Effect of antihypertensive agents on the development of type 2 diabetes mellitus

Differential IL18 signaling via IL18 receptor and Na-Cl co-transporter discriminating thermogenesis and glucose metabolism regulation

White adipose tissue (WAT) plays a role in storing energy, while brown adipose tissue (BAT) is instrumental in the re-distribution of stored energy when dietary sources are unavailable. Interleukin-18 (IL18) is a cytokine playing a role in T-cell polarization, but also for regulating energy homeostasis via the dimeric IL18 receptor (IL18r) and Na-Cl co-transporter (NCC) on adipocytes. Here we show that IL18 signaling in metabolism is regulated at the level of receptor utilization, with preferential role for NCC in brown adipose tissue (BAT) and dominantly via IL18r in WAT. In Il18r^-/-Ncc^-/- mice, high-fat diet (HFD) causes more prominent body weight gain and insulin resistance than in wild-type mice. The WAT insulin resistance phenotype of the double-knockout mice is recapitulated in HFD-fed Il18r^-/- mice, whereas decreased thermogenesis in BAT upon HFD is dependent on NCC deletion. BAT-selective depletion of either NCC or IL18 reduces thermogenesis and increases BAT and WAT inflammation. IL18r deletion in WAT reduces insulin signaling and increases WAT inflammation. In summary, our study contributes to the mechanistic understanding of IL18 regulation of energy metabolism and shows clearly discernible roles for its two receptors in brown and white adipose tissues.

Effects of high-intensity statin combined with telmisartan versus amlodipine on glucose metabolism in hypertensive atherosclerotic cardiovascular disease patients with impaired fasting glucose: A randomized multicenter trial

BACKGROUND

There is lacking evidence that telmisartan can improve insulin resistance in patients on high-intensity statins. This study compared the effects of telmisartan and amlodipine on glucose metabolism in hypertensive atherosclerotic cardiovascular disease (ASCVD) patients with impaired fasting glucose (IFG) requiring high-intensity rosuvastatin therapy.

METHODS

Ninety-nine patients were randomly assigned to 2 groups [telmisartan-statin group (n=48) and amlodipine-statin group (n=51)] as add-on therapy to high-intensity rosuvastatin therapy (20 mg). The primary endpoint was to assess insulin resistance using the homeostatic model assessment (HOMA-IR) value at week 24. The secondary endpoint was the change in glucose metabolism indices from baseline to week 24.

RESULTS

The HOMA-IR at week 24 (2.4 [interquartile range, 1.8-3.8] versus 2.7 [1.7-3.7]; P = .809) and changes in the HOMA-IR from baseline to week 24 (-7.0 [-29.0 to 21.0] versus -5.5 [-53.3 to 27.3]; P = .539) were not significantly different between 2 groups. However, the fasting glucose level at week 24 was significantly lower in the telmisartan-statin group than in the amlodipine-statin group (107.7 ± 13.4 mg/dL versus 113.3 ± 12.4 mg/dL; P = .039) and significantly decreased in the telmisartan-statin group (-3.2 ± 8.6% versus 3.8 ± 13.2%; P = .003). The proportion of patients with fasting glucose ≥100 mg/dL (71.1% versus 89.6%; P = .047) or new-onset diabetes mellitus (12.5% versus 31.4%, P = .044) at week 24 was also significantly lower in the telmisartan-statin group than in the amlodipine-statin group.

CONCLUSION

In comparison to amlodipine, telmisartan did not decrease the HOMA-IR. However, telmisartan preserved insulin secretion, led to a regression from IFG to euglycemia and prevented new-onset diabetes mellitus in ASCVD patients with IFG requiring high-intensity statins.

Angiotensin-converting enzyme inhibitors versus angiotensin receptor blockers: New-onset diabetes mellitus stratified by statin use

WHAT IS KNOWN AND OBJECTIVES

Regardless of statin use, which is known to induce hyperglycaemia, comparative studies on the risk of new-onset diabetes mellitus (NODM) with angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin II receptor blockers (ARBs) are needed. This study evaluated the effects of ACEIs and ARBs on NODM in the clinical setting.

METHODS

This retrospective cohort study utilized electronic medical record data from Seoul St. Mary's Hospital and Seoul National University Hospital from 2009 to 2012. Patients who were prescribed ACEIs or ARBs for the first time (irrespective of concomitant statin use) were followed up for 5 years.

RESULTS AND DISCUSSIONS

A total of 11,703 patients were included, 24.9% (n = 2916) were taking ACEIs and 75.1% (n = 9189) were taking ARBs. Patients on ACEIs had a significantly lower incidence of NODM both with statin use (HR = 0.13, p < 0.001) and without (HR = 0.15, p = 0.009) than patients on ARBs. Age ≥60 years (HR = 1.49, p = 0.010), BMI ≥25 (HR = 1.96, p < 0.010), use of calcium channel blockers (HR = 1.47, p = 0.010), and diuretics (HR = 1.48, p = 0.010) were risk factors for NODM with statin use.

