Table 2.
Continuous secondary outcome variables at baseline and final follow-up at study end (24 weeks) in study participants with available values at both study visits
| Baseline | Follow-up (24 weeks) | Treatment effect (95% CI) | p value | |
|---|---|---|---|---|
| Fasting glucose (mg/dL) | ||||
| Vitamin D (n = 81) | 84 ± 8 | 82 ± 8 | − 1.2 (− 3.6 to 1.3) | 0.353 |
| Placebo (n = 42) | 84 ± 8 | 83 ± 7 | ||
| OGTT glucose 30 min (mg/dL) | ||||
| Vitamin D (n = 80) | 133 ± 24 | 130 ± 23 | − 1.6 (− 10.0 to 6.8) | 0.711 |
| Placebo (n = 42) | 128 ± 25 | 129 ± 26 | ||
| OGTT glucose 60 min (mg/dL) | ||||
| Vitamin D (n = 80) | 123 ± 39 | 105 ± 31 | − 10.2 (− 20.2 to − 0.3) | 0.045 |
| Placebo (n = 42) | 107 ± 31 | 107 ± 34 | ||
| OGTT glucose 120 min (mg/dL) | ||||
| Vitamin D (n = 81) | 98 ± 24 | 88 ± 24 | 0.5 (− 7.6 to 8.6) | 0.903 |
| Placebo (n = 42) | 93 ± 24 | 85 ± 24 | ||
| HbA1c (mmol/mol)a | ||||
| Vitamin D (n = 74) | 33 (31–35) | 33 (32–35) | − 0.4 (− 0.9 to 0.2) | 0.192 |
| Placebo (n = 38) | 34 (32–35) | 33 (32–35) | ||
| HOMA-IRa | ||||
| Vitamin D (n = 81) | 1.95 (1.09–3.51) | 2.29 (1.43–3.47) | − 0.26 (− 0.80 to 0.27) | 0.935 |
| Placebo (n = 42) | 2.15 (1.28–3.00) | 2.31 (1.28–3.81) | ||
| QUICKIa | ||||
| Vitamin D (n = 81) | 0.345 (0.317−0.378) | 0.337 (0.318−0.362) | − 0.004 (− 0.028 to 0.019) | 0.823 |
| Placebo (n = 42) | 0.340 (0.324−0.367) | 0.337 (0.317−0.368) | ||
| Triglycerides (mg/dL)a | ||||
| Vitamin D (n = 79) | 62 (49–85) | 71 (52–93) | 3 (− 7 to 12) | 0.455 |
| Placebo (n = 42) | 78 (50–118) | 74 (48–106) | ||
| Total cholesterol (mg/dL)a | ||||
| Vitamin D (n = 79) | 173 (158–188) | 172 (158–189) | 4 (− 3 to 11) | 0.180 |
| Placebo (n = 42) | 179 (148–203) | 172 (143–204) | ||
| Total testosterone (mg/dL)a | ||||
| Vitamin D (n = 78) | 1.60 (1.10–2.20) | 1.55 (1.28–2.00) | 0.09 (− 0.11 to 0.28) | 0.616 |
| Placebo (n = 41) | 1.40 (1.15–1.80) | 1.40 (1.20–1.90) | ||
| Free testosterone (mg/dL)a | ||||
| Vitamin D (n = 77) | 0.020 (0.016–0.032) | 0.021 (0.015–0.029) | 0.002 (− 0.002 to 0.005) | 0.445 |
| Placebo (n = 41) | 0.019 (0.015–0.035) | 0.021 (0.013–0.028) | ||
Data are shown as means with standard deviation or medians and interquartile range, as appropriate. Treatment effects with 95% confidence interval and p values were calculated by ANCOVA for group differences at follow-up with adjustment for baseline values
HbA1c glycated hemoglobin, HOMA-IR homeostatic model assessment-insulin resistance, OGTT glucose 30 min plasma glucose at 30 min during 75 g oral glucose tolerance test, OGTT glucose 60 min plasma glucose at 60 min during 75 g oral glucose tolerance test, OGTT glucose 120 min plasma glucose at 120 min during 75 g oral glucose tolerance test, QUICKI quantitative insulin sensitivity check index
aSkewed variables for which logarithmic transformed values were used in ANCOVA, but untransformed values are shown in the table