von Willebrand factor and its propeptide in children with diabetes. Relation between endothelial dysfunction and microalbuminuria

Microvascular Changes in the Diabetic Foot

Impairment of the microcirculation of diabetic patients may contribute to secondary complications in the lower extremity, such as foot infections and ulcerations. These microcirculatory changes, which are mainly functional rather than structural, are responsible for the impaired ability of the microvasculature to vasodilate in response to injury. Dysfunction of vascular endothelial cells and vascular smooth muscle cells both contribute to the reduction in vasodilation that is observed in diabetic patients. Nerve-axon reflex related microvascular vasodilation is also impaired in the diabetic population, and there is a growing belief that both the failure of the vessels to dilate and the impairment of the nerve axon reflex are major causes for impaired wound healing in diabetic patients. Further studies are necessary to clarify the precise etiology of endothelial and smooth muscle dysfunction in diabetic patients so that potential therapeutic interventions may be identified.

Aging and ABO blood type influence von Willebrand factor and factor VIII levels through interrelated mechanisms

Essentials von Willebrand factor (VWF) and factor VIII (FVIII) levels are modulated by age and ABO status. The effect of aging and ABO blood type on VWF and FVIII was assessed in 207 normal individuals. Aging and ABO blood type showed combined and bidirectional influences on VWF and FVIII levels. Aging and ABO blood type influence VWF levels through both secretion and clearance mechanisms.

SUMMARY

Background The effect of aging and ABO blood type on plasma levels of von Willebrand factor (VWF) and factor VIII (FVIII) have been widely reported; however, a comprehensive analysis of their combined effect has not been performed and the mechanisms responsible for the age-related changes have not been determined. Objectives To assess the influence of aging and ABO blood type on VWF and FVIII levels, and to evaluate the contribution of VWF secretion and clearance to the age-related changes. Methods A cross-sectional observational study was performed in a cohort of 207 normal individuals, whose levels of VWF, FVIII, VWF propeptide (VWFpp), VWFpp/VWF:Ag ratio and blood type A antigen content on VWF (A-VWF) were quantified. Results Aging and ABO blood type exerted interrelated effects on VWF and FVIII plasma levels, because the age-related increase in both proteins was significantly higher in type non-O individuals (β = 0.011 vs. 0.005). This increase with age in non-O subjects drove the differences between blood types in VWF levels, as the mean difference increased from 0.13 U/mL in the young to 0.57 U/mL in the old. Moreover, A-VWF was associated with both VWF antigen (β = 0.29; 95% confidence interval [CI], 0.09, 0.50) and VWF clearance (β = -0.15; 95% CI, -0.25, -0.06). We also documented an effect of ABO blood type on VWF secretion with aging, as old individuals with blood type non-O showed higher levels of VWFpp (mean difference 0.29 U/mL). Conclusions Aging and ABO blood type have an interrelated effect on VWF and FVIII levels, where the effect of one is significantly influenced by the presence of the other.

Levels of Serum 25(OH)VD3, HIF-1α, VEGF, vWf, and IGF-1 and Their Correlation in Type 2 Diabetes Patients with Different Urine Albumin Creatinine Ratio

OBJECTIVE

To investigate changes in serum 25(OH)VD3, HIF-1α, VEGF, vWf, IGF-1, and their correlation in type 2 diabetes patients at different stages of diabetic kidney disease (DKD).

METHODS

502 type 2 diabetes patients were divided into three groups: Normoalbuminuric group (201 patients), Microalbuminuric group (171 patients), and Macroalbuminuric group (130 patients). Serum 25-hydroxyvitamin D3 [25(OH)VD3] was measured by chemiluminescence. Serum hypoxia-inducible factor-1α (HIF-1α), vascular endothelial growth factor (VEGF), von Willebrand factor (vWf), and insulin-like growth factor-1 (IGF-1) were determined by enzyme-linked immunosorbent assay. We detected the aforementioned serum factors in all cases and 224 control subjects.

RESULTS

Serum HIF-1α, VEGF, vWf, and IGF-1 in type 2 diabetes patients were significantly higher than those in the control group and increased with the increase of Ln(ACR), respectively (P < 0.001). Serum 25(OH)VD3 was significantly lower in type 2 diabetes patients and decreased with the increase of Ln(ACR) (P < 0.001). Ln(ACR) was positively correlated with duration, HbA1c, Scr, BUN, TC, LDL, TG, UA, HIF-1α, VEGF, IGF-1, vWf, and Fg and negatively correlated with 25(OH)VD3 and eGFR.

