Table 2 Summary of meta-analysis for the proportion of vitamin D deficiency in children/adolescents with T1D

Total proportion

45

6995

2436

0.45 (0.37, 0.54)

97.94

0.00

Year

 2009–2015

21

3921

1314

0.48 (0.36, 0.59)

97.91

0.00

 2016–2022

24

3074

1122

0.43 (0.31, 0.56)

98.05

0.00

Design

 Cross-sectional

19

3233

841

0.31 (0.22, 0.40)

96.91

0.00

 Case-control

23

2028

1129

0.58 (0.45, 0.72)

97.33

0.00

 Cohort

1

244

125

0.51 (0.45, 0.58)

-

-

 Longitudinal

2

1490

341

0.22 (0.20, 0.25)

-

-

Geographical region

 Africa

3

162

104

0.65 (0.42, 0.85)

-

-

 Oceania

2

573

85

0.15 (0.12, 0.18)

-

-

 Europe

11

1323

636

0.50 (0.32, 0.69)

97.82

0.00

 North America

9

2899

629

0.24 (0.15, 0.34)

96.42

0.00

 Asia

20

2038

982

0.54 (0.40, 0.68)

97.39

0.00

Latitude

 Low

3

307

217

0.50 (0.12, 0.88)

-

-

 Mid-Low

13

1749

636

0.56 (0.38, 0.72)

97.86

0.00

 Mid

27

4608

1445

0.39 (0.29, 0.50)

97.85

0.00

 Mid-High

2

331

138

0.42 (0.37, 0.47)

-

-

VD Classify

 < 30ng/ml

2

199

170

0.87 (0.82, 0.92)

-

-

 < 25ng/ml

1

104

83

0.80 (0.71, 0.87)

-

-

 < 20ng/ml

29

3143

1394

0.49 (0.39, 0.60)

96.87

0.00

 < 15ng/ml

6

1237

279

0.24 (0.11, 0.41)

97.31

0.00

 < 12ng/ml

4

2099

386

0.14 (0.09, 0.20)

89.17

0.00

 < 10ng/ml

3

213

124

0.67 (0.26, 0.97)

-

-

Seasons

 Winter

6

530

240

0.50 (0.37, 0.64)

85.06

0.00

 Summer

6

530

99

0.17 (0.08, 0.27)

81.52

0.00

 Spring

4

412

117

0.28 (0.23, 0.33)

4.19

0.37

 Fall

4

412

74

0.20 (0.12, 0.29)

53.33

0.09