A possible association between primary aldosteronism and a lower β-cell function

Recent progress in unraveling cardiovascular complications associated with primary aldosteronism: a succinct review

This comprehensive review offers a thorough exploration of recent advancements in our understanding of the intricate cardiovascular complications associated with Primary Aldosteronism (PA). PA encompasses a spectrum of conditions characterized by hypertension and excessive production of aldosterone operating independently of the renin-angiotensin system. Given its association with an elevated risk of cardiovascular and cerebrovascular complications, as well as a higher incidence of metabolic syndrome in comparison to individuals with essential hypertension (EH), an accurate diagnosis of PA is of paramount importance. This review delves into the intricate interplay between PA and cardiovascular health and focuses on the key pathophysiological mechanisms contributing to adverse cardiac outcomes. The impact of different treatment modalities on cardiovascular health is also examined, offering insights into potential therapeutic approaches. By highlighting the significance of recognizing PA as a significant contributor to cardiovascular morbidity, this review emphasizes the need for improved screening, early diagnosis, and tailored management strategies to both enhance patient care and mitigate the burden of cardiovascular diseases. The findings presented herein underscore the growing importance of PA in the context of cardiovascular medicine and emphasize the potential for translating these insights into targeted interventions to improve patient outcomes.

The Effect of Aldosterone on Cardiorenal and Metabolic Systems

Aldosterone, a vital hormone of the human body, has various pathophysiological roles. The excess of aldosterone, also known as primary aldosteronism, is the most common secondary cause of hypertension. Primary aldosteronism is associated with an increased risk of cardiovascular disease and kidney dysfunction compared to essential hypertension. Excess aldosterone can lead to harmful metabolic and other pathophysiological alterations, as well as cause inflammatory, oxidative, and fibrotic effects in the heart, kidney, and blood vessels. These alterations can result in coronary artery disease, including ischemia and myocardial infarction, left ventricular hypertrophy, heart failure, arterial fibrillation, intracarotid intima thickening, cerebrovascular disease, and chronic kidney disease. Thus, aldosterone affects several tissues, especially in the cardiovascular system, and the metabolic and pathophysiological alterations are related to severe diseases. Therefore, understanding the effects of aldosterone on the body is important for health maintenance in hypertensive patients. In this review, we focus on currently available evidence regarding the role of aldosterone in alterations of the cardiovascular and renal systems. We also describe the risk of cardiovascular events and renal dysfunction in hyperaldosteronism.

Diabetes mellitus is associated with more adverse non-hemodynamic left ventricular remodeling and less recovery in patients with primary aldosteronism

The elevated aldosterone in primary aldosteronism (PA) is associated with increased insulin resistance and prevalence of diabetes mellitus (DM). Both aldosterone excess and DM lead to left ventricular (LV) pathological remodeling. In this study, we investigated the impact of DM on LV non-hemodynamic remodeling in patients with PA. We enrolled 665 PA patients, of whom 112 had DM and 553 did not. Clinical, biochemical, and echocardiographic data were analyzed at baseline and 1 year after adrenalectomy. LV non-hemodynamic remodeling was represented by inappropriate excess left ventricular mass index (ieLVMI), which was defined as the difference between left ventricular mass index (LVMI) and predicted left ventricular mass index (pLVMI). Propensity score matching (PSM) was used with age, sex, systolic, and diastolic blood pressure to adjust for baseline variables. After PSM, the patient characteristics were balanced between the DM and non-DM groups, except for fasting glucose, HbA1c, and lipid profile. A total of 111 DM and 419 non-DM patients were selected for further analysis. Compared to the non-DM group, the DM group had significantly higher ieLVMI and LVMI. After multivariable linear regression analysis, the presence of DM remained a significant predictor of increased ieLVMI. After adrenalectomy, ieLVMI decreased significantly in the non-DM group but not in DM group. The presence of DM in PA patients was associated with more prominent non-hemodynamic LV remodeling and less recovery after adrenalectomy.

Secondary diabetes mellitus due to primary aldosteronism

Primary aldosteronism (PA) and diabetes mellitus (DM) are clinical conditions that increase cardiovascular risk. Approximately one in five patients with PA have DM. Nevertheless, the pathophysiology linking these two entities is not entirely understood. In addition, the majority of patients with PA have glucocorticoid co-secretion, which is associated with increased risk of impaired glucose homeostasis. In the present review, we aim to comprehensively discuss all the available research data concerning the interplay between mineralocorticoid excess and glucose metabolism, with separate analysis of the sequalae in muscle, adipose tissue, liver and pancreas. Aldosterone binds both mineralocorticoid and glucocorticoid receptors and amplifies tissue glucocorticoid activity, via 11-β-hydroxysteroid dehydrogenase type 1 stimulation. A clear classification of the molecular events as per specific receptor in insulin-sensitive tissues is impossible, while their synergistic interaction is plausible. Furthermore, aldosterone induces oxidative stress and inflammation, perturbs adipokine expression, thermogenesis and lipogenesis in adipose tissue, and increases hepatic steatosis. In pancreas, enhanced oxidative stress and inflammation of beta cells, predominantly upon glucocorticoid receptor activation, impair insulin secretion. No causality between hypokalemia and impaired insulin response is yet proven; in contrast, hypokalemia appears to be implicated with insulin resistance and hepatic steatosis. The superior efficacy of adrenalectomy in ameliorating glucose metabolism vs. mineralocorticoid receptor antagonists in clinical studies highlights the contribution of non-mineralocorticoid receptor-mediated mechanisms in the pathophysiologic process. The exact role of hypokalemia, the mechanisms linking mineralocorticoid excess with hepatic steatosis, and possible disease-modifying role of pioglitazone warrant further studies.

Meta-analysis of blood parameters related to lipid and glucose metabolism between two subtypes of primary aldosteronism

It remains unclear whether metabolic profiles differ within the subtypes of primary aldosteronism (PA). This meta-analysis aimed to compare the blood parameters related to lipid and glucose metabolism at baseline between unilateral PA and bilateral PA. A search was performed using PubMed, Web of Science, and Sciencedirect databases, supplemented by hand-searching of related references. Standardized mean differences (SMDs) with 95% confidence intervals (CIs) were calculated for each parameter. Twenty-one studies involving 4197 patients with PA were included. Compared with bilateral PA groups, unilateral PA groups demonstrated significantly lower low-density lipoprotein cholesterol (LDL-C, SMD: -.14 mmol/L, 95% CI: -.20, -.07), total cholesterol (TC, SMD: -.16 mmol/L, 95% CI: -.23, -.09), triglyceride (TG, SMD: -.22 mmol/L, 95% CI: -.29, -.16), fasting blood glucose (FBG, SMD: -.11 mmol/L, 95% CI: -.18, -.04), hemoglobin A1c (HbA1c, SMD: -.21%, 95% CI: -.30, -.13), and homeostasis model assessment-insulin resistance (HOMA-IR, SMD: -.40, 95% CI: -.58, -.23). No significant difference was found in high-density lipoprotein cholesterol (HDL-C) level between the two groups (SMD: .40 mmol/L, 95% CI: -.02, .11). To sum up, comparison of several blood metabolic parameters between the two subtypes suggested that the bilateral PA may associate with a higher prevalence of impaired glucose and lipid metabolism than unilateral PA; however, results should be treated with caution. Additional well-designed studies are needed to prove the present results and better elucidate the link between metabolic abnormalities and etiologies of each PA subtype.

Newly diagnosed diabetes mellitus is a risk factor for cardiocerebrovascular events in primary aldosteronism

OBJECTIVE

To explore the prevalence and clinical significance of newly diagnosed diabetes mellitus (DM) in patients with primary aldosteronism (PA). Investigating the risk factors for cardiocerebrovascular disease (CCVD) will guide strategies for reducing CCVD in patients with PA.

METHODS

We retrospectively included 729 PA patients without DM and conducted oral glucose tolerance tests.

RESULTS

We found that 15.0% of PA patients had newly diagnosed DM. The DM prevalence increased with elevated aldosterone levels [OR = 3.20 (1.77, 5.78), P value < 0.001]. The rate of CCVD in newly diagnosed diabetic PA patients was higher than that in nondiabetic PA patients at diagnosis (11.9% vs. 5.0%, P = 0.005). Furthermore, multivariate logistic analysis revealed that HT duration [1.055 (1.002,1.111), P = 0.041] and newly diagnosed DM [2.600 (1.072,6.303), P = 0.034] were significantly associated with CCVD in PA patients.

CONCLUSION

The prevalence of newly diagnosed DM in PA patients was higher than that in the general population. Aldosterone level was an independent risk factor for DM not for CCVD. CCVD was correlated with longer HT duration and newly diagnosed DM. Therefore, it is crucial to screen DM at the diagnosis in PA patients.

