Can Vitamin D Supplementation Prevent Type 2 Diabetes?
Condition: Type 2 Diabetes Mellitus
MeSH terms: Diabetes Mellitus; Diabetes Mellitus, Type 2
Study type: Interventional
Phase: Phase 4

Summary: 
      The aim of this study is to determine whether vitamin D supplementation in overweight/obese
      individuals with vitamin D deficiency can improve insulin secretion and/or insulin resistance
      by decreasing subclinical inflammation.

      Results of the present study may help to identify new strategies to prevent type 2 diabetes
      in high-risk groups (i.e. overweight and obese individuals, and individuals with a strong
      family history of diabetes).

      Hypothesis: That increasing plasma 25(OH)D concentrations in healthy individuals at risk for
      type 2 diabetes with low vitamin D levels through vitamin D supplementation, will improve
      insulin sensitivity and also insulin secretion by reducing the underlying sub-clinical
      chronic inflammation.

      Aims: To establish whether 16-week vitamin D supplementation given to healthy individuals
      with low vitamin D levels will:

        1. improve insulin sensitivity (in vivo and tissue) and/or insulin secretory function

        2. determine whether this relationship is mediated by a reduced chronic inflammation
    

Detailed description: 
      Numerous studies documented that low vitamin D levels are a serious health risk. Despite the
      sunny climate in Australia, low vitamin D status is becoming increasingly prevalent and
      people with vitamin deficiency represent more than 30% of the healthy Australian population.
      Although sun exposure can maintain good vitamin D levels, often sun exposure is limited as
      people work long hours indoors, and use sunscreen or protective clothing to reduce skin
      cancer risk when outdoors. Moreover, it is difficult to obtain sufficient vitamin D from food
      alone; few foods are naturally rich in vitamin D and in Australia, few foods are fortified.

      While the importance of vitamin D for bone mineralization is well known, it is less clear how
      vitamin D protects against type 2 diabetes and cardiovascular disease. Every day in Australia
      around 275 adults develop diabetes and its prevalence continues to rise.

      We are therefore arguing for a well-designed intervention trial to define the preventive
      potential and physiological mechanisms of the effects of vitamin D supplementation. In
      addition, we plan to explore the mechanisms underlying the relationship between vitamin D
      deficiency and the risk for type 2 diabetes, via its influence on chronic inflammation. Our
      clinical trial will focus on healthy adults with low vitamin D status and will examine the
      effects on insulin sensitivity and secretion measured by 'gold standard' methodology when
      vitamin D is restored to optimum levels. It is in particularly important to determine whether
      vitamin D affects both or only one of these defects because there is evidence from
      observational studies that there is a relationship between vitamin D levels and both insulin
      sensitivity and secretion.

      The proposed intervention study will potentially supply important evidence on how restoring
      vitamin D levels may protect against type 2 diabetes. Such findings could have direct
      relevance for novel approaches to diabetes prevention.
    

Intervention name(s): Vitamin D; Placebo
Intervention type(s): Dietary Supplement; Dietary Supplement
Other intervention name(s): Ostellin
Intervention MeSH terms: Vitamin D
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Primary purpose: Prevention