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. 2017 Jan 13;7:40751. doi: 10.1038/srep40751

Table 1. Characteristics of the included studies of the effects of micronutrients on blood pressure in patients with type 2 diabetes.

Author Year Design/Trial Duration   Diabetes duration (years) BMI (kg/m2) Baseline BP (mmHg) Diet characteristics and micronutrient measurements BP change (mean, mmHg) Medications in use (% of users)
Sodium
Dodson 1989 Parallel/3 months (1st phase of study) n = 34 4.6 ± 4.3 NA SBP Intervention Intervention Oral hypoglycaemic: 18%
    67.6% males     I.179.7 ± 18.2 Advised to restrict daily dietary sodium intake SBP: −19.2 ± 13.5 Atenolol: 12%
    I.61.9 ± 7.5 y     C.173.8 ± 20.3 Sodium intake* (g/NaCl) DBP: −3.8 ± 6.9  
    C.61.1 ± 6.3 y       Baseline: 11.7 g ± 3.9    
    Hypertensive subjects       End-of-study: 8.04 ± 2.2    
            Change: −3.44 ± 2.48    
          DBP Control Control  
          I.91.4 ± 11.1 Usual diet for diabetes (ADA) SBP: −6.2 ± 13.1  
          C.92.4 ± 10.9 Sodium intake* (g/NaCl) DBP: −2.0 ± 7.2  
            Baseline: 10.8 g ± 1.6    
            End-of-study: 10.6 ± 1.9    
            Change: −0.2 ± 1.13    
Magnesium
Guerrero Romero 2009 Parallel/3 weeks n = 82 8.6 ± 0.9 29.1 ± 1.3 SBP Intervention Intervention Glibenclamide: 100%
    48.1% males     I.161 ± 26 Daily oral supplement: 2.5 MgCl (=0.45 g Mg) SBP: −20.4 ± 15.9  
    I.58.9 ± 9.0 y     C.154.5 ± 21.2 Magnesium nmol/l† DBP: −8.7 ± 16.3  
    C.60.5 ± 9.4 y       Baseline: 0.62 ± 0.10    
    Hypertensive subjects with low serum magnesium and without use of diuretics       End-of-study: 0.81 ± 0.11    
            Change: 0.18 ± 0.10    
          DBP Control/nmol/l† Control  
          I.88.4 ± 14.5 Baseline: 0.61 ± 0.10 SBP: −4.7 ± 12.7  
          C.84.9 ± 12.4 End-of-study: 0.68 ± 0.11 DBP: −1.2 ± 12.6  
            Change: 0.08 ± 0.14    
Vitamin C
Darko 2002 Parallel/3 weeks n = 35 I.9.3 ± 1.2 29.1 ± 1.3 SBP Intervention Intervention Diuretics = 9%
    66% males C.7.8 ± 0.6   I.141.0 ± 5.0 Daily oral supplement: 1.5 g ascorbic acid SBP 0.0 ± 13.4 ACE inhibitors = 11%
    I.56.6 ± 1.1 y     C.138.0 ± 4.0 Plasma ascorbate/μmmol DBP1.0 ± 8.0 Sulphonylureas = 23%
    C.55.5 ± 1.8 y       Baseline: 58 ± 6   Metformin = 37%
            End-of-study: 122 ± 10    
            Change: 64 ± 6.5    
          DBP Control (placebo) Control  
          I.80.0 ± 2.0 Plasma ascorbate/μmmol SBP: −2.0 ± 10.3  
          C.76.0 ± 3.0 Baseline: 51 ± 5 DBP: 1.0 ± 7.6  
            End-of-study: 53 ± 5    
            Change: 2 ± 3    
Mullan 2002 Parallel Double Blind/4 weeks n = 30 NA 28.6 ± 4.3 SBP Intervention Intervention NA
    73% males     I.130.1 ± 12.4 Daily oral supplement: 500 mg ascorbic acid SBP: −10.1 ± 7.9  
    I.57.9 ± 6.6 y     C.129.7 ± 11.7 Plasma ascorbic acid/μmmol/l DBP: −4.4 ± 3.7  
    C.61.0 ± 6.5 y       Baseline: 43.3 ± 19.3    
            End-of-study: 78.1 ± 19.5    
            Change: 34.8 ± 12    
          DBP Control (placebo) Control:  
          I.80.5 ± 6.2 Plasma ascorbic acid: NA SBP: −1.0 ± 7.4  
