Urinary Vitamin C Loss in Diabetic Subjects
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ClinicalTrials.gov Identifier: NCT00071526 |
Recruitment Status :
Recruiting
First Posted : October 28, 2003
Last Update Posted : May 20, 2024
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Tracking Information | |||||||||
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First Submitted Date | October 27, 2003 | ||||||||
First Posted Date | October 28, 2003 | ||||||||
Last Update Posted Date | May 20, 2024 | ||||||||
Actual Study Start Date | April 11, 2006 | ||||||||
Primary Completion Date | Not Provided | ||||||||
Current Primary Outcome Measures |
Plasma, neutrophil and RBC Vitamin C concentrates [ Time Frame: end of study ] Measurements of plasma, neutrophil and red blood cell vitamin c concentrations in diabetic subjects as compared to healthy controls.
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Original Primary Outcome Measures | Not Provided | ||||||||
Change History | |||||||||
Current Secondary Outcome Measures |
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Original Secondary Outcome Measures | Not Provided | ||||||||
Current Other Pre-specified Outcome Measures | Not Provided | ||||||||
Original Other Pre-specified Outcome Measures | Not Provided | ||||||||
Descriptive Information | |||||||||
Brief Title | Urinary Vitamin C Loss in Diabetic Subjects | ||||||||
Official Title | Urinary Vitamin C Loss in Subjects With and Without Diabetes | ||||||||
Brief Summary | Several studies have reported that diabetic subjects have lower plasma vitamin C concentrations than non-diabetic subjects. Although urinary vitamin C loss in diabetic subjects was reported to be increased in two studies, these are difficult to interpret due to lack of controlled vitamin C intake, inadequate sampling, lack of control subjects, or methodology uncertainties in vitamin C assay and sample processing. Consequently, it is unclear whether diabetic subjects truly have both low plasma and high urine vitamin C concentrations. We propose that low plasma vitamin C concentrations in diabetic subjects are due in part to inappropriate renal loss of vitamin C in these subjects but not in healthy controls. We will study vitamin C concentrations in patients with type 1 and type 2 diabetes and in matched healthy research subjects. Vitamin C concentrations in plasma, neutrophils (as a proxy for tissue concentrations) and in urine will be measured in outpatients. In those willing to be admitted to the Clinical Center, we will measure 24-hour urinary excretion of vitamin C while on a vitamin C free diet, and creatinine clearance, a measure of glomerular filtration rate. On day 2 of the inpatient study, subjects will receive a single 200mg dose of oral vitamin C and we will measure vitamin C concentrations in frequent blood and urine samples to determine the renal threshold and relative bioavailability for vitamin C. Single nucleotide polymorphisms (SNPs) will be determined in genomic DNA responsible for the two proteins mediating sodium-dependent vitamin C transport, SVCT1 and SVCT2. If low plasma and high urine vitamin C concentrations are found in diabetic subjects, further studies will be needed to explore mechanisms and to determine recommended dietary allowances for this patient population. | ||||||||
Detailed Description | Several studies have reported that diabetic subjects have lower plasma vitamin C concentrations than non-diabetic subjects. Although urinary vitamin C loss in diabetic subjects was reported to be increased in two studies, these are difficult to interpret due to lack of controlled vitamin C intake, inadequate sampling, lack of control subjects, or methodology uncertainties in vitamin C assay and sample processing. Consequently, it is unclear whether diabetic subjects truly have both low plasma and high urine vitamin C concentrations. We propose that low plasma vitamin C concentrations in diabetic subjects are due in part to inappropriate renal loss of vitamin C in these subjects but not in healthy controls. We will study vitamin C concentrations in patients with type 1 and type 2 diabetes and in matched healthy research subjects. Vitamin C concentrations in plasma, neutrophils (as a proxy for tissue concentrations) and in urine will be measured in outpatients. In those willing to be admitted to the Clinical Center, we will measure 24-hour urinary excretion of vitamin C while on a vitamin C free diet, and creatinine clearance, a measure of glomerular filtration rate. On day 2 of the inpatient study, subjects will receive a single 200mg dose of oral vitamin C and we will measure vitamin C concentrations in frequent blood and urine samples to determine the renal threshold and relative bioavailability for vitamin C. Single nucleotide polymorphisms (SNPs) will be determined in genomic DNA responsible for the two proteins mediating sodium-dependent vitamin C transport, SVCT1 and SVCT2. If low plasma and high urine vitamin C concentrations are found in diabetic subjects, further studies will be needed to explore mechanisms and to determine recommended dietary allowances for this patient population. | ||||||||
Study Type | Observational | ||||||||
Study Design | Observational Model: Cohort Time Perspective: Prospective |
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Target Follow-Up Duration | Not Provided | ||||||||
Biospecimen | Not Provided | ||||||||
Sampling Method | Probability Sample | ||||||||
Study Population | Community sample. | ||||||||
Condition | Diabetes | ||||||||
Intervention | Not Provided | ||||||||
Study Groups/Cohorts |
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Publications * |
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* Includes publications given by the data provider as well as publications identified by ClinicalTrials.gov Identifier (NCT Number) in Medline. |
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Recruitment Information | |||||||||
Recruitment Status | Recruiting | ||||||||
Estimated Enrollment |
5000 | ||||||||
Original Enrollment |
150 | ||||||||
Study Completion Date | Not Provided | ||||||||
Primary Completion Date | Not Provided | ||||||||
Eligibility Criteria |
We propose to study of five thousand male and female subjects between the ages of 18 and 65. This will include healthy subjects and subjects with type 1 or type 2 diabetes. To be included in the study, study subjects should
The aim of this study is to determine whether diabetic subjects lose vitamin C in the urine in their normal clinical condition (i.e. while on treatment) and not in the native untreated state of uncontrolled hyperglycemia. Therefore the patients will not discontinue medication. EXCLUSION CRITERIA (for arm 1): Exclusion criteria will include the following:
EXCLUSION CRITERIA (for arms 2 and 3): Exclusion criteria will include the following:
For inpatient subjects, an additional exclusion criterion is consumption during the hospitalization of any foods or beverages other than those in the vitamin C free diet. |
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Sex/Gender |
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Ages | 18 Years to 65 Years (Adult, Older Adult) | ||||||||
Accepts Healthy Volunteers | Yes | ||||||||
Contacts |
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Listed Location Countries | United States | ||||||||
Removed Location Countries | |||||||||
Administrative Information | |||||||||
NCT Number | NCT00071526 | ||||||||
Other Study ID Numbers | 040021 04-DK-0021 |
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Has Data Monitoring Committee | Not Provided | ||||||||
U.S. FDA-regulated Product |
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IPD Sharing Statement | Not Provided | ||||||||
Current Responsible Party | National Institutes of Health Clinical Center (CC) ( National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) ) | ||||||||
Original Responsible Party | Not Provided | ||||||||
Current Study Sponsor | National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) | ||||||||
Original Study Sponsor | Same as current | ||||||||
Collaborators | Not Provided | ||||||||
Investigators |
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PRS Account | National Institutes of Health Clinical Center (CC) | ||||||||
Verification Date | May 15, 2024 |