Glucose Metabolism Effects of Vitamin D in Prediabetes: The VitDmet Randomized Placebo-Controlled Supplementation Study
Table 2
Changes over time in the outcome parameters by supplementation group ().
Parameter
Placebo ()
40 g/d ()
80 g/d ()
Serum 25(OH)D3 (nmol/L)a
4.1 (17.3)
27.7 (17.2)c
45.0 (23.4)c
<0.001
<0.001, <0.001
<0.001
Serum PTH (pg/mL)b
5.6 (7.4)c
−2.6 (10.8)
−6.4 (9.6)c
<0.001
0.003, <0.001
<0.001
Serum calcium (mM)a
−0.06 (0.08)c
−0.04 (0.07)c
−0.03 (0.08)
0.367
—
0.082
HbA1c (mmol/mol)a
−1.8 (1.2)c
−1.2 (2.0)c
−1.0 (2.0)c
0.130
—
0.024
HbA1c (%)b
−0.2 (0.2)c
−0.1 (0.2)c
−0.1 (0.2)c
0.231
—
0.061
Fasting glucose (nmol/L)a
−0.1 (0.4)
−0.1 (0.3)c
−0.2 (0.5)c
0.483
—
0.104
30 min glucose (nmol/L)a,e
−0.4 (1.1)
−0.2 (1.0)
−0.3 (1.4)
0.811
—
0.380
120 min glucose (nmol/L)a
−0.5 (1.6)
0.7 (1.7)
0.5 (1.8)
0.039
0.011, 0.021
0.021
Fasting insulin (mU/L)b
0.3 (6.1)
0.6 (2.0)
−0.1 (5.3)
0.690
—
0.241
30 min insulin (mU/L)b
−0.8 (29.6)
−0.8 (35.1)
−7.7 (31.7)
0.142
—
0.030
120 min insulin (mU/L)b,e
1.0 (34.7)
10.5 (33.8)
1.4 (60.6)
0.584
—
0.430
HOMA2 %betaa
6.2 (24.5)
8.0 (14.5)c
6.6 (17.3)
0.605
—
0.300
HOMA2 %ISa
−2.9 (28.8)
−6.0 (23.7)
2.0 (20.6)
0.554
—
0.287
HOMA2 %IRa
0.13 (0.71)
0.09 (0.33)
0.03 (0.99)
0.714
—
0.243
Insulin sensitivity indexa
−0.1 (1.2)
−0.4 (1.4)
0.3 (1.5)
0.624
—
0.398
Insulinogenic indexb,e
1.5 (9.2)
0.1 (8.4)
−2.8 (7.3)c
0.306
—
0.063
Waist circumference (cm)a,e
0.02 (3.0)
0.1 (2.3)
0.5 (1.9)
0.741
—
0.311
Body mass index (kg/m2)a
0.25 (0.86)
0.34 (0.55)c
0.30 (0.58)c
0.973
—
0.404
Serum ALAT (U/L)b
0.3 (10.1)
1.6 (8.7)
0.07 (7.5)
0.345
—
0.505
Serum GGT (U/L)b
−0.5 (14.2)
0.9 (7.3)
−1.0 (8.6)
0.462
—
0.211
Serum adiponectin (µg/mL)b
−0.3 (1.6)
−0.1 (1.7)
−0.1 (1.1)
0.997
—
0.497
Serum C-reactive protein (mg/L)b
−0.01 (2.6)
−0.1 (1.4)
−0.6 (1.0)c
0.328
—
0.122
Plasma TNF receptor II (pg/mL)b
46.5 (387.5)
−15.8 (265.1)
42.5 (312.7)
0.635
—
0.235
Plasma IL-6 (pg/mL)b
−0.2 (0.6)
0.04 (0.7)
−0.1 (0.6)
0.371
—
0.380
Plasma IL-1 beta (pg/mL)b
na
na
na
(0.775)
—
(0.287)
Plasma IL-1 receptor antagonist (pg/mL)b
19.2 (85.1)
2.7 (43.2)
−8.9 (52.6)
0.383
—
0.070
Values are mean (standard deviation). bValues are median (interquartile range). cWilcoxon Signed Rank test for the change within group, . dMann-Whitney value for the difference is computed in the following order: placebo and 40 µg/d, placebo and 80 µg/d. . 25(OH)D3: 25-hydroxyvitamin D3; ALAT: alanine aminotransferase; GGT: gamma-glutamyl transferase; HOMA: homeostatic modeling assessment; IL: interleukin; IR: insulin resistance; IS: insulin sensitivity; J-T: Jonckheere-Terpstra; K-W: Kruskal-Wallis; M-WU: Mann-Whitney ; PTH: parathyroid hormone.