Table 1 Characteristics of the included studies in the meta-analysis.

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

Author, year Country Study design Geographic Location NOS Participants
    Region Latitude, °N   Ethnicity, case/control No. of gender, male/female Age of cases/controls, year BMI of cases/controls, kg/m2
Bener [21] Qatar case-control study Doha 25 8 White, wheat, brown or black people 168/172 10.5 ± 3.8/9.9 ± 4.2 16.76/17.88
Borkar [35] India cross-sectional
case-control study
Chandigarh 31 8 NA 55/45 8.63 ± 2.01/8.48 ± 1.58 15.74 ± 1.88/16.25 ± 2.43
Hamed [22] India case-control study Assuit 27 7 NA 20/31 10.38 ± 3.17/8.47 ± 4.17 17.83 ± 7.07/16.42 ± 2.88
Gorham [33] USA nested case-control study San Diego 32 7 White, black, and other NA 33.28/33.26 NA
Ghandchi [23] Iran case-control study Tehran 35 8 NA 58/62 14.4(0.5)/14.6(0.8)a 21.4(0.6)/20.8(0.7)a
Munger [34] USA nested case-control study Boston 42 7 Non-Hispanic Whites 439/23 20.6 ± 4.1/20.6 ± 4.0 NA
Franchi [26] Italy case-control study Verona 45 4 Caucasian and other 124/100 9.2(1.1–16.0)/8.7(1.1–16.3)b 16.6(11.4–25.8)/16.9(11.0–38.3)b
Azab [24] Egypt case-control study Zagazig 30 7 NA 58/62 11.4 ± 2.5/10.8 ± 2.3 23.6 ± 5.7/21.8 ± 4.7
Abd-Allah [25] Egypt case-control study Zagazig 30 6 NA 90/150 11.7 ± 2.8/11.1 ± 2.6 18.5 ± 4.3/21.6 ± 1.5
Cadario [27] Italy case-control study Novara 45 6 Italian, Northern African, and Eastern European 145/158 7.0 ± 0.25/7.2 ± 0.49 NA
Jacobsen [28] Denmark case-cohort study Denmark 55 6 Danish, other western, other non-western 1933/1852 10.2(7.5,12.5)/10.5(5.1,11.5)c NA
Jacobsen [28] Denmark case-control study Denmark 55 9 Danish, other western, other non-western 551/503 8.5(5.0,22.4)/NAc NA
Rasoul [29] Kuwait case-control study Safat 29 8 Kuwaiti Arab 210/210 9.59 ± 3.20/9.60 ± 2.73 NA
Bae [30] Korea case-control study Seoul 37 9 Korean 276/327 14.5 ± 4.4/13.8 ± 3.8 SDS: −0.01 ± 0.95/−0.09 ± 1.19
Liu [32] China case-control study Nanjing 32 8 Chinese 295/296 8.66 ± 3.75/8.40 ± 3.60 NA
Federico [31] Italy case-control study Varese, Pisa 45 5 NA 107/92 9.5 ± 3.8(5.0)/9.4 ± 3.9(6.5)d NA
  1. T1DM type 1 diabetes mellitus, NOS Newcastle–Ottawa Scale, BMI body mass index, NA not available, N number, SDS standard deviation score.
  2. aAge and BMI were presented as mean ± standard deviation except a was mean (standard error).
  3. bMedian, full range (min–max).
  4. cMedian (interquartile range).
  5. dMedian ± standard deviation (interquartile range).