Table 2 Characteristics of categories of serum 25(OH)D concentration and risk of T1DM.

From: A dose–response meta-analysis between serum concentration of 25-hydroxy vitamin D and risk of type 1 diabetes mellitus

Author, year Cat. of vitamin D, nmol/L Number (case/control) Risk of T1DM Assay method of 25(OH)D Matched or adjustment variables Duration of T1DM
    OR 95% CI    
Bener [21] <75 154/145 1 (reference) RIA Age, gender, and ethnicity of case NA
  75–200 16/25 0.6 (0.31, 1.17)    
Borkar [35] <50 29/16 1 (reference) HPLC Age, gender The cases were diagnosed within 1 week.
  50–75 14/22 0.35 (0.14, 0.87)    
  >75 7/12 0.32 (0.11, 0.98)    
Hamed [22] <50 19/0 1 (reference) CPBA Age, pubertal stage, and physical activity The duration of T1DM was 2.67 ± 3.52 years.
  >50 17/15 0.03 (0, 0.52)    
Gorham [33] <43 52/15 1 (reference) CLIA The date that the blood sample was drawn, age, length of military service, gender, and whether the control was on active duty when the case was diagnosed NA
  43–59 50/20 0.72 (0.33, 1.56)    
  60–77 33/26 0.37 (0.17, 0.79)    
  78–99 34/32 0.31 (0.14, 0.65)    
  ≥100 933/805 0.33 (0.19, 0.6)    
Ghandchi [23] <28 51/50 1 (reference) HPLC Siblings at the same age The duration of T1DM for anti-GAD-Ab+ cases was 3.1 ± 2.4 years while for anti-GAD-Ab- cases was 6.6 ± 4.8 years.
  28–50 6/4 1.47 (0.39, 5.53)    
  ≥50 3/6 0.49 (0.12, 2.07)    
Munger [34] 31–77 47/50 1 (reference) CLIA Age, gender, race/ethnicity, dates of serum collection, and branch of military service NA
  77–89 30/62 0.52 (0.28, 0.93)    
  89–101 29/66 0.47 (0.26, 0.84)    
  101–114 19/66 0.31 (0.16, 0.59)    
  114–211 29/64 0.48 (0.27, 0.87)    
Franchi [26] ≤50 39/86 1 (reference) CLIA Age, gender, and season of hospitalization All cases were newly diagnosed.
  51–74 14/44 0.7 (0.35, 1.43)    
  ≥75 5/36 0.31 (0.11, 0.84)    
Azab [24] <50 44/12 1 (reference) ELISA Age and gender The median (min–max) of duration of T1DM was 17(3–52) months.
  >50 36/28 0.35 (0.16, 0.79)    
Abd-Allah [25] <38 84/36 1 (reference) ELISA Age, gender, and ethnic origin NA
  38–50 6/18 0.41 (0.05, 0.39)    
  >50 30/66 0.2 (0.11, 0.35)    
Cadario [27] <5 36/103 1 (reference) LC-MS Birthday, place of birth, and ethnic group The age at diagnosis was 4.2 ± 3.4 years old.
  ≥5 31/133 0.67 (0.39, 1.15)    
Jacobsen [28]a,b 0–12 NA 1 (reference) LC-MS NA The age of onset was 10.2(7.5,12.5) for 912 cases and 10.5(5.1,11.5) for 7 cases in cohort.
  12–20 NA 1.13 (0.80, 1.58)    
  20–28 NA 1.16 (0.90, 1.50)    
  28–41 NA 1.01 (0.72, 1.42)    
  41–130 NA 1.13 (0.81, 1.57)    
Jacobsen [28]b 0–11 NA 1 (reference) LC-MS Date and season of birth The age of onset was 8.5(5.0,11.4).
  11–17 NA 1.66 (0.69, 3.99)    
  17–25 NA 1.61 (0.84, 3.09)    
  25–36 NA 1.32 (0.56, 3.12)    
  36–118 NA 1.32 (0.55, 3.18)    
Rasoul [29] <53 182/158 1 (reference) ELISA Age, gender, and ethnicity The onset age of T1DM was <4 years in 20% patients, 4–6 years in 28% patients and >6 years in 52% patients.
  53–73 31/29 0.93 (0.54, 1.61)    
  >73 3/11 0.24 (0.07, 0.86)    
Bae [30] <50 41/136 1 (reference) RIA Age, gender, and body mass index 4.6 ± 4.0 years for 25(OH)D < 48nmol/L; 5.4 ± 3.4 for 25(OH)D 48–72nmol/L; 2.4 ± 2.4 for 25(OH)D ≥72 nmol/L
  50–75 30/206 0.48 (0.29, 0.81)    
  ≥75 14/176 0.26 (0.14, 0.50)    
Liu [32] <30 39/17 1 (reference) ELISA Age, gender, and ethnicity 106 cases were diagnosed not longer than 30 days, while 190 cases were diagnosed longer than 30 days.
  30–50 108/73 0.65 (0.34, 1.23)    
  >50 149/205 0.32 (0.17, 0.58)    
Federico [31] ≤50 41/20 1 (reference) HPLC Age, gender The age at the clinical onset of T1DM was 9.4 ± 3.9 years (range 2.1–1.8).
  50–75 21/36 0.28 (0.13, 0.61)    
  75–250 20/61 0.16 (0.08, 0.33)    
  1. Duration of T1DM was presented as mean ± standard deviation.
  2. T1DM type 1 diabetes mellitus, 25(OH)D 25-hydroxy vitamin D, Cat. categories, OR odds ratio, 95% CI 95% confidential interval, NA not available, RIA radioimmunoassay, ELISA enzyme-linked immunosorbent assay, LC-MS liquid chromatography coupled with mass spectrometry, HPLC high-performance liquid chromatography, CLIA chemiluminescence immunoassay, CPBA competitive binding protein assay, NOS Newcastle–Ottawa Scale, BMI body mass index, NA not available, N number, SDS standard deviation score.
  3. aWe used hazard ratios to present the risk of T1DM.
  4. bThe duration of T1DM was presented as median (interquartile range).