The effect of aldosterone on glucose metabolism

Effects of thiazides and new findings on kidney stones and dysglycemic side effects

Thiazide and thiazide-like diuretics (thiazides) belong to the most frequently prescribed drugs worldwide. By virtue of their natriuretic and vasodilating properties, thiazides effectively lower blood pressure and prevent adverse cardiovascular outcomes. In addition, through their unique characteristic of reducing urine calcium, thiazides are also widely employed for the prevention of kidney stone recurrence and reduction of bone fracture risk. Since their introduction into clinical medicine in the early 1960s, thiazides have been recognized for their association with metabolic side effects, particularly impaired glucose tolerance, and new-onset diabetes mellitus. Numerous hypotheses have been advanced to explain thiazide-induced glucose intolerance, yet underlying mechanisms remain poorly defined. Regrettably, the lack of understanding and unpredictability of these side effects has prompted numerous physicians to refrain from prescribing these effective, inexpensive, and widely accessible drugs. In this review, we outline the pharmacology and mechanism of action of thiazides, highlight recent advances in the understanding of thiazide-induced glucose intolerance, and provide an up-to-date discussion on the role of thiazides in kidney stone prevention.

Primary hyperaldosteronism is associated with increased mortality and morbidity in patients with hypertension and diabetes

Aims

Primary hyperaldosteronism (PA) is a common cause of hypertension. It is more prevalent in patients with diabetes. We assessed the cardiovascular impact of PA in patients with established hypertension and diabetes.

Methods

Data from the National Inpatient Sample (2008-2016) was used to identify adults with PA with hypertension and diabetes comorbidities and then compared to non-PA patients. The primary outcome was in-hospital death. Secondary outcomes included ischemic stroke, hemorrhagic stroke, acute renal failure, atrial fibrillation, and acute heart failure.

Results

A total of 48,434,503 patients with hypertension and diabetes were included in the analysis, of whom 12,850 (0.03%) were diagnosed with primary hyperaldosteronism (PA). Compared to patients with hypertension and diabetes but no PA, those with PA were more likely to be younger [63(13) vs. 67 (14), male (57.1% vs. 48.3%), and African-Americans (32% vs. 18.5%) (p<0.001 for all). PA was associated with a higher risk of mortality (adjusted OR 1.076 [1.076-1.077]), ischemic stroke [adjusted OR 1.049 (1.049-1.05)], hemorrhagic stroke [adjusted OR 1.05 (1.05-1.051)], acute renal failure [adjusted OR 1.058 (1.058-1.058)], acute heart failure [OR 1.104 (1.104-1.104)], and atrial fibrillation [adjusted OR 1.034 (1.033-1.034)]. As expected, older age and underlying cardiovascular disease were the strongest predictors of mortality. However, the female gender conferred protection [OR 0.889 (0.886-0.892].

Conclusion

Primary hyperaldosteronism in patients with hypertension and diabetes is associated with increased mortality and morbidity.

The Role of Aldosterone and Ideal Cardiovascular Health in Incident Cardiovascular Disease: The Jackson Heart Study

Background

Higher levels of ideal cardiovascular health (ICH) are associated with lower levels of aldosterone and incidence of cardiovascular disease (CVD). However, the degree to which aldosterone mediates the association between ICH and CVD incidence has not been explored. Thus, we investigated the mediational role of aldosterone in the association of 5 components of ICH (cholesterol, body mass index (BMI), physical activity, diet and smoking) with incident CVD and the mediational role of blood pressure (BP) and glucose in the association of aldosterone with incident CVD in a cohort of African Americans (AA).

Methods

The Jackson Heart Study is a prospective cohort of AAs adults with data on CVD outcomes. Aldosterone, ICH metrics and baseline characteristics were collected at exam 1 (2000-2004). ICH score was developed by summing 5 ICH metrics (smoking, dietary intake, physical activity, BMI, and total cholesterol) and grouped into two categories (0-2 and ≥3 metrics). Incident CVD was defined as stroke, coronary heart disease, or heart failure. Cox proportional hazard regression models were used to model the association of categorical ICH score with incident CVD. The R Package Mediation was utilized to examine: 1) The mediational role of aldosterone in the association of ICH with incident CVD and 2) The mediational role of blood pressure and glucose in the association of aldosterone with incident CVD.

Results

Among 3,274 individuals (mean age: 54±12.4 years, 65% female), there were 368 cases of incident CVD over a median of 12.7 years. The risk of incident CVD was 46% lower (HR: 0.54; 95%CI 0.36, 0.80) in those with ≥3 ICH metrics at baseline compared to 0-2. Aldosterone mediated 5.4% (p = 0.006) of the effect of ICH on incident CVD. A 1-unit increase in log-aldosterone was associated with a 38% higher risk of incident CVD (HR 1.38, 95%CI: 1.19, 1.61) with BP and glucose mediating 25.6% (p<0.001) and 4.8% (p = 0.048), respectively.

Conclusion

Aldosterone partially mediates the association of ICH with incident CVD and both blood pressure and glucose partially mediate the association of aldosterone with incident CVD, emphasizing the potential importance of aldosterone and ICH in risk of CVD among AAs.

The role of aldosterone and ideal cardiovascular health in incident diabetes: The Jackson Heart Study

Background

Greater attainment of ideal cardiovascular health (ICH) and lower serum aldosterone are associated with lower diabetes risk. Higher levels of ICH are associated with lower aldosterone. The mediational role of aldosterone in the association of ICH with incident diabetes remains unexplored. Thus, we examined the mediational role of aldosterone in the association of 5 ICH components (smoking, diet, physical activity, body mass index [BMI], and cholesterol) with incident diabetes. Additionally, we investigated the mediational role of glucose and blood pressure (BP) in the association of aldosterone with incident diabetes in an African American (AA) cohort.

Methods

We conducted a prospective cohort analysis among AA adults, aged 21-94 years, in the Jackson Heart Study. Data on ICH, aldosterone, and cardiometabolic risk factors were collected at exam 1 (2000-2004). Diabetes (fasting glucose ≥ 126 mg/dL, physician diagnosis, use of diabetes drugs, or glycated hemoglobin ≥ 6.5%) was assessed at exams 1 through 3 (2009-2012). ICH metrics were defined by American Heart Association 2020 goals for smoking, dietary intake, physical activity, BMI, total cholesterol, BP and glucose. The number of ICH metrics attained at exam 1, excluding BP and fasting glucose, were summed (0-2, vs. 3+). R Package Mediation was used to examine: 1) The mediational role of aldosterone in the association of ICH with incident diabetes; and 2) the mediational role of BP and glucose in the association of aldosterone with incident diabetes.

Results

Among 2,791 participants (mean age: 53±12, 65% female) over a median of 7.5 years, there were 497 incident diabetes cases. Risk of incident diabetes was 37% (HR: 0.63, 95%CI: 0.47, 0.84) lower in 3+ ICH category compared to 0-2 ICH category. Aldosterone mediated 6.98% (95% CI: 1.8%, 18.0%) of the direct effect of ICH on incident diabetes. A 1-unit increase in log-aldosterone was associated with a 44% higher risk of diabetes (HR 1.44, 95%CI 1.25-1.64). BP and glucose mediated 16.3% (95% CI: 7.0%, 31.0%) and 19.7% (95% CI: 6.5%, 34.0%) of the association of aldosterone with incident diabetes, respectively.

Conclusion

Aldosterone is a mediator of the association of ICH with incident diabetes, whereas BP and glucose are mediators of the association of aldosterone with incident diabetes, emphasizing the importance of the renin-angiotensin-aldosterone system and ICH in lowering risk of diabetes in AA populations.

