Short-term dietary salt supplementation blunts telmisartan induced increases in plasma renin activity in hypertensive patients with type 2 diabetes mellitus

Short-term effects of modest salt reduction combined with DASH diet on changing salt eating habits in hypertensive patients with type II diabetes

OBJECTIVE

Excessive salt intake is currently the foremost universal risk factor for controllable chronic disease. This study evaluated the short-term effects of a modest salt intake reduction combined with the Chinese Modified Dietary Approaches to Stop Hypertension (CM-DASH) diet on sodium and potassium intake, mean arterial pressure (MAP), and pulse pressure (PP) in hypertensive patients with type II diabetes.

METHODS

Sixty-one participants were randomized to the intervention group (52% low-sodium salt and DASH) and control group (normal salt and DASH). An 8-week dietary intervention was applied. Daily salt intake, blood pressure (BP), and drug use were recorded every week. Twenty-four-hour urine, casual urine, and blood samples were measured at baseline, the 4th week, and the end of the intervention.

RESULTS

Fifty-nine patients (25 men) completed the entire study. Sodium intake decreased by 1259.66 (792.76, 1726.56)/705.80 (149.21, 1262.39) mg/day after 4 weeks (intervention: P < .001; control: P = .015). Potassium intake increased by 641.14 (73.31, 1208.96)/43.43 (-259.66, 346.53) mg/day (intervention: P = .028); MAP decreased by 9.06 (6.69, 11.43)/7.16 (4.03, 10.28) mmHg (both: P < .001); PP decreased by 7.97 (3.05, 12.88)/5.74 (2.55,8.94) mmHg (intervention: P = .002; control: P = .001) after 8 weeks. However, the difference between the two groups was not statistically significant.

CONCLUSION

Modest salt reduction and the CM-DASH diet for hypertensive patients with type II diabetes can achieve short-term salt reduction effects. The effect on changing salt-eating habits needs to be investigated with an extended follow-up.

Effect of Salt Supplementation on Sympathetic Activity and Endothelial Function in Salt-Sensitive Type 2 Diabetes

CONTEXT

Lower sodium intake is paradoxically associated with higher mortality in type 2 diabetes (T2D).

OBJECTIVE

To determine whether sympathetic nervous system (SNS) activation and endothelial dysfunction contribute to these observations, we examined the effect of salt supplementation on these systems in people with T2D with habitual low sodium. We hypothesized that salt supplementation would lower SNS activity and improve endothelial function compared to placebo.

DESIGN

We conducted a randomized, double-blinded, placebo-controlled crossover trial.

SETTING

The study took place in a tertiary referral diabetes outpatient clinic.

PARTICIPANTS

Twenty-two people with T2D with habitual low sodium intake (24-hour urine sodium <150 mmol/24h) were included.

INTERVENTION

Salt supplementation (100 mmol NaCl/24h) or placebo for 3 weeks was administered.

MAIN OUTCOME MEASURES

The primary outcome of SNS activity and endothelial function was assessed as follows: Microneurography assessed muscle sympathetic nerve activity (MSNA), pulse amplitude tonometry assessed endothelial function via reactive hyperemic index (RHI), and arterial stiffness was assessed via augmentation index (AI). Secondary outcomes included cardiac baroreflex, serum aldosterone, ambulatory blood pressure monitoring (ABPM), heart rate variability (HRV), and salt sensitivity.

RESULTS

Compared to placebo, salt supplementation increased MSNA (burst frequency P = .047, burst incidence P = .016); however, RHI (P = .24), AI (P = .201), ABPM (systolic P = .09, diastolic P = .14), and HRV were unaffected. Salt supplementation improved baroreflex (slope P = .026) and lowered aldosterone (P = .004), and in salt-resistant individuals there was a trend toward improved RHI (P = .07).