WHAT IS NEW AND CONCLUSION

Patients taking ACEIs are less likely to develop NODM than patients taking ARBs, irrespective of statin use. Patients' conditions, including the risk of NODM, should be considered before prescribing ACEIs or ARBs. Future randomized clinical trials are needed to clarify further the relationship between ACEIs and ARBs and their effect on NODM.

Effects of enalapril and paricalcitol treatment on diabetic nephropathy and renal expressions of TNF-α, p53, caspase-3 and Bcl-2 in STZ-induced diabetic rats

This study aimed to assess the renopreventive effect of enalapril and/or paricalcitol on streptozotocin (STZ) diabetes-induced nephropathy and to elucidate their mechanisms of action through investigation of the effects on renal oxidative stress, antioxidant defense system and expressions of TNF-α, p53, caspase-3, and Bcl-2. Diabetes mellitus was induced in fasting male Wistar rats by single intraperitoneal injection of STZ (45 mg /kg b.w.) dissolved in citrate buffer (pH 4.5). Ten days after STZ injection, the diabetic rats were treated with enalapril (25 mg/l of drinking water) and/or paricalcitol (8 μg/kg b.w. per os) dissolved in 5% DMSO daily for 4 weeks. The obtained data revealed that the treatment of diabetic Wistar rats with enalapril and/or paricalcitol led to significant decreases in the elevated serum urea, uric acid, creatinine, sodium and potassium levels; thereby reflecting the improvement of the impaired kidney function. The deteriorated kidney lipid peroxidation, GSH content and GST and catalase activities in diabetic rats were significantly ameliorated as a result of treatment with enalapril and/or paricalcitol. The elevated fasting and post-prandial serum glucose levels and the lowered serum insulin and C-peptide levels were also improved. The treatment with enalapril and paricalcitol in combination was the most potent in decreasing the elevated serum glucose levels. Moreover, the treatment of diabetic rats successfully prevented the diabetes-induced histopathological deleterious changes of kidney and islets of Langerhans of pancreas. In association, the immunohistochemically detected pro-inflammatory cytokine, TNF-α, and apoptotic mediators, p53 and caspase-3, were remarkably decreased in kidney of diabetic rats as a result of treatment while the expression of anti-apoptotic protein Bcl-2 was increased. Based on these findings, it can be concluded that enalapril and paricalcitol alone or in combination can prevent STZ diabetes-induced nephropathy through amelioration of the glycemic state and antioxidant defense system together with the suppression of oxidative stress, inflammation and apoptosis. However, the treatment of diabetic rats with enalapril and paricalcitol in combination has no further significant improvement effects on renal function and damage when compared with enalapril or paclitaxel treated diabetic groups.

Levels of Systolic and Diastolic Blood Pressure and Their Relation to Incident Metabolic Syndrome

Background: Elevated blood pressure (BP) is a component of the metabolic syndrome (MetS), and one third of individuals with hypertension simultaneously have MetS. However, the evidence is still unclear regarding the predictive ability of BP for incident MetS. Methods: In total, 5,809 Koreans without baseline MetS were grouped by baseline systolic (SBP) and diastolic BP (DBP) and monitored for 10 years to identify incident MetS. A Cox proportional hazards model was used to evaluate the HR and 95% CI for MetS according to SBP and DBP. Subgroup analysis was conducted in the normotensive population based on a new guideline of the American College of Cardiology and the American Heart Association. Results: High-BP groups tended to have worse metabolic profiles than the lowest-BP group in both SBP and DBP categories. In all of the participants, elevated SBP and DBP levels were significantly associated with the increased HR for MetS, even after adjusting for covariates. Subgroup analysis for normotensive participants indicated that the HR for MetS increased proportionally to both SBP (<110 mm Hg: reference, 110–119 mm Hg: HR = 1.60 [95% CI 1.40–1.84], and 120–129 mm Hg: HR = 2.12 [95% CI 1.82–2.48]) and DBP levels (<70 mm Hg: reference, 71–74 mm Hg: HR = 1.31 [95% CI 1.09–1.58], and 75–79 mm Hg: HR = 1.51 [95% CI 1.25–1.81]). Conclusion: The risk of incident MetS increased proportionally to baseline SBP and DBP, and this was identically observed even in normotensive participants.