Differences in Glycemic Abnormalities Between Primary Aldosteronism and Essential Hypertension: A Systematic Review and Meta-Analysis

Background

The relationship of glycemic abnormalities between primary aldosteronism (PA) patients and essential hypertension (EH) patients is still debatable. This meta-analysis aimed to explore differences in the prevalence of glycemic abnormalities and levels of abnormal glucose metabolism in PA and EH patients.

Methods

A search was performed using PubMed, Scopus, Cochrane and Web of Science databases from their inception through January 2022. Inclusion criteria for this study were 1) observational studies which contained specific data of interest, 2) studies including data which compared adult PA and EH patients and 3) studies which used appropriate methods to diagnose PA. Risk ratio (RR) or standardized mean difference (SMD) with a 95% confidence interval (95% CI) was calculated.

Results

Twenty-six studies involving 53,186 patients were included in the meta-analysis. Patients with PA demonstrated significantly higher overall incidence of glycemic abnormalities than patients with EH [RR 1.54; 95% CI (1.20,1.98)]. Risk of diabetes mellitus (DM) and impaired glucose tolerance (IGT) in PA patients were higher than in EH patients [RR 1.27; 95%CI (1.08, 1.49) and RR 2.99; 95%CI (1.74, 5.16), respectively]. There was no statistically significant difference of risk between these groups for impaired fasting glucose (IFG) [RR 1.70; 95%CI (0.55, 5.26)]. Moderate heterogeneity was observed in overall glycemic abnormalities outcomes. A high level of heterogeneity was observed for IFG, while the level was low for DM and IGT.

Conclusions

PA patients have a higher risk of glycemic abnormalities than in EH patients. Further study should be conducted to investigate underlying mechanisms of glycemic abnormalities in PA.

Systematic Review Registration

www.inplasy.com, INPLASY, identifier 202220004.

Diabetes mellitus is associated with worse baseline and less post-treatment recovery of arterial stiffness in patients with primary aldosteronism

Background:

Aldosterone excess in primary aldosteronism (PA) has been linked to insulin resistance, and diabetes mellitus has been associated with increased arterial stiffness and worse cardiovascular outcomes. However, the impact of diabetes on baseline and post-treatment arterial stiffness in patients with PA is unknown.

Methods:

This study prospectively enrolled 1071 PA patients, of whom 177 had diabetes and 894 did not. Clinical, biochemical, and brachial-ankle pulse wave velocity (baPWV) data were analyzed at baseline and 1 year after PA-specific treatment. After propensity score matching of age, sex, body mass index, systolic and diastolic blood pressure, hypertension duration, and number of antihypertensive medications, 144 patients with diabetes and 320 without diabetes were included for further analysis.

Results:

After propensity score matching, the baseline characteristics were balanced between the diabetes and nondiabetes groups except for fasting glucose, HbA1c, and lipid profiles. The patients with diabetes had significantly worse baseline baPWV compared with those without diabetes. After multivariable linear regression, the presence of diabetes mellitus remained a significant predictor of worse baseline mean baPWV (β: 46.3, 95% confidence interval: 2.9–89.7, p = 0.037). After 1 year of PA-specific treatment, only the nondiabetes group had significant recovery of mean baPWV (1661.8 ± 332.3 to 1565.0 ± 329.2 cm/s, p < 0.001; Δ = −96.8 ± 254.6 cm/s). In contrast, the diabetes group had less improvement (1771.2 ± 353.8 cm/s to 1742.0 ± 377.2 cm/s, p = 0.259; Δ = −29.2 ± 263.2 cm/s) even though the systolic and diastolic blood pressure significantly improved in both groups.

Conclusion:

The presence of diabetes mellitus in PA patients was associated with worse baseline and less post-treatment recovery of arterial stiffness.

Insulin sensitivity and pancreatic β-cell function in patients with primary aldosteronism

BACKGROUND

Primary aldosteronism (PA) is associated with an increased risk for dysglycemia. However, the effects of hyperaldosteronism on insulin sensitivity and β-cell function are unclear.

METHODS

Using a cross-sectional study design, we assessed insulin sensitivity and pancreatic β-cell function from an oral glucose tolerance test (OGTT) in patients from two cohorts: subjects with PA (n = 21) and essential hypertension control (EHC) subjects (n = 22). Age, sex, BMI, and mean arterial pressure adjusted measures of insulin sensitivity and β-cell function were compared between the groups.

RESULTS

PA individuals were less insulin sensitive compared to EHC subjects (Quantitative insulin sensitivity check index [QUICKI]: 0.340 ± 0.006 vs. 0.374 ± 0.013, p < 0.001; Matsuda index: 4.14 ± 0.49 vs. 7.87 ± 1.42, p < 0.001; S_I: 11.45 ± 4.85 vs. 21.23 ± 6.11 dL/kg/min per μU/mL, p = 0.02). The hepatic insulin resistance index (HIRI) was higher in PA subjects (PA: 5.61 ± 1.01 vs. EHC: 4.13 ± 0.61, p = 0.002). The insulinogenic index (IGI), an index of β-cell function was higher in the PA cohort (PA: 1.49 ± 0.27 vs. 1.11 ± 0.21 μU/mL/mg/dL, p = 0.03). However, the oral disposition index (DI) was similar between the groups (PA: 4.77 ± 0.73 vs. EHC: 5.46 ± 0.85, p = 0.42), which likely accounts for the similar glucose tolerance between the two cohorts, despite lower sensitivity.

CONCLUSIONS

In summary, insulin sensitivity is significantly lower in PA with an appropriately compensated β-cell function. These results suggest that excess aldosterone and/or other steroids in the context of PA may negatively affect insulin action without adversely impacting β-cell function.

Mineralocorticoid receptors in the pathogenesis of insulin resistance and related disorders: from basic studies to clinical disease

Aldosterone is a steroid hormone that regulates blood pressure and cardiovascular function by acting on renal and vascular mineralocorticoid receptors (MRs) to promote sodium retention and modulate endothelial function. Indeed, MRs are expressed in endothelial cells, vascular smooth muscle cells, adipocytes, immune cells, skeletal muscle cells, and cardiomyocytes. Excessive aldosterone and associated MR activation impair insulin secretion, insulin metabolic signaling to promote development of diabetes, and the related cardiometabolic syndrome. These adverse effects of aldosterone are mediated, in part, via increased inflammation, oxidative stress, dyslipidemia, and ectopic fat deposition. Therefore, inhibition of MR activation may have a beneficial effect in prevention of impaired insulin metabolic signaling, type 2 diabetes, and cardiometabolic disorders. This review highlights findings from the recent surge in research regarding MR-related cardiometabolic disorders as well as our contemporary understanding of the detrimental effects of excess MR activation on insulin metabolic signaling.

The mineralocorticoid receptor-an emerging player in metabolic syndrome?

Metabolic syndrome is a cluster of conditions that increase the risk of cardiovascular diseases, and comprises obesity, hypertension, impaired glucose metabolism and dyslipidaemia. It is well recognised that the mineralocorticoid receptor (MR) plays an important role in blood pressure regulation via its effect on salt and water retention in renal tubules, with hypertension being a key feature in primary aldosteronism patients with excess adrenal production of aldosterone, the primary ligand for MRs in the epithelial tissues. MRs are also expressed in a number of non-epithelial tissues including adipose tissue; in these tissues, glucocorticoids or cortisol can also activate MRs due to low levels of 11-beta-hydroxysteroid-dehydrogenase type 2 (11-βHSD2), the enzyme which inactivates cortisol. There is increasing evidence suggesting that over-activation of MRs plays a role in the pathophysiology of the other components of metabolic syndrome, promoting adiposity, inflammation and glucose intolerance, and that MR antagonists may confer beneficial effects on energy and substrate homeostasis and cardiometabolic diseases. This review discusses the advances in the literature shedding light on the MR as an emerging player in metabolic syndrome.

Association of visceral adiposity and clinical outcome among patients with aldosterone producing adenoma

INTRODUCTION

Primary aldosteronism (PA) is a common form of secondary hypertension that has significant cardiovascular events and increased prevalence of metabolic syndrome and diabetics. Although plasma aldosterone concentration is positively correlated with visceral fat area (VFA) in non-PA individuals, the role of visceral adiposity associated with clinical success after surgery is not known.

RESEARCH DESIGN AND METHODS

We analyzed patients who underwent adrenalectomy for aldosterone-producing adenoma (APA) at the Taiwan PA Investigator group. VFA was calculated from the abdominal CT scan at APA diagnosis, and all patients received adrenalectomy.