CONCLUSIONS

In people with T2D and low habitual sodium intake, salt supplementation increased SNS activity without altering endothelial function or blood pressure but improved baroreflex function, a predictor of cardiac mortality. Salt-resistant individuals trended toward improved endothelial function with salt supplementation.

Effect of angiotensin II receptor blocker and salt supplementation on short-term blood pressure variability in type 2 diabetes

High blood pressure variability (BPV) has been associated with increased cardiovascular (CV) risk. The effect of dietary salt and renin-angiotensin-aldosterone system (RAAS) activity on short-term BPV in type 2 diabetes mellitus (T2DM) is not well characterised. We aimed to determine the effect of dietary salt (sodium chloride, NaCl) supplementation on 24-h mean arterial BPV (24hBPV) during angiotensin II receptor blocker (telmisartan) use and to evaluate the effects of age, sex, plasma renin activity (PRA) and serum aldosterone on 24hBPV. In a randomised, double-blind, crossover study, patients with T2DM (n = 28), treated with telmisartan received NaCl (100 mmol/24 h) or placebo capsules during 2 weeks of telmisartan. Following a 6-week washout, the protocol was repeated in reverse. 24hBPV was evaluated as a co-efficient of variation [CV (%) = mean/standard deviation] × 100). Twenty-four hour urinary sodium excretion, ambulatory BP and biochemical tests were performed at each phase. Results were analysed using a linear mixed model to generate predicted values for 24hBPV. Predicted 24hBPV was higher with telmisartan vs baseline (p = 0.01), with a trend towards reduced 24hBPV with salt (p = 0.052). Predicted 24hBPV was lower in females (p = 0.017), increasing age (p = 0.001) and increasing PRA (p = 0.011). In patients with T2DM, predicted 24hBPV increased from baseline with telmisartan, but there was no additional increase in predicted 24hBPV with salt supplementation. This suggests that in the short-term, salt supplementation has no apparent deleterious effects on 24hBPV. Long-term studies are required to evaluate the effect of 24hBPV on CV outcomes in patients with T2DM.

Sodium Intake, Circulating Microvesicles and Cardiovascular Outcomes in Type 2 Diabetes

There is ongoing debate surrounding the complex relationship between dietary sodium intake and cardiovascular morbidity and mortality. The existing literature consists largely of observational studies that have demonstrated positive, negative, U-/J-shaped or unclear associations between sodium intake and cardiovascular outcomes. Our group and others have previously demonstrated an inverse relationship between dietary sodium intake and cardiovascular outcomes in people with type 2 diabetes. Increased activity of the renin-angiotensin-aldosterone system and sympathetic nervous system is postulated to contribute to these paradoxical findings through endothelial dysfunction, a precursor to the development of cardiovascular disease. Microvesicles are submicron (0.1 - 1.0μm) vesicles that form during cellular activation, injury or death with endothelial microvesicles being recognized markers of endothelial dysfunction. They are pathologically elevated in a variety of vascular-related conditions including type 2 diabetes. Lower habitual sodium intake in type 2 diabetes has been associated with higher pro-coagulant platelet microvesicles levels but not with endothelial microvesicles. Research utilizing endothelial microvesicles to evaluate the mechanistic relationship between dietary sodium intake and adverse cardiovascular outcomes in type 2 diabetes remains scarce.

The relationship between habitual dietary sodium intake and RAAS blockade on circulating microparticle levels in type two diabetes

OBJECTIVE

Low sodium intake is paradoxically associated with adverse cardiovascular outcomes in individuals with type 2 diabetes mellitus (T2D), possibly from renin-angiotensin-aldosterone system (RAAS) activation, leading to endothelial dysfunction. In the present study, we investigated the associations between habitual sodium intake and RAAS blockade on endothelial function by measuring circulating microparticles (MPs) in individuals with T2D.

METHODS

We conducted a prospective, cross-sectional study in 74 individuals with T2D. Habitual dietary sodium intake was estimated by using the mean of three corrected 24-h urine sodium excretion measurements (24hUNa). MP subtypes in platelet-free plasma were quantitated using flow cytometry.