          C.85.1 ± 6.4   DBP: −0.6 ± 3.9  
Vitamin D
Sugden 2008 Parallel double blind/8 weeks n = 34 NA 31.7 ± 5.4 SBP Intervention Intervention ACE inhibitor or angiotensin blocker = 62%
    53% males     I.145 ± 9.2 Single dose supplement: 100,000 IU D2 (12,500 IU/week) SBP: −7.3 ± 11.8 Metformin = 53%
    64.2 ± 9.9 years old plasma vitamin D < 50 mmol/l     C.137 ± 14.1 Serum 25 OHD/nmol/l DBP: −2.2 ± 8.6 Insulin = 18%
            Baseline: 40.2 ± 10.3    
            Change: 22.9 ± 16.6    
          DBP Control Control  
          I.82 ± 10.5 Single dose placebo Miglyol® oil SBP: 6.6 ± 9.7  
          C.79 ± 6.0 Serum 25OHD/nmol/l DPB: 2.3 ± 5.7  
            Baseline: 36.4 ± 8.5    
            Change: 7.6 ± 12.5    
Witham 2010 Parallel/16 Weeks n = 61 NA I.31.1 ± 6.7 SBP Intervention: 1 Intervention - 1 NA
    68% males   C.33.3 ± 7.1 I.149.6 ± 24.8 Single dose supplement: 100,000 IU D3 (6,250 IU/week) SBP: −8.2 ± 15.2  
    I.65.3 ± 9.7 y     C.143.9 ± 24.4   DBP: −3.6 ± 8.6  
    C.66.7 ± 9.7 y     DBP Serum 25 OHD/nmol/l    
          I.80.7 ± 14.3 Baseline: 41 ± 14    
          C.80.3 ± 9.7 End-of-study: 63 ± 20    
            Change: 23.0 ± 18.4    
          SBP Intervention: 2 Intervention - 2  
          I.145.1 ± 25.0 Single dose supplement: 200,000 IU D3 (12,500 IU/week) SBP: −5.6 ± 15.7  
          C.143.9 ± 24.4   DBP: −3.1 ± 8.6  
          DBP Serum 25 OHD/nmol/l    
          I.80.7 ± 14.3 Baseline: 48 ± 21    
          C.80.3 ± 9.7 End-of-study: 79 ± 31    
            Change: 31.0 ± 19.0    
            Control (for interventions 1 and 2) Control  
            Single dose placebo Miglyol® oil SBP: 2.5 ± 14.6  
            Serum 25OHD (nmol/l) DBP: −1.4 ± 6.0  
            Baseline: 45 ± 17    
            End-of-study: 54 ± 20    
            Change: 9 ± 12    
ShabBidar 2011 Parallel double blind/12 weeks n = 100 I.8.3 ± 4.6 NA SBD Intervention Intervention Oral antihyperglycemic = 100% (metformin, glibenclamide, glitazones)
    43% males C.7.0 ± 5.2   I.125.7 ± 14.4 Vitamin D3-fortified yogurt: 170 mg calcium and 500 IU D3/250 ml, twice/day (total dose 90,000 IU) SBP: −7.2 ± 12.8  
    I.52.4 ± 8.4 y     C.128.2 ± 16.6   DBP: −5.1 ± 6.2  
    C.52.6 ± 6.3 y     DBP Serum 25OHD/nmol/l    
          I.78.5 ± 10.3 Baseline: 38.5 ± 20.2    
          C.77.8 ± 10.8 End-of-study: 72 ± 23.5    
            Change: 33.5 ± 14.2    
            Control Control  
            Plain yogurt: 170 mg calcium without vitamin D3/250ml SBP: −2.5 ± 11.8  
            Serum 25OHD/nmol/l DBP: −0.8 ± 6.5  
            Baseline: 38.5 ± 22.8    
            End-of-study: 33.4 ± 22.8    
            Change: −4.6 ± 14.4    
Nikooyeh 2011 Parallel 12 weeks n = 90 NA I.29.9 ± 4.7 SBP Intervention (n = 30) Intervention Oral antihyperglycemic = 100% (metformin, glibenclamide, glitazones)
    39% males   C.29.2 ± 4.4 I.131.5 ± 21.6 Vitamin D3-fortified yogurt: 150 mg calcium and 500 IU D3/250 ml, twice/day (total dose 90,000 IU) (7,500 IU/week) SBP: −3.4 ± 10.3  
    50.7 ± 6.1 years old     C.127.3 ± 14.8   DBP: 0.3 ± 14.0  
          DBP Serum 25OHD/nmol/l    