Cerebro-Cardiovascular Risk, Target Organ Damage, and Treatment Outcomes in Primary Aldosteronism

Primary aldosteronism (PA) is the most common type of endocrine hypertension, and numerous experimental and clinical evidence have verified that prolonged exposure to excess aldosterone is responsible for an increased risk of cerebro-cardiovascular events and target organ damage (TOD) in patients with PA. Therefore, focusing on restoring the toxic effects of excess aldosterone on the target organs is very important to reduce cerebro-cardiovascular events. Current evidence convincingly demonstrates that both surgical and medical treatment strategies would benefit cerebro-cardiovascular outcomes and mortality in the long term. Understanding cerebro-cardiovascular risk in PA would help clinical doctors to achieve both early diagnosis and treatment. Therefore, in this review, we will summarize the cerebro-cardiovascular risk in PA, focusing on the TOD of aldosterone, including brain, heart, vascular system, renal, adipose tissues, diabetes, and obstructive sleep apnea (OSA). Furthermore, the various treatment outcomes of adrenalectomy and medical treatment for patients with PA will also be discussed. We hope this knowledge will help improve cerebro-cardiovascular prognosis and reduce the incidence and mortality of cerebro-cardiovascular events in patients with PA.

Lipid Profiles in Primary Aldosteronism Compared with Essential Hypertension: Propensity-Score Matching Study

BACKGROUND

There has been controversy regarding the association between primary aldosteronism (PA) and dyslipidemia and few studies considered the effects of diabetes and renal function on lipid metabolism. We analyzed lipid profiles of PA patients and compared them to propensity-score (PS)-matched essential hypertension (EH) patients adjusting for glycemic status and renal function.

METHODS

Patients who were diagnosed with PA using a saline-infusion test at Seoul National University Hospital from 2000 to 2018 were retrospectively analyzed. EH patients who had aldosterone-renin ratio (ARR) results were selected as controls. Covariates, including diabetes, were PS-matched for patients with PA, lateralized PA, non-lateralized PA, and high ARR to EH patients, respectively.

RESULTS

Among a total of 80 PA and 80 EH patients, total cholesterol (TC) and triglyceride (TG) levels were significantly lower in the PA patients than in the EH patients (least-squares mean±standard error: 185.5±4.4 mg/dL vs. 196.2±4.4 mg/dL, P=0.047, for TC; and 132.3±11.5 mg/dL vs. 157.4±11.4 mg/dL, P=0.035, for TG) in fully adjusted model (adjusting for multiple covariates, including diabetes status, glycosylated hemoglobin level, and estimated glomerular filtration rate). There were no significant differences in high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol levels between the two groups. According to increments in aldosterone levels, an increasing tendency of HDL-C and decreasing tendencies of TG and non-HDL-C were observed.

CONCLUSION

PA patients had lower TC and TG levels than EH patients, independent of glycemic status and renal function.

Non-Alcoholic Fatty Liver Disease and Hypokalemia in Primary Aldosteronism Among Chinese Population

BACKGROUND

In recent years, evidence that aldosteronism is a risk factor for metabolic disorders has increased. This study was designed to investigate the role of nonalcoholic fatty liver disease (NAFLD) and hypokalemia in primary aldosteronism (PA).

METHODS

A total of 222 patients diagnosed with PA and 222 non-PA patients were included in our study. Demographic data, medical histories, clinical evaluations, complete blood counts, serum biochemical analyses, aldosterone and potassium levels were obtained. Data are presented as the means ± standard deviation (SD). To compare the parameters between cases and controls, Student's t-tests or Mann-Whitney U tests were used for continuous variables, and χ2 tests were used for categorical variables. Pearson correlation analysis was used to define relationships between pairs of parameters. A two-sided P < 0.05 was considered statistically significant. Multivariate logistic regression was performed to assess the independent effects of potassium and other metabolic variables on NAFLD in PA patients.

RESULTS

The diagnosis of NAFLD was more common in PA patients (n=222, 35.1%) than in non-PA subjects (29.7%). PA patients with and without NAFLD had similar metabolic imbalance characteristics. In PA patients with hypokalemia, relatively higher prevalences of NAFLD (44% vs. 27%, P < 0.05) and diabetes mellitus (19.8% vs. 9.9%, P < 0.05) were observed. Hypokalemic PA patients had a worse metabolic status than PA patients without hypokalemia, including higher body mass index (BMI) (25.4 ± 3.4 vs. 24.1 ± 3.9 kg/m², P < 0.05), more severe dyslipidemia as well as insulin resistance, higher serum uric acid levels (354 ± 95 vs. 319 ± 87 μmol/L, P < 0.01) and aggravated inflammation.

CONCLUSION

The prevalence of NAFLD was higher in PA patients than in non-PA patients, although the patterns of obesity, dyslipidemia and insulin resistance were similar. Hypokalemic PA patients had a worse metabolic status than normokalemic PA patients. This study provides new insights that can inform further mechanistic studies about metabolic imbalance in patients with aldosteronism.

Effect of sodium-glucose cotransporter-2 inhibitors on aldosterone-to-renin ratio in diabetic patients with hypertension: a retrospective observational study

BACKGROUND

Plasma aldosterone-to-renin ratio (ARR) is popularly used for screening primary aldosteronism (PA). Some medications, including diuretics, are known to have an effect on ARR and cause false-negative and false-positive results in PA screening. Currently, there are no studies on the effects of sodium-glucose cotransporter-2 (SGLT2) inhibitors, which are known to have diuretic effects, on ARR. We aimed to investigate the effects of SGLT2 inhibitors on ARR.

METHODS

We employed a retrospective design; the study was conducted from April 2016 to December 2018 and carried out in three hospitals. Forty patients with diabetes and hypertension were administered SGLT2 inhibitors. ARR was evaluated before 2 to 6 months after the administration of SGLT2 inhibitors to determine their effects on ARR.

RESULTS

No significant changes in the levels of ARR (90.9 ± 51.6 vs. 81.4 ± 62.9) were found. Body mass index, diastolic blood pressure, heart rate, fasting plasma glucose, and hemoglobin A1c were significantly decreased by SGLT2 inhibitors. Serum creatinine was significantly increased.

CONCLUSION

SGLT2 inhibitor administration yielded minimal effects on ARR and did not increase false-negative results in PA screening in patients with diabetes and hypertension more than 2 months after administration.

The Association of ARMC5 with the Renin-Angiotensin-Aldosterone System, Blood Pressure, and Glycemia in African Americans

CONTEXT

Armadillo repeat containing 5 (ARMC5) on chromosome 16 is an adrenal gland tumor suppressor gene associated with primary aldosteronism, especially among African Americans (AAs). We examined the association of ARMC5 variants with aldosterone, plasma renin activity (PRA), blood pressure, glucose, and glycosylated hemoglobin A1c (HbA1c) in community-dwelling AAs.

METHODS

The Jackson Heart Study is a prospective cardiovascular cohort study in AAs with baseline data collection from 2000 to 2004. Kernel machine method was used to perform a single joint test to analyze for an overall association between the phenotypes of interest (aldosterone, PRA, systolic and diastolic blood pressure [SBP, DBP], glucose, and HbA1c) and the ARMC5 single nucleotide variants (SNVs) adjusted for age, sex, BMI, and medications; followed by Baysian Lasso methodology to identify sets of SNVs in terms of associated haplotypes with specific phenotypes.

RESULTS

Among 3223 participants (62% female; mean age 55.6 (SD ± 12.8) years), the average SBP and DBP were 127 and 76 mmHg, respectively. The average fasting plasma glucose and HbA1c were 101 mg/dL and 6.0%, respectively. ARMC5 variants were associated with all 6 phenotypes. Haplotype TCGCC (ch16:31476015-31476093) was negatively associated, whereas haplotype CCCCTTGCG (ch16:31477195-31477460) was positively associated with SBP, DBP, and glucose. Haplotypes GGACG (ch16:31477790-31478013) and ACGCG (ch16:31477834-31478113) were negatively associated with aldosterone and positively associated with HbA1c and glucose, respectively. Haplotype GCGCGAGC (ch16:31471193-ch16:31473597(rs114871627) was positively associated with PRA and negatively associated with HbA1c.

CONCLUSIONS

ARMC5 variants are associated with aldosterone, PRA, blood pressure, fasting glucose, and HbA1c in community-dwelling AAs, suggesting that germline mutations in ARMC5 may underlie cardiometabolic disease in AAs.

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.