CONCLUSION

Serum HIF-1α, VEGF, vWf, and IGF-1 may be involved in DKD process through inflammation, angiogenesis, and endothelial injury. Serum 25(OH)VD3 may have protective effects on DKD partly by inhibiting inflammation, abnormal angiogenesis, and vascular endothelial dysfunction.

von Willebrand Factor Propeptide: A Potential Disease Biomarker Not Affected by ABO Blood Groups

Epidemiological studies have shown that vascular-related disorders are associated with high von Willebrand factor antigen (VWF:Ag) and VWF propeptide (VWFpp). VWFpp is secreted together with VWF:Ag upon endothelial cell activation, hence it could be a potential biomarker. This study was conducted to compare between VWF:Ag and VWFpp levels among 30 healthy individuals and 42 patients with high levels of VWF:Ag in different medical conditions and ABO blood groups. VWFpp levels were strongly correlated with VWF:Ag. VWF:Ag and VWFpp levels were significantly increased in patients compared to healthy individuals. VWFpp is not affected by ABO blood group in both healthy individual and patient groups unlike VWF:Ag. As expected, this study showed that VWFpp levels increased in parallel with VWF:Ag levels in patients with diseases associated with endothelial activation. VWFpp though nonspecific is a potential biomarker reflecting underlying pathophysiological changes in various medical conditions with an additional advantage of not being influenced by ABO blood groups.

von Willebrand factor propeptide: biology and clinical utility

von Willebrand factor (VWF) is a large multimeric glycoprotein that mediates the attachment of platelets to damaged endothelium and also serves as the carrier protein for coagulation factor VIII (FVIII), protecting it from proteolytic degradation. Quantitative or qualitative defects in VWF result in von Willebrand disease (VWD), a common inherited bleeding disorder. VWF is synthesized with a very large propeptide (VWFpp) that is critical for intracellular processing of VWF. VWFpp actively participates in the process of VWF multimerization and is essential for trafficking of VWF to the regulated storage pathway. Mutations identified within VWFpp in VWD patients are associated with altered VWF structure and function. The assay of plasma VWFpp has clinical utility in assessing acute and chronic vascular perturbation associated with diseases such as thrombotic thrombocytopenic purpura, sepsis, and diabetes among others. VWFpp assay also has clear utility in the diagnosis of VWD subtypes, particularly in discriminating true type 3 subjects from type 1C (reduced plasma survival of VWF), which is clinically important and has implications for therapeutic treatment.

Suboptimal glycaemic control enhances the risk of impaired prothrombotic state in youths with type 1 diabetes mellitus

OBJECTIVE

To estimate markers of prothrombotic state and endothelial dysfunction in youths with type 1 diabetes mellitus (T1DM) and investigate possible associations with anthropometric/demographic data, glycaemic control and lipid profile.

METHODS

In a cross-sectional design, we recruited 155 youths with T1DM and determined levels of plasminogen activator inhibitor-1-antigen (PAI-1-Ag), von Willebrand factor-antigen (vWF-Ag), fibrinogen (FB), lipids and glycosylated haemoglobin (HbA1c).

RESULTS

Of all the participants, 76 (49%) had increased levels of at least one of prothrombotic factors. Suboptimal glycaemic control was associated with a worse lipid profile and an eightfold increased risk of elevated vWF-Ag levels. Higher vWF-Ag concentrations were also correlated with impaired lipid profile and increased HbA1c values, whereas PAI-1-Ag was positively correlated only with triglyceride levels. After adjustment for potential confounders, only HbA1c contributed independently to the variation in vWF-Ag levels.

CONCLUSION

Impaired prothrombotic state and consequently endothelial dysfunction are present in youths with T1DM, representing a cumulative risk factor for future cardiovascular disease (CVD). Achievement and maintenance of euglycaemia and normolipidaemia are crucial to decelerate progress of this process.

Albuminuria in children

PURPOSE OF REVIEW

Albuminuria is a marker of present and future cardiovascular and renal morbidity, and mortality, in adults. Because the roots of these diseases extend back into childhood, assessment of albuminuria has become relevant to child and adolescent clinical care.