The activation of α2-adrenergic receptor in the spinal cord lowers sepsis-induced mortality

The effect of clonidine administered intrathecally (i.t.) on the mortality and the blood glucose level induced by sepsis was examined in mice. To produce sepsis, the mixture of D-galactosamine (GaLN; 0.6 g/10 ml)/lipopolysaccharide (LPS; 27 µg/27 µl) was treated intraperitoneally (i.p.). The i.t. pretreatment with clonidine (5 µg/5 µl) increased the blood glucose level and attenuated mortality induced by sepsis in a dose-dependent manner. The i.t. post-treatment with clonidine up to 3 h caused an elevation of the blood glucose level and protected sepsis-induced mortality, whereas clonidine post-treated at 6, 9, or 12 h did not affect. The pre-treatment with oral D-glucose for 30 min prior to i.t. post-treatment (6 h) with clonidine did not rescue sepsis-induced mortality. In addition, i.t. pretreatment with pertussis toxin (PTX) reduced clonidine-induced protection against mortality and clonidine-induced hyperglycemia, suggesting that protective effect against sepsis-induced mortality seems to be mediated via activating PTX-sensitive G-proteins in the spinal cord. Moreover, pretreatment with clonidine attenuated the plasma tumor necrosis factor α (TNF-α) induced by sepsis. Clonidine administered i.t. or i.p. increased p-AMPKα1 and p-AMPKα2, but decreased p-Tyk2 and p-mTOR levels in both control and sepsis groups, suggesting that the up-regulations of p-AMPKα1 and p-AMPKα2, or down-regulations of p-mTOR and p-Tyk2 may play critical roles for the protective effect of clonidine against sepsis-induced mortality.

Utilization of antihypertensive drugs in obesity-related hypertension: a retrospective observational study in a cohort of patients from Southern Italy

Background

Although the pathophysiological mechanisms of arterial hypertension are different in obese and lean patients, hypertension guidelines do not include specific recommendations for obesity-related hypertension and, therefore, there is a considerable uncertainty on which antihypertensive drugs should be used in this condition. Moreover, studies performed in general population suggested that some antihypertensive drugs may increase body weight, glycemia and LDL-cholesterol but it is unclear how this impact on drug choice in clinical practice in the treatment of obese hypertensive patients. Therefore, in order to identify current preferences of practitioners for obesity-related hypertension, in the present work we evaluated antihypertensive drug therapy in a cohort of 129 pharmacologically treated obese hypertensive patients (46 males and 83 females, aged 51.95 ± 10.1 years) that came to our observation for a nutritional consultation.

Methods

Study design was retrospective observational. Differences in the prevalence of use of the different antihypertensive drug classes among groups were evaluated with χ² square analysis. Threshold for statistical significance was set at p < 0.05.

Results

41.1 % of the study sample was treated with one, 36.4 % with two and the remaining 22.5 % with three or more antihypertensive drugs. In patients under single drug therapy, β-blockers, ACEIs and ARBs accounted each for about 25 % of prescriptions. The prevalence of use of β-blockers was about sixfold higher in females than males. Diuretics were virtually never used in monotherapy regimens but were used in more than 60 % of patients on dual antihypertensive therapy and in all patients assuming three or more drugs. There was no significant difference in the prevalence of use of any of the aforementioned drugs among patients with obesity of type I, II and III or between patients with or without metabolic syndrome.

Conclusions

Our data show that no first choice protocol seems to be adopted in clinical practice for the treatment of obesity-related hypertension. Importantly, physicians do not seem to differentiate drug use according to the severity of obesity or to the presence of metabolic syndrome or to avoid drugs known to detrimentally affect body weight and metabolic profile in general population.

Dose-response relationships between sedentary behaviour and the metabolic syndrome and its components

AIMS/HYPOTHESIS

The aim of this study was to examine the relationship among sedentary behaviour (SB) and the metabolic syndrome and its components by age, moderate-to-vigorous physical activity (MVPA) and sex.

METHODS

A cross-sectional analysis was performed on 2003-2006 National Health and Nutrition Examination Survey data from 5,076 adults aged ≥18 years (mean ± SD = 43.8 ± 19.5). SB was measured using ActiGraph accelerometers worn for 1 week and defined as <100 counts/min. Metabolic syndrome was defined using the Adult Treatment Panel III criteria. Natural cubic spline logistic regression models were used to estimate the odds of meeting criteria for the metabolic syndrome and its components by total daily SB time and breaks in SB. Statistical interactions between SB and age, sex and MVPA were explored.

RESULTS

The prevalence of the metabolic syndrome was 19% and the average daily SB time was 8.1 ± 2.8 h, with 90 ± 25 breaks/day. The relationship between daily SB time and the metabolic syndrome was linear and characterised by an OR of 1.09 (95% CI 1.01, 1.18) for each hour of SB. Total SB was associated with the following components: high triacylglycerol, low HDL-cholesterol and high fasting glucose. All three associations were modified by MVPA level. No relationship between breaks in SB and the metabolic syndrome was found.

CONCLUSIONS/INTERPRETATION

There appears to be no SB threshold at which the risk of the metabolic syndrome is elevated. Therefore, an effort should be made to maintain low levels of total time spent in SB and so lessen the risk of the metabolic syndrome.

