title: Study protocol: a randomised placebo-controlled clinical trial to study the effect of vitamin D supplementation on glycaemic control in type 2 Diabetes Mellitus SUNNY trial.
abstract: BACKGROUND
  Besides the classical role of vitamin D on calcium and bone homeostasis, vitamin D deficiency has recently been identified as a contributing factor in the onset of insulin resistance in type 2 diabetes mellitus. However, it is uncertain whether vitamin D deficiency and poor glycaemic control are causally interrelated or that they constitute two independent features of type 2 diabetes mellitus. There are limited clinical trials carried out which measured the effect of vitamin D supplementation on glycaemic control.The objective of this study is to investigate the effect of vitamin D supplementation on glycaemic control and quality of life in patients with type 2 diabetes mellitus.
  
  
  METHODS
  In a randomised double-blind placebo-controlled trial conducted in five general practices in the Netherlands three hundred patients with type 2 diabetes mellitus treated with lifestyle advises or metformin or sulphonylurea-derivatives are randomised to receive either placebo or 50,000 IU Vitamin D3 at monthly intervals. The primary outcome measure is the change in glycated haemoglobin level between baseline and six months. Secondary outcome measures include blood pressure, anthropometric parameters, lipid profile, insulin resistance, quality of life, advanced glycation end products and safety profiles. Quality of life will be measured by The Short Form (SF-36) Health Survey questionnaire. Advanced glycation end products are measured by an AGE-reader.
  
  
  CONCLUSIONS
  This trial will be the first study exploring the effect of vitamin D supplementation on both glycaemic control and quality of life in patients with type 2 diabetes mellitus. Our findings will contribute to the knowledge of the relationship between vitamin D status and insulin resistance in patients with type 2 diabetes mellitus.
  
  
  BACKGROUND
  The Netherlands trial register: NTR3154.
authors.forename: Yvonne H M
authors.initials: YH
authors.lastname: Krul-Poel
authors.forename: Hans
authors.initials: H
authors.lastname: van Wijland
authors.forename: Frank
authors.initials: F
authors.lastname: Stam
authors.forename: Edwin
authors.initials: E
authors.lastname: ten Boekel
authors.forename: Paul
authors.initials: P
authors.lastname: Lips
authors.affiliation: From the Department of Internal Medicine, Medical Centre Alkmaar, PO Box 7057, 1815 JD, Wilhelminalaan 12, Alkmaar, The Netherlands. s.simsek@mca.nl.
authors.forename: Suat
authors.initials: S
authors.lastname: Simsek
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000032:analysis; D001786:Blood Glucose / Q000032:analysis; D002985:Clinical Protocols; D003924:Diabetes Mellitus, Type 2 / Q000178:diet therapy* / Q000378:metabolism / Q000503:physiopathology; D019587:Dietary Supplements; D004311:Double-Blind Method; D005260:Female; D005500:Follow-Up Studies; D006442:Glycated Hemoglobin / Q000032:analysis; D006801:Humans; D006943:Hyperglycemia / Q000378:metabolism / Q000517:prevention & control*; D007003:Hypoglycemia / Q000378:metabolism / Q000517:prevention & control*; D007333:Insulin Resistance; D008297:Male; D017063:Outcome Assessment, Health Care; D011379:Prognosis; D011788:Quality of Life; D014807:Vitamin D / Q000008:administration & dosage*; D014808:Vitamin D Deficiency / Q000150:complications; D014815:Vitamins / Q000008:administration & dosage
chemical_list: D015415:Biomarkers; D001786:Blood Glucose; D006442:Glycated Hemoglobin; D014807:Vitamin D; D014815:Vitamins