RECENT FINDINGS

Normal levels of albumin excretion in children are well below the cut-off for microalbuminuria. In healthy children, albuminuria relates to fasting insulin, but not blood pressure, BMI, lipid levels, fasting glucose, or insulin resistance. In obese children, albuminuria relates to multiple measures of insulin resistance. In children with type 1 diabetes, hemoglobin A1c seems to be the most consistent clinical predictor of microalbuminuria although multiple mechanisms seem to be involved, including genetic polymorphisms. Children with type 2 diabetes and hypertension already exhibit microalbuminuria.

SUMMARY

When considering the population as a whole, children make ideal subjects in which to study the natural history of albuminuria given their relative lack of multiple morbidities commonly seen in adults. The unfortunate rise in 'adult' diseases in the pediatric age group makes this especially relevant. There is a need for longitudinal studies examining predictors of elevated urinary albumin levels as well as potential treatment strategies.

Endothelial dysfunction in diabetes mellitus

Diabetes mellitus is associated with an increased risk of cardiovascular disease, even in the presence of intensive glycemic control. Substantial clinical and experimental evidence suggest that both diabetes and insulin resistance cause a combination of endothelial dysfunctions, which may diminish the anti-atherogenic role of the vascular endothelium. Both insulin resistance and endothelial dysfunction appear to precede the development of overt hyperglycemia in patients with type 2 diabetes. Therefore, in patients with diabetes or insulin resistance, endothelial dysfunction may be a critical early target for preventing atherosclerosis and cardiovascular disease. Microalbuminuria is now considered to be an atherosclerotic risk factor and predicts future cardiovascular disease risk in diabetic patients, in elderly patients, as well as in the general population. It has been implicated as an independent risk factor for cardiovascular disease and premature cardiovascular mortality for patients with type 1 and type 2 diabetes mellitus, as well as for patients with essential hypertension. A complete biochemical understanding of the mechanisms by which hyperglycemia causes vascular functional and structural changes associated with the diabetic milieu still eludes us. In recent years, the numerous biochemical and metabolic pathways postulated to have a causal role in the pathogenesis of diabetic vascular disease have been distilled into several unifying hypotheses. The role of chronic hyperglycemia in the development of diabetic microvascular complications and in neuropathy has been clearly established. However, the biochemical or cellular links between elevated blood glucose levels, and the vascular lesions remain incompletely understood. A number of trials have demonstrated that statins therapy as well as angiotensin converting enzyme inhibitors is associated with improvements in endothelial function in diabetes. Although antioxidants provide short-term improvement of endothelial function in humans, all studies of the effectiveness of preventive antioxidant therapy have been disappointing. Control of hyperglycemia thus remains the best way to improve endothelial function and to prevent atherosclerosis and other cardiovascular complications of diabetes. In the present review we provide the up to date details on this subject.

Endothelial dysfunction and microvascular complications in type 1 diabetes mellitus

We examined whether alterations in vascular endothelial function and early structural changes in atherosclerosis are associated with microvascular complications in patients with type 1 diabetes mellitus (DM). Flow-mediated dilation (FMD) of the brachial artery and carotid intima-media thickness (IMT) measurement were performed in 70 young adults (aged 19 to 35 yr), 48 with type 1 DM, and 22 normal controls. Patients with diabetes had a lower peak FMD response (7.8+/-3.9 vs. 11.1+/-1.9%, p<0.001) and increased IMT (0.51+/-0.10 vs. 0.42+/-0.07 mm, p<0.001) compared with controls. Twenty (41.7%) of the patients had microvascular complications including neuropathy, nephropathy, or retinopathy. In these complicated diabetic patients, we found a lower FMD response (6.1+/-2.5 vs. 9.9+/-3.5%, p=0.001) compared with diabetics without microvascular complications. The presence of microvascular complications was also associated with older age and longer duration of the disease. However, no differences were observed in IMT, body size, blood pressure, HbA1c, C-reactive protein, low-density lipoprotein or high-density lipoprotein cholesterol levels between complicated and non-complicated patients. Endothelial dysfunction and early structural atherosclerotic changes are common manifestations in type 1 DM, and endothelial dysfunction is thought to be an early event in the atherosclerotic process and important in the pathogenesis of microvascular complications.