Predictors for glucose change in hypertensive participants following short-term treatment with atenolol or hydrochlorothiazide

STUDY OBJECTIVE

To develop and validate a predictive model for glucose change and risk for new-onset impaired fasting glucose in hypertensive participants following treatment with atenolol or hydrochlorothiazide (HCTZ).

DESIGN

Randomized multicenter clinical trial.

PATIENTS

A total of 735 white or African-American men and women with uncomplicated hypertension.

MEASUREMENTS AND MAIN RESULTS

Pharmacogenomic Evaluation of Antihypertensive Responses (PEAR) is a randomized clinical trial to assess the genetic and nongenetic predictors of blood pressure response and adverse metabolic effects following treatment with atenolol or HCTZ. To develop and validate predictive models for glucose change, PEAR participants were randomly divided into a derivation cohort of 367 and a validation cohort of 368. Linear and logistic regression modeling were used to build models of drug-associated glucose change and impaired fasting glucose (IFG), respectively, in the derivation cohorts. These models were then evaluated in the validation cohorts. For glucose change after atenolol or HCTZ treatment, baseline glucose was a significant (p<0.0001) predictor, explaining 13% of the variability in glucose change after atenolol and 12% of the variability in glucose change after HCTZ. Baseline glucose was also the strongest and most consistent predictor (p<0.0001) for development of IFG after atenolol or HCTZ monotherapy. The area under the receiver operating curve was 0.77 for IFG after atenolol and 0.71 after HCTZ treatment, respectively.

CONCLUSION

Baseline glucose is the primary predictor of atenolol or HCTZ-associated glucose increase and development of IFG after treatment with either drug.

The metabolic cost of lowering blood pressure with hydrochlorothiazide

BACKGROUND

The landmark Antihypertensive and Lipid-Lowering treatment to prevent Heart Attack Trial (ALLHAT) placed a new spotlight on thiazide diuretics as the first-line therapy for hypertension. This is concerning as thiazide-diuretics may contribute to comorbidities associated with the current epidemic of obesity. Previous randomized clinical trials have linked thiazide diuretic treatment to insulin resistance, metabolic syndrome, and increased incidence of type 2 diabetes.

METHODS

This proof of concept, longitudinal, randomized, double-blind study evaluated the effects of the angiotensin II receptor blocker Valsartan and the specific thiazide diuretic Hydrochlorothiazide (HCTZ) on hepatic triglyceride level (primary outcome), as well as triglyceride levels within other organs including the heart, skeletal muscle, and pancreas. Additionally, we evaluated whether myocardial function, insulin sensitivity, and insulin secretion were affected by these treatments.

RESULTS

Hepatic TG levels increased by 57% post HCTZ treatment: ∆hTG HCTZ = 4.12% and remained unchanged post Valsartan treatment: ∆hTG V = 0.06%. The elevation of hepatic TG levels after HCTZ treatment was additionally accompanied by a reduction in insulin sensitivity: ∆SI HCTZ = -1.14. Treatment with Valsartan resulted in improved insulin sensitivity: ∆SI V = 1.24. Treatment-induced changes in hepatic TG levels and insulin sensitivity were statistically significant between groups (phTG = 0.0098 and pSI = 0.0345 respectively). Disposition index, DI, remained unchanged after HCTZ treatment: ∆DI HCTZ = -141 but it was increased by a factor of 2 after treatment with Valsartan: ∆DI V =1018). However, the change between groups was not statistically significant. Both therapies did not modify abdominal visceral and subcutaneous fat mass as well as myocardial structure and function. Additionally, myocardial, pancreatic, and skeletal muscle triglyceride deposits remained unchanged in both therapeutic arms.

CONCLUSIONS

Our findings are two-fold and relate to hepatic steatosis and insulin sensitivity. HCTZ treatment worsened hepatic steatosis measured as hepatic triglyceride content and reduced insulin sensitivity. Valsartan treatment did not affect hepatic triglyceride levels and improved insulin sensitivity. The results of this study reinforce the message that in patients at risk for type 2 diabetes it is particularly important to choose an antihypertensive regimen that lowers blood pressure without exacerbating patient's metabolic profile.

Intake of Gnetum africanum and Dacryodes edulis, imbalance of oxidant/antioxidant status and prevalence of diabetic retinopathy in central Africans

OBJECTIVE

To estimate the prevalence of DR and to correlate cardiometabolic, sociodemographic, and oxidant/antioxidant imbalance data to the prevalence of DR.

DESIGN

This case-control study included type 2 DM (T2 DM) patients with DR (n = 66), T2 DM patients without DR (N = 84), and healthy controls (n = 45) without DR, in Kinshasa town. Diet, albuminemia, serum vitamins, and 8-isoprostane were examined.