          I.77.5 ± 20.0 Baseline: 44.4 ± 28.7    
          C.77.5 ± 10.6 End-of-study: 77.7 ± 28.6    
            Change: 33.3 ± 18.1    
            Control (n = 30) Control  
            Plain yogurt: 150 mg calcium without vitamin D3/250 ml SBP: 0.4 ± 10.0  
            Serum 25OHD/nmol/l DBP: 0.5 ± 7.7  
            Baseline: 41.6 ± 44.5    
            End-of-study: 37.2 ± 44.0    
            Change: −4.4 ± 28.0    
Breslavsky 2013 Parallel placebo/controlled 52 weeks n = 47 NA NA SBP Intervention Intervention Metformin = 49%
    46.8% males     I.154.2 ± 21.5 Daily supplement of vitamin D3 1000 mg (total dose 360,000 IU) (6,667 IU/week) SBP: −10.7 ± 12.8 Sulfonylurea = 23,4%
    I.66.8 ± 9.2 y     C.151.8 ± 18.0   DBP: 0.1 ± 5.3  
    C.65.8 ± 9.7 y     DBP Serum 25OHD/ng/ml    
          I.76.2 ± 8.8 Baseline: 11.8 ± 10.9    
          C.72.2 ± 10.8 End-of-study: 17.6 ± 11.5    
            Change: 5.8 ± 7.1    
            Control Placebo (microcrystalline cellulose) Control Diuretics = 34%
            Serum 25OHD/ng/ml SBP: −11.1 ± 11.4 ACE inhibitors = 66%
            Baseline: 11.7 ± 6.5 DBP: 2.5 ± 6.6 B-Blockers = 51%
            End-of-study: 14.0 ± 5.9    
            Change: 2.3 ± 3.9    
Al-Zahari 2013 Parallel placebo/controlled 12 weeks n = 200 NA I.31.3 ± 4.6 SBP Intervention Intervention NA
    45% males   C.32.0 ± 5.7 I.123.4 ± 15.8 45.000 IU of vitamin D3 every week for 2 months and a single dose of 45000 IU in the last month (total dose 225,000 IU) (18,750 IU/week) SBP: −1 ± 9.8  
    I.56.9 ± 9.4 y     C.124.0 ± 15.4   DBP: −3.2 ± 6.6  
    C.52.5 ± 8.1 y     DBP Serum 25OHD/nmol/l    
          I.76.4 ± 10.8 Baseline: 25.3 ± 15.8    
          C.75.3 ± 9.2 End-of-study: 82.8 ± 31.7    
            Change: 57.5 ± 21.3    
            Control Control  
            Placebo (microcrystalline cellulose) SBP: 0 ± 9.6  
            Serum 25OHD/nmol/l DBP: −1.6 ± 5.5  
            Baseline: 22.0 ± 15.2    
            End-of-study: 55.0 ± 37.5    
            Change: 33 ± 27.2    
Nasri 2014 Parallel double blind placebo controlled/12 weeks n = 60 NA NA SBP Intervention Intervention NA
    28.3% males     I.121.0 ± 13.0 50,000 IU of vitamin D3 per week (total dose 600,000 IU) SBP: −11 ± 7.9  
    55 ± 10.7 years old     C.118.8 ± 11.0   DBP: −4.2 ± 4.8  
          DBP Serum 25OHD/nmol/l    
          I.80.5 ± 8.0 Baseline: 83.9 ± 52    
          C.80.3 ± 7.0 End-of-study: 164 ± 57    
            Change: 80.1 ± 34.8    
            Control Control  
            Serum 25OHD/nmol/l SBP: −4.2 ± 6.6  
            Baseline: 105.7 ± 64 DBP: −1.3 ± 4.5  
            End-of-study: 115.8 ± 94    
            Change: 10.1 ± 57.5    

Abbreviations: ADA = American Diabetes Association; BP = blood pressure; C = control group; DBP = diastolic blood pressure; DM = diabetes mellitus; I = intervention group; NA = not available; SBP = systolic blood pressure; y = years old; *NaCl intake estimated by 24-h urinary sodium (g), †magnesium intake based on 24-h urinary magnesium (mmol/L).

Data are expressed as the mean (standard deviation).