Mineralocorticoids, glucose homeostasis and type 2 diabetes mellitus: The Henan Rural Cohort study

AIMS

We aimed to evaluate the associations of mineralocorticoids with type 2 diabetes mellitus (T2DM) and glucose homeostasis among rural Chinese adults.

METHODS

A total of 2713 participants were selected from the Henan Rural Cohort study. Serum mineralocorticoids were measured by liquid chromatography-tandem mass spectrometry. Logistic regression and restricted cubic splines were employed to evaluate the associations of mineralocorticoids with pre-diabetes and T2DM. Linear regression was implemented to assess the associations of aldosterone and 11-deoxycorticosterone with different markers of glucose homeostasis by different diabetes status.

RESULTS

Elevated aldosterone and 11-deoxycorticosterone were associated with an increased prevalence of pre-diabetes and T2DM (P < 0.05), with a nonlinear dose-response trend, but the association between 11-deoxycorticosterone and T2DM was no statistical significance after adjustment. A 100% increase in ln-aldosterone was associated with a 0.029 mg/dl higher fasting plasma glucose (FPG) and a 1.2% higher HOMA2-IR among those with normal glucose tolerance (NGT), and related to a 0.034 mg/dl lower FPG, a 1.1% higher HbA1c and a 1.3% higher HOMA2-β among individuals with pre-diabetes. A 100% increment in ln-11-deoxycorticosterone was associated with a 16% increase in HbA1c and a 5.6% decrease in HOMA2-β in participants with T2DM.

CONCLUSIONS

Higher aldosterone and 11-deoxycorticosterone are associated with T2DM risk and glucose homeostasis disorder among different diabetes status.

Clinical characterization of patients with primary aldosteronism plus subclinical Cushing's syndrome

BACKGROUND

Primary aldosteronism (PA) plus subclinical Cushing's syndrome (SCS), PASCS, has occasionally been reported. We aimed to clinically characterize patients with PASCS who are poorly profiled.

METHODS

A population-based, retrospective, single-center, observational study was conducted in 71 patients (age, 58.2 ± 11.2 years; 24 males and 47 females) who developed PA (n = 45), SCS (n = 12), or PASCS (n = 14). The main outcome measures were the proportion of patients with diabetes mellitus (DM), serum potassium concentration, and maximum tumor diameter (MTD) on the computed tomography (CT) scans.

RESULTS

The proportion of DM patients was significantly greater in the PASCS group than in the PA group (50.0% vs. 13.9%, p <  0.05), without a significant difference between the PASCS and SCS groups. Serum potassium concentration was significantly lower in the PASCS group than in the SCS group (3.2 ± 0.8 mEq/L vs. 4.0 ± 0.5 mEq/L; p <  0.01), without a significant difference between the PASCS and PA groups. Among the 3 study groups of patients who had a unilateral adrenal tumor, MTD was significantly greater in the PASCS group than in the PA group (2.7 ± 0.1 cm vs. 1.4 ± 0.1 cm; p <  0.001), without a significant difference between the PASCS and SCS groups.

CONCLUSIONS

Any reference criteria were not obtained that surely distinguish patients with PASCS from those with PA or SCS. However, clinicians should suspect the presence of concurrent SCS in patients with PA when detecting a relatively large adrenal tumor on the CT scans.

Assessment of Glycometabolism Impairment and Glucose Variability Using Flash Glucose Monitoring System in Patients With Adrenal Diseases

BACKGROUND

This study aimed to investigate the characteristics and extent of glycometabolism impairment in patients with adrenal diseases, including Cushing syndrome, primary aldosteronism, pheochromocytoma, and nonfunctional adrenal incidentaloma.

METHODS

This study enrolled thirty-two patients with adrenal diseases as adrenal disease groups and eight healthy individuals as healthy controls. Blood glucose levels were indicated by glucose concentration in interstitial fluid, which was documented using flash glucose monitoring system. According to flash glucose monitoring system data, parameters representing general blood glucose alterations, within-day and day-to-day glucose variability, and glucose-target-rate were calculated. Furthermore, blood glucose levels at nocturnal, fasting, and postprandial periods were analyzed. Besides, islet β-cell function and insulin resistance were assessed.

RESULTS

Analysis of flash glucose monitoring system-related parameters indicated impaired glycometabolism in patients with adrenal diseases compared with that of healthy controls at general blood glucose, within-day and day-to-day glucose variability, and glucose-target-rate levels. Furthermore, the dynamic glucose monitoring data revealed that significantly affected blood glucose levels compared with that of healthy controls were observed at postprandial periods in the Cushing syndrome and primary aldosteronism groups; at nocturnal, fasting and postprandial periods in the pheochromocytoma group. Significant insulin resistance and abnormal β-cell function were observed in the Cushing syndrome group compared with that in healthy controls.

CONCLUSION

Adrenal diseases can negatively affect glucose metabolism. Patients diagnosed with adrenal diseases should receive timely and appropriate treatment to avoid adverse cardiovascular events linked to hyperglycemia and insulin resistance.

The Association of Life's Simple 7 with Aldosterone among African Americans in the Jackson Heart Study

Background: Among African Americans (AAs), attaining higher levels of American Heart Association (AHA) ideal cardiovascular health (Life’s Simple 7 [LS7]) is associated with lower risk of diabetes and cardiovascular disease (CVD). We previously showed that aldosterone is associated with higher risk of diabetes and CVD in AAs. Thus, we investigated the association of LS7 metrics with aldosterone in the Jackson Heart Study (JHS). Methods: Ideal metrics were defined by AHA 2020 goals for health behaviors (smoking, dietary intake, physical activity, and body mass index) and health factors (total cholesterol, blood pressure, and fasting glucose). The number of ideal LS7 metrics attained at baseline were summed into a continuous score (0–7) and categorical groups (Poor: 0–1, Intermediate: 2–3, and Ideal: ≥4 ideal LS7 metrics). Multivariable linear regression was used. Results: Among 4,095 JHS participants (mean age 55 ± 13 years, 65% female), median serum aldosterone was 4.90, 4.30, and 3.70 ng/dL in the poor (n = 1132), intermediate (n = 2288) and ideal (n = 675) categories respectively. Aldosterone was 15% [0.85 (0.80, 0.90)] and 33% [0.67 (0.61, 0.75)] lower in the intermediate and ideal LS7 categories compared to the poor LS7 category. Each additional LS7 metric attained on continuous LS7 score (0–7) was associated with an 11% [0.89 (0.86, 0.91)] lower aldosterone level with variation by sex with women having a 15% lower aldosterone vs. 5% in men. Conclusions: Higher attainment of ideal LS7 metrics was associated with lower serum aldosterone among AAs with a greater magnitude of association among women compared to men.

How Hypertension Affects Heart Metabolism

Hypertension is one of the most frequently observed cardiovascular diseases, which precedes heart failure in 75% of its cases. It is well-established that hypertensive patients have whole body metabolic complications such as hyperlipidemia, hyperglycemia, decreased insulin sensitivity or diabetes mellitus. Since myocardial metabolism is strictly dependent on hormonal status as well as substrate milieu, the above mentioned disturbances may affect energy generation status in the heart. Interestingly, it was found that hypertension induces a shift in substrate preference toward increased glucose utilization in cardiac muscle, prior to structural changes development. The present work reports advances in the aspect of heart metabolism under high blood pressure conditions, including human and the most common animal models of hypertension.

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.

Aldosterone, Renin, and Diabetes Mellitus in African Americans: The Jackson Heart Study

CONTEXT

Previous research has suggested that activation of the renin-angiotensin-aldosterone system may promote insulin resistance and β-cell dysfunction, but the association with incident diabetes in African Americans is unknown.

OBJECTIVE

We examined the association of aldosterone and renin with insulin resistance, β-cell function, and incident diabetes in a large African American cohort.

DESIGN

The Jackson Heart Study is a prospective study of the development and progression of cardiovascular disease in African Americans.

SETTING

Participants were recruited from the tricounty area of metropolitan Jackson, Mississippi.

