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Journal of Diabetes Research
Volume 2015 (2015), Article ID 672653, 8 pages
Clinical Study

Glucose Metabolism Effects of Vitamin D in Prediabetes: The VitDmet Randomized Placebo-Controlled Supplementation Study

1Unit of Public Health, The Institute of Public Health and Clinical Nutrition, University of Eastern Finland, P.O. Box 1627, 70211 Kuopio, Finland
2The Unit of Clinical Nutrition, The Institute of Public Health and Clinical Nutrition, University of Eastern Finland, P.O. Box 1627, 70211 Kuopio, Finland
3Institute of Clinical Medicine, Internal Medicine, Kuopio University Hospital (KYS), P.O. Box 100, 70029 Kuopio, Finland
4Department of Clinical Chemistry, Institute of Clinical Medicine, University of Eastern Finland and Eastern Finland Laboratory Centre, P.O. Box 1627, 70211 Kuopio, Finland

Received 16 December 2014; Revised 28 April 2015; Accepted 28 April 2015

Academic Editor: Geoff Werstuck

Copyright © 2015 Tomi-Pekka Tuomainen et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Epidemiological evidence suggests a role for vitamin D in type 2 diabetes prevention. We investigated the effects of vitamin D3 supplementation on glucose metabolism and inflammation in subjects with prediabetes. A 5-month randomized, double-blind, placebo-controlled intervention with three arms (placebo, 40 μg/d, or 80 μg/d vitamin D3) was carried out among sixty-eight overweight (BMI 25–35) and aging (≥60 years) subjects from Finland, with serum 25-hydroxyvitamin D3 [25(OH)D3] < 75 nmol/L and either impaired fasting glucose or impaired glucose tolerance. Analyses included 66 subjects who completed the trial. Glucose metabolism was evaluated by fasting and 2-hour oral glucose tolerance test-derived indices and glycated hemoglobin. Inflammation was evaluated by high-sensitive C-reactive protein and five cytokines. Although a dose-dependent increase in serum 25(OH)D3 over the supplementation period was observed (P trend < 0.001), there were no other statistically significant differences in changes in the 13 glucose homeostasis indicators between the study groups other than increase in the 120 min glucose concentration (P trend = 0.021) and a decreasing trend both in 30 min plasma insulin (P trend = 0.030) and glycated hemoglobin (P trend = 0.024) concentrations. A borderline statistically significant decreasing trend in interleukin-1 receptor antagonist concentration was observed (P = 0.070). Vitamin D3 supplementation does not improve glucose metabolism in ageing subjects with prediabetes but may have modest anti-inflammatory effects.