A prospective randomized controlled trial of the effects of vitamin D supplementation on long-term glycemic control in type 2 diabetes mellitus of Korea.

Abstract

Epidemiologic studies have shown that low vitamin D levels are associated with reduced insulin sensitivity and increased risk of developing type 2 diabetes mellitus (T2DM). However, there is little evidence that vitamin D supplementation improves glucose intolerance. We evaluated the glucose-lowering effect of vitamin D in Korean T2DM subjects. We enrolled 158 T2DM patients who had stable glycemic control [hemoglobin A1c (HbA1c) <8.5%] and vitamin D levels less than 20 ng/mL. The participants were randomized into two groups: Placebo (100 mg daily of elemental calcium administered twice a day) or Vitamin D (1000 IU daily of cholecalciferol combined with 100 mg of elemental calcium administered twice a day). We compared outdoor physical activity, glycemic control, homeostasis model of assessment - insulin resistance (HOMA-IR), and parathyroid hormone (PTH), during the 24-week intervention. We analyzed the data of 129 participants (placebo =65, vitamin D =64) who completely followed the protocol. Outdoor physical activity and oral anti-diabetic drugs did not differ between the groups. While there were significant differences in the vitamin D levels (15.6 ± 7.1 ng/mL vs 30.2 ± 10.8 ng/mL, P<0.001) and change in PTH levels (1.4 ± 15.3 pg/mL vs -5.5 ± 9.8 pg/mL, P=0.003) between the placebo and vitamin D groups, there were no differences in HbA1c (7.27 ± 0.87% vs 7.40 ± 0.90%) (P=0.415) and HOMA-IR. Serum calcium and kidney function results showed that the vitamin D supplementation was safe. While vitamin D supplementation is safe and effective in the attainment of vitamin D sufficiency, it had no effect on long-term glycemic control for T2DM in our study.

• Authors: Ohk-Hyun Ryu, Sungwha Lee, Jaemyung Yu, Moon-Gi Choi, Hyung Joon Yoo, Franco Mantero
• Journal: Endocrine journal (Endocr J) Vol. 61 Issue 2 Pg. 167-76 ( 2014) ISSN: 1348-4540 [Electronic] Japan
• PMID: 24240575 (Publication Type: Journal Article, Randomized Controlled Trial, Research Support, Non-U.S. Gov't)

Chemical References

• Blood Glucose
• Calcium, Dietary
• Glycated Hemoglobin A
• Parathyroid Hormone
• hemoglobin A1c protein, human
• Cholecalciferol
• Calcium

Topics

• Adult
• Aged
• Blood Glucose
• Calcium
• Calcium, Dietary (therapeutic use)
• Cholecalciferol (therapeutic use)
• Diabetes Mellitus, Type 2 (drug therapy, etiology)
• Double-Blind Method
• Female
• Glycated Hemoglobin (metabolism)
• Humans
• Insulin Resistance
• Male
• Middle Aged
• Parathyroid Hormone
• Republic of Korea
• Vitamin D Deficiency (complications, drug therapy)