RecruitingNot Applicable

Urinary Vitamin C Loss in Diabetic Subjects

United States5,000 participantsStarted 2006-04-11

Plain-language 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 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....

Who can participate

Age range

18 Years – 65 Years

Sex

ALL

See this in plain English?

AI-rewrites the medical criteria so a patient or caregiver can understand them. Always confirm with the trial site.

* INCLUSION CRITERIA: To be included in the study, study subjects should be: * Aged 18-65 years. * Either: * Have no diagnosis of diabetes: "nondiabetic controls", or * Have a diagnosis in their medical history of either Type 1 or Type 2 diabetes EXCLUSION CRITERIA (for outpatient study, arm 1) Exclusion criteria will include the following: * Unable or unwilling to provide a signed and dated informed consent form * Unable or unwilling to comply with study procedures and lifestyle considerations EXCLUSION CRITERIA (for inpatient studies, arms 2 and 3) Study participants interested in participating in Arms 2 and/or 3 will be excluded from this further participation if they meet any of the following: * significant organ malfunction leading to clinical instability including liver disease, pulmonary disease, ischemic heart disease, heart failure, stroke, peripheral vascular disease, and anemia at investigator discretion * other serious or chronic illness; history of serious or chronic illness; coronary artery disease, or peripheral vascular disease resulting in clinical instability * pregnancy or lactation * presence of other conditions which, in the judgment of the investigators, can influence vitamin C metabolism or vitamin C renal handling

Questions worth asking your doctor

Bring these to your next appointment. They're a starting point for a shared conversation — not a sign you qualify or a recommendation to enrol.

1Based on my diagnosis and history, is this trial worth exploring for me — or is there a standard treatment we should try first?
2What does this trial's phase tell us about how much is already known about its safety and benefit?
3What would taking part actually involve for me — visits, tests, time, and travel?
4What are the known and possible risks or side effects I should weigh, and how would they be monitored?
5If this trial isn't the right fit, what other options or trials would you suggest I look into?

Generated to help you prepare — always confirm anything about your own eligibility and care with the study team and your doctor.

Questions for the trial coordinator

The trial coordinator is the person who runs the study day to day. These cover the practical side — logistics, costs, and what taking part would actually mean for your life. The study team confirms whether you meet the criteria; these are questions to ask, not a sign you qualify.

1What does taking part actually involve week to week — how many visits, where, and how long does each one take?
2What costs are covered by the study, and what might I have to pay for myself, including travel, parking, or time off work?
3What happens during screening, and what happens if the study team confirms I don't meet the criteria after those tests?
4Who pays for the scans, blood work, and other tests the trial requires — the study, my insurance, or me?
5How will being in the trial affect my regular care, and will my own doctor stay informed and involved?
6Can I leave the trial at any point if I change my mind, and what would happen to my care if I do?

A starting point for the conversation — always confirm anything about your own eligibility, costs, and care with the study team and your doctor.

What they're measuring

Plasma, neutrophil and RBC Vitamin C concentrates

Timeframe: end of study

Trial details

NCT IDNCT00071526

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

Sponsor typeNIH

Study typeOBSERVATIONAL

Contact for this trial

Razi S Berman, C.R.N.P.

(301) 827-5757 razi.berman@nih.gov

View on ClinicalTrials.gov More Diabetes trials