RESULTS

No intake of safou (OR = 2.7 95% CI 1.2-5.8; P = 0.014), low serum albumin <4.5 g/dL (OR-2.9 95% CI 1.4-5.9; P = 0.003), no intake of fumbwa (OR = 2.8 95% CI 1.2-6.5; P = 0.014), high 8-isoprostane (OR = 14.3 95% CI 4.5-46; P<0.0001), DM duration ≥ 5 years (OR = 3.8 95% CI 1.6-9.1; P = 0.003), and low serum vitamin C (OR = 4.5 95% CI 1.3-15.5; P = 0.016) were identified as the significant independent determinants of DR.

CONCLUSION

The important role of oxidant/antioxidant status imbalance and diet is demonstrated in DR.

Office and ambulatory blood pressure-lowering effects of combination valsartan/hydrochlorothiazide vs. hydrochlorothiazide-based therapy in obese, hypertensive patients

The authors evaluated the blood pressure (BP)-lowering effects of combination valsartan/hydrochlorothiazide (HCTZ) vs. amlodipine/HCTZ in a 16-week, double-blind, randomized, forced-titration study and ambulatory BP monitoring (ABPM) substudy involving centrally obese hypertensive patients 40 years and older. Patients were started on valsartan/HCTZ 160/12.5 mg or HCTZ 12.5 mg monotherapy, force-titrated at week 4 to valsartan/HCTZ 320/25 mg and HCTZ 25 mg, respectively. The HCTZ group initiated amlodipine 5 mg at week 8 and 10 mg at week 12. A subset of patients had 24-hour ABPM at baseline and weeks 8 and 16. At week 16 in the intent-to-treat population (n=401), valsartan/HCTZ and amlodipine/HCTZ lowered office systolic BP (-30.6 vs. -28.3 mm Hg; P=.14). In the ABPM subgroup (n=111), valsartan/HCTZ was more effective than amlodipine/HCTZ in reducing 24-hour systolic BP (-20.6 vs. -14.5 mm Hg; P=.011). In obese hypertensive patients, valsartan/HCTZ reduced office BP similar to amlodipine/HCTZ but lowered 24-hour systolic BP more.

Effect of clonidine on blood glucose levels in euglycemic and alloxan-induced diabetic rats and its interaction with glibenclamide

Objectives:

Clonidine, a known antihypertensive, is currently used for many purposes including diabetic gastroparesis, postmenopausal hot flushes, opioid/nicotine/alcohol withdrawal. Its effects on carbohydrate metabolism appear to be variable. Hence, the present study was undertaken to evaluate the influence of clonidine on euglycemic and alloxan -induced diabetic rats and its interaction with glibenclamide.

Materials and Methods:

Alloxan - induced (150 mg/kg, i.p) diabetic rats were divided into six groups of six animals each. Group I - Normal Control; Group II - Nondiabetic + Clonidine (25 μg/kg); Group III - Diabetic Control; Group IV - Diabetic + Glibenclamide (5 mg/kg); Group V - Diabetic + Glibenclamide + Clonidine. All drugs were given orally once daily. Blood glucose was estimated from rat tail vein using glucometer before start of the experiment and at the end of 30 days.

Results:

After 30 days of treatment, clonidine (25 μg/kg) produced significant hyperglycemia in both euglycemic and diabetic rats. It also reduced the hypoglycemic effect of glibenclamide in diabetic rats.

Conclusion:

The results of present study indicate that clonidine has hyperglycemic effect and it also interacts with glibenclamide to reduce its hypoglycemic activity. If these findings are true to human beings then clonidine should not be used in diabetic patients on sulfonylureas.

Drug mechanisms to help in managing resistant hypertension in obesity

Obesity is a major risk factor for the development of hypertension. Because the prevalence of obesity is increasing worldwide, the prevalence of obesity hypertension is also increasing. Importantly, hypertension in obesity is commonly complicated by dyslipidemia and type 2 diabetes mellitus and hence imposes a high cardiovascular disease risk. Furthermore, obesity is strongly associated with resistant hypertension. Activation of the sympathetic nervous system and the renin-angiotensin system, leading to renal sodium and water retention, links obesity with hypertension. There is also evidence for the release of factors by visceral adipose tissue promoting excessive aldosterone production, and a more central role of aldosterone in obesity hypertension is emerging. Randomized studies evaluating the effect of different classes of antihypertensive agents in obesity hypertension are scarce, short-lasting, and small. Considering the emerging role of aldosterone in the pathogenesis of obesity hypertension, mineralocorticoid receptor antagonism may play a more central role in the pharmacologic treatment of obesity hypertension in the near future.

The role of fixed-dose combinations in the management of hypertension: focus on lercanidipine-enalapril

Achieving optimal blood pressure (BP) control is the most important single issue in the management of hypertension, and in most patients, it is difficult or impossible to achieve target levels with one drug. Blocking two or more regulatory systems provides a more effective and more physiologic reduction in BP, and current guidelines have recommended the use of combination therapy as first-line treatment, or early in the management of hypertension. Fixed-dose combination therapy is an efficacious, relatively safe and cost-effective treatment option in most patients with essential hypertension. Of note, the once-daily administration of a fixed-dose enalapril/lercanidipine, by bringing together two distinct and complementary mechanisms of action, reduces BP effectively and has the potential for improved target organ protection relative to either class agent alone.

