56.9 | 31.3 | NR | 12 weeks | 45,000 IU/week | T2DM+metformin Insulin |
| Mohammadi et al. (2016) [71] | 2016 | Iran | 28 | 25 | 38.5 | 28.8 | NR | 12 weeks | 50,000 IU/week | T2DM |
| Forouhi et al. (2016) [72] | 2016 | United Kingdom | 114 | 112 | 53.5 | 28.9 | NR | 16 weeks | 20,000 IU/week | T2DM |
| Lo, Abushamat, and Mramba (2018) [73] | 2018 | United States | 14 | 16 | NR | NR | NR | 24 weeks | 50,000 IU/week | T2DM |
| Breslavsky et al. (2013) [74] | 2013 | Israel | 24 | 23 | 66.8 | 27.9 | NR | 48 weeks | 1000 IU/day | T2DM+metformin+sulfonilure+repaglinid+DDP-4 inhibitors |
| Dadrass et al. (2018) [75] | 2018 | Iran | 12 | 12 | 53.7 | 27.7 | NR | 12 weeks | 5000 IU/day | T2DM |
| Bhosle and Mubeen (2018) [18] | 2018 | India | 60 | 60 | NR | NR | NR | 12 weeks; 24 weeks | 60,000 IU/week | T2DM |
| Sadiya et al. (2015) [76] | 2015 | UAE | 43 | 39 | 49.8 | 37.9 | 9.5 | 24 weeks; 12 weeks | 3000 IU/day | T2DM |
| Sugden et al. (2007) [77] | 2007 | United Kingdom | 17 | 17 | 64.9 | 31.7 | 8 weeks | 100,000 IU/once | T2DM+metformin+sulfonylureas+insulin+thiazolidinedione | |
| Momeni et al. (2017) [78] | 2017 | Iran | 30 | 30 | 62.4 | 8 weeks | 50,000 IU/week | T2DM | ||
| Baziar et al. (2014) [79] | 2014 | Iran | 41 | 40 | 50.34 | 27.33 | 5.44 | 8 weeks | 50,000 IU/week | T2DM |
| Razzaghi et al. (2016) [80] | 2016 | Iran | 30 | 30 | 59.6 | 26 | 12 weeks | 50,000 IU/week | T2DM+metformin+insulin | |
| Dalan et al. (2016) [81] | 2016 | Singapore | 31 | 30 | 52.2 | 27.3 | 16 weeks | 4000 IU/day | T2DM+metformin+sulfonilure+DDP-4 inhibitors | |
| Witham et al. (2010) [82] | 2010 | United Kingdom | 19 | 22 | 65.3 | 31.1 | 8 weeks; 16 weeks | 100,000 IU/once | T2DM | |
| 200,000 IU/once | ||||||||||
| Shaseb et al. (2016) [83] | 2016 | Iran | 48 | 47 | 54.9 | 27.2 | 3.9 | 8 weeks | 300,000 IU/once | T2DM |
| Ghavamzadeh, Mobasseri, and Mahdavi (2014) [84] | 2014 | Iran | 26 | 25 | 52.26 | 28.9 | 14 weeks | 400 IU/day | T2DM+metformin+insulin | |
| Krul-Poel et al. (2016) [29] | 2016 | Netherlands | 129 | 132 | 67 | 28.7 | 6 | 24 weeks | 50,000 IU/week | T2DM+metformin+sulfonylurea |
| Barzegari et al. (2018) [85] | 2018 | Iran | 25 | 25 | 39.7 | 21.1 | 8 weeks | 50,000 IU/week | T2DM | |
| Kampmann et al. (2014) [86] | 2014 | Denmark | 7 | 8 | 61.6 | 33.8 | 5.6 | 12 weeks | 5600 IU/day | T2DM+insulin |
| Farrokhian et al. (2017) [87] | 2017 | Iran | 30 | 30 | 61.7 | 30.2 | 24 weeks | 50,000 IU/week | T2DM | |
| Shahriari, Eftekhari, and Jeddi (2018) [88] | 2018 | Iran | 28 | 29 | 57.1 | 27.6 | 6.9 | 8 weeks | 50,000 IU/week | T2DM |
| Parekh et al. (2010) [89] | 2010 | India | 14 | 13 | 42.36 | 23.54 | 4.8 | 4 weeks | 300,000 IU/once | T2DM+metformin+glibenclamide |
| Gulseth et al. (2017) [90] | 2017 | Norway | 33 | 29 | 55.5 | 31.8 | 11.9 | 24 weeks | 400,000 IU/once | T2DM+metformin, sulfonylureas, pioglitazone, exenatide, and dipeptidyl peptidase 4 inhibitors |
| Imanparast et al. (2020) [91] | 2020 | Iran | 23 | 23 | 53.63 | 28.29 | 16 weeks | 50,000 IU/week | T2DM+glibenclamide or repaglinide+metformin or only metformin | |
| Agarwal, Marwah, and Kulshrestha (2017) [92] | 2017 | India | 30 | 30 | 57.13 | 12 weeks | 60,000 IU/week | T2DM | ||
| Al-Sofiani et al. (2015) [22] | 2015 | Saudi Arabia | 10 | 10 | 54.8 | 9.3 | 12 weeks | 5000 IU/day | T2DM | |
| Barchetta et al. (2016) [93] | 2016 | Italy | 26 | 29 | 57.4 | 29.3 | 5.9 | 24 weeks | 2000 IU/day | T2DM |
| Elkassaby et al. (2014) [94] | 2014 | Australia | 26 | 24 | 12 weeks; 24 weeks | 6000 IU/day | T2DM+metformin | |||
| Ebrahimkhani, Ghavamzadeh, and Mehdizadeh (2020) [95] | 2020 | Iran | 17 | 19 | 50.53 | 30.2 | 6.5 | 12 weeks | 50,000 IU/week | T2DM |
| Fazelian et al. (2020) [96] | 2020 | Iran | 26 | 25 | 48.5 | 30.21 | 16 weeks | 50,000 IU/week | T2DM | |
| Maggi et al. (2014) [97] | 2014 | Italy | 12 | 13 | 69 | 29 | 12 weeks; 24 weeks | 300,000 IU/once | T2DM | |
| Moreira-Lucas et al. (2017) [98] | 2017 | Canada | 35 | 36 | 49.1 | 30.1 | 24 weeks | 28,000 IU/week | T2DM | |
| Mousa et al. (2017) [99] | 2017 | Australia | 28 | 26 | 30.5 | 30.5 | 16 weeks | 100,000 IU/once | T2DM | |
| Nasri et al. (2014) [66] | 2014 | Iran | 30 | 30 | 55 | 29.3 | 12 weeks | 50,000 IU/week | T2DM | |
| Qasemi et al. (2021) [100] | 2021 | Iran | 23 | 21 | 55.13 | 9.83 | 12 weeks | 2000 IU/day | T2DM+metformin+glibenclamide+glitazone | |
| Raygan et al. (2018) [101] | 2018 | Iran | 30 | 30 | 71.5 | 29 | 12 weeks | 50,000 IU/week | T2DM | |
| Shehab et al. (2015) [102] | 2015 | Kuwait | 57 | 55 | 61.8 | 8 weeks | 50,000 IU/week | T2DM |