RESULTS

The study involved 100 consecutive patients with APA (42 males; mean age 49.3 years) matched with 41 essential hypertension (EH) patients. Patients with APA had smaller VFA (p=0.010) than their EH counterparts. Multiple linear regression analysis revealed that the duration of hypertension (p=0.007), but not plasma aldosterone, was negatively correlated with VFA in patients with APA. Logistic regression analysis showed that log VFA (OR=0.065, p<0.001) and duration of hypertension before PA diagnosis (OR=0.919, p=0.011) can predict complete clinical success after adrenalectomy. Multifactor-adjusted generalized additive model demonstrated that log VFA <9.2 was associated with complete cure of hypertension. Furthermore, VFA was increased at 6 months after adrenalectomy (p=0.045).

CONCLUSIONS

Patients with APA had smaller VFA than their EH counterparts, and VFA increased after adrenalectomy. Clinical complete cure of hypertension after surgery was associated with smaller VFA and shorter duration of hypertension at PA diagnosis, suggesting a potential interplay of visceral adiposity and aldosterone of the patients with APA.

Eplerenone Implantation Improved Adipose Dysfunction Averting RAAS Activation and Cell Division

Introduction: Mineralocorticoid receptor (MR) activation within adipose tissue, triggers inflammation and metabolic syndrome development. The pharmacological blockade of MR provides beneficial effects for adipose tissue. Our study evaluates the impact of eplerenone implantation upon obesity. Experimental approach: A group of mice with implanted placebo pellets were fed using two types of diet, a normal (ND) or a high fat (HFD) diet. Additionally, a group of mice fed HFD were implanted with an eplerenone pellet. Metabolic and biochemical parameters were assessed in each animal group. Adipocyte size and lipid accumulation were investigated in the liver and adipose tissue. We evaluated the components of renin-angiotensin-aldosterone system (RAAS) locally in adipose tissue. Key results: Eplerenone reduced HFD-induced body weight gain, fasting glucose levels, fat accumulation, HFD-induced adipocyte size and liver lipid accumulation and improved glucose tolerance. In the adipose tissue, HFD significantly increased the mRNA levels of the RAAS molecules relative to the ND group. Eplerenone lowered RAAS mRNA levels, components of lipid metabolism and markers of inflammation in HFD-fed animals. Conclusion: MR antagonism with eplerenone diminishes insulin resistance that is related to obesity partly via a reduction of RAAS activation, inflammatory progression and cytokines induction. This suggests that eplerenone should be further studied as a therapeutic option for obesity and overweight.

Associations Between Metabolic Profiles and Target-Organ Damage in Chinese Individuals With Primary Aldosteronism

Purpose: Patients with primary aldosteronism (PA) have an increased risk of target-organ damage (TOD), but whether metabolic syndrome (MetS) is more prevalent and contributes to TOD in PA patients remains unresolved. We aimed to evaluate the associations between MetS profiles and TOD in Chinese PA individuals. Methods: Metabolic parameters and pre-clinical TOD including left ventricular hypertrophy, estimated glomerular filtration, and microalbuminuria; insulin sensitivity or resistance; and islet β-cell function were assessed by the homeostasis models (HOMA-IR, HOMA-β) and the other surrogate indexes [composite insulin sensitivity index (ISI), modified β-cell function index (MBCI)] determined from the oral glucose tolerance test were compared in PA vs. matched essential hypertension (EH) patients. Results: A total of 109 PA patients and 109 essential hypertension (EH) controls individually matched for sex, age, and office systolic blood pressure and duration of hypertension were studied. The prevalence of MetS and its individual components in PA was significantly lower than in EH [MetS: 28 (25.6%) vs. 54 (49.5%), P < 0.001]. PA patients had a higher composite ISI but a lower HOMA-IR, HOMA-β, and MBCI than EH controls (all P < 0.05). Concerning TOD, PA patients had significantly higher prevalence of microalbuminuria and left ventricular hypertrophy (LVH), and lower levels of estimated glomerular filtration (eGFR) than EH controls (all P < 0.05). On multivariate logistic regression analysis, female gender and elevated plasma aldosterone levels were significantly associated with TOD in PA. However, there were no significant associations between MetS and its individual components and TOD in PA patients. Conclusions: PA patients had a lower MetS prevalence but exhibited more severe TOD than matched EH controls. The study highlights the deleterious effects of aldosterone excess on the development of TOD, whereas MetS or its individual components might be less influential in PA.

Associations between primary aldosteronism and diabetes, poor bone health, and sleep apnea-what do we know so far?

Primary aldosteronism (PA), the most common cause of secondary hypertension, is a well-recognized condition that can lead to cardiovascular and renal complications. PA is frequently left undiagnosed and untreated, leading to aldosterone-specific morbidity and mortality. In this review we highlight the evidence linking PA with other conditions such as (i) diabetes mellitus, (ii) obstructive sleep apnea, and (iii) bone health, along with clinical implications and proposed underlying mechanisms.

Effects of Primary Aldosteronism and Different Therapeutic Modalities on Glucose Metabolism

Despite findings that aldosterone impairs glucose metabolism, studies concerning the effect of primary aldosteronism (PA) and its treatment on glucose metabolism are controversial. We aimed to determine glucose metabolism in PA and the effect of the treatment modality. We compared glucose metabolism between PA patients (N = 286) and age-, sex-, and body mass index-matched controls (N = 816), and the changes in glucose metabolism depending on the treatment modality (adrenalectomy vs. spironolactone treatment). Hyperglycemia including diabetes mellitus (DM; 19.6% vs. 13.1%, p = 0.011) was more frequent in PA patients. Hyperglycemia was also more frequent in PA patients without subclinical hypercortisolism (SH: p < 0.001) and in those regardless of hypokalemia (p < 0.001-0.001). PA patients and PA patients without SH had higher DM risk (odds ratio (OR); 95% confidence interval (CI): 1.63; 1.11-2.39 and 1.65; 1.08-2.51, respectively) after adjusting confounders. In PA patients, there was significant decrease in the DM prevalence (21.3% to 16.7%, p = 0.004) and fasting plasma glucose (p = 0.006) after adrenalectomy. However, there was no significant change in them after spironolactone treatment. Adrenalectomy was associated with more improved glucose status than spironolactone treatment (OR; 95% CI: 2.07; 1.10-3.90). Glucose metabolism was impaired in PA, regardless of hypokalemia and SH status, and was improved by adrenalectomy, but not spironolactone treatment.

Dietary Approaches to Stop Hypertension (DASH): potential mechanisms of action against risk factors of the metabolic syndrome

The metabolic syndrome is a cluster of disorders dominated by abdominal obesity, hypertriacylglycerolaemia, low HDL-cholesterol, high blood pressure and high fasting glucose. Diet modification is a safe and effective way to treat the metabolic syndrome. Dietary Approaches to Stop Hypertension (DASH) is a dietary pattern rich in fruits, vegetables and low-fat dairy products, and low in meats and sweets. DASH provides good amounts of fibre, K, Ca and Mg, and limited quantities of total fat, saturated fat, cholesterol and Na. Although DASH was initially designed for the prevention or control of hypertension, using a DASH diet has other metabolic benefits. In the present review, the effect of each dietary component of DASH on the risk factors of the metabolic syndrome is discussed. Due to limited fat and high fibre and Ca content, individuals on the DASH diet are less prone to overweight and obesity and possess lower concentrations of total and LDL-cholesterol although changes in TAG and HDL-cholesterol have been less significant and available evidence in this regard is still inconclusive. Moreover, high amounts of fruit and vegetables in DASH provide great quantities of K, Mg and fibre, all of which have been shown to reduce blood pressure. K, Mg, fibre and antioxidants have also been effective in correcting glucose and insulin abnormalities. Evidence is provided from cross-sectional investigations, cohort studies and randomised controlled trials, and, where available, from published meta-analyses. Mechanisms are described according to human studies and, in the case of a lack of evidence, from animal and cell culture investigations.

The Aldosterone/Renin Ratio Predicts Cardiometabolic Disorders in Subjects Without Classic Primary Aldosteronism

BACKGROUND

Aldosterone has been linked with obesity, metabolic syndrome (MetS), pro-inflammatory, and prothrombotic states; however, most studies relate these indicators with primary aldosteronism (PA), excluding non-PA patients.

OBJECTIVE

To determine whether aldosterone, renin, or the plasma aldosterone/renin ratio (ARR) are associated with metabolic disorders and inflammatory/vascular biomarkers in a non-PA population.

METHODS

We studied 275 patients including adolescents and adults of both genders and measured plasma and urinary aldosterone and determined the plasma renin activity. In all subjects, the presence of MetS was determined according to Adult Treatment Panel III. Renal, vascular, inflammatory, and mineralocorticoid activity biomarkers were evaluated.