Angiotensin II and the development of insulin resistance: implications for diabetes

Angiotensin II (Ang II), the major effector hormone of the renin-angiotensin system (RAS), has an important role in the regulation of vascular and renal homeostasis. Clinical and pharmacological studies have recently shown that Ang II is a critical promoter of insulin resistance and diabetes mellitus type 2. Ang II exerts its actions on insulin-sensitive tissues such as liver, muscle and adipose tissue where it has effects on the insulin receptor (IR), insulin receptor substrate (IRS) proteins and the downstream effectors PI3K, Akt and GLUT4. The molecular mechanisms involved have not been completely identified, but the role of serine/threonine phosphorylation of the IR and IRS-1 proteins in desensitization of insulin action has been well established. The purpose of this review is to highlight recent advances in the understanding of Ang II actions which lead to the development of insulin resistance and its implications for diabetes.

Metabolic and antihypertensive effects of combined angiotensin receptor blocker and diuretic therapy in prediabetic hypertensive patients with the cardiometabolic syndrome

Hypertensive patients with the cardiometabolic syndrome (CMS) are at increased risk for type 2 diabetes and cardiovascular disease. The authors examined effects of valsartan and hydrochlorothiazide (HCTZ) combined and alone on insulin sensitivity (using homeostasis model assessment-insulin resistance [HOMA-IR]), and inflammatory/metabolic biomarkers in prediabetic hypertensive persons with CMS. Eligible patients entered 16-week therapy with valsartan 320 mg/d (n=189), HCTZ 25 mg/d (n=190), or valsartan/HCTZ 320/25 mg/d (n=187). At the end point, there were no statistically significant differences in HOMA-IR among the 3 groups. HCTZ significantly increased hemoglobin A(1c) and triglyceride concentrations and lowered serum potassium levels vs valsartan. HCTZ also increased plasma aldosterone and C-reactive protein levels. Blood pressure reduction and blood pressure control rates were highest with valsartan/HCTZ. There were no differences between combination valsartan/HCTZ or monotherapies on a measure of insulin sensitivity; however, the negative metabolic effects of HCTZ (increase in triglyceride and hemoglobin A(1c) values) were absent with valsartan/HCTZ, indicating an ameliorating effect of valsartan on these measures.

Risk factor assessment for new onset diabetes: literature review

Metabolic syndrome (MS), typified by hypertension, abdominal obesity, dyslipidaemia and impaired glucose metabolism, is a precursor of type 2 diabetes. Thiazide diuretics (TD) and beta-blockers are associated with increased risk of diabetes in patients with hypertension; however, the role of these agents in development of diabetes in MS patients is unknown. We reviewed the literature regarding risk factors for diabetes development and compared this with data from the Study of Trandolapril/Verapamil SR And Insulin Resistance (STAR), which investigated the effects of two fixed-dose combinations (FDCs) [trandolapril/verapamil SR and losartan/hydrochlorothiazide (L/H)] on glucose control and new diabetes in MS patients. In STAR, logistic regression modelling identified haemoglobin A1c [odds ratio (OR) 4.21 per 1% increment; p = 0.003), L/H treatment (OR 4.04; p = 0.002) and 2-h oral glucose tolerance test glucose levels (OR 1.39 per 10 mg/dl increments; p < 0.001) as baseline predictors of diabetes. These data support prior analyses and suggest that choice of antihypertensive agent is important. Patients with MS may be at lower risk of diabetes when using a FDC calcium channel blocker + angiotensin-converting enzyme inhibitor compared with an angiotensin receptor blocker + TD.

Angiotensin II reduces mitochondrial content in skeletal muscle and affects glycemic control

OBJECTIVE

Blockade of angiotensin (Ang) II has been shown to prevent new-onset type 2 diabetes. We focused on the effects of AngII on muscle mitochondria, especially on their biogenesis, as an underlining mechanism of type 2 diabetes.

RESEARCH DESIGN AND METHODS

C2C12 cells and C57bl/6 mice were used to examine roles for AngII in the regulation of muscle mitochondria and to explore whether the effect was mediated by type 1 AngII receptor (AT1R) or type 2 receptor (AT2R).

RESULTS

C2C12 cells treated with 10(-8)-10(-6) mol/l AngII reduced the mitochondrial content associated with downregulation of the genes involved in mitochondrial biogenesis. The action of AngII was diminished by blockade of AT2R but not AT1R, whereas overexpression of AT2R augmented the effect. AngII increased mitochondrial ROS and decreased mitochondrial membrane potential, and these effects of AngII were significantly suppressed by blockade of either AT1R or AT2R. Chronic AngII infusion in mice also reduced muscle mitochondrial content in association with increased intramuscular triglyceride and deteriorated glycemic control. The AngII-induced reduction in muscle mitochondria in mice was partially, but significantly, reversed by blockade of either AT1R or AT2R, associated with increased fat oxidation, decreased muscle triglyceride, and improved glucose tolerance. Genes involved in mitochondrial biogenesis were decreased via AT2R but not AT1R under these in vivo conditions.

