Vitamin D Supplementation in CAD and Postchallenge Hyperglycemia

Study Overview
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Brief Summary
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The main aim of the investigation is to clarify, whether vitamin D supplementation in coronary artery disease patients with vitamin D deficiency and postchallenge hyperglycemia has an impact on endothelial dysfunction and parameters of insulin sensitivity and beta-cell function.

Detailed Description
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An improvement of endothelial dysfunction as a cardiovascular surrogate parameter could be translated in a reduced risk for future cardiovascular events, which is of major interest, since patients with postchallenge hyperglycemia face a significantly higher cardiovascular risk than patients with normal glucose tolerance. Furthermore an improvement in insulin sensitivity and/or beta-cell function would identify vitamin D as an important strategy for the prevention of type 2 diabetes. In consideration of the rapidly increasing prevalence of diabetes and the failure of current prevention strategies this could be an important, safe and cheap way to support ongoing lifestyle modifying programs. Our study of course investigates surrogate cardiovascular and insulin sensitivity parameters. Assuming a beneficial effect of vitamin D in our study, this concept would have to be proven in further large outcome as well as diabetes prevention trials.

Official Title
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Effects of Vitamin D Supplementation in Coronary Artery Disease Patients With Postchallenge Hyperglycemia and Vitamin D Deficiency on Endothelial Function and Insulin Sensitivity

Conditions
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Coronary Artery Disease, Postprandial Hyperglycemia, Vitamin D Deficiency

Intervention / Treatment
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* Drug: vitamin D


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Age 40-75 Postchallenge hyperglycemia (2h-whole blood glucose value in oral glucose tolerance test above 119 mg/dl, normal fasting glucose) Angiographically verified coronary artery disease (>50% stenosis) Serum 25-OH- vitamin D < 20 ng/ml in winter/spring/autumn and <25 ng/ml during june-september Stable antihypertensive therapy in the last 3 month Exclusion Criteria: Acute coronary syndrome or cerebrovascular event within the previous 1 month BMI > 40 kg/m² Serum creatinine >2.5 times the upper limit of normal GOT or GPT > 3 times the upper limit of normal Heart failure > NYHA class II Uncontrolled hypertension (>160/100 mmHg) New onset of statins, ACE-inhibitors or ARBs within the previous 4 weeks History of urolithiasis Hypercalcaemia Major psychiatric disorders Ongoing treatment with spironolactone, canrenoate, eplerenone, amiloride, triamterene and aliskiren. Treatment with antipsychotic drugs Regular significant antioxidants, vitamins or protein supplementation Immunosuppressive therapy Glucocorticoid therapy Ongoing chemotherapy Pregnancy Any other disease with an estimated life expectancy below 1 year.

Ages Eligible for Study
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Minimum Age: 40 Years
Maximum Age: 75 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: vitamin D (Oleovit®)<br>vitamin D drops | Drug: vitamin D<br>* orally administered 2800 IU of vitamin D or placebo daily<br>* Other names: vitamin d (Oleovit®);|
| Placebo Comparator: Placebo<br>placebo drops | Drug: vitamin D<br>* orally administered 2800 IU of vitamin D or placebo daily<br>* Other names: vitamin d (Oleovit®);|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| endothelial dysfunction | Changes in endothelial dysfunction (peripheral artery tone (PAT) and biochemical) | 1 year | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| insulin resistance and beta-cell function | Changes in indices for insulin resistance and beta-cell function | 1 year | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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endothelial function, insulin sensitivity