RESULTS

The ARR correlated with the number of variables of MetS (r = 0.191, P = 0.002), body mass index (BMI; r = 0.136, P = 0.026), systolic blood pressure (r = 0.183, P = 0.002), diastolic blood pressure (r = 0.1917, P = 0.0014), potassium excreted fraction (r = 0.174, P = 0.004), low-density lipoprotein (r = 0.156, P = 0.01), plasminogen activator inhibitor type 1 (r = 0.158, P = 0.009), microalbuminuria (r = 0.136, P = 0.029), and leptin (r = 0.142, P = 0.019). In a linear regression model adjusted by age, BMI, and gender, only the ARR was still significant (r = 0.108, P = 0.05). In a logistic regression analysis, the ARR predicted MetS index (odds ratio (OR) = 1.07 [95% confidence interval (CI) = 1.011-1.131], P= 0.02) even after adjusting for age, BMI, and gender. On the other hand, aldosterone showed no association with MetS or inflammatory markers.

CONCLUSION

These results suggest a continuum of cardiometabolic risk beyond the classic PA threshold screening. The ARR could be a more sensitive marker of obesity, MetS, and endothelial damage in non-PA patients than aldosterone or renin alone. Prospective studies are needed to develop future screening cutoff values.

Glycemia Lowering Effect of an Aqueous Extract of Hedychium coronarium Leaves in Diabetic Rodent Models

Hedychium coronarium has a long history of use worldwide as a food and in folk medicine. In this study, we aimed to investigate the effect of an aqueous extract of H. coronarium leaves (HC) on type 2 diabetes mellitus (T2DM). Two types of animal models were used in this study: Streptozotocin (STZ)-induced T2DM (Wistar rats; N = 8) and C57BKSdb/db mice (N = 5). After treatment with HC for 28 days, glucose tolerance improved in both of the diabetic animal models. As significant effects were shown after 14 days of treatment in the STZ-induced T2DM model, we carried out the experiments with it. After 28 days of treatment with HC, the levels of cholesterol, triglyceride, high-density lipoprotein, and low-density lipoprotein were significantly improved in the STZ-induced T2DM model. The lesions degree of islet β-cells was decreased after the HC treatment. Although the insulin level increased moderately, the aldosterone level was significantly decreased in the HC-treated groups, suggesting that aldosterone might play an important role in this effect. In summary, HC is a natural product and it is worth exploring its effect on T2DM.

Links between aldosterone excess and metabolic complications: A comprehensive review

Shortly after the first description of primary aldosteronism (PA) appeared in the 1950s by Jerome Conn, an association of the condition with diabetes mellitus was documented. However, a clear pathophysiological interrelationship linking the two entities has yet to be established. Nevertheless, so far, many mechanisms contributing to insulin resistance and dysregulation of glucose uptake have been described. At the same time, many observational studies have reported an increased prevalence of the metabolic syndrome (MetS) among patients with PA. Regarding the relationship between aldosterone levels and obesity, a vicious cycle of adipokine-induced aldosterone production and aldosterone adipogenic action may be further contributing to MetS manifestations in PA patients. However, whether aldosterone excess affects lipid metabolism is still under investigation. Also, recent findings of the coexistence of glucocorticoid excess in many cases of PA highlight the need for further studies to examine the presumed link between high aldosterone levels and various metabolic parameters. In the present review, our focus is to comprehensively present the spectrum of available research findings concerning the possible associations between aldosterone excess and metabolic alterations, including impaired glucose metabolism, insulin resistance and, consequently, diabetes, altered lipid metabolism and the development of fatty liver. In addition, the complex relationship between obesity and aldosterone is discussed in detail.

Primary aldosteronism is associated with decreased low-density and high-density lipoprotein particle concentrations and increased GlycA, a pro-inflammatory glycoprotein biomarker

BACKGROUND

Primary aldosteronism (PA) may confer increased cardiovascular risk beyond effects on systemic blood pressure, but contributing mechanisms remain incompletely understood. We compared plasma (apo)lipoproteins and lipoprotein particle characteristics, GlycA, a pro-inflammatory glycoprotein biomarker of enhanced chronic inflammation, and plasma total branched-chain amino acids (BCAA), measured using nuclear magnetic resonance (NMR) spectroscopy, between patients with PA, control subjects without hypertension, subjects with untreated hypertension and subjects with treated hypertension.

METHODS

Twenty PA patients were individually matched with 2819 control subjects without hypertension, 501 subjects with untreated hypertension and 878 subjects with treated hypertension participating in the PREVEND (Prevention of Renal and Vascular End-Stage Disease) cohort study with respect to age, sex, body mass index, smoking and statin use. The Vantera® Clinical Analyzer was used to determine NMR-based laboratory parameters.

RESULTS

Total cholesterol, low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), apolipoprotein (apo) B, apolipoprotein A-I (apoA-I), LDL particle and HDL particle concentrations were all decreased in PA subjects vs control subjects and subjects with untreated hypertension (P < 0.016). Triglycerides (TG) and triglyceride-rich lipoprotein (TRL) concentrations were lower in PA subjects vs subjects with (untreated) hypertension. GlycA was increased in PA vs the three comparator groups (P < 0.016). Total BCAA concentrations were unaltered in PA.

CONCLUSIONS

Primary aldosteronism is associated with lower concentrations of LDL and HDL particles and to some extent also with lower TG and TRL particle concentrations. PA is also characterized by increased GlycA levels, indicating enhanced low-grade chronic inflammation. Low HDL particle concentrations and increased GlycA could contribute to accelerated cardiovascular disease development in PA.

Obesity as a Key Factor Underlying Idiopathic Hyperaldosteronism

CONTEXT

Recently, the relationship between primary aldosteronism (PA) and various metabolic disorders, including obesity, diabetes mellitus, and dyslipidemia, has been discussed. However, in PA, aldosterone-producing adenoma (APA) and idiopathic hyperaldosteronism (IHA) have different etiologies.

OBJECTIVE

Our objectives were to clarify differences in obesity and metabolic disorders between APA and IHA and to gain insight in the pathogenesis of IHA.

DESIGN, SETTING, AND PARTICIPANTS

This is a retrospective cross-sectional study. We assessed the PA database established by the multicenter Japan Primary Aldosteronism Study. For comparative analysis, data were also collected from 274 patients with essential hypertension (EHT).

MAIN OUTCOME MEASURES

We compared prevalences of obesity and metabolic disorders between patients with APA and patients with IHA. Comparisons with sex-, age-, and blood pressure-matched patients with EHT were also performed. Correlations between metabolic parameters and plasma aldosterone concentrations (PACs) in each subtype were analyzed.

RESULTS

Analysis of 516 patients with APA and 1015 patients with IHA revealed PACs were significantly higher in patients with APA than patients with IHA. By contrast, after we adjusted for clinical backgrounds, the prevalence of obesity was significantly higher in patients with IHA than in patients with APA or EHT. Although the prevalences of diabetes mellitus and dyslipidemia did not significantly differ between patients with IHA and patients with APA, triglyceride and HbA1c were significantly higher in patients with IHA than in patients with APA. There was no significant correlation between metabolic parameters and PACs in either subtype.

CONCLUSIONS

Patients with IHA tend to be obese despite lower PACs than in patients with APA. The present results suggest that obesity-related factors contribute to the pathogenesis of IHA.

Risk of new-onset diabetes mellitus in primary aldosteronism: a population study over 5 years

OBJECTIVE

Abnormal glucose metabolism due to insulin resistance has been linked to aldosterone overproduction. However, the long-term incidence of new-onset diabetes mellitus (NODM) among patients with primary aldosteronism after targeted treatment has not been well documented.

METHODS

The diagnosis of primary aldosteronism and essential hypertension were identified, and then the occurrence of NODM, all-cause mortality among these patients, was ascertained by a validated algorithm from a 23-million population insurance registry.

RESULTS

From 1999 to 2007, 2367 primary aldosteronism patients without previously diabetes mellitus were identified and propensity score-matched with 9468 patients with essential hypertension. Among those primary aldosteronism patients, 754 aldosterone-producing adenomas patients were identified and matched with 3016 essential hypertension controls. After a mean 5.2 years of follow-up, primary aldosteronism patients who underwent adrenalectomy had an attenuated NODM incidence (hazard ratio = 0.60, P < 0.01, versus essential hypertension); whereas those treated with mineralocorticoid receptor antagonist had augmented risk of NODM (hazard ratio = 1.16, P < 0.001, versus essential hypertension). Among the aldosterone-producing adenoma patients, adrenalectomy is also protective from developing NODM (hazard ratio = 0.61, P < 0.001, versus essential hypertension), however, mineralocorticoid receptor antagonist treatment did not alter the risk of NODM (P = 0.10, versus essential hypertension). Adjusted hazard ratios for long-term risk of mortality from this analysis revealed that adrenalectomy is protective, but NODM and major cardiovascular disease are deleterious.

CONCLUSION

The primary aldosteronism patients who underwent adrenalectomy had reduced risk for incident NODM and all-cause of mortality, compared with matched hypertensive controls. This observation adds more evidence on the association of primary aldosteronism with a higher risk of metabolic syndrome and long-term mortality.

