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Diabetol Metab Syndr. 2018 Feb 14;10:7. doi: 10.1186/s13098-018-0306-9. eCollection 2018.

Acute vitamin C improves cardiac function, not exercise capacity, in adults with type 2 diabetes.

Author information

1
1Division of Endocrinology, Department of Medicine, University of Colorado School of Medicine (UCSOM), 12801 E17th Ave, Aurora, CO 80045 USA.
2
5Department of Medicine, Center for Women's Health Research, University of Colorado School of Medicine (UCSOM), Aurora, CO USA.
3
2Division of General Internal Medicine, Department of Medicine, University of Colorado School of Medicine (UCSOM), Aurora, CO USA.
4
3Division of Geriatrics, Department of Medicine, University of Colorado School of Medicine (UCSOM), Aurora, CO USA.
5
VAMC-Geriatric Research Education and Clinical Center (GRECC), Denver, CO 80215 USA.
6
4Division of Cardiology, Department of Medicine, University of Colorado School of Medicine (UCSOM), Aurora, CO USA.
7
6Veterans Administration Medical Center (VAMC), Denver, CO 80215 USA.
#
Contributed equally

Abstract

Background:

People with type 2 diabetes (T2D) have impaired exercise capacity, even in the absence of complications, which is predictive of their increased cardiovascular mortality. Cardiovascular dysfunction is one potential cause of this exercise defect. Acute infusion of vitamin C has been separately shown to improve diastolic and endothelial function in prior studies. We hypothesized that acute vitamin C infusion would improve exercise capacity and that these improvements would be associated with improved cardiovascular function.

Methods:

Adults with T2D (n = 31, 7 female, 24 male, body mass index (BMI): 31.5 ± 0.8 kg/m2) and BMI-similar healthy adults (n = 21, 11 female, 10 male, BMI: 30.4 ± 0.7 kg/m2) completed two randomly ordered visits: IV infusion of vitamin C (7.5 g) and a volume-matched saline infusion. During each visit peak oxygen uptake (VO2peak), brachial artery flow mediated dilation (FMD), reactive hyperemia (RH; plethysmography), and cardiac echocardiography were measured. General linear mixed models were utilized to assess the differences in all study variables.

Results:

Acute vitamin C infusion improved diastolic function, assessed by lateral and septal E:E' (P < 0.01), but did not change RH (P = 0.92), or VO2peak (P = 0.33) in any participants.

Conclusion:

Acute vitamin C infusion improved diastolic function but did not change FMD, forearm reactive hyperemia, or peak exercise capacity. Future studies should further clarify the role of endothelial function as well as other possible physiological causes of exercise impairment in order to provide potential therapeutic targets.Trial registration NCT00786019. Prospectively registered May 2008.

KEYWORDS:

Brachial artery flow mediated dilation; Cardiac echocardiography; Cardiorespiratory fitness; Oxygen uptake kinetics

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