Table 3.
Changes in β-cell function over time among those with 25(OH)D < 12 ng/mL at baseline
| Baseline | Month 12 | Month 24 | Average percent difference compared with baseline (95% CI)a | Overall (unadjusted) least-squares mean percent difference for vitamin D vs placebo (95% CI)b | |
|---|---|---|---|---|---|
| DIcpep | |||||
| Vitamin D | 107.9 (92.0, 152.0) | 122.7 (78.6, 195.8) | 111.0 (82.2, 161.4) | 3.6% (-1.5 to 8.8) | 8.5% (0.2 to 16.8) |
| n | 42 | 42 | 32 | ||
| Placebo | 121.9 (74.0, 170.3) | 83.1 (54.9, 170.5) | 137.9 (49.1, 180.3) | -4.9% (-11.4 to 1.6) | |
| n | 30 | 29 | 18 | ||
| P value | 0.74 | 0.16 | 0.90 | ||
| DIins | |||||
| Vitamin D | 6579.9 (4333.0, 8807.0) | 5552.0 (3971.7, 10 336.0) | 6730.8 (3815.1, 10 385.5 | 4.9% (-5.9 to 15.7) | 18.5% (1.1 to 35.9) |
| n | 42 | 42 | 32 | ||
| Placebo | 7784.8 (4124.6, 9680.0) | 4852.5 (2710.5, 9180.4) | 6841.6 (3387.3, 10 101.7 | -13.6% (-27.2 to 0) | |
| n | 30 | 29 | 18 | ||
| P value | 0.74 | 0.19 | 0.72 |
Data are presented as median (IQR). P values for each visit are from Wilcoxon rank-sum test.
Abbreviations: DIcpep, change in the disposition index for C peptide; DIins, disposition index using insulin-based indices; IQR, interquartile range.
a Average percent difference compared with baseline is based on linear mixed model for repeated measures data.
b Unadjusted between-group difference in least square means using all available visits.