A prospective randomized controlled trial of the effects of vitamin D supplementation on long-term glycemic control in type 2 diabetes mellitus of Korea.
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.
Department of Internal Medicine, College of Medicine, Hallym University, Chuncheon, Korea.
Ohk-Hyun
OH
Ryu
Sungwha
S
Lee
Jaemyung
J
Yu
Moon-Gi
MG
Choi
Hyung Joon
HJ
Yoo
Franco
F
Mantero
D000328:Adult; D000368:Aged; D001786:Blood Glucose; D002118:Calcium; D002136:Calcium, Dietary / Q000627:therapeutic use; D002762:Cholecalciferol / Q000627:therapeutic use*; D003924:Diabetes Mellitus, Type 2 / Q000188:drug therapy* / Q000209:etiology; D004311:Double-Blind Method; D005260:Female; D006442:Glycated Hemoglobin / Q000378:metabolism; D006801:Humans; D007333:Insulin Resistance; D008297:Male; D008875:Middle Aged; D010281:Parathyroid Hormone; D056910:Republic of Korea; D014808:Vitamin D Deficiency / Q000150:complications / Q000188:drug therapy*
D001786:Blood Glucose; D002118:Calcium; D002136:Calcium, Dietary; D002762:Cholecalciferol; D006442:Glycated Hemoglobin; D010281:Parathyroid Hormone; C517652:hemoglobin A1c protein, human