Urinary Vitamin C Loss in Diabetic Subjects

Part of paid clinical trials in Bethesda, Maryland.

Sponsor
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Study ID
NCT00071526
Status
Recruiting
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Conditions

  • Diabetes

Eligibility Criteria

Sex
ALL
Age
18 Years - 65 Years
Healthy Volunteers
Accepted

Study Details

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 nondiabetic controls and cohorts with diabetes. Vitamin C concentrations in plasma, RBCs, and urine will be measured in outpatients. In those willing to be admitted to the Clinical Center, we will measure vitamin C pharmacokinetics to determine the relative bioavailability for vitamin C in individuals with and without abnormal urinary loss of vitamin C (or renal leak). Single nucleotide polymorphisms (SNPs) will be determined in genomic DNA responsible for the two proteins mediating sodium dependent vitamin C transport, SVCT1 and SVCT2. We will also explore mechanisms underlying abnormal urinary vitamin C loss.

Key Dates

Start date
Apr 11, 2006
Status verified
May 2026

Study Design

Enrollment
5,000 participants (estimated)

Arms

  • Arm: Diabetes Type I
    Subjects with Type I diabetes mellitus
  • Arm: Diabetes Type II
    Subjects with Type II diabetes mellitus
  • Arm: Healthy Volunteers
    Healthy Volunteers

Primary Outcome Measure

Plasma, neutrophil and RBC Vitamin C concentrates [ Time Frame: end of study ]

Central Contacts

Locations (1)

FacilityCityStateZIPSite coordinators
National Institutes of Health Clinical CenterBethesdaMaryland20892-

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National Institutes of Health Clinical Center· Bethesda, MD

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