| Study | Participants | Vitamin D Supplementation | Mean 25OHD Levels After Supplementation |
25OHD >75 nmol/l (% subjects) |
Association 25OHD/HbA1c | Association Supplementation/HbA1c | Results |
|---|---|---|---|---|---|---|---|
| Savastio et al. [13] | 141 T1D (35 migrants, 106 Italians) | Subjects with 25OHD <75 nmol/l Cholecalciferol 1000 IU/day |
56.6±23.7 nmol/l | 20.6% | + | + | At baseline: significant inverse correlation between 25OHD levels and diabetic keto-acidosis severity. Relationship between HbA1c and 25OHD levels in a multivariate regression analysis. |
| Talaat et al. [63] | 250 T1D and 250 healthy controls | None | / | / | + | Not evaluated | Significant negative relationship between 25OHD levels and HbA1c values. Levels of islet antibodies, anti-GAD antibodies and anti-insulin antibodies were significantly associated with 25OHD deficiency. Significant association between 25OHD deficiency and high levels of pro-inflammatory cytokines. |
| Nwosu et al. [68] | Total population: 88 T1D, 43 T2D Subjects with 25OHD <50 nmol/l: 33 T1D, 31 T2D |
Subjects with 25OHD <50 nmol/l Ergocalciferol or cholecalciferol 400-7.000 IU/day for 8-16 weeks |
T1D: 67.6±20.6 nmol/l T2D: 60.7±27.7 nmol/l |
Not reported | Not evaluated | - | No changes in total daily dose of insulin per kg body weight in T1D and T2D. Significant decrease in HbA1c in T2D after 3 months of vitamin D supplementation but not in T1D. |
| Al Sawah et al. [69] | 197 T1D | None | / | / | - | Not evaluated | No differences in HbA1c across 25OHD levels (≤50; 50-75; >75 nmol/l). Not significant correlation between 25OHD and HbA1c in the multivariate model. |
| Perchard et al. [70] | Total population: 51 T1D (35 Caucasian, 11 South Asian, 5 other) Subjects with 25OHD <50 nmol/l: 40 T1D |
Subjects with 25OHD <50 nmol/l Cholecalciferol 100.000 IU (2-10 years)-160.000 IU (>10 years) single dose |
Not reported | Not reported | Only in white Caucasian subgroup | - | At baseline: no significant correlation between 25OHD and HbA1c in the whole cohort. Significant inverse relationship between 25OHD and HbA1c in the Caucasian group. After treatment: no difference in HbA1c at 3 months or at 1 year. |
| Giri et al. [71] | Total population: 271 T1D Subjects with 25OHD <50 nmol/l: 124 T1D |
Subjects with 25OHD <50 nmol/l Cholecalciferol 400 IU (25OHD 30-50 nmol/l)-6.000 IU (25OHD <30 nmol/l)/day for 3 months |
65.3±9.3 nmol/l | Not reported | + | + | Significant positive association between baseline HbA1c and HbA1c reduction after treatment. Significant direct relationship between baseline 25OHD levels and HbA1c reduction after treatment. |