PARTICIPANTS

A total of 5301 African American adults, aged 21–94 years, were assessed at baseline and through 12 years of follow-up. Data on aldosterone, renin, and risk factors were collected at baseline (2000–2004). Diabetes (fasting glucose ≥ 126 mg/dL, physician diagnosis, use of diabetes drugs, or glycated hemoglobin ≥ 6.5%) was assessed at baseline and through 12 years of follow-up. Participants were excluded for missing data on baseline covariates or diabetes follow-up. Cox regression was used to estimate hazard ratios (HR) for incident diabetes using sequential modeling adjusting for age, sex, education, occupation, systolic blood pressure, current smoking, physical activity, dietary intake, and body mass index.

EXPOSURES

Aldosterone, renin, and diabetes risk factors were measured.

OUTCOME

Outcomes included the homeostatic model assessment of insulin resistance (HOMA-IR) and incident diabetes.

RESULTS

Among 3234 participants over a median of 8.0 years of follow-up, there were 554 cases of incident diabetes. Every 1% increase in log-transformed aldosterone was associated with a 0.18% higher log-transformed HOMA-IR in cross-sectional analyses of nondiabetic participants (P < .001). Log-transformed aldosterone and renin levels in the fifth vs first quintile were associated with a 78% (HR 1.78, 95% confidence interval 1.35–2.34) and 35% (HR 1.35, 95% confidence interval 1.06–1.72) increase in diabetes risk, respectively, in fully adjusted models.

CONCLUSIONS

Activation of the renin-angiotensin-aldosterone system may play a significant role in the development of insulin resistance and diabetes in African Americans.

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.

Screening for primary aldosteronism in an argentinian population: a multicenter prospective study

OBJECTIVES

Primary aldosteronism (PA) is characterized by the autonomous overproduction of aldosterone. Its prevalence has increased since the use of the aldosterone (ALD)/plasma renin activity (PRA) ratio (ARR). The objective of this study is to determine ARR and ARC (ALD/plasma renin concentration ratio) cut-off values (COV) and their diagnostic concordance (DC%) in the screening for PA in an Argentinian population.Design multicenter prospective study.

SUBJECTS AND METHODS

We studied 353 subjects (104 controls and 249 hypertensive patients). Serum aldosterone, PRA and ARR were determined. In 220 randomly selected subjects, 160 hypertensive patients and 60 controls, plasma renin concentration (PRC) was simultaneously measured and ARC was determined.

RESULTS

According to the 95th percentile of controls, we determined a COV of 36 for ARR and 2.39 for ARC, with ALD ≥ 15 ng/dL. In 31/249 hypertensive patients, ARR was ≥ 36. PA diagnosis was established in 8/31 patients (23/31 patients did not complete confirmatory tests). DC% between ARR and ARC was calculated. A significant correlation between ARR and ARC (r = 0.742; p < 0.0001) was found only with PRA > 0.3 ng/mL/h and PRC > 5 pg/mL. DC% for ARR and ARC above or below 36 and 2.39 was 79.1%, respectively.

CONCLUSION

This first Argentinian multicenter study determined a COV of 36 for ARR and 2.39 for ARC. Applying an ARR ≥ 36 in the hypertensive group, we confirmed PA in a higher percentage of patients than the previously reported one in our population. As for ARC, further studies are needed for its clinical application, since DC% is acceptable only for medium range renin values.

Comparison of the effects of chlormadinone acetate versus drospirenone containing oral contraceptives on metabolic and hormonal parameters in women with PCOS for a period of two-year follow-up

OBJECTIVE

A randomized trial to compare the effects of two oral contraceptive pills containing either chlormadinone acetate or drospirenone as the progestogen, in women with PCOS for a period of two-year follow-up.

METHODS

Group A received ethinyl-estradiol 0.03 mg + drospirenone 3 mg (EE + DRSP; n = 56) and Group B received ethinyl-estradiol 0.03 mg + chlormadinone acetate 2 mg (EE + CMA; n = 50). Clinical, hormonal and biochemical parameters were compared at baseline, 6 months, 12 months and 24 months.

RESULTS

The increase in total cholesterol and hsCRP levels was statistically significantly higher at 6, 12 and 24 months in Group B when compared with Group A. The change in the high-density lipoprotein cholesterol level at the 24 months of treatment was statistically significantly higher in Group A. Group A has a significantly higher reduction in FAI at 6 and 24 months, in FGS at 6, 12 and 24 months and in HOMA-IR index at 12 and 24 months when compared with Group B.

CONCLUSIONS

Drospirenone containing combined oral contraceptive (COC) is found to have more favorable effects on lipid profiles, hsCRP levels, insulin resistance and hyperandrogenism when compared with the CMA containing COC and appears to be more beneficial for the long-term cardiovascular and metabolic aspects of PCOS.

Role of mineralocorticoid receptor and renin-angiotensin-aldosterone system in adipocyte dysfunction and obesity

The mineralocorticoid receptor (MR) classically mediates aldosterone effects on salt homeostasis and blood pressure regulation in epithelial target tissues. In recent years, functional MRs have been identified in non classical targets of aldosterone actions, in particular in adipose tissue, where they mediate the effects of aldosterone and glucocorticoids in the control of adipogenesis, adipose expansion and its pro-inflammatory capacity. In this context, inappropriate MR activation has been demonstrated to be a causal factor in several pathologic conditions such as vascular inflammation, endothelial dysfunction, insulin resistance and obesity. The aim of this review is to summarize the latest developments in this rapidly developing field, and will focus on the role of MR and renin-angiotensin-aldosterone system (RAAS) as potential leading characters in the early steps of adipocyte dysfunction and obesity. Indeed modulation of MR activity in adipose tissue has promise as a novel therapeutic approach to treat obesity and its related metabolic complications. This article is part of a Special Issue entitled 'CSR 2013'.

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.

Effects of drospirenone-ethinylestradiol and/or metformin on CD4(+)CD28(null) T lymphocytes frequency in women with hyperinsulinemia having polycystic ovary syndrome: a randomized clinical trial

OBJECTIVE

To evaluate the long-term effects of drospirenone (DRSP)/ethinylestradiol (EE) alone, metformin alone, and DRSP/EE-metformin on CD4(+)CD28(null) T lymphocytes frequency, a cardiovascular risk marker, in patients with hyperinsulinemic polycystic ovary syndrome (PCOS).

DESIGN

Randomized clinical trial.

INTERVENTIONS

Ninety three patients with hyperinsulinemic PCOS were age matched and body mass index matched and randomized to receive a 6 months daily treatment with DRSP (3 mg)/EE (0.03 mg), or metformin (1500 mg), or DRSP/EE combined with metformin.

MAIN OUTCOME MEASURES

CD4(+)CD28(null) T-cell frequencies.

RESULTS

The DRSP/EE and metformin groups did not show any significant change in the CD4(+)CD28(null) frequency compared to the baseline. Interestingly, a statistically significant decrease in CD4(+)CD28(null) frequency occurred after 6 months of DRSP/EE-metformin (median 3-1.5; P < .01). Of note, this statistically significant association was confirmed after adjusting for baseline values in DRSP/EE-metformin group by analysis of covariance (P < .05).

CONCLUSIONS

In women with hyperinsulinemic PCOS, combined therapy with DRSP/EE and metformin may reduce cardiovascular risk.

Prevalence and clinical characteristics of primary aldosteronism in Japanese patients with type 2 diabetes mellitus and hypertension

The prevalence of primary aldosteronism (PA) is around 3-15% in patients with hypertension. Hypertension is a frequent complication of type 2 diabetes mellitus (DM) because of the close etiological relationship between these two diseases. However, the possibility of PA in patients with DM and hypertension is often overlooked and the prevalence of PA in patients with DM and hypertension in Japan is unknown. We enrolled 124 hospitalized patients with both DM and hypertension. PA was diagnosed according to the modified criteria for Japanese patients. We examined the prevalence of PA and compared clinical characteristics between patients with and without PA. In another analysis of 43 patients with a confirmed diagnosis of PA, we compared the characteristics of patients with and without DM. Overall, 14/124 patients with DM and hypertension (11.3%) were diagnosed with PA. Multivariate logistic regression showed that the duration of DM was significantly shorter in the PA group. Fisher's direct probability test revealed that history of hypertension before the diagnosis of DM was a significant factor in patients with PA. Treatment with an angiotensin II receptor blocker (ARB) did not affect the diagnosis of PA in these patients. Among 43 patients with PA, those with DM were significantly older and the delay to the diagnosis of PA was significantly longer compared with patients without DM. In conclusion, almost 10% of patients with DM and hypertension actually have PA. More extensive screening for PA is recommended in patients with DM and hypertension, regardless of the use of ARBs.