CONCLUSIONS

Taken together, these findings imply the novel roles for AngII in the regulation of muscle mitochondria and lipid metabolism. AngII reduces mitochondrial content possibly through AT1R-dependent augmentation of their degradation and AT2R-dependent direct suppression of their biogenesis.

The role of renin-angiotensin-aldosterone system-based therapy in diabetes prevention and cardiovascular and renal protection

Hypertension increases the risk of type 2 diabetes mellitus (T2DM) and cardiovascular disease. In addition to lowering blood pressure, blockade of the renin-angiotensin-aldosterone system (RAAS) reduces the risk of new-onset T2DM and offers renal protection. Using a MEDLINE search, we identified multiple trials that reported the incidence of T2DM in patients taking inhibitors of RAAS. In this review, we will discuss the RAAS as a potential target in diabetes prevention and the mechanisms through which inhibitors of this system achieve such an important effect. We will also shed light on the beneficial cardiovascular and renal effects of RAAS blockade. Although multiple studies have demonstrated that inhibitors of RAAS, especially angiotensin-converting enzyme inhibitors and angiotensin receptor blockers, can reduce the incidence of T2DM, randomized controlled studies are still needed to further elucidate their exact role in diabetes prevention.

Treating hypertension while protecting the vulnerable islet in the cardiometabolic syndrome

Hypertension, a multifactorial-polygenic disease, interacts with multiple environmental stressors and results in functional and structural changes in numerous end organs, including the cardiovascular system. This can result in coronary heart disease, stroke, peripheral vascular disease, congestive heart failure, end-stage renal disease, insulin resistance, and damage to the pancreatic islet. Hypertension is the most important modifiable risk factor for major health problems encountered in clinical practice. Whereas hypertension was once thought to be a medical condition based on discrete blood pressure readings, a new concept has emerged defining hypertension as part of a complex and progressive metabolic and cardiovascular disease, an important part of a cardiometabolic syndrome. The central role of insulin resistance, oxidative stress, endothelial dysfunction, metabolic signaling defects within tissues, and the role of enhanced tissue renin-angiotensin-aldosterone system activity as it relates to hypertension and type 2 diabetes mellitus are emphasized. Additionally, this review focuses on the effect of hypertension on functional and structural changes associated with the vulnerable pancreatic islet. Various classes of antihypertensive drugs are reviewed, especially their roles in delaying or preventing damage to the vulnerable pancreatic islet, and thus delaying the development of type 2 diabetes mellitus.

Antioxidant supplemention in the treatment of skeletal muscle insulin resistance: potential mechanisms and clinical relevance

The incidence of type 2 diabetes has increased dramatically over the past several decades and this trend is projected to continue into the foreseeable future. Skeletal muscle insulin resistance is thought to be a key development in the pathogenesis of type 2 diabetes. Given this fact, interventions that prevent or reverse impairments in skeletal muscle action can have profound effects on whole-body glucose homeostasis. Traditional approaches used in this regard include exercise, weight loss, and insulin-sensitizing drugs such as thiazolidinediones (TZDs). Although these interventions have proven effective in improving glucose homeostasis, there are adherence issues seen with lifestyle interventions and undesirable side effects have been reported with TZDs. With these points in mind, the development of alternative strategies to maintain or improve skeletal muscle insulin sensitivity is warranted. In this context, the purpose of the present review is to highlight the role of antioxidant compounds in the prevention and treatment of skeletal muscle insulin resistance. Specifically, we will briefly describe the mechanisms of insulin-stimulated skeletal muscle glucose uptake and the potential mediators of oxidative stress induced insulin resistance, highlight data suggesting that antioxidant compounds can have beneficial effects on skeletal muscle insulin action, and discuss potential mechanisms mediating this effect.

Angiotensin II-induced skeletal muscle insulin resistance mediated by NF-kappaB activation via NADPH oxidase

