Influence of Vitamin D on Vascular Function in Adolescents and Young Adults With Type 1 Diabetes

Study Overview
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Brief Summary
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The purpose of this study is to study the role of low vitamin D levels on the health of blood vessels or vascular function in adolescents and young adults with type 1 diabetes.

Detailed Description
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Vitamin D deficiency is known to be common in patients with type 1 diabetes. Studies in adults have shown that vitamin D deficiency is associated with cardiovascular events such as stroke, myocardial infarction and peripheral arterial disease. However, the impact of this deficiency on vascular health in adolescents with diabetes has not been examined. Furthermore given that endothelial dysfunction is reversible, early detection of this process may have therapeutic and prognostic implications in this population.

Official Title
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Influence of Vitamin D on Vascular Function in Adolescents and Young Adults With Type 1 Diabetes

Conditions
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Diabetes Mellitus, Type 1

Intervention / Treatment
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* Dietary Supplement: Vitamin D


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Diagnosed with type 1 diabetes, according to Canadian Diabetes Association guidelines Diagnosed with type 1 diabetes for at least 2 years Between the ages of 12 and 18 years Exclusion Criteria: Previous organ transplantation Diagnosed with familial hypercholesterolemia Active smoker Receiving lipid lowering medications Receiving anti hypertensive medication Significant chronic medical illness, including granulomatous disease History of hypertension BMI >95%tile Known renal failure HbA1c greater than 12% on two successive occasions Known peripheral vascular disease Known hypercalcemia

Ages Eligible for Study
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Minimum Age: 12 Years
Maximum Age: 18 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: Non-Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| No Intervention: Vitamin D Sufficient<br>Sufficient is defined as a 25 OH vitamin D level >50 nmol/l measured at baseline. No clinical intervention will be assigned to this group. Subjects will have fasting bloodwork done. Other study measurements to be taken include: height and weight, stage of puberty, blood pressure, vitamin D and calcium intake information, diabetes risk information, demographic information and spot urine sample. We will also do a non-invasive test called a PAT or 'peripheral arterial tonometry' to look at the health of your blood vessels. | |
| Experimental: Vitamin D Deficient<br>Deficient is defined as a 25 OH vitamin D level ≤ 37.5 nmol/l. This group will receive Vitamin D. Subjects will have fasting bloodwork done. Other study measurements to be taken include: height and weight, stage of puberty, blood pressure, vitamin D and calcium intake information, diabetes risk information, demographic information and spot urine sample. We will also do a non-invasive test called a PAT or 'peripheral arterial tonometry' to look at the health of your blood vessels. | Dietary Supplement: Vitamin D<br>* Dosing If the 25 OH Vitamin D level at Baseline/Screening is less than 20 nmol/L then the subject will receive 2000 IU daily. If the 25 OH Vitamin D level at Baseline/Screening is between 20 and 37.5 nmol/L then the subject will receive 1000 IU daily.<br>* Other names: Ddrops®;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Comparison of Endothelial Function | We will compare endothelial function in adolescents with type 1 diabetes divided into 2 groups on the basis of vitamin D status (deficient and sufficient). Endothelial function will be assessed by peripheral arterial tonometry (PAT) which measures the elasticity of the arteries. | Baseline | 
| Change in Endothelial Function after Treatment with Vitamin D | We will measure the change in endothelial function from baseline in the children that were vitamin D deficient. This measurement will be done once the child has become vitamin D sufficient. Vitamin D status will be assessed at 3 months. If the levels remain deficient treatment would continue for another 3 months, with repeat testing at 6 months. Endothelial function will be assessed by peripheral arterial tonometry (PAT) which measures the elasticity of the arteries. | Baseline, 3 or 6 months | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Monitoring of Vitamin D Levels in Vitamin D deficient subjects | At a vist to take place at 2-3 months, the Vitamin D deficient sujects will undergo blood sampling for 25 hydroxyvitamin D levels to ensure appropriate treatment with D Drops to normalize 25 OH vitamin D levels greater than 50 nmol/L. | 2-3 months | 
| Monitoring of Calcium Creatine Ratio in Vitamin D deficient subjects | At a vist to take place at 2-3 months, the Vitamin D deficient sujects will have a urine assessment of spot calcium creatinine ratio to ensure that hypercalcemia (calcium/ creatinine ratio greater than 0.7) is not present. | 2-3 months | 
| Comparison of Systemic Blood Pressure | We will compare endothelial function in adolescents with type 1 diabetes divided into 2 groups on the basis of vitamin D status (deficient and sufficient). | Baseline | 
| Comparison of Urinary Albumin/Creatinine Ratio | We will compare the urinary albumin/creatinine ratio in adolescents with type 1 diabetes divided into 2 groups on the basis of vitamin D status (deficient and sufficient). | Baseline | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Type 1 Diabetes, Adolescents and Young Adults, Vitamin D, Cardiovascular Disease