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The effect of high-dose vitamin D supplementation on insulin resistance and arterial stiffness in patients with type 2 diabetes

The Korean Journal of Internal Medicine 2014년 29권 5호 p.620 ~ p.629

류옥현(Ryu Ohk-Hyun) - Hallym University College of Medicine Department of Internal Medicine
정완교(Chung Wan-Kyo) - Hallym University School of Business Department of Healthcare Management
이성화(Lee Sung-Wha) - Hallym University College of Medicine Department of Internal Medicine
홍경순(Hong Kyung-Soon) - Hallym University College of Medicine Department of Internal Medicine
최문기(Choi Moon-Gi) - Hallym University College of Medicine Department of Internal Medicine
유형준(Yoo Hyung-Joon) - Hallym University College of Medicine Department of Internal Medicine

Abstract

Background/Aims: Recent epidemiological studies revealed a striking inverse relationship between vitamin D levels, glucose intolerance/insulin resistance (IR), and cardiovascular disease. However, few interventional studies have evaluated the effect of vitamin D supplementation on cardiovascular risk, such as IR and arterial stiffness, in diabetes. We investigated the role of vitamin D supplemen-tation on cardiovascular risk in type 2 diabetes patients, including metabolic pa-rameters, IR, and arterial stiffness.

Methods: We enrolled patients who were taking antidiabetic medications or man-aged their diabetes using lifestyle changes. We excluded patients who were taking vitamin D or calcium supplements. We randomized participants into the vitamin D group (cholecalciferol 2,000 IU/day + calcium 200 mg/day, n = 40) or the placebo group (calcium 200 mg/day, n = 41). We compared their IR (homeostasis model of assessment [HOMA]-IR) and arterial stiffness (brachial-ankle pulse wave velocity and radial augmentation index) before and after 24 weeks of intervention.

Results: The baseline characteristics of the two groups were similar. A total of 62 participants (placebo, 30; vitamin D, 32) completed the study protocol. At the end of the study period, the 25-hydroxyvitamin D [25(OH)D] levels were significantly higher in the vitamin D group than in the placebo group (35.4 ± 8.5 ng/mL vs. 18.4 ± 7.3 ng/mL, p < 0.001). There was no difference in HOMA-IR or changes in arte-rial stiffness (placebo, 21, vitamin D, 24) between the groups.

Conclusions: Our data suggest that high-dose vitamin D supplementation might be effective in terms of elevating 25(OH)D levels. However, we identified no ben-eficial effects on cardiovascular risk in type 2 diabetes, including IR and arterial stiffness.