Cardiovascular events and target organ damage in primary aldosteronism compared with essential hypertension: a systematic review and meta-analysis

BACKGROUND

There is conflicting evidence, relying on heterogeneous studies, as to whether aldosterone excess is responsible for an increased risk of cardiovascular and cerebrovascular complications in patients with primary aldosteronism. We aimed to assess the association between primary aldosteronism and adverse cardiac and cerebrovascular events, target organ damage, diabetes, and metabolic syndrome, compared with the association of essential hypertension and these cardiovascular and end organ events, by integrating results of previous studies.

METHODS

We did a meta-analysis of prospective and retrospective observational studies that compared patients with primary aldosteronism and essential hypertension, to analyse the association between primary aldosteronism and stroke, coronary artery disease (as co-primary endpoints), atrial fibrillation and heart failure, target organ damage, metabolic syndrome, and diabetes (as secondary endpoints). We searched MEDLINE and Cochrane Library for articles published up to Feb 28, 2017, with no start date restriction. Eligible studies compared patients with primary aldosteronism with patients with essential hypertension (as a control group) and reported on the clinical events or endpoints of interest. We also compared primary aldosteronism subtypes, aldosterone-producing adenoma, and bilateral adrenal hyperplasia.

FINDINGS

We identified 31 studies including 3838 patients with primary aldosteronism and 9284 patients with essential hypertension. After a median of 8·8 years (IQR 6·2-10·7) from the diagnosis of hypertension, compared with patients with essential hypertension, patients with primary aldosteronism had an increased risk of stroke (odds ratio [OR] 2·58, 95% CI 1·93-3·45), coronary artery disease (1·77, 1·10-2·83), atrial fibrillation (3·52, 2·06-5·99), and heart failure (2·05, 1·11-3·78). These results were consistent for patients with aldosterone-producing adenoma and bilateral adrenal hyperplasia, with no difference between these subgroups. Similarly, primary aldosteronism increased the risk of diabetes (OR 1·33, 95% CI 1·01-1·74), metabolic syndrome (1·53, 1·22-1·91), and left ventricular hypertrophy (2·29, 1·65-3·17).

INTERPRETATION

Diagnosing primary aldosteronism in the early stages of disease, with early initiation of specific treatment, is important because affected patients display an increased cardiovascular risk compared with patients with essential hypertension.

FUNDING

None.

A systematic review and meta-analysis of the impact of mineralocorticoid receptor antagonists on glucose homeostasis

BACKGROUND

Spironolactone, a nonselective mineralocorticoid receptor antagonist (MRA), may have a deleterious effect on glycemia. The objective of this review was to assess current knowledge on MRAs' influence (spironolactone, eplerenone, and canrenone) on glucose homeostasis and the risk of diabetes.

METHOD

A systematic review was conducted using the Medline database on articles published from 1946 to January 2017 that studied the effects of MRAs on any glucose-related endpoints, without any restrictions regarding the participants' characteristics.Study design, patient population, dose and duration of intervention, and the quantitative results on glycemic markers were extracted, interpreted for result synthesis, and evaluated for sources of bias. From the articles included in the qualitative analysis, a select number were used in a meta-analysis on studies having measured glycated hemoglobin (HbA1c) or risk of diabetes.

RESULTS

Seventy-two articles were selected from the Medline database and references of articles. Results on spironolactone were heterogeneous, but seemed to be disease-specific. A potential negative effect on glucose regulation was mainly observed in heart failure and diabetes trials, while a neutral or positive effect was detected in diseases characterized by hyperandrogenism, and inconclusive for hypertension. Interpretation of data from heart failure trials was limited by the small number of studies. From a meta-analysis of 12 randomized controlled studies evaluating spironolactone's impact on HbA1c in diabetic patients, spironolactone had a nonsignificant effect in parallel-group studies (mean difference 0.03 [-0.20;0.26]), but significantly increased HbA1c in crossover studies (mean difference 0.24 [0.18;0.31]). Finally, eplerenone did not seem to influence glycemia, while limited data indicated that canrenone may exert a neutral or beneficial effect.The studies had important limitations regarding study design, sample size, duration of follow-up, and choice of glycemic markers.

CONCLUSION

Spironolactone may induce disease-specific and modest alterations on glycemia. It is uncertain whether these effects are transient or not. Data from the most extensively studied population, individuals with diabetes, do not support a long-term glycemic impact in these patients. Further prospective studies are necessary to establish spironolactone's true biological effects and their clinical implications.

Dominance of the hypothalamus-pituitary-adrenal axis over the renin-angiotensin-aldosterone system is a risk factor for decreased insulin secretion

How the association between the hypothalamus-pituitary-adrenal (HPA) axis and the renin-angiotensin-aldosterone system (RAAS) affects glucose metabolism were not well examined in a general population. Participants of the population-based 2015 Iwaki study were enrolled (n: 1,016; age: 54.4 ± 15.1 years). Principal component (PC) analysis identified two PCs: PC1 represented levels of the HPA axis (serum cortisol) and the RAAS (plasma aldosterone) as a whole, and PC2 represented the HPA axis relative to the RAAS (HPA axis dominance). We examined the association between these PCs and glucose metabolism using homeostasis model assessment indices of reduced insulin sensitivity (HOMA-R) and secretion (HOMA-β). Univariate linear regression analyses showed a correlation between PC2 and HOMA-β (β = −0.248, p < 0.0001), but not between PC1 and HOMA-β (β = −0.004, p = 0.9048). The correration between PC2 and HOMA-β persisted after adjustment for multiple factors (β = −0.101, p = 0.0003). No correlations were found between the PCs and HOMA-R. When subjects were tertiled based on PC2, the highest tertile was at greater risk of decreased insulin secretion (defined as the lower one third of HOMA-β (≤68.9)) than the lowest tertile after adjustment for multiple factors (odds ratio, 2.00; 95% confidence interval, 1.35–2.97). The HPA axis dominance is associated with decreased insulin secretion in a Japanese population.

Glucose Metabolism Abnormalities in Cushing Syndrome: From Molecular Basis to Clinical Management

An impaired glucose metabolism, which often leads to the onset of diabetes mellitus (DM), is a common complication of chronic exposure to exogenous and endogenous glucocorticoid (GC) excess and plays an important part in contributing to morbidity and mortality in patients with Cushing syndrome (CS). This article reviews the pathogenesis, epidemiology, diagnosis, and management of changes in glucose metabolism associated with hypercortisolism, addressing both the pathophysiological aspects and the clinical and therapeutic implications. Chronic hypercortisolism may have pleiotropic effects on all major peripheral tissues governing glucose homeostasis. Adding further complexity, both genomic and nongenomic mechanisms are directly induced by GCs in a context-specific and cell-/organ-dependent manner. In this paper, the discussion focuses on established and potential pathologic molecular mechanisms that are induced by chronically excessive circulating levels of GCs and affect glucose homeostasis in various tissues. The management of patients with CS and DM includes treating their hyperglycemia and correcting their GC excess. The effects on glycemic control of various medical therapies for CS are reviewed in this paper. The association between DM and subclinical CS and the role of screening for CS in diabetic patients are also discussed.

Renin Phenotypes Characterize Vascular Disease, Autonomous Aldosteronism, and Mineralocorticoid Receptor Activity

CONTEXT

Mild cases of autonomous aldosterone secretion may go unrecognized using current diagnostic criteria for primary aldosteronism (PA).

OBJECTIVE

To investigate whether the inability to stimulate renin serves as a biomarker for unrecognized autonomous aldosterone secretion and mineralocorticoid receptor (MR) activation.

PARTICIPANTS

Six hundred sixty-three normotensive and mildly hypertensive participants, who were confirmed to not have PA using current guideline criteria and were on no antihypertensive medications.

DESIGN

Participants had their maximally stimulated plasma renin activity (PRA) measured while standing upright after sodium restriction. Tertiles of maximally stimulated PRA were hypothesized to reflect the degree of MR activation: lowest PRA tertile = "Inappropriate/Excess MR Activity;" middle PRA tertile = "Intermediate MR Activity;"; and highest PRA tertile = "Physiologic MR Activity." All participants underwent detailed biochemical and vascular characterizations under conditions of liberalized sodium intake, and associations with stimulated PRA phenotypes were performed.

RESULTS

Participants with lower stimulated PRA had greater autonomous aldosterone secretion [higher aldosterone-to-renin ratio (P = 0.002), higher urine aldosterone excretion rate (P = 0.003), higher systolic blood pressure (P = 0.004), and lower renal plasma flow (P = 0.04)] and a nonsignificant trend toward lower serum potassium and higher urine potassium excretion, which became significant after stratification by hypertension status.

CONCLUSIONS

In participants without clinical PA, the inability to stimulate renin was associated with greater autonomous aldosterone secretion, impaired vascular function, and suggestive trends in potassium handling that indicate an extensive spectrum of unrecognized MR activation.

