Table 1.
Meta-analysis of vitamin D supplementation on indices of glucose and insulin homeostasis stratified by dose.
| Outcomes | Overall | ≤1000 IU/d | >1000 and ≤4000 IU/d | >4000 IU/d | p for trend | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| n/N | WMD | I 2 (%) | n/N | WMD | I 2 (%) | n/N | WMD | I 2 (%) | n/N | WMD | I 2 (%) | ||
| 25 (OH) D | 46/4992 | 40.14 (37.07, 43.22) | 97.8 | 13/1661 | 31.16 (27.63, 34.09) | 97.4 | 15/1603 | 39.64 (35.47, 43.82) | 89.2 | 18/1728 | 47.34 (37.85, 56.84) | 97.8 | 0.02 |
| HbA1c | 16/2298 | −0.04 (−0.07, 0.00) | 86.2 | 4/527 | −0.07 (−0.16, 0.01) | 88.7 | 7/1159 | 0.01 (−0.05, 0.07) | 83.9 | 5/612 | −0.11 (−0.26, 0.05) | 84.1 | 0.97 |
| Fasting glucose | 40/5509 | −0.11 (−0.17, −0.04) | 96.1 | 12/2506 | −0.08 (−0.18, 0.02) | 97.8 | 14/1581 | −0.08 (−0.14, −0.02) | 46.9 | 14/1480 | −0.16 (−0.38, 0.06) | 94.5 | 0.42 |
| Insulin | 32/4740 | −1.47 (−2.00, −0.95) | 90.8 | 10/2192 | −0.89 (−1.83, 0.05) | 94.5 | 12/1381 | −0.94 (−1.98, 0.11) | 51.7 | 10/1167 | −3.03 (−5.29, −0.76) | 81.1 | 0.08 |
| 2 h glucose | 15/1929 | −0.06 (−0.47, 0.35) | 88.4 | 3/171 | 0.13 (−0.21, 0.46) | 0 | 8/1182 | 0.08 (−0.60, 0.77) | 91.9 | 4/576 | −0.47 (−1.34, 0.39) | 89.3 | 0.24 |
| 2 h insulin | 5/1379 | −2.17 (−15.60, 11.25) | 93.4 | NA | NA | NA | 3/870 | 5.70 (4.92, 6.47) | 0 | 2/509 | −13.29 (−39.69, 13.11) | 94.0 | 0.17 |
| Insulin sensitivity | |||||||||||||
| QUICKI | 12/1740 | 0.00 (−0.00, 0.01) | 72.1 | 1/123 | −0.02 (−0.05, 0.01) | NA | 4/919 | 0.00 (−0.00, 0.01) | 75.2 | 7/698 | 0.01 (−0.00, 0.01) | 73.9 | 0.55 |
| HOMA-IR | 36/5484 | −0.32 (−0.47, −0.17) | 96.1 | 13/2867 | −0.24 (−0.50, 0.02) | 97.0 | 9/1178 | −0.22 (−0.54, 0.10) | 67.3 | 14/1439 | −0.45 (−0.90, −0.01) | 95.9 | 0.34 |
| HOMA2-IR | 5/353 | −0.14 (−0.31, 0.04) | 46.6 | NA | NA | NA | 3/178 | −0.21 (−0.46, 0.04) | 42.1 | 2/175 | −0.05 (−0.26, 0.16) | 33.2 | 0.43 |
| HOMA2-%S | 5/329 | 0.57 (−3.24, 4.37) | 22.6 | NA | NA | NA | 5/329 | 0.57 (−3.24, 4.37) | 22.6 | NA | NA | NA | NA |
| Beta cell function | |||||||||||||
| HOMA-B | 6/404 | −10.69 (−19.10, −2.29) | 87.1 | NA | NA | NA | 1/70 | −14.80 (−24.76, −4.84) | NA | 5/334 | −9.88 (−19.69, −0.07) | 89.5 | 0.87 |
| HOMA-%B | 2/139 | 4.87 (−44.59, 54.34) | 84.4 | NA | NA | NA | NA | NA | NA | 2/139 | 4.87 (−44.59, 54.34) | 84.4 | NA |
| HOMA2-%B | 5/320 | 1.57 (−3.98, 7.12) | 0 | NA | NA | NA | 4/249 | 0.28 (−5.61, 6.16) | 0 | 1/71 | 12.03 (−4.70, 28.76) | NA | 0.29 |
| Disposition index | 4/287 | −0.05 (−0.39, 0.29) | 1.9 | NA | NA | NA | 4/287 | −0.05 (−0.39, 0.29) | 1.9 | NA | NA | NA | NA |
n/N: number of studies/number of participants; 25 (OH) D: 25-hydroxyvitamin D; HOMA-IR: homeostatic model assessment-insulin resistance; QUICKI: quantitative insulin sensitivity check index; WMD: weighted mean difference; 2 h glucose: 2-hour plasma glucose; 2 h insulin: 2-hour plasma insulin; NA: not applicable.