Alterations of von Willebrand Factor and Ristocetin Cofactor Activity During Atrial Fibrillation

The aim of this study was to assess the plasma levels of von Willebrand factor antigen and ristocetin cofactor activity, which are well-known markers of endothelial function, in atrial fibrillation (AF) with or without mitral stenosis (MS). Forty-two patients (16 patients with MS and AF [MS(+)AF(+)], 13 patients with nonvalvular AF [MS(−)AF(+)], and 13 patients with MS and sinus rhythm [MS(+)AF(−)]) were included. Von Willebrand factor antigen levels and ristocetin cofactor activities in all participants were assessed. Overall, von Willebrand factor antigen levels and ristocetin cofactor activities in the AF(+) patients were higher than in the AF(−) patients ( P = .003 and P = .002, respectively). Von Willebrand factor antigen levels and ristocetin cofactor activities in the 3 groups were found to be different ( P = .012 and P = .01, respectively). Von Willebrand factor antigen levels were similar between the MS(+)AF(+) and MS(−)AF(+) groups and were higher than that of the MS(+)AF(−) group. Ristocetin cofactor activity in the MS(−)AF(+) group was significantly higher than in the other 2 groups. The ristocetin cofactor activity and von Willebrand factor antigen levels were significantly higher in diabetic or hypertensive patients than in nondiabetic or normotensive patients. According to the results of this study, circulating von Willebrand factor antigen levels and plasma ristocetin cofactor activities are affected by the presence of AF, MS, and associated comorbidities including type 2 diabetes mellitus and systemic hypertension. Further studies are needed to assess the role of von Willebrand factor antigen and ristocetin cofactor activity in predicting vascular thrombotic events in AF, MS, systemic hypertension, and diabetes mellitus.

The prediction of major outcomes of type 1 diabetes: a 12-year prospective evaluation of three separate definitions of the metabolic syndrome and their components and estimated glucose disposal rate: the Pittsburgh Epidemiology of Diabetes Complications Study experience

OBJECTIVE

The metabolic syndrome has been shown to confer an increased risk of cardiovascular disease in both the general and type 2 diabetic populations, but few studies have assessed the metabolic syndrome in type 1 diabetic patients. In a type 1 diabetic cohort, we assessed the prevalence and value of the metabolic syndrome in improving the prediction of major complication outcomes compared with its components and a surrogate measure of insulin resistance, estimated glucose disposal rate (eGDR).

RESEARCH DESIGN AND METHODS

A total of 514 (78%) subjects participating in the Pittsburgh Epidemiology of Diabetes Complications Study with complete 12-year follow-up clinical data were classified by baseline metabolic syndrome status according to three definitions: those of the National Cholesterol Education Program Adult Treatment Panel III (modified by the American Heart Association), the International Diabetes Federation (IDF), and the World Health Organization (WHO). The complication outcomes included coronary artery disease, renal failure, diabetes-related death, and the aggregate of these three major outcomes of diabetes (MOD).

RESULTS

Metabolic syndrome prevalence ranged from 8% (IDF) to 21% (WHO). All definitions showed reasonable specificity (> or = 83%) for each outcome, while the WHO definition had the highest sensitivity for all outcomes except renal failure, for which eGDR was most sensitive. However, the components of each definition predicted better than the overall syndrome. Microalbuminuria was clearly the strongest predictor of all individual measures, yielding hazard ratios of 9 and 6 for mortality and MOD, respectively.

CONCLUSIONS

Though the three metabolic syndrome classifications predict major complication outcomes in type 1 diabetes, their individual components predict better. Of the variables studied, including HbA1, microalbuminuria appears to be the best single predictor of MOD.

Microalbuminuria and endothelial dysfunction: emerging targets for primary prevention of end-organ damage

A minor increase in urinary albumin excretion (microalbuminuria) is known to predict adverse renal and cardiovascular events in diabetic and hypertensive patients. Recent intriguing findings show that microalbuminuria is an early and sensitive marker of future cardiovascular events even in healthy subjects. The mechanisms linking microalbuminuria with end-organ damage have not been fully explained yet; however, generalized endothelial dysfunction might play an important role. Prevailing experimental and clinical data suggest that generalized endothelial dysfunction, frequently characterized by decreased nitric oxide bioavailability, actually precedes the development of microalbuminuria. This review summarizes the current knowledge about the intricate relationship between microalbuminuria and endothelial dysfunction. On the basis of the current evidence, we propose that microalbuminuria and endothelial dysfunction are an emerging target for primary prevention strategies in cardiovascular disease. In near future, dietary components improving nitric oxide bioavailability, such as cocoa-derived flavanols may play important role in these preventive strategies.