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.

Visceral adipose tissue: emerging role of gluco- and mineralocorticoid hormones in the setting of cardiometabolic alterations

Several clinical and experimental lines of evidence have highlighted the detrimental effects of visceral adipose tissue excess on cardiometabolic parameters. Besides, recent findings have shown the effects of gluco-and mineralocorticoid hormones on adipose tissue and have also underscored the interplay existing between such adrenal steroids and their respective receptors in the modulation of adipose tissue biology. While the fundamental role played by glucocorticoids on adipocyte differentiation and storage was already well known, the relevance of the mineralocorticoids in the physiology of the adipose organ is of recent acquisition. The local and systemic renin–angiotensin–aldosterone system (RAAS) acting on adipose tissue seems to contribute to the development of the cardiometabolic phenotype so that its modulation can have deep impact on human health. A better understanding of the pathophysiology of the adipose organ is of crucial importance in order to identify possible therapeutic approaches that can avoid the development of such cardiovascular and metabolic sequelae.

Plasma aldosterone levels and development of insulin resistance: prospective study in a general population

Aldosterone plays a role in hypertension, and hypertension is prevalent in patients with insulin resistance. Cross-sectional studies have reported that plasma aldosterone levels are higher in patients with insulin resistance. However, it is not known whether plasma aldosterone levels predict the development of insulin resistance. Subjects of the present study were 1235 local residents (490 men and 745 women) who participated in health screenings in Japan in 1999. Plasma aldosterone levels were measured by radioimmunoassay. We investigated the cross-sectional relationship between plasma aldosterone levels and insulin resistance (homeostasis model assessment index ≥1.73 according to the diagnostic criteria used in Japan) in 1088 nondiabetic participants. At the 10-year follow-up, 141 subjects had died, and 260 subjects refused re-examination. We performed a prospective analysis of 564 subjects to predict incident insulin resistance. We found a significant (P<0.001) cross-sectional relationship between plasma aldosterone and homeostasis model assessment index at baseline. In the prospective analysis, a significantly higher (P<0.05) relative risk (1.71 [95% CI: 1.03-2.84]) was observed in the highest tertile versus lowest tertile of plasma aldosterone for the development of insulin resistance, after adjustment for confounding factors. This 10-year prospective study demonstrated that plasma aldosterone levels predicted the development of insulin resistance in a general population.

Potassium and risk of Type 2 diabetes

The rising incidence and prevalence of Type 2 diabetes worldwide requires us to try to identify the determinants of this epidemic and to identify improved measures to prevent and treat this condition. While obesity is a major risk factor for diabetes, there are other risk factors that could potentially be corrected more easily. Potassium, both serum levels and to a lesser extent dietary intake levels, has been associated with incident diabetes. Lower levels of potassium have been found to be associated with a higher risk of diabetes in some studies. This article will review the literature available describing these associations and will help to identify where further research is needed.

[Drug-induced hyperglycemia: a study in the French pharmacovigilance database]

OBJECTIVE

To analyse drugs inducing hyperglycemia by using data reported to the French spontaneous reporting system and recorded in the French PharmacoVigilance Database (FPVD).

METHODS

All cases with a report of hyperglycemia and/or diabetes in the French database between 1985 and 2008 were included in the study. We estimated the risk of hyperglycemia linked to drugs by the case/non-case method. Cases were reports including hyperglycemia and non cases all other reports. This risk was estimated through calculation of reporting odds ratios (ROR).

RESULTS

During this period, 1219 reports including the words "hyperglycemia and/or diabetes" were registered (0.34% of the database). This adverse drug reaction occurred 1 fold over 4 in diabetics or as a part of HIV infection. Effect was "serious" in approximatively 50% of cases. We found an increase of risk during exposition with methylprednisolone [ROR=43.5; 95% CI (37.3-50.8)], tacrolimus [ROR=25; 95% CI (17.9-34.8)], olanzapine [ROR=19.9; 95% CI (14.9-26.5)], prednisone [ROR=18.9; 95% CI (15.7-22.8)] or pentamidine [ROR=15.4; 95% CI (8.2-28.3)].

CONCLUSION

Drug classes most frequently found in FPVD linked to hyperglycemia are antiretroviral, steroidal anti-inflammatory, second generation neuroleptic, immunosuppressive and diuretic drugs.

Comparison of effects of 3 mg drospirenone plus 20 μg ethinyl estradiol alone or combined with metformin or cyproterone acetate on classic metabolic cardiovascular risk factors in nonobese women with polycystic ovary syndrome

OBJECTIVE

To evaluate the effects of a pill with drospirenone (3 mg) plus ethinyl E(2) (20 μg) (DRP/20EE) alone or associated with metformin or cyproterone acetate (CPA) on some metabolic cardiovascular risk factors in women with polycystic ovary syndrome (PCOS).

DESIGN

Randomized, open-label clinical trial.

SETTING

Academic medical clinic.

PATIENT(S)

Forty-eight hirsute women with PCOS.

INTERVENTION(S)

Patients were randomized to treatment with DRP/20EE or with DRP/20EE plus metformin (1,500 mg/d) or with DRP/20EE plus CPA (12.5 mg/d, 10 days per cycle) for 6 months.

MAIN OUTCOME MEASURE(S)

Blood pressure, lipid profile, and indexes of glucose tolerance and insulin sensitivity were assessed before and after 6 months of treatment.

RESULT(S)

Body mass index and blood pressure were not modified by any treatment. Treatment with DRP/EE20 did not change the lipid profile; DRP/EE20 plus metformin significantly increased high-density lipoprotein cholesterol concentrations; DRP/EE20 plus CPA significantly increased triglycerides and total cholesterol. The area under the curve for insulin was significantly decreased by DRP/EE20 and DRP/EE20 plus metformin, but it was significantly increased by DRP/EE20 plus CPA. Treatment with DRP/EE20 plus CPA significantly increased the homeostasis model assessment of insulin resistance index and significantly reduced the glucose to insulin ratio index. Treatment with DRP/EE20 significantly increased the glucose to insulin ratio index.

CONCLUSION(S)

Treatment with DRP/EE20 improved insulin sensitivity in hirsute women with PCOS, with no deterioration of lipid profile. This effect was not ameliorated by the addition of metformin. The positive metabolic effects of DRP are abolished by the concomitant use of CPA.

The heme oxygenase system attenuates pancreatic lesions and improves insulin sensitivity and glucose metabolism in deoxycorticosterone acetate hypertension