Aldosterone Synthase Inhibition Improves Glucose Tolerance in Zucker Diabetic Fatty (ZDF) Rats

Plasma aldosterone is elevated in type 2 diabetes and obesity in experimental and clinical studies and can act to inhibit both glucose-stimulated insulin secretion by the β-cell and insulin signaling. Currently mineralocorticoid receptor antagonism is the best characterized treatment to ameliorate aldosterone-mediated effects. A second alternative is inhibition of aldosterone synthase, an approach with protective effects on end-organ damage in heart or kidney in animal models. The effect of aldosterone synthase inhibition on metabolic parameters in type 2 diabetes is not known. Therefore, male Zucker diabetic fatty (ZDF) rats were treated for 11 weeks with the aldosterone synthase inhibitor FAD286, beginning at 7 weeks of age. Results were compared with the mineralocorticoid receptor antagonist eplerenone. Plasma aldosterone was abolished by FAD286 and elevated more than 9-fold by eplerenone. The area under the curve calculated from an oral glucose tolerance test (OGTT) was lower and overall insulin response during OGTT was increased by FAD286. In contrast, eplerenone elevated blood glucose levels and blunted insulin secretion during the OGTT. Fasting glucose was lowered and fasting insulin was increased by FAD286 in the prediabetic state. Glycated hemoglobin was lowered by FAD286, whereas eplerenone showed no effect. We conclude that aldosterone synthase inhibition, in contrast to mineralocorticoid receptor antagonism, has the potential for beneficial effects on metabolic parameters in type 2 diabetes.

Evaluation of insulin sensitivity and secretion in primary aldosteronism

In primary aldosteronism (PA), insulin response to glucose is not fully understood. Insulin action was elucidated using indices in 32 PA and 21 essential hypertension (EH) patients. These patients were evaluated using homeostasis model assessment (HOMA) indices, quantitative insulin sensitivity check index (QUICKI), and insulinogenic index (IGI), which were expressed for insulin sensitivity/secretion and the early phase of insulin secretion. Insulin sensitivity and early phase of insulin secretion were decreased in PA, and there was a negative correlation between serum potassium concentration and insulin sensitivity indices. These findings suggest that glucose intolerance in PA may be caused by hypokalemia-induced insulin resistance and hypokalemia-independent impairment of early-phase insulin secretion.

Aldosterone and type 2 diabetes mellitus

Primary hyperaldosteronism (PA) has recently been demonstrated to be strictly associated to metabolic syndrome as compared with essential hypertension (EH). Besides, the characteristics of metabolic syndrome are different in PA compared to EH, as high fasting glucose is more frequent in the former condition. The adverse effect of excess aldosterone on insulin metabolic signaling has generated increasing interest in the role of hyperaldosteronism in the pathogenesis of insulin resistance and resistant hypertension. Moreover, aldosterone receptor antagonist therapy in diabetic and cardiopathic patients improved coronary flow. The aim of this review is to present recent knowledge about the relationship between aldosterone, insulin resistance and diabetes.

Glucose Metabolism in Primary Aldosteronism

In recent years, an increasing number of studies have revealed deleterious effects of aldosterone via the mineralocorticoid receptor (MR). Especially in patients with primary aldosteronism (PA) a significant higher estimated risk of developing cardiovascular comorbidities and comortalities compared to essential hypertensives was reported. As diabetes mellitus and the metabolic syndrome are one of the major contributors to cardiovascular morbidity and mortality their connection to aldosterone excess became a focus of research in PA patients. Several studies assessed the effect of PA on glucose metabolism, the prevalence of diabetes mellitus, and the effect of PA treatment on both revealing different results. Therefore, we performed an extensive literature research. This review focuses on the current knowledge of the connection between aldosterone excess, glucose homeostasis, and diabetes mellitus in patients with PA. We have highlighted this topic from a pro and contra perspective followed by a summarizing concluding remark. Additionally, we have briefly reviewed the data on possible underlying mechanisms and indicated future considerations on the possible impact of cortisol co-secretion in PA.

Increased prevalence of diabetes mellitus and the metabolic syndrome in patients with primary aldosteronism of the German Conn's Registry

DESIGN

Abnormalities in glucose homeostasis have been described in patients with primary aldosteronism (PA) but most studies show inconsistent results. Therefore, we aimed to compare the prevalence of type 2 diabetes mellitus and metabolic syndrome (MetS) in newly diagnosed PA patients to a matched control cohort of the background population.

METHODS

In total, 305 PA patients of the prospective German Conn's Registry were compared to the population-based Study of Health In Pomerania (SHIP1; n=2454). A 1:1 match regarding sex, age, and BMI resulted in 269 matched pairs regarding type 2 diabetes and 183 matched pairs regarding MetS. Of the total, 153 PA patients underwent oral glucose tolerance testing (OGTT) at diagnosis and 38 PA patients were reevaluated at follow-up.

RESULTS

Type 2 diabetes and MetS were significantly more frequent in PA patients than in the control population (17.2% vs 10.4%, P=0.03; 56.8% vs 44.8%, P=0.02 respectively). Also, HbA1c levels were higher in PA patients than in controls (P<0.01). Of the total, 35.3% of non-diabetic PA patients showed an abnormal OGTT (¼ newly diagnosed type 2 diabetes and ¾ impaired glucose tolerance). PA patients with an abnormal OGTT at baseline presented with significantly improved 2 h OGTT glucose (P=0.01) at follow-up. We detected a negative correlation between 2 h OGTT glucose levels and serum potassium (P<0.01).

CONCLUSIONS

Type 2 diabetes and MetS are more prevalent in patients with PA than in controls matched for sex, age, BMI, and blood pressure. This may explain in part the increased cardiovascular disease morbidity and mortality in PA patients.

Pancreatic functions in high salt fed female rats

Salt consumption has been increased worldwide and the association of high salt diets with enhanced inflammation and target organ damage was reported. Little data were available about the effect of high salt diet on exocrine function of pancreas, while the relation between high salt intake and insulin sensitivity was controversial. This study was designed to investigate the effect of high salt diet on exocrine and endocrine pancreatic functions, and to elucidate the possible underlying mechanism(s). Twenty adult female Wistar rats were randomly divided into two groups; control group; fed standard rodent diet containing 0.3% NaCl, and high salt fed group; fed 8% NaCl for 8 weeks. On the day of sacrifice, rats were anesthized by i.p. pentobarbitone (40 μg/kg B.W.). Nasoanal length was measured and fasting blood glucose was determined from rat tail. Blood samples were obtained from abdominal aorta for determination of plasma sodium, potassium, amylase, lipase, aldosterone, insulin, transforming growth factor-β (TGF-β1), and interleukin 6 (IL6). Pancreata of both groups were histologically studied. Compared to control group, 8-week high salt fed group showed: significant elevation in body weight, body mass index, Lee index, plasma sodium, TGF-β1 and IL6, however, plasma aldosterone, amylase, lipase, and insulin levels were significantly decreased. A nonsignificant increase in plasma potassium and nonsignificant changes in fasting blood glucose and HOMA-IR were detected between groups. Pancreatic fibrosis was observed in test group. High salt diet for 8 weeks caused pancreatic fibrosis evidenced by decline of both exocrine and endocrine functions of pancreas in Wistar rats.

Higher blood aldosterone level in metabolic syndrome is independently related to adiposity and fasting plasma glucose

BACKGROUND

Hypoadiponectinemia is a well-known state associated with metabolic syndrome (MetS) and insulin resistance (IR). Recently aldosterone has been highly associated with high blood pressure, and may thus be a possible biomarker for MetS and IR. In this study, we investigate the association of aldosterone with MetS and IR, and compare it with that of adiponectin.

METHODS

In this cross-sectional study, we recruited 556 women receiving physical examinations at a general hospital in central Taiwan. At the time of examination, we collected data on various demographic and physical characteristics and measured blood levels of aldosterone, adiponectin and a variety of metabolic factors. Multiple linear regression analysis was performed using adiponectin or aldosterone as the dependent variables.

RESULTS

We found an inverse correlation between blood adiponectin and aldosterone (γ = -0.11, P = 0.009). Adiponectin levels were lower and aldosterone levels higher in women with MetS that those without (8.1 ± 0.4 vs. 11.5 ± 0.2 μg/mL, P < 0.001 and 691 ± 50 vs. 560 ± 11 pmol/L, P = 0.013, respectively), as they were in women with and without IR (adiponectin 10.4 ± 0.5 vs. 11.3 ± 0.2 μg/mL, P = 0.003 and aldosterone 635 ± 31 vs. 560 ± 11 pmol/L, P = 0.022). Although aldosterone was significantly related to body fat %, fasting plasma glucose and serum creatinine levels, the relationship between adiponectin and aldosterone was not obvious after adjustment in the multivariate analysis.