Cross-sectional relations of serum aldosterone and urine sodium excretion to urinary albumin excretion in a community-based sample

Experimental models suggest that increased aldosterone and sodium intake are associated with renovascular damage and resultant proteinuria. We hypothesized that serum aldosterone and urinary sodium would be associated with urinary albumin excretion, an indicator of kidney damage. We evaluated 2700 participants (53% women, mean age 58 years) from the Framingham Offspring Study who attended a routine examination between 1995 and 1998, who were free of heart failure and renal failure, and underwent testing for serum aldosterone, spot urinary sodium, and urinary albumin excretion (urine albumin/creatinine ratio, UACR), the latter two indexed to urinary creatinine. Stepwise multivariable linear regression was used to evaluate the relations between UACR with urinary sodium index and serum aldosterone. In multivariable regression, log urinary sodium index was associated positively with log-UACR (P<0.0001). UACR levels in the fourth and fifth quintiles of urinary sodium index were 24% (95% confidence interval (CI) 3-49%), and twofold higher (95% CI 72-150%), respectively, relative to the lowest quintile (P-value for trend across quintiles <0.001). In multivariable models, log-transformed aldosterone was not related to log-UACR. The top quintile of serum aldosterone levels was associated with a 21% higher (95% 1-44%) UACR levels relative to the lowest quintile. Urinary albumin excretion was strongly and positively associated in a continuous fashion with urinary sodium excretion, whereas a weaker nonlinear positive relation with serum aldosterone was noted. Our cross-sectional observations raise the possibility that dietary salt intake may be associated with early renovascular damage.

Vascular complications in diabetes mellitus: the role of endothelial dysfunction

The endothelium is a complex organ with a multitude of properties essential for control of vascular functions. Dysfunction of the vascular endothelium is regarded as an important factor in the pathogenesis of diabetic micro- and macro-angiopathy. Endothelial dysfunction in Type I and II diabetes complicated by micro- or macro-albuminuria is generalized in that it affects many aspects of endothelial function and occurs not only in the kidney. The close linkage between microalbuminuria and endothelial dysfunction in diabetes is an attractive explanation for the fact that microalbuminuria is a risk marker for atherothrombosis. In Type I diabetes, endothelial dysfunction precedes and may cause diabetic microangiopathy, but it is not clear whether endothelial dysfunction is a feature of the diabetic state itself. In Type II diabetes, endothelial function is impaired from the onset of the disease and is strongly related to adverse outcomes. It is not clear whether impaired endothelial function is caused by hyperglycaemia or by other factors. Impaired endothelial function is closely associated with and may contribute to insulin resistance regardless of the presence of diabetes. Endothelial dysfunction in diabetes originates from three main sources. Hyperglycaemia and its immediate biochemical sequelae directly alter endothelial function or influence endothelial cell functioning indirectly by the synthesis of growth factors, cytokines and vasoactive agents in other cells. Finally, the components of the metabolic syndrome can impair endothelial function.

Effects of irbesartan on intracellular antioxidant enzyme expression and activity in adolescents and young adults with early diabetic angiopathy

OBJECTIVE

Defective intracellular antioxidant enzyme production (IAP) has been demonstrated in adults with diabetic nephropathy. The objective of this study was to evaluate the effects of irbesartan, an angiotensin II receptor antagonist, on IAP in adolescents and young adults with type 1 diabetes and early signs of retinopathy and nephropathy.

RESEARCH DESIGN AND METHODS

This prospective, matched case-control study was conducted between November 2001 and December 2002 among 14 type 1 diabetic patients with early signs of angiopathy (ages 14-21 years), 11 type 1 diabetic patients without angiopathy (ages 12-22 years), and 10 healthy volunteers (ages 16-22 years). Skin fibroblasts were obtained by skin biopsies from the anterior part of the forearm and cultured in Dulbecco's modified Eagle's medium. The activity and mRNA expression of CuZn superoxide dismutase (CuZnSOD), Mn superoxide dismutase (MnSOD), catalase (CAT), and glutathione peroxidase (GPX) were measured before and after 6 months of treatment with irbesartan (150 mg/day); on both occasions, antioxidant enzyme activity was evaluated at different glucose concentrations (5 and 22 mmol/l).