Recent clinical reports indicate that impaired glucose tolerance is a common phenomenon in primary aldosteronism. Aldosterone stimulates NF-κB and activating protein-1 (AP-1) to cause oxidative injury. Elevated oxidative stress impairs insulin signaling. We recently showed that the heme oxygenase (HO) system lowers blood pressure (BP) in deoxycorticosterone-acetate (DOCA)+salt hypertension, a model of primary aldosteronism. However, the effect of the HO system on insulin sensitivity in this model remains largely unclear. Here we report the effects of the HO-inducer hemin and the HO-blocker [chromium mesoporphyrin (CrMP)] on insulin sensitivity/glucose metabolism. Our experimental design included the following 10 groups: (A) controls [(i) surgery-free or normal Sprague-Dawley (SD), (ii) uninephrectomized (UnX)-sham, (iii) UnX+salt (0.9%NaCl+0.2%KCl) and (iv) UnX+DOCA]; (B) DOCA+salt; (C) hemin+DOCA+salt; (D) hemin+CrMP+DOCA+salt; (E) CrMP+DOCA+salt; (F) vehicle-treated rats and (G) normal SD+hemin. Hemin therapy lowered BP and increased plasma insulin and the insulin-sensitizing protein adiponectin with slight but significant reduction of glycemia, while CrMP abolished the hemin effects. Furthermore, hemin improved intraperitoneal glucose and insulin tolerance, suggesting that although DOCA+salt-hypertensive rats were normoglycemic, insulin signaling may be impaired. In contrast, the HO-inhibitor CrMP aggravated insulin resistance and exacerbated glucose and insulin tolerance. Interestingly, the enhanced insulin sensitization in hemin-treated animals was accompanied by reduced urinary/gastrocnemius muscle 8-iso-prostaglandin F2α (8-isoprostane), inflammatory/oxidative transcription factors like NF-κB, AP-1, JNK, and heme content, whereas HO-1, HO-activity, cGMP, and plasma/gastrocnemius muscle antioxidants including bilirubin, ferritin, SOD, catalase, and the total antioxidant capacity were increased. Similarly, hemin enhanced pancreatic HO, cGMP, and cAMP but suppressed 8-isoprostane and attenuated pancreatic histopathological lesions including fibrosis, interstitial edema, acinar cell necrosis, vacuolization, and mononuclear cell infiltration, with corresponding improvement of insulin production. Our results suggest that impaired insulin signaling may be a forerunner to hyperglycemia in aldosteronism. By preserving pancreatic morphology, potentiating insulin signaling, and lowering BP, the HO system may prevent metabolic and cardiovascular complications in aldosteronism.

Type 2 diabetic patients with resistant hypertension should be screened for primary aldosteronism

BP control in diabetic patients is often poor. The contribution of secondary hypertension due to undiagnosed PA in hypertensive type 2 diabetic patients is not well studied. We prospectively screened 100 consecutive Asian type 2 diabetic patients with difficult-to-control or resistant hypertension for PA. PAC (pmol/L) to PRA (ng/mL/h) ratio was measured; those with PAC-to-PRA ratio >550 (corresponding PAC >415) underwent intravenous 0.9% SLT. Patients with PAC >/=140 following SLT had CT adrenals and bilateral AVS. Thirteen patients (13%) were confirmed to have PA, and all had resistant hypertension. Eight had a surgically correctable form of PA. Patients with PA had higher mean (SD) systolic [159.0 (10.6) vs. 146.0 (10.7) mmHg, p=0.001] and diastolic BP [94.6 (6.0) vs. 87.6 (5.9) mmHg, p=0.001], lower serum potassium [3.5 (0.6) vs. 4.3 (0.5) mmol/L, p=0.001], and higher PAC [679.3 (291.0) vs. 239.5 (169.4) pmol/L, p=0.001]. Identification and institution of definitive treatment for PA resulted in better BP control and in a reduction in the use of antihypertensive medications. Our findings demonstrate a high prevalence of PA in type 2 diabetic patients with resistant hypertension. Systematic screening for PA in this select group is recommended, as targeted treatment improves BP control.

Impact of excess aldosterone on glucose homeostasis in adult male rat

BACKGROUND

Clinical and experimental data demonstrate that excess aldosterone and insulin interact at target tissues. It has been shown that increased levels of aldosterone contribute to development of insulin resistance and thus act as a risk factor for the development of type-II diabetes mellitus. However, the molecular mechanisms involved are yet to be identified. The present study was designed to assess the impact of excess aldosterone on GLUT2 and GLUT4 gene expression and glucose uptake in liver and skeletal muscles (gracilis and quadriceps) of adult male rat.

METHODS

Healthy adult male albino rats of Wistar strain (Rattus norvegicus), weighing 180-210 g were used in the present study. The rats were divided into two groups (control and aldosterone treated) each consisting of five animals. Rats were treated with aldosterone at a dose of 10 microg/kg body weight, subcutaneously, twice daily at 8 AM and 6 PM for 15 days.

RESULTS

Excess aldosterone impaired the rate of glucose uptake through defective expression of GLUT2 and GLUT4 genes and also decreased translocation of GLUT4 to the plasma membrane.

CONCLUSION

Excess aldosterone has an adverse effect on glucose uptake in liver and skeletal muscle and the defective expression of GLUT2 and GLUT4 appears to be responsible for such changes.

Small tumor size as favorable prognostic factor after adrenalectomy in Conn's adenoma

OBJECTIVE

Primary aldosteronism (PA) due to aldosterone-producing adenoma (APA) is the most common curable form of secondary hypertension.

DESIGN

In order to evaluate blood pressure outcome after adrenalectomy for APA and to identify new favorable prognostic factors, data from 42 consecutive APA patients who underwent adrenalectomy were collected from 2005 to 2007.

METHODS

Renin-angiotensin-aldosterone system (upright and postsaline infusion test), serum and urinary electrolytes, office and ambulatory blood pressure monitoring were evaluated at baseline and after a follow-up of 2.7+/-2.2 years. Drug history and adenoma size at morphological evaluation were also collected.

RESULTS

Multiple regression analysis showed that, before surgery, patients with a small adenoma (diameter <20 mm) displayed higher postsaline aldosterone values (P=0.0001), and lower serum potassium levels (P=0.020), than patients with adenoma >20 mm. Before surgery, mineralocorticoid receptor (MR) antagonists were used in patients with small APA in greater percentage than patients with bigger adenomas (64 vs 30% respectively, P=0.037). At follow-up, blood pressure normalized in 63% of the subjects. Recovered patients had a shorter duration of hypertension (P=0.038), and a smaller adenoma size (P=0.035). Receiver operating characteristic curves showed that a duration of hypertension <or=6 years and an APA size <20 mm were the best predictors of blood pressure normalization. Patients with APA <20 mm showed the complete restoration of blood pressure circadian rhythm.

CONCLUSIONS

The presence of APA <20 mm, duration of hypertension equal or less than 6 years, and preoperative MR antagonists use are favorable prognostic factors for hypertension recovery after adrenalectomy.

Fasting plasma glucose and serum lipids in patients with primary aldosteronism: a controlled cross-sectional study

An association between primary aldosteronism and metabolism disorders has been reported. The aim of this retrospective study was to test for this association by comparison between large cohorts of patients with primary aldosteronism and with essential hypertension. We retrieved the records of 460 cases with primary aldosteronism (103 lateralized, 150 not lateralized, and 207 undetermined) and of 1363 controls with essential hypertension individually matched for age and sex. We compared clinical history; blood pressure levels; body mass index; levels of fasting plasma glucose and serum triglycerides; total, high-density lipoprotein, and low-density lipoprotein cholesterol; and the prevalence of diabetes mellitus and impaired fasting glucose among subtypes of primary aldosteronism, as well as between cases with primary aldosteronism and their matched controls. Fasting plasma glucose and serum lipid levels did not differ among the 3 subtypes of primary aldosteronism. The prevalence of impaired fasting glucose was lower in patients with primary aldosteronism than their matched controls, but the prevalence of hyperglycemia (impaired fasting glucose or diabetes mellitus) and blood levels of glucose and lipids did not differ between cases and controls. There was no significant difference between preoperative and postoperative levels of either fasting plasma glucose or serum lipids in patients who underwent adrenalectomy and had follow-up data available. The analysis of this large group of patients with primary aldosteronism and essential hypertension does not confirm a higher prevalence of carbohydrate or lipid metabolism disorders in the former. It is unlikely that the prevalence of metabolic syndrome differs significantly between patients with primary aldosteronism and those with essential hypertension.

The role of aldosterone in cardiovascular disease in people with diabetes and hypertension: an update

The role of mineralocorticoids in the development of cardiovascular disease (CVD), cardiometabolic syndrome, type 2 diabetes mellitus, chronic kidney disease (CKD), and hypertension is a growing field of interest. Aldosterone, mainly through nongenomic actions that result in proliferation, fibrosis, inflammation, and tissue remodeling, has been linked to CVD and CKD. Increased circulating aldosterone is also associated with insulin resistance and impaired glucose homeostasis that contribute to the development of endothelial dysfunction, atherosclerosis, and kidney disease. Aldosterone-induced oxidative stress and inflammation play a key role in impairing insulin signaling. Mineralocorticoid receptor blockade restores insulin sensitivity, counterbalances the deleterious cardiovascular and renal effects of aldosterone, and emerges as an alternative to improve blockade of the renin-angiotensin-aldosterone system, which potentially could contribute to reduce the burden of CVD and CKD.

