title: Effect of Vitamin D Supplementation on Glycemic Control in Patients With Type 2 Diabetes (SUNNY Trial): A Randomized Placebo-Controlled Trial.
abstract: OBJECTIVE
  Low vitamin D status has been associated with impaired glycemic control in patients with type 2 diabetes. The purpose of our study was to evaluate the effect of vitamin D supplementation on glycemic control in patients with type 2 diabetes.
  
  
  METHODS
  This randomized, double-blind, placebo-controlled trial was conducted in 275 adult patients with type 2 diabetes without insulin treatment. Patients were randomly assigned to receive either vitamin D3 (50,000 IU/month) or placebo for 6 months. To assess the primary outcome of the study, change in HbA(1c), we performed a linear regression analysis.
  
  
  RESULTS
  Mean baseline serum 25-hydroxyvitamin D [25(OH)D] increased from 60.6 ± 23.3 to 101.4 ± 27.6 nmol/L and 59.1 ± 23.2 to 59.8 ± 23.2 nmol/L in the vitamin D and placebo group, respectively. Mean baseline HbA(1c) was 6.8 ± 0.5% (51 ± 6 mmol/mol) in both groups. After 6 months, no effect was seen on HbA(1c) (mean difference: β = 0.4 [95% CI -0.6 to 1.5]; P = 0.42) and other indicators of glycemic control (HOMA of insulin resistance, fasting insulin, and glucose) in the entire study population. Subgroup analysis in patients with a serum 25(OH)D <50 nmol/L or an HbA(1c) level >7% (53 mmol/mol) did not differ the results.
  
  
  CONCLUSIONS
  In a well-controlled group of patients with type 2 diabetes, intermittent high-dose vitamin D supplementation did not improve glycemic control.
authors.affiliation: Department of Internal Medicine, Medical Center Alkmaar, Alkmaar, the Netherlands.
authors.forename: Yvonne H M
authors.initials: YH
authors.lastname: Krul-Poel
authors.affiliation: Department of Internal Medicine, Medical Center Alkmaar, Alkmaar, the Netherlands.
authors.forename: Sanne
authors.initials: S
authors.lastname: Westra
authors.affiliation: Department of Clinical Chemistry, Medical Center Alkmaar, Alkmaar, the Netherlands.
authors.forename: Edwin
authors.initials: E
authors.lastname: ten Boekel
authors.affiliation: Amsterdam Rheumatology and Immunology Center, VU University Medical Center, Amsterdam, the Netherlands.
authors.forename: Marieke M
authors.initials: MM
authors.lastname: ter Wee
authors.affiliation: Department of Epidemiology and Biostatistics, EMGO Institute for Health and Care Research, VU University Medical Center, Amsterdam, the Netherlands.
authors.forename: Natasja M
authors.initials: NM
authors.lastname: van Schoor
authors.affiliation: Department of General Practice, DIAZON, Alkmaar, the Netherlands.
authors.forename: Hans
authors.initials: H
authors.lastname: van Wijland
authors.affiliation: Department of Internal Medicine, Medical Center Alkmaar, Alkmaar, the Netherlands.
authors.forename: Frank
authors.initials: F
authors.lastname: Stam
authors.affiliation: Department of Internal Medicine/Endocrinology, VU University Medical Center, Amsterdam, the Netherlands.
authors.forename: Paul T A M
authors.initials: PT
authors.lastname: Lips
authors.affiliation: Department of Internal Medicine, Medical Center Alkmaar, Alkmaar, the Netherlands Department of Internal Medicine/Endocrinology, VU University Medical Center, Amsterdam, the Netherlands s.simsek@mca.nl.
authors.forename: Suat
authors.initials: S
authors.lastname: Simsek
mesh_terms: D000368:Aged; D001786:Blood Glucose / Q000032:analysis; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000188:drug therapy*; D019587:Dietary Supplements; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007004:Hypoglycemic Agents / Q000008:administration & dosage; D008297:Male; D008875:Middle Aged; D014807:Vitamin D / Q000008:administration & dosage* / Q000031:analogs & derivatives / Q000097:blood
chemical_list: D001786:Blood Glucose; D007004:Hypoglycemic Agents; D014807:Vitamin D; C104450:25-hydroxyvitamin D