Table 2.

Vitamin D and type 1 diabetes mellitus: observational case-control studies.

Place of Study	Cases and Controls	25(OH)D Level at Diagnosis	Vitamin D Deficiency	Significant Findings	References
Sweden	Age: 15–34 y Cases: 459 Controls: 208	Cases: 82.5 ± 1.3 nmol/L ♂: 77.9 ± 1.4; ♀: 90.1 ± 2.4 nmol/L Controls: 96.7 ± 2.0 nmol/L		Significantly lower 25(OH)D level in cases than in controls. Significantly lower 25(OH)D in diabetic men than women.	[119]
Australia	Age: pediatric Cases: 56 Controls: 46	Cases: 78.7 (71.8–85.6) nmol/L Controls: 91.4 (83.5–98.7) nmol/L		Significantly lower 25(OH)D level in cases than in controls.	[120]
India	Age: <25 y Cases: 72 Controls: 41	Cases: 7.88 ± 1.2 ng/mL Controls: 16.64 ± 7.83 ng/mL	Cases: 91.1% Controls: 58.5%	Significantly lower 25(OH)D level and higher prevalence of vitamin D deficiency in cases than in controls.	[121]
Italy	Age: pediatric Cases: 82 Controls: 117	Cases: 54.4 ± 27.3 nmol/L Controls: 74.1 ± 28.5 nmol/L	Cases: 48.8% Controls: 17.9%	Significantly lower 25(OH)D level and higher prevalence of vitamin D deficiency in cases than in controls.	[122]
Qatar	Age: <16 y Cases: 170 Controls: 170		Cases: 90.6% Controls: 85.3%	Significantly higher prevalence of vitamin D deficiency in cases than in controls.	[123]
Kuwait	Age: pediatric Cases: 216 Controls: 204		Cases: total 99% Deficiency: 84% Insufficiency: 15% Controls: total 92% Deficiency: 77% Insufficiency: 15%	Significantly higher prevalence of vitamin D deficiency and vitamin D (deficiency + insufficiency) in cases than in controls.	[124]
Finland	Age: pediatric Cases: 35 Controls: 80	Cases (β-cell Aab+): 70.6 ± 20.8 nmol/L Controls (β-cell Aab−): 65.7 ± 19.4 nmol/L		No significant difference in 25(OH)D level in cases and controls.	[126]

♂—males; ♀—females; Aab+: autoantibodies-positive; Aab−: autoantibodies-negative.