The metabolic syndrome in primary aldosteronism

Patients with hypertension have a high prevalence of concurrent metabolic abnormalities (eg, obesity, dyslipidemia, and hyperglycemia). Clustering of these risk factors, defined as the metabolic syndrome, is associated with a high cardiovascular risk profile. This review summarizes current knowledge about the prevalence and characteristics of the metabolic syndrome in primary aldosteronism, and discusses the possible pathophysiological link between aldosterone and individual components of the metabolic syndrome, other than hypertension. Impaired glucose metabolism due to insulin resistance appears to be the major contributor to metabolic dysfunction in primary aldosteronism. Experimental observations support the possibility that aldosterone could act directly on insulin receptor function. The potential proadipogenic role of aldosterone and its negative effect on insulin sensitivity through production of cytokines remains to be investigated. Higher rates of cardiovascular events reported in primary aldosteronism could be due in part to the increased prevalence of the metabolic syndrome in this disorder.

Adrenocortical dysregulation as a major player in insulin resistance and onset of obesity

The aim of this review is to explore the dysregulation of adrenocortical secretions as a major contributor in the development of obesity and insulin resistance. Disturbance of adipose tissue physiology is one of the primary events in the development of pathologies associated with the metabolic syndrome, such as obesity and type 2 diabetes. Several studies indicate that alterations in metabolism of glucocorticoids (GC) and androgens, as well as aldosterone in excess, are involved in the emergence of metabolic syndrome. Cross talk among adipose tissue, the hypothalamo-pituitary complex, and adrenal gland activity plays a major role in the control of food intake, glucose metabolism, lipid storage, and energy balance. Perturbation of this cross talk induces alterations in the regulatory mechanisms of adrenocortical steroid synthesis, secretion, degradation, and/or recycling, at the level of the zonae glomerulosa (aldosterone), fasciculata (GC and GC metabolites), and reticularis (androgens and androgen precursors DHEA and DHEAS). As a whole, these adrenocortical perturbations contribute to the development of metabolic syndrome at both the paracrine and systemic level by favoring the physiological dysregulation of organs responsive to aldosterone, GC, and/or androgens, including adipose tissue.

Aldosterone Suppresses Insulin Signaling Via the Downregulation of Insulin Receptor Substrate-1 in Vascular Smooth Muscle Cells

Clinical reports indicate that patients with primary aldosteronism commonly have impaired glucose tolerance; however, the relationship between aldosterone and insulin signaling pathway has not been clarified. In this study, we examined the effects of aldosterone treatment on insulin receptor substrate-1 expression and insulin signaling pathway including Akt phosphorylation and glucose uptake in rat vascular smooth muscle cells. Insulin receptor substrate-1 protein expression and Akt phosphorylation were determined by Western blot analysis with anti-insulin receptor substrate-1 and phosphorylated-Akt antibodies, respectively. Glucose metabolism was evaluated using (3)H-labeled 2-deoxy-d-glucose uptake. Aldosterone (1-100 nmol/L) dose-dependently decreased insulin receptor substrate-1 protein expression with a peak at 18 hours (n=4). Aldosterone-induced degradation of insulin receptor substrate-1 was markedly attenuated by treatment with the selective mineralocorticoid receptor antagonist eplerenone (10 micromol/L; n=4). Furthermore, degradation was blocked by the Src inhibitor PP1 (20 micromol/L; n=4). Treatment with antioxidants, N-acetylcysteine (10 mmol/L), or ebselen (40 micromol/L) also attenuated aldosterone-induced insulin receptor substrate-1 degradation (n=4). In addition, proteasome inhibitor MG132 (1 micromol/L) prevented insulin receptor substrate-1 degradation (n=4). Aldosterone treatment abolished insulin-induced Akt phosphorylation (100 nmol/L; 5 minutes; n=4). Furthermore, aldosterone pretreatment decreased insulin-stimulated (100 nmol/L; 60 minutes; n=4) glucose uptake by 50%, which was reversed by eplerenone (10 micromol/L; n=4). These data indicate that aldosterone decreases insulin receptor substrate-1 expression via Src and reactive oxygen species stimulation by proteasome-dependent degradation in vascular smooth muscle cells; thus, aldosterone may be involved in the pathogenesis of vascular insulin resistance via oxidative stress.

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

OBJECTIVE

Primary aldosteronism (PA) is the most common secondary cause of hypertension and recently has been implicated as a cause of impaired glucose tolerance. We investigated the glucose insulin sensitivity and insulin secretion in patients with idiopathic primary aldosteronism.

DESIGN

Thirty PA patients and 60 essential hypertensive (EH) patients as controls were included, matched (1: 2) by their body mass index (BMI) (29.9 +/- 4.3 versus 29.8 +/- 5.8 m/kg), age (53.7 +/- 9.4 versus 59.9 +/- 8.6 years old) and gender (male/female: 8/22 versus 17/43). In all patients, we measured insulin, total cholesterol, triglycerides, C-peptide and fasting glucose levels. Homeostasis model assessment for insulin resistance (HOMA-IR) and HOMA of pancreatic beta-cell function (HOMA-betaF) indexes were calculated. We also evaluated the response to spironolactone in 19 PA patients.

RESULTS

PA patients had higher levels of glucose (5.2 +/- 0.7 versus 4.9 +/- 0.7 mmol/l; P = 0.017). Insulin levels (10.7 +/- 6.5 versus 11.5 +/- 5.8 uUI/ml, P = 0.525) and HOMA-IR (2.51 +/- 1.59 versus 2.45 +/- 1.29 uUI/ml x mmol/l, P = 0.854) were similar in both groups. HOMA-betaF index (138.9 +/- 89.8 versus 179.8 +/- 100.2%, P = 0.049) and C-peptide (0.83 +/- 0.63 versus 1.56 +/- 0.84 ng/dl, P = 0.0001) were lower in PA patients. Potassium was normal in both groups. Negative correlations between serum aldosterone/plasma renin activity (SA/PRA) ratio and HOMA-betaF, and between C-peptide and SA levels were found in all patients. After the spironolactone treatment, we found an increase of C-peptide and insulin levels without changes in HOMA-IR or HOMA-betaF.

CONCLUSION

Our results showed differences in glucose metabolism between PA patients and those with hypertension suggesting that these findings could probably be determined by a lower beta-cell function influenced by aldosterone. These findings highlight the importance of aldosterone in glucose metabolism.

Insulin resistance and hyperinsulinemia are related to plasma aldosterone levels in hypertensive patients

OBJECTIVE

An association between aldosterone and insulin resistance has been demonstrated in obesity and primary aldosteronism and in blacks with the metabolic syndrome. The aim of this study was to evaluate the relationship of plasma aldosterone with insulin sensitivity in white subjects.

RESEARCH DESIGN AND METHODS

In 356 patients with essential hypertension and 102 normotensive control subjects of comparable age and BMI, we measured, after discontinuation of treatment, plasma active renin, aldosterone, cortisol, glucose, insulin, and C-peptide levels and calculated markers of insulin sensitivity. Direct assessment of insulin sensitivity was obtained in a subset of 64 hypertensive patients by a hyperinsulinemic clamp.

RESULTS

Hypertensive patients had significantly greater fasting plasma insulin and C-peptide concentrations and homeostasis model assessment (HOMA) indexes than normotensive control subjects. A positive association with increasing plasma aldosterone concentrations was demonstrated for plasma glucose, insulin, C-peptides, and HOMA. Assessment of insulin sensitivity by clamp showed a significant decrease of the metabolic clearance rate of glucose with increasing aldosterone levels. Significant correlations were found between plasma aldosterone, plasma insulin, and C-peptide levels, HOMA, and glucose metabolic clearance rate. Blood pressure and plasma potassium, plasma cortisol, and renin levels, but not BMI, were also directly correlated with plasma aldosterone. Multiple regression analysis showed that HOMA, together with plasma potassium, cortisol, and renin levels, was independently correlated with plasma aldosterone.

