NCT00071526

Urinary Vitamin C Loss in Diabetic Subjects

Recruiting now Last updated 24 March 2026

What this trial tests

trial in Diabetes in 5,000 participants. Currently enrolling.

Timeline

11 April 2006

Quick facts

Lead sponsor	National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Status	Recruiting now
Study type	OBSERVATIONAL
Enrollment	5,000
Start date	11 April 2006
Sites	1 location across United States

Conditions studied

• Diabetes — all drugs for Diabetes →

Sponsor

National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)

Who can join

Adults 18 to 65, any sex, with Diabetes. Patients with the condition only — healthy volunteers not accepted.

Sponsor's own 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 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.

Publications & conference data

5 peer-reviewed publications reference this trial (live from Europe PMC):

1. Low Red Blood Cell Vitamin C Concentrations Induce Red Blood Cell Fragility: A Link to Diabetes Via Glucose, Glucose Transporters, and Dehydroascorbic Acid.
   Tu H, Li H, Wang Y, Niyyati M, et al · · 2015 · cited 69× · PMID 26870799 · DOI 10.1016/j.ebiom.2015.09.049
2. Altered RBC deformability in diabetes: clinical characteristics and RBC pathophysiology.
   Ebenuwa I, Violet PC, Tu H, Lee C, et al · · 2024 · cited 17× · PMID 39425096 · DOI 10.1186/s12933-024-02453-2
3. Vitamin C Urinary Loss in Fabry Disease: Clinical and Genomic Characteristics of Vitamin C Renal Leak.
   Ebenuwa I, Violet PC, Padayatty SJ, Wang Y, et al · · 2023 · cited 6× · PMID 37229630 · DOI 10.1016/j.tjnut.2022.12.009
4. Vitamin C Urinary Loss and Deficiency in Human Immunodeficiency Virus (HIV): Cross-sectional Study of Vitamin C Renal Leak in Women With HIV.
   Ebenuwa I, Violet PC, Michel K, Padayatty SJ, et al · · 2023 · cited 1× · PMID 37264998 · DOI 10.1093/cid/ciad333
5. Altered RBC aggregability in diabetes: a threshold for pathophysiological structure-function RBC changes.
   Ebenuwa I, Violet PC, Teng S, Greene T, et al · · 2025 · PMID 41408588 · DOI 10.1186/s40842-025-00256-2