RESULTS

At a normal glucose concentration (5 mmol/l), the activity and mRNA expression of CuZnSOD (0.50 +/- 0.21 units/mg protein, 4.4 +/- 1.5 mRNA/glyceraldehyde-3-phosphate dehydrogenase), MnSOD (0.26 +/- 0.04 units/mg protein, 0.08 +/- 0.07 mRNA), CAT (0.32 +/- 0.08 units/mg protein, 4.8 +/- 1.3 mRNA), and GPX (0.53 +/- 0.09 units/mg protein, 2.2 +/- 0.9 mRNA) were not different among the three groups (only values of diabetic subjects with angiopathy are shown). At high glucose concentrations, the activity and mRNA expression of CuZnSOD increased similarly in all groups (diabetic subjects with angiopathy: 0.93 +/- 0.26 units/mg protein, 9.4 +/- 2.1 mRNA); that of CAT and GPX increased in only control subjects and diabetic subjects without angiopathy (diabetic subjects with angiopathy: 0.33 +/- 0.09 units/mg protein and 5.0 +/- 1.4 mRNA; 0.54 +/- 0.10 units/mg protein and 2.3 +/- 1.0 mRNA, respectively). MnSOD did not change in any group. Treatment with irbesartan in adolescents with diabetic angiopathy was able to restore CAT and GPX activity and mRNA expression after exposure to high glucose concentrations. Markers of oxidative stress (serum malondialdehyde, fluorescent products of lipid peroxidation, monocyte chemoattractant protein-1, and 8-isoprostanes prostaglandin F(2alpha)) were significantly reduced after treatment with irbesartan.

CONCLUSIONS

Adolescents and young adults with early signs of diabetic angiopathy have defective intracellular antioxidant enzyme production and activity. Treatment with irbesartan can substantially improve the activity and production of these enzymes in skin fibroblasts.

Renal functional reserve in patients with Type 1 diabetes mellitus

AIM

Decreased renal functional reserve might precede incipient diabetic nephropathy in patients with Type 1 diabetes. The aim of this study was to assess the relationship between renal functional reserve and easily assessable estimates of systemic endothelial dysfunction in normoalbuminuric patients with Type 1 diabetes and diabetic retinopathy.

METHODS

Renal functional reserve was calculated as the relative change in glomerular filtration rate after protein ingestion. Glomerular filtration rate was measured using pharmacokinetic compartmental analysis of single-shot plasma sinistrin clearance. We measured the activity of von Willebrand factor and concentrations of C-reactive protein and apolipoprotein B, as easily assessable estimates of systemic endothelial dysfunction.

RESULTS

Twenty-two patients were studied. Renal functional reserve was inversely associated with activity of von Willebrand factor (R=-0.431, p=0.045) and, in a multivariate model, with concentration of C-reactive protein (R=0.652, p=0.031).

CONCLUSION

Renal functional reserve is inversely associated with concentration of C-reactive protein in normoalbuminuric patients with Type 1 diabetes and diabetic retinopathy. This finding provides evidence that decreased renal functional reserve might reflect endothelial dysfunction. We speculate that decreased renal functional reserve might possibly show as an early marker of diabetic nephropathy.

Folic acid improves endothelial function in children and adolescents with type 1 diabetes

OBJECTIVE

To evaluate the effect of folate supplementation on endothelial function in children and adolescents with type 1 diabetes.

STUDY DESIGN

Thirty-six subjects with type 1 diabetes age 13.6+/-2.6 years completed a randomized, double-blind, placebo-controlled crossover trial. Each subject received 8 weeks of oral folic acid (5 mg/d) and 8 weeks of placebo, with an 8-week washout period. Before and after each intervention, we assessed endothelial function by using brachial artery responses to flow (flow-mediated dilatation [FMD]) and glyceryl trinitrate, von Willebrand factor, glucose, hemoglobin A1c, total plasma homocyst(e)ine (tHcy), vitamin B(12), serum folate, and red cell folate (RCF).

RESULTS

Folic acid increased FMD by 2.58 (3.1-5.7) % (95% confidence interval, 1.28-3.88), whereas placebo did not change FMD (-0.42%; 95% confidence interval, -1.67 to 0.83; P<.001). Folic acid increased serum folate by 14 nmol/L (6.2 ng/mL, P<.001) and RCF by 467.2 nmol/L (206 ng/mL, P<.001). Change in FMD was related to change in serum folate (r=0.46, P=.005) and RCF (r=0.39, P=.02). Glyceryl trinitrate responses, von Willebrand factor, tHcy, and hemoglobin A1c were not affected by the intervention.

CONCLUSIONS

Short-term high-dose folic acid improves endothelial function in children and adolescents with type 1 diabetes and normal folate status independently of tHcy.