CONCLUSION

Although aldosterone was related to metabolic factors, including body fat % and fasting plasma glucose in our female subjects, the relationship between aldosterone and adiponectin remains unclear.

Effects of aldosterone on insulin sensitivity and secretion

Dr. Conn originally reported an increased risk of diabetes in patients with hyperaldosteronism in the 1950s, although the mechanism remains unclear. Aldosterone-induced hypokalemia was initially described to impair glucose tolerance by impairing insulin secretion. Correction of hypokalemia by potassium supplementation only partially restored insulin secretion and glucose tolerance, however. Aldosterone also impairs glucose-stimulated insulin secretion in isolated pancreatic islets via reactive oxygen species in a mineralocorticoid receptor-independent manner. Aldosterone-induced mineralocorticoid receptor activation also impairs insulin sensitivity in adipocytes and skeletal muscle. Aldosterone may produce insulin resistance secondarily by altering potassium, increasing inflammatory cytokines, and reducing beneficial adipokines such as adiponectin. Renin-angiotensin system antagonists reduce circulating aldosterone concentrations and also the risk of type 2 diabetes in clinical trials. These data suggest that primary and secondary hyperaldosteronism may contribute to worsening glucose tolerance by impairing insulin sensitivity or insulin secretion in humans. Future studies should define the effects of MR antagonists and aldosterone on insulin secretion and sensitivity in humans.

Dietary sodium restriction decreases insulin secretion without affecting insulin sensitivity in humans

CONTEXT

Interruption of the renin-angiotensin-aldosterone system prevents incident diabetes in high-risk individuals, although the mechanism remains unclear.

OBJECTIVE

To test the hypothesis that activation of the endogenous renin-angiotensin-aldosterone system or exogenous aldosterone impairs insulin secretion in humans.

DESIGN

We conducted a randomized, blinded crossover study of aldosterone vs vehicle and compared the effects of a low-sodium versus a high-sodium diet.

SETTING

Academic clinical research center.

PARTICIPANTS

Healthy, nondiabetic, normotensive volunteers.

INTERVENTIONS

Infusion of exogenous aldosterone (0.7 μg/kg/h for 12.5 h) or vehicle during low or high sodium intake. Low sodium (20 mmol/d; n = 12) vs high sodium (160 mmol/d; n = 17) intake for 5-7 days.

MAIN OUTCOME MEASURES

Change in acute insulin secretory response assessed during hyperglycemic clamps while in sodium balance during a low-sodium vs high-sodium diet during aldosterone vs vehicle.

RESULTS

A low-sodium diet increased endogenous aldosterone and plasma renin activity, and acute glucose-stimulated insulin (-16.0 ± 5.6%; P = .007) and C-peptide responses (-21.8 ± 8.4%; P = .014) were decreased, whereas the insulin sensitivity index was unchanged (-1.0 ± 10.7%; P = .98). Aldosterone infusion did not affect the acute insulin response (+1.8 ± 4.8%; P = .72) or insulin sensitivity index (+2.0 ± 8.8%; P = .78). Systolic blood pressure and serum potassium were similar during low and high sodium intake and during aldosterone infusion.

CONCLUSIONS

Low dietary sodium intake reduces insulin secretion in humans, independent of insulin sensitivity.

Antioxidant N-acetylcysteine protects pancreatic β-cells against aldosterone-induced oxidative stress and apoptosis in female db/db mice and insulin-producing MIN6 cells

Previous studies have shown that primary aldosteronism is associated with glucose-related metabolic disorders. However, the mechanisms by which aldosterone (ALDO) triggers β-cell dysfunction remains unclear. This study aimed to investigate whether oxidative stress is involved in and whether the antioxidant N-acetylcysteine (NAC) or the mineralocorticoid receptor antagonist spironolactone (SPL) could prevent or delay β-cell damage in vivo and in vitro. As expected, 8 weeks after ALDO treatment, 12-week-old female diabetic db/db mice exhibited impaired oral glucose tolerance, decreased β-cell mass, and heightened levels of oxidative stress marker (urinary 8-hydroxy-2'-deoxyguanosine). NAC reversed these symptoms completely, whereas SPL treatment did so only partially. After exposure to ALDO, the mouse pancreatic β-cell line MIN6 exhibited decreased viability and increased caspase-3 activity, as well as reduced expression of Bcl-2/Bax and p-AKT, even if mineralocorticoid receptor was completely suppressed with small interfering RNA. NAC, but not SPL, suppressed oxidative stress in MIN6 cells, as revealed by the decrease in inducible NOS levels and expression of the proteins p22-phox and p67-phox. These findings suggest that oxidative stress may be involved in ALDO-induced β-cell dysfunction and that NAC, but not SPL, may protect pancreatic β-cells of mice from ALDO-induced oxidative stress and apoptosis in a manner independent of its receptor.

Marine natural product des-O-methyllasiodiplodin effectively lowers the blood glucose level in db/db mice via ameliorating inflammation

AIM

des-O-methyllasiodiplodin (DML) from Cerbera manghas has shown antagonistic activity against mineralocorticoid receptor (MR). Considering the involvement of MR in the insulin tolerance, we attempted to investigate the potential of DML in the treatment of type 2 diabetes mellitus (T2DM).

METHODS

Surface plasmon resonance (SPR) technology and reporter gene-based assays were used to study protein-small molecule interactions. HepG2 and 3T3-L1 cells were treated with H2O2 (0.2 mmol/L) or aldosterone (10 nmol/L) for 24 h. The expression of MR in the cells was downregulated with siRNA. The anti-inflammatory effect of the compound was evaluated, respectively. db/db mice were administered DML (30 mg·kg(-1)·d(-1)) for 4 weeks. Serum biochemical parameters and insulin sensitivity were examined. The expression levels of pro-inflammatory cytokines (MCP-1, TNF-α and IL-6) and ROS-related genes (NADPH p47 subunit and transcriptional factor PU.1) in adipose tissues and livers were analyzed using real-time RT-PCR.

RESULTS

In HepG2 and 3T3-L1 cells, both H2O2 and aldosterone markedly stimulates the expression of MCP-1, TNFα, IL-6, p47 and PU.1 genes. Co-treatment with DML (10 μmol/L) significantly reduced the H2O2- or aldosterone-induced expression of these genes. SPR-based assay confirmed the antagonistic activity of DML against the interaction between SRC-1 and MR-LBD. Furthermore, DML decreased aldosterone-induced MR transcriptional activity in a dose-dependent manner. Downregulation of MR with siRNA in the cells prevented or significantly attenuated aldosterone-stimulated expression of these genes, whereas DML did no longer affect the expression of these genes except that of IL-6. Oral administration of DML effectively reduced the levels of blood glucose and glycosylated hemoglobin (HbA1c) in db/db mice. The treatment also rectified the expression of pro-inflammatory factor and ROS-related genes in db/db mice.

CONCLUSION

DML effectively lowers the blood glucose level in db/db mice possibly via ameliorating the expression of obesity-related pro-inflammatory cytokines, highlighting the potential of the marine natural product as a drug lead for the treatment of metabolic disorders.

The mineralocorticoid receptor: a new player controlling energy homeostasis

Numerous studies have demonstrated the interaction that exists between adipocyte differentiation, energy balance and factors involved in fluid and electrolyte homeostasis, such as the renin-angiotensin-aldosterone system. More specifically, a potential impact of aldosterone on the function of several organs implicated in the control of energy homeostasis, such as adipose tissue, liver, skeletal muscle or pancreas, has been recently described. In addition, the mineralocorticoid receptor (MR, NR3C2), a transcription factor, was shown to play a crucial role on white and brown adipocyte differentiation and function, mediating the effects of both mineralocorticoid and glucocorticoid hormones on adipose tissues. Transgenic mouse models as well as pharmacological inactivation of MR signaling provided compelling evidence that MR is an important control point for energy homeostasis. Herein, we review recent findings on the involvement of aldosterone but also of MR on energy metabolism and discuss the therapeutic potential of manipulating MR signaling for the management of metabolic disorders in humans.

Genetics of mineralocorticoid excess: an update for clinicians

Aldosterone plays a major role in the regulation of sodium and potassium homeostasis and blood pressure. More recently, aldosterone has emerged as a key hormone mediating end organ damage. In extreme cases, dysregulated aldosterone production leads to primary aldosteronism (PA), the most common form of secondary hypertension. However, even within the physiological range, high levels of aldosterone are associated with an increased risk of developing hypertension over time. PA represents the most common and curable form of hypertension, with a prevalence that increases with the severity of hypertension. Although genetic causes underlying glucocorticoid-remediable aldosteronism, one of the three Mendelian forms of PA, were established some time ago, somatic and inherited mutations in the potassium channel GIRK4 have only recently been implicated in the formation of aldosterone-producing adenoma (APA) and in familial hyperaldosteronism type 3. Moreover, recent findings have shown somatic mutations in two additional genes, involved in maintaining intracellular ionic homeostasis and cell membrane potential, in a subset of APAs. This review summarizes our current knowledge on the genetic determinants that contribute to variations in plasma aldosterone and renin levels in the general population and the genetics of familial and sporadic PA. Various animal models that have significantly improved our understanding of the pathophysiology of excess aldosterone production are also discussed. Finally, we outline the cardiovascular, renal, and metabolic consequences of mineralocorticoid excess beyond blood pressure regulation.