CONCLUSIONS

This study demonstrates a direct relationship between aldosterone, insulin resistance, and hyperinsulinemia in white subjects. In patients with hypertension, this relationship might contribute to maintenance of high blood pressure and increased cardiovascular risk.

Salt intake and insulin sensitivity in healthy human volunteers

The literature on salt intake and insulin sensitivity presents a mixed picture, as some studies have shown an increase, whereas others have shown a decrease, in insulin action as sodium intake is enhanced. In some cases, this may relate to the study of salt intake in patients with co-morbidities such as hypertension or diabetes. In the present study, we selected healthy normotensive lean volunteers who underwent a euglycaemic clamp following 6 days of a low-salt diet (20 mmol sodium daily) and, subsequently, 6 days of a high-salt diet (200 mmol sodium daily). Our results show an increase in insulin-mediated glucose disposal during euglycaemic clamp conditions that was significantly higher following the high-salt diet compared with the low-salt diet (7.41+/-0.41 compared with 6.11+/-0.40 mg x kg(-1) of body weight x min(-1) respectively; P=0.03). We measured calf blood flow before and during insulin infusion (no significant change after the two dietary salt interventions was detected) and plasma non-esterified fatty acids (also no significant differences were detected). We observed the expected increases in renin concentration and aldosterone activity in subjects on the low-salt diet, and also observed a significantly less increase in plasma noradrenaline concentration during euglycaemic insulin infusion following the high-salt compared with the low-salt diet. We propose that the 4-5-fold increase in serum aldosterone and the greater increase in plasma noradrenaline concentration following the low-salt intervention compared with the high-salt period may have contributed to the differences in insulin sensitivity following the adjustment in dietary sodium intake.

Primary aldosteronism in diabetic subjects with resistant hypertension

OBJECTIVE

Despite the high prevalence of hypertension in patients with type 2 diabetes, the prevalence of primary aldosteronism in this population has not been determined.

RESEARCH DESIGN AND METHODS

One hundred subjects with type 2 diabetes and resistant hypertension, defined as blood pressure > 140/90 mmHg despite the use of > or = 3 antihypertensive agents, were screened for primary aldosteronism. Screening was performed by measuring the plasma aldosterone (PAC)-to-plasma renin activity (PRA) ratio. Subjects with a PAC-to-PRA ratio > 30 ng x ml(-1) x h(-1) underwent confirmatory salt load testing. Diagnostic criteria included 24-h urine aldosterone > or = 12 microg during the 3rd day of the oral salt load or a PAC > or = 5 ng/dl after the 4-h intravenous saline load.

RESULTS

Thirty-four subjects had a PAC-to-PRA ratio >30 ng x ml(-1) x h(-1). Fourteen subjects (14% [95% CI 7.2-20.8]) had a confirmed diagnosis of primary aldosteronism. Ninety-three patients were African Americans. There were no differences in age, glycemic control, and number of antihypertensive drugs between subjects with and without primary aldosteronism. Subjects with primary aldosteronism had lower serum potassium (3.7 +/- 0.4 vs. 4.0 +/- 0.4 mmol/l, P = 0.012), higher PAC (15.6 +/- 8 vs. 9.1 +/- 6 ng/dl, P = 0.0016), and higher PAC-to-PRA ratio (98 +/- 74 vs. 21 +/- 30 x ml(-1) x h(-1), P < 0.001) than patients without primary aldosteronism.

CONCLUSIONS

Primary aldosteronism is common in diabetic patients with resistant hypertension, with a prevalence of 14%. Our results indicate that diabetic subjects with poorly controlled hypertension who are taking > or = 3 antihypertensive drugs should be screened for primary aldosteronism.

The metabolic syndrome in primary aldosteronism

Patients with hypertension have a high prevalence of concurrent metabolic abnormalities (eg, obesity, dyslipidemia, and hyperglycemia). Clustering of these risk factors, defined as the metabolic syndrome, is associated with a high cardiovascular risk profile. This review summarizes current knowledge about the prevalence and characteristics of the metabolic syndrome in primary aldosteronism, and discusses the possible pathophysiological link between aldosterone and individual components of the metabolic syndrome, other than hypertension. Impaired glucose metabolism due to insulin resistance appears to be the major contributor to metabolic dysfunction in primary aldosteronism. Experimental observations support the possibility that aldosterone could act directly on insulin receptor function. The potential proadipogenic role of aldosterone and its negative effect on insulin sensitivity through production of cytokines remains to be investigated. Higher rates of cardiovascular events reported in primary aldosteronism could be due in part to the increased prevalence of the metabolic syndrome in this disorder.

Aldosterone as a key mediator of the cardiometabolic syndrome in primary aldosteronism: an observational study

OBJECTIVE

Primary aldosteronism (PA) is characterized by the onset of both cardiac and gluco-metabolic alterations. The aim of this study was to evaluate the impact of aldosterone excess on the development of such complications, and the effects of surgical and pharmacological treatment on their long-term outcome.

METHODS

We prospectively re-examined 61 patients: 25 with aldosterone-producing adenoma (APA), after surgery, and 36 patients with idiopathic hyperaldosteronism (IHA) on pharmacological treatment. The lipid, fasting and dynamic glucose profiles and the echocardiographic parameters were evaluated at diagnosis and at follow-up.

RESULTS

After adrenalectomy all patients had normalization of aldosterone levels and were cured of hypokalaemia, and a resolution of hypertension was achieved in 12 of 25 patients. APA patients showed a significant reduction of both plasma glucose (P=0.017) and insulin levels (P=0.001) after 75 g oral glucose tolerance test. Stabilization of glucose metabolism complications was observed in IHA patients. Multiple regression analysis at diagnosis showed a positive correlation between homeostasis model assessment (HOMA) insulin resistance index and HOMA beta cell and serum aldosterone levels in both APA and IHA. Echocardiographic parameters were improved in both APA and IHA at follow-up and the difference was statistically significant for left ventricular mass index (P=0.017) and interventricular septum thickness (P=0.007) in APA patients.

CONCLUSIONS

The removal of aldosterone excess in APA patients induces the regression of both cardiac and gluco-metabolic complications, indicating aldosterone as a main determinant of such alterations. In IHA patients the medical treatment seems to avoid the possible progression of the these alterations that appear to be stable.

Serum aldosterone concentration and cardiovascular risk in women with polycystic ovarian syndrome

CONTEXT

Polycystic ovary syndrome (PCOS) is associated with early impairment of vascular structure and a low-grade chronic inflammation. Aldosterone is a well-recognized cardiovascular risk (CVR) factor and is related to inflammatory processes.

OBJECTIVE

Our objective was to investigate serum aldosterone levels in PCOS and correlate them to some CVR factors and early atherosclerotic markers.

DESIGN AND SETTING

A prospective baseline-controlled clinical study was conducted at the University "Federico II" of Naples School of Medicine (Naples, Italy).

PATIENTS

Fifty PCOS women age- and body mass index-matched with 50 healthy women were enrolled.

MEAN OUTCOME MEASURES

Anthropometric, hormonal, and metabolic patterns, including plasma aldosterone, renin, and C-reactive protein, were measured in each subject. Intima-media thickness was also evaluated in each patient and control.

RESULTS

Aldosterone levels were significantly increased (P < 0.001) in PCOS compared with healthy women (10.5 +/- 3.2 vs. 5.7 +/- 2.5 ng/dl). In PCOS, a significant (P < 0.001) direct correlation between plasma aldosterone and homeostasis model assessment, C-reactive protein, intima-media thickness, and mean blood pressure was found. On the other hand, high-density lipoprotein cholesterol and potassium were inversely (P < 0.001) related to serum aldosterone. Multiple linear regression analysis showed that the area under the curve for insulin and homeostasis model assessment was linearly related to aldosterone in PCOS.

CONCLUSION

PCOS women show an insulin resistance related increase in serum aldosterone levels.