Diabetes and Vascular Disease

SUN-609 - Association between Vitamin C Dysregulation and Pathophysiological RBC Changes in Diabetes

Sunday, June 14, 2026

9:00 AM - 4:00 PM CT

Location: ENDOExpo; Poster Floor

Abstract Poster Presenter(s)

EO

Eden Obodum-Kusi Appiah, n/a

National Institute on Diabetes & Digestive & Kidney Diseases
Bethesda, Maryland, United States

Co-Author(s)

PV

Pierre-Christian Violet, PhD

National Institute on Diabetes & Digestive & Kidney Diseases
Bethesda, Maryland, United States
RB

Razi Berman, CRNP

National Institute on Diabetes & Digestive & Kidney Diseases
Bethesda, Maryland, United States
YW

Yu Wang, MD

Endocrinology fellow
National Institutes of Health
Bethesda, Maryland, United States
ST

Stephanie Teng, n/a

National Institute on Diabetes & Digestive & Kidney Diseases
Bethesda, Maryland, United States
MN

Mahtab Niyyati, MD

National Institute on Diabetes & Digestive & Kidney Diseases
Bethesda, Maryland, United States
YW

Yaohui Wang, MD

National Institute on Diabetes & Digestive & Kidney Diseases
Bethesda, Maryland, United States
JG

Juen Guo, PhD

National Institute on Diabetes & Digestive & Kidney Diseases
Bethesda, Maryland, United States
NP

Nermi Parrow, PhD

National Institute on Diabetes & Digestive & Kidney Diseases
Bethesda, Maryland, United States
ML

Mark Levine, MD

National Institute on Diabetes & Digestive & Kidney Diseases
Bethesda, Maryland, United States

Senior Author/Primary Investigator(s)

IE

Ifechukwude Ebenuwa, MD

Physician, Clinical Investigator
National Institute on Diabetes & Digestive & Kidney Diseases
Bethesda, United States

Background: Diabetic vascular complications have been associated with measures of vitamin C dysregulation including reduced plasma concentrations and abnormal urinary loss: vitamin C renal leak. We investigated associations between vitamin C dysregulation and pathophysiological RBC changes also linked to diabetic vascular complications, including reduced RBC deformability (RBCD): the ability of RBCs to change their shape in the microvasculature, increased aggregability (RBCA): the tendency of RBCs to form aggregates, and decreased osmotic fragility, indicative of RBC dehydration.

Methods: We conducted an outpatient cross-sectional study of participants with diabetes (N81) and nondiabetic controls (N78). Clinical history was obtained using standardized forms, matched fasting plasma and urine samples were obtained for vitamin C measurements using coulometric electrochemical detection with high performance liquid chromatography (HPLC). Vitamin C insufficiency was defined as plasma vitamin C concentrations < 50 µM. Vitamin C renal leak was defined as the abnormal presence of urinary vitamin C at fasting plasma concentrations below the minimal elimination threshold ( < 43.2µM in women and < 38.1 µM in men). Blood samples were used for ektacytometry studies of RBC parameters, with reduced RBCD indicated by increased half-maximal shear stress [SS1/2], increased RBCA reflected by increased Aggregation Index [AI] and increased OF reflected by higher minimum osmolality [Omin]. Outcomes assessed associations between plasma vitamin C, vitamin C insufficiency, renal leak status and RBC parameters. Due to sample size limitation, outcomes assessed associations in the combined cohorts.

Results: In the combined cohorts (N159), 50% (N80) had vitamin C insufficiency and 21% (N34) had a vitamin C renal leak. Reduced RBCD was associated with lower plasma vitamin C concentrations (r=-0.25; p=0.001), vitamin C insufficiency status (0.17 ± 0.06; p=0.007) and presence of vitamin C renal leak (0.20 ±0.08; p=0.009). Increased RBCA (higher AI) was associated with lower plasma vitamin C concentrations (r=-0.16; p=0.04) but not vitamin C insufficiency or renal leak. Reduced osmotic fragility was significantly associated with vitamin C renal leak (6.20±2.73; p=0.03), but not plasma vitamin C or insufficiency status.

Conclusions: All three measures of vitamin C dysregulation are associated with pathophysiological RBC changes associated with vascular complications in diabetes. In contrast to other vitamin C measures, renal leak assessment incorporates both plasma and urine vitamin C concentrations, a possible explanation for unique association reduced osmotic fragility.

*Unless otherwise noted, all abstracts presented at ENDO must not be released to the press or the public until the date and time of presentation. For oral presentations, the abstracts are embargoed until the session begins. The Endocrine Society reserves the right to lift the embargo on specific abstracts that are selected for promotion prior to or during ENDO.*