Self-reported street drug usage in young adults with Type 1 diabetes is common and may contribute to poor glycaemic control and serious complications of diabetes.
Type II diabetes is characterized by increased oxidative stress, endothelial dysfunction and hypertension. We investigated whether short-term treatment with oral vitamin C reduces oxidative stress and improves endothelial function and blood pressure in subjects with Type II diabetes. Subjects ( n =35) received vitamin C (1.5 g daily in three doses) or matching placebo for 3 weeks in a randomized, double-blind, parallel-group design. Plasma concentrations of 8-epi-prostaglandin F(2alpha) (8-epi-PGF(2alpha)), a non-enzymically derived oxidation product of arachidonic acid, were used as a marker of oxidative stress. Endothelial function was assessed by measuring forearm blood flow responses to brachial artery infusion of the endothelium-dependent vasodilator acetylcholine (with nitroprusside as an endothelium-independent control) and by the pulse wave responses to systemic albuterol (endothelium-dependent vasodilator) and glyceryl trinitrate (endothelium-independent vasodilator). Plasma concentrations of vitamin C increased from 58+/-6 to 122+/-10 micromol/l after vitamin C, but 8-epi-PGF(2alpha) levels (baseline, 95+/-4 pg/l; after treatment, 99+/-5 pg/l), blood pressure (baseline, 141+/-5/80+/-2 mmHg; after treatment, 141+/-5/81+/-3 mmHg) and endothelial function, as assessed by the systemic vasodilator response to albuterol and by the forearm blood flow response to acetylcholine, were not significantly different from baseline or placebo. Thus treatment with vitamin C (1.5 g daily) for 3 weeks does not significantly improve oxidative stress, blood pressure or endothelial function in patients with Type II diabetes.
Background
Evidence from imaging studies suggests a high prevalence of coronary artery disease (CAD) in patients with type 2 diabetes mellitus (T2DM). However, there are no criteria for initiating screening for CAD in this population. The current study investigated whether clinical and demographic characteristics can be used to predict significant CAD in patients with T2DM.
Methods
Computed tomography coronary angiography (CTCA) and laboratory assessments were performed in 259 patients diagnosed with T2DM attending clinics in Northwest London, UK. Coronary artery calcium (CAC) was calculated during CTCA. Significant plaque was defined as one causing more than 50% luminal stenosis. Associations between groups and variables were evaluated using Student’s
t
test, Chi-square tests and univariate and multivariate regression analysis. P < 0.05 was considered statistically significant.
Results
Among patients with a median duration of T2DM of 13 years and a mean age of 62.0 years, median CAC score was 105.91 Agatston Units. In a multivariate analyses, duration of diabetes, CAC score and the presence and number of coronary artery plaques and presence of significant plaque were significant predictors of cardiovascular adverse events. Systolic blood pressure (SBP) had borderline significance as a predictor of cardiovascular events (p = 0.05). In a receiver operating characteristic curve (ROC) analysis, duration of diabetes of > 10.5 years predicted significant CAD (sensitivity, 75.3%; specificity 48.2%). Area under the ROC curve was 0.67 when combining duration of T2DM > 10.5 years and SBP of > 139 mm Hg. Adverse cardiovascular events after a median follow-up of 22.8 months were also significantly higher in those with duration of T2DM > 10.5 years and SBP > 140 mm Hg (log rank p = 0.02 and 0.009, respectively).
Conclusions
Routine screening for CAD using CTCA should be considered for patients with a diagnosis of T2DM for > 10.5 years and SBP > 140 mm Hg.
Trial registration
Clinicaltrials.gov identifier: NCT02109835, 10 April 2014 (retrospectively registered)
This study supports the evidence that oestrogen-progestagen HRT, both oral and transdermal, although attenuating some of the benefit of oestrogen alone on fibrinogen and high-density lipoprotein, significantly reduces cardiovascular risk factors, which should diminish post-menopausal risk of coronary disease.
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