Aldosterone excess impairs first phase insulin secretion in primary aldosteronism

CONTEXT

Primary aldosteronism (PA) represents the most frequent cause of secondary arterial hypertension. Conflicting data have been published regarding the effect of aldosterone excess on glucose metabolism.

OBJECTIVE

Our aim was to analyze insulin sensitivity and β-cell function in a cohort of PA patients. Prospective follow-up investigations were performed in a subgroup of patients before and after adrenalectomy to assess the metabolic outcome.

DESIGN

Oral glucose tolerance test, combined intravenous glucose tolerance test, hyperinsulinemic-euglycemic glucose clamp test, and arginine test were carried out after a 12-hour fasting period.

PATIENTS

Twenty-two consecutive patients with both unilateral aldosterone-producing adenoma and bilateral idiopathic adrenal hyperplasia were recruited through the Munich center of the German Conn's Registry. The control group of patients with essential hypertension (n = 11) of corresponding age and body mass index was recruited from our hypertension unit. A normotensive cohort (n = 11) served as a further control group.

RESULTS

At baseline, first-phase insulin reaction in intravenous glucose tolerance test was significantly reduced in patients with PA as compared to normal controls (36.0 [24.0; 58.7] vs 90.1 [52.6; 143.8] μU/mL, P = .031) and lower in comparison to essential hypertension without reaching statistical significance (53.2 [30.8; 73.3] μU/mL, P = .123). The study was repeated 6 months after unilateral adrenalectomy in 9 consecutive patients with aldosterone-producing adenoma. At this time point, blood pressure had been normalized in most of the patients while body mass index remained unchanged (26.9 [25.5; 37.6] vs 27.5 [25.1; 35.6] kg/m(2), P = .401). First-phase insulin reaction in response to glucose significantly increased at follow-up (from 36.0 [25.5; 58.7] to 48.5 [40.4; 95.2] μU/mL, P = .038, n = 9). In contrast, insulin sensitivity and response to iv arginine did not differ before and after adrenalectomy.

CONCLUSION

Aldosterone excess has a direct negative effect on β-cell function in patients with PA. After adrenalectomy, glucose-induced first-phase insulin secretion improves significantly in the patients.

The role of mineralocorticoid receptor antagonists (MRAs) in very old patients with heart failure

Mineralocorticoid receptor antagonists (MRAs) have been effective in reducing total mortality in patients with heart failure (HF) and a reduced left ventricular ejection fraction. Due to the finding that aldosterone levels decrease with age, one might question the effectiveness of MRAs in very old patients (≥80 years of age), those at the greatest risk for developing HF with a preserved left ventricular ejection fraction (PEF). However, while aldosterone levels decrease with age, there is also a decrease in the enzyme 11 beta HSD2 levels with age, thereby allowing cortisol to stimulate the mineralocorticoid receptor (MR), which in younger patients with higher levels of 11 beta HSD 2 levels is converted to cortisone which cannot activate the MR. There is also an increase in the expression of the MR in the vascular wall with age. Thus, there is reason to believe that MRAs might be effective in reducing cardiovascular mortality and the incidence of hospitalizations for HF in very old patients with HFPEF. There is also reason to believe that MRAs might favorably affect many of the comorbid conditions associated with HFPEF in very old patients. The safety and efficacy of this hypothesis is currently under investigation in the NHLBI sponsored TOPCAT trial.

Aldosterone deficiency prevents high-fat-feeding-induced hyperglycaemia and adipocyte dysfunction in mice

AIMS/HYPOTHESIS

Obesity is associated with aldosterone excess, hypertension and the metabolic syndrome, but the relative contribution of aldosterone to obesity-related complications is debated. We previously demonstrated that aldosterone impairs insulin secretion, and that genetic aldosterone deficiency increases glucose-stimulated insulin secretion in vivo. We hypothesised that elimination of endogenous aldosterone would prevent obesity-induced insulin resistance and hyperglycaemia.

METHODS

Wild-type and aldosterone synthase-deficient (As (-/-)) mice were fed a high-fat (HF) or normal chow diet for 12 weeks. We assessed insulin sensitivity and insulin secretion using clamp methodology and circulating plasma adipokines, and examined adipose tissue via histology.

RESULTS

HF diet induced weight gain similarly in the two groups, but As (-/-) mice were protected from blood glucose elevation. HF diet impaired insulin sensitivity similarly in As (-/-) and wild-type mice, assessed by hyperinsulinaemic-euglycaemic clamps. Fasting and glucose-stimulated insulin were higher in HF-fed As (-/-) mice than in wild-type controls. Although there was no difference in insulin sensitivity during HF feeding in As (-/-) mice compared with wild-type controls, fat mass, adipocyte size and adiponectin increased, while adipose macrophage infiltration decreased. HF feeding significantly increased hepatic steatosis and triacylglycerol content in wild-type mice, which was attenuated in aldosterone-deficient mice.

CONCLUSIONS/INTERPRETATION

These studies demonstrate that obesity induces insulin resistance independently of aldosterone and adipose tissue inflammation, and suggest a novel role for aldosterone in promoting obesity-induced beta cell dysfunction, hepatic steatosis and adipose tissue inflammation.

Adverse cardiovascular outcomes of corticosteroid excess

Corticosteroid excess is associated with adverse cardiovascular outcomes. Patients with Cushings's syndrome, either caused by endogenous or exogenous glucocorticoid excess, and patients with primary aldosteronism have increased cardiovascular risk. The increase in risk is mediated partly by traditional cardiovascular risk factors including hypertension and metabolic syndrome but also by other, less well-characterized mechanisms. Experimental and human studies have shown that target organ deterioration induced by aldosterone depends on concomitant high dietary salt intake. Key ongoing research questions that warrant further study by both clinical and experimental approaches include the following: 1) beyond inducing the metabolic syndrome, what are the mechanisms by which glucocorticoids are associated with excess cardiovascular risk, 2) what are the cellular pathways by which excessive mineralocorticoid receptor activation brings about cardiovascular and renal damage, and 3) why is salt critical in this process?

Effect of metformin and spironolactone therapy on OGTT in patients with polycystic ovarian syndrome - a retrospective analysis

BACKGROUND

Metformin (an insulin sensitizer) and spironolactone (an antiandrogen) are both used for treatment of polycystic ovary syndrome. We analyzed the effect of 6 months of therapy with these drugs on body weight and glucose tolerance.

RESULTS

This was a retrospective analysis of polycystic ovarian syndrome (PCOS) cases on treatment. There were 88 patients with PCOS-42 were on metformin 1 g daily and 46 were taking spironolactone 50-75 mg daily. 21 of 42 had abnormal glucose tolerance (AGT) in the metformin group and 13 of 46 had AGT in the spironolactone group. Patients on metformin reported a greater reduction in body weight, whereas there was no change in body weight with spironolactone therapy (67.6-63.7 versus 59.6-59.2 kg). There was a significant reduction in the 1 and 2 h glucose and insulin levels with metformin therapy in those with AGT. However, fasting glucose increased in those with normal glucose tolerance. There was no change in either body weight or insulin levels with spironolactone. But, there was a significant reduction in both the 0 and 2 h glucose with spironolactone also in those with AGT.

CONCLUSION

Spironolactone and metformin had similar effect in reducing the glucose levels in PCOS patients with AGT. PCOS patients with normal glucose tolerance had higher fasting plasma glucose at the end of 6 months of metformin therapy inspite of weight reduction.

Prevalence of primary aldosteronism in hypertensive subjects with hyperglycemia

The aim of this study was to examine the prevalence of primary aldosteronism (PA) in hypertensive patients with hyperglycemia. Two hundred and thirty-two hypertensive patients with hyperglycemia were screened for PA. Fifty-four subjects with an aldosterone/rennin activity ratio >20 ng/dL per ng/mL/hour underwent a saline loading test. Primary aldosteronism was present in 22.4% of patients with a plasma aldosterone concentration >5 ng/dL and 11.6% of those with plasma aldosterone concentrations >10 ng/dL. There were 14.0%-23.0% patients with PA in the diabetes mellitus group, 2.3%-23.3% in the impaired glucose tolerance group, and 9.1% in the impaired fasting glucose group. Primary aldosteronism is common in hypertensive individuals with hyperglycemia.