Effect of Vitamin D Supplementation on Glucose Tolerance in Subjects at Risk for Diabetes With Low Vitamin D.
Condition: Type 2 Diabetes Mellitus; Vitamin D Deficiency
MeSH terms: Diabetes Mellitus; Diabetes Mellitus, Type 2; Vitamin D Deficiency
Study type: Interventional
Phase: Phase 2

Summary: 
      Type 2 diabetes (T2D) is an increasingly common and serious condition. Studies show that low
      vitamin D levels are associated with increased diabetes risk and that vitamin D may protect
      against diabetes by reducing chronic inflammation and improving insulin sensitivity and
      insulin secretion. However, no studies have been able to show that vitamin D actually reduces
      post-prandial blood glucose levels, the most clinically relevant marker of diabetes.
      Previously the investigators have shown that cheddar cheese and low-fat cheese can be
      fortified with high levels of vitamin D and that this cheese is at least as a effective as
      vitamin D supplements in raising blood vitamin D levels.

      The main purpose of this study is to see whether vitamin D enriched cheese can improve oral
      glucose tolerance (reduce blood glucose 2 hours after consuming a drink containing 75g sugar)
      in people who have low vitamin D levels and are at risk for developing T2D.

      Other aims are to determine the effect of vitamin D may on insulin sensitivity, insulin
      secretion, markers of inflammation, blood cholesterol levels, and safety markers such as
      urinary calcium excretion.
    

Detailed description: 
      Type 2 diabetes (T2D) is an increasingly prevalent and serious condition whose risk appears
      to be increased by low serum vitamin D concentrations. Epidemiological studies show an
      association between increased diabetes risk and low serum vitamin D and studies suggest that
      vitamin D may protect against diabetes by reducing chronic inflammation and improving insulin
      sensitivity and insulin secretion. Although clinical studies show some of these effects, no
      studies have been able to show that vitamin D supplementation reduces post-prandial blood
      glucose, the most clinically relevant marker of diabetes and dysglycemia. Previously, the
      investigators showed that cheddar cheese and low-fat cheese can be fortified with high levels
      of vitamin D3 (28,000IU/ 30g portion) and that, in this form, it is at least as a effective
      as vitamin D3 supplements in raising serum vitamin D concentrations. Since post-prandial
      glucose is most sensitive to changes in insulin sensitivity the main purpose of this study is
      to determine the effect of vitamin D supplementation on oral glucose tolerance (ie. serum
      glucose 2h after 75g oral glucose) in individuals who are at risk for developing T2D.
      Secondary objective are to determine the effect of vitamin D supplementation on insulin
      sensitivity, insulin secretion, inflammatory markers, blood lipids and markers of safety
      including serum parathyroid hormone levels and urinary calcium excretion.
    

Intervention name(s): Control; Vitamin D
Intervention type(s): Dietary Supplement; Dietary Supplement
Intervention description(s): Normal cheddar cheese; Vitamin D3 supplemented cheddar cheese
Other intervention name(s): Vitamin D3
Intervention MeSH terms: Vitamin D; Ergocalciferols; Cholecalciferol; Vitamins
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Primary purpose: Treatment
Keywords: Randomized controlled clinical trial; Diabetes; Vitamin D; Oral glucose tolerance; Blood glucose; Insulin resistance