RESULTS

No associations between 24hUNa with levels of endothelial MPs were observed. Instead, a trend toward higher diabetes related CD36+/CD235a+ MP levels was associated with lower 24hUNa (rho = -0.23, P=0.05). When stratified according to tertiles of 24hUNa, platelet-derived CD42b+/CD41+ and CD42+/CD41+/Annexin V+ MPs were higher in the lowest tertile (24hUNa < 157 mmol/24 h) (P=0.02 respectively). Despite RAAS blockade being associated with lower levels of most MP subsets, it was not associated with lower MPs, in the setting of low sodium intake.

CONCLUSION

Lower sodium intake is associated with higher circulating procoagulant MPs, but not with evidence of endothelial dysfunction in individuals with T2D.

Effects of telmisartan on vascular endothelial function, inflammation and insulin resistance in patients with coronary heart disease and diabetes mellitus

The aim of the present study was to investigate the effects of telmisartan on vascular endothelial functions, inflammatory factors and insulin resistance of coronary heart disease patients complicated with diabetes mellitus. In total, 80 coronary heart disease patients complicated with type 2 diabetes mellitus, admitted and treated in the Zhangqiu Hospital from January 2016 to March 2017 were enrolled in the study. Each patient was randomly assigned to an observation (n=40) or a control group (n=40) using a random number table. Conventional symptomatic and supporting therapies were administered to all the patients in the two groups for 12 consecutive weeks, while additional telmisartan was given only to patients in the observation group. Markers of glucose metabolism, vascular endothelial function and inflammation were determined before and after intervention, to compare averages between groups. Results showed the levels of fasting blood glucose and blood glucose in the observation group were significantly lower than those in the control group (p<0.05) after 4 weeks of treatment. The levels of HOMA-IR in the observation group were clearly improved compared to those in the control group during the same period (p<0.05). After the intervention, the levels of FINS and HOMA-IR in the observation group improved significantly more compared with those in the control group (p<0.05), while the levels of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and C-reactive protein (CRP) were much lower than those in the control group (p<0.05). Furthermore, at the 4th, 8th and 12th week after starting the treatment, the vascular endothelin (ET) levels in the observation group were significantly lower than those in the control group (p<0.05). In addition, the brachial artery diameters in the basal state were significantly larger than those in the control group (p<0.05) for the same time-points. Coronary heart disease patients complicated with diabetes mellitus whose treatment includes telmisartan can better regulate their blood glucose, reduce the insulin resistance and body inflammatory responses and improve their vascular endothelial functions.

Sodium and Its Role in Cardiovascular Disease - The Debate Continues

Guidelines have recommended significant reductions in dietary sodium intake to improve cardiovascular health. However, these dietary sodium intake recommendations have been questioned as emerging evidence has shown that there is a higher risk of cardiovascular disease with a low sodium diet, including in individuals with type 2 diabetes. This may be related to the other pleotropic effects of dietary sodium intake. Therefore, despite recent review of dietary sodium intake guidelines by multiple organizations, including the dietary guidelines for Americans, American Diabetes Association, and American Heart Association, concerns about the impact of the degree of sodium restriction on cardiovascular health continue to be raised. This literature review examines the effects of dietary sodium intake on factors contributing to cardiovascular health, including left ventricular hypertrophy, heart rate, albuminuria, rennin-angiotensin-aldosterone system activation, serum lipids, insulin sensitivity, sympathetic nervous system activation, endothelial function, and immune function. In the last part of this review, the association between dietary sodium intake and cardiovascular outcomes, especially in individuals with diabetes, is explored. Given the increased risk of cardiovascular disease in individuals with diabetes and the increasing incidence of diabetes worldwide, this review is important in summarizing the recent evidence regarding the effects of dietary sodium intake on cardiovascular health, especially in this population.