Clinical Study

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 ().

ParameterPlacebo ()40 g/d ()80 g/d ()

Serum 25(OH)D3 (nmol/L)a4.1 (17.3)27.7 (17.2)c45.0 (23.4)c<0.001<0.001, <0.001<0.001
Serum PTH (pg/mL)b5.6 (7.4)c−2.6 (10.8)−6.4 (9.6)c<0.0010.003, <0.001<0.001
Serum calcium (mM)a−0.06 (0.08)c−0.04 (0.07)c−0.03 (0.08)0.3670.082
HbA1c (mmol/mol)a−1.8 (1.2)c−1.2 (2.0)c−1.0 (2.0)c0.1300.024
HbA1c (%)b−0.2 (0.2)c−0.1 (0.2)c−0.1 (0.2)c0.2310.061
Fasting glucose (nmol/L)a−0.1 (0.4)−0.1 (0.3)c−0.2 (0.5)c0.4830.104
30 min glucose (nmol/L)a,e−0.4 (1.1)−0.2 (1.0)−0.3 (1.4)0.8110.380
120 min glucose (nmol/L)a−0.5 (1.6)0.7 (1.7)0.5 (1.8)0.0390.011, 0.0210.021
Fasting insulin (mU/L)b0.3 (6.1)0.6 (2.0)−0.1 (5.3)0.6900.241
30 min insulin (mU/L)b−0.8 (29.6)−0.8 (35.1)−7.7 (31.7)0.1420.030
120 min insulin (mU/L)b,e1.0 (34.7)10.5 (33.8)1.4 (60.6)0.5840.430
HOMA2 %betaa6.2 (24.5)8.0 (14.5)c6.6 (17.3)0.6050.300
HOMA2 %ISa−2.9 (28.8)−6.0 (23.7)2.0 (20.6)0.5540.287
HOMA2 %IRa0.13 (0.71)0.09 (0.33)0.03 (0.99)0.7140.243
Insulin sensitivity indexa−0.1 (1.2)−0.4 (1.4)0.3 (1.5)0.6240.398
Insulinogenic indexb,e1.5 (9.2)0.1 (8.4)−2.8 (7.3)c0.3060.063
Waist circumference (cm)a,e0.02 (3.0)0.1 (2.3)0.5 (1.9)0.7410.311
Body mass index (kg/m2)a0.25 (0.86)0.34 (0.55)c0.30 (0.58)c0.9730.404
Serum ALAT (U/L)b0.3 (10.1)1.6 (8.7)0.07 (7.5)0.3450.505
Serum GGT (U/L)b−0.5 (14.2)0.9 (7.3)−1.0 (8.6)0.4620.211
Serum adiponectin (µg/mL)b−0.3 (1.6)−0.1 (1.7)−0.1 (1.1)0.9970.497
Serum C-reactive protein (mg/L)b−0.01 (2.6)−0.1 (1.4)−0.6 (1.0)c0.3280.122
Plasma TNF receptor II (pg/mL)b46.5 (387.5)−15.8 (265.1)42.5 (312.7)0.6350.235
Plasma IL-6 (pg/mL)b−0.2 (0.6)0.04 (0.7)−0.1 (0.6)0.3710.380
Plasma IL-1 beta (pg/mL)bnanana (0.775) (0.287)
Plasma IL-1 receptor antagonist (pg/mL)b19.2 (85.1)2.7 (43.2)−8.9 (52.6)0.3830.070

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.