Reduced insulin sensitivity is a key factor in the pathogenesis of type 2 diabetes and hypertension. Skeletal muscle insulin resistance is particularly important for its major role in insulin-mediated glucose disposal. Angiotensin II (ANG II) is integral in regulating blood pressure and plays a role in the pathogenesis of hypertension. In addition, we have documented that ANG II-induced skeletal muscle insulin resistance is associated with generation of reactive oxygen species (ROS). However, the linkage between ROS and insulin resistance in skeletal muscle remains unclear. To explore potential mechanisms, we employed the transgenic TG(mRen2)27 (Ren-2) hypertensive rat, which harbors the mouse renin transgene and exhibits elevated tissue ANG II levels, and skeletal muscle cell culture. Compared with Sprague-Dawley normotensive control rats, Ren-2 skeletal muscle exhibited significantly increased oxidative stress, NF-kappaB activation, and TNF-alpha expression, which were attenuated by in vivo treatment with an angiotensin type 1 receptor blocker (valsartan) or SOD/catalase mimetic (tempol). Moreover, ANG II treatment of L6 myotubes induced NF-kappaB activation and TNF-alpha production and decreased insulin-stimulated Akt activation and GLUT-4 glucose transporter translocation to plasma membranes. These effects were markedly diminished by treatment of myotubes with valsartan, the antioxidant N-acetylcysteine, NADPH oxidase-inhibiting peptide (gp91 ds-tat), or NF-kappaB inhibitor (MG-132). Similarly, NF-kappaB p65 small interfering RNA reduced NF-kappaB p65 subunit expression and nuclear translocation and TNF-alpha production but improved insulin-stimulated phosphorylation (Ser(473)) of Akt and translocation of GLUT-4. These findings suggest that NF-kappaB plays an important role in ANG II/ROS-induced skeletal muscle insulin resistance.

Role of low energy expenditure and sitting in obesity, metabolic syndrome, type 2 diabetes, and cardiovascular disease

It is not uncommon for people to spend one-half of their waking day sitting, with relatively idle muscles. The other half of the day includes the often large volume of nonexercise physical activity. Given the increasing pace of technological change in domestic, community, and workplace environments, modern humans may still not have reached the historical pinnacle of physical inactivity, even in cohorts where people already do not perform exercise. Our purpose here is to examine the role of sedentary behaviors, especially sitting, on mortality, cardiovascular disease, type 2 diabetes, metabolic syndrome risk factors, and obesity. Recent observational epidemiological studies strongly suggest that daily sitting time or low nonexercise activity levels may have a significant direct relationship with each of these medical concerns. There is now a need for studies to differentiate between the potentially unique molecular, physiologic, and clinical effects of too much sitting (inactivity physiology) separate from the responses caused by structured exercise (exercise physiology). In theory, this may be in part because nonexercise activity thermogenesis is generally a much greater component of total energy expenditure than exercise or because any type of brief, yet frequent, muscular contraction throughout the day may be necessary to short-circuit unhealthy molecular signals causing metabolic diseases. One of the first series of controlled laboratory studies providing translational evidence for a molecular reason to maintain high levels of daily low-intensity and intermittent activity came from examinations of the cellular regulation of skeletal muscle lipoprotein lipase (LPL) (a protein important for controlling plasma triglyceride catabolism, HDL cholesterol, and other metabolic risk factors). Experimentally reducing normal spontaneous standing and ambulatory time had a much greater effect on LPL regulation than adding vigorous exercise training on top of the normal level of nonexercise activity. Those studies also found that inactivity initiated unique cellular processes that were qualitatively different from the exercise responses. In summary, there is an emergence of inactivity physiology studies. These are beginning to raise a new concern with potentially major clinical and public health significance: the average nonexercising person may become even more metabolically unfit in the coming years if they sit too much, thereby limiting the normally high volume of intermittent nonexercise physical activity in everyday life. Thus, if the inactivity physiology paradigm is proven to be true, the dire concern for the future may rest with growing numbers of people unaware of the potential insidious dangers of sitting too much and who are not taking advantage of the benefits of maintaining nonexercise activity throughout much of the day.

Diagnosis and treatment of low-renin hypertension

Plasma renin levels can be used to classify hypertension. A significant proportion of hypertensive individuals display a low-renin profile and thus low-renin hypertension (LRH) requires appropriate diagnosis and treatment. LRH includes essential, secondary and genetic forms, the most common of which are low-renin essential hypertension and primary aldosteronism. Several studies have investigated the relationship between PRA status and clinical response to different antihypertensive therapies. The present review will discuss the differential diagnosis of LRH subtypes and the most appropriate treatment options based on the pathophysiological background of this condition.

Angiotensin II Type 1 receptor antagonism mediates uncoupling protein 2-driven oxidative stress and ameliorates pancreatic islet beta-cell function in young Type 2 diabetic mice

We recently identified a local pancreatic islet renin-angiotensin system (RAS), and demonstrated that it is upregulated in an animal model of obesity-induced type 2 diabetes mellitus (T2DM). Moreover, angiotensin II type 1 receptor (AT1R) antagonism improves beta-cell function and glucose tolerance in young T2DM mice and delays the onset of diabetes. Meanwhile, obesity-induced T2DM results in oxidative stress-mediated activation of uncoupling protein 2 (UCP2), a negative regulator of islet function. In the present study, we postulated that some of the protective effects of AT1R antagonism might be mediated through interference with this pathway and tested this hypothesis in a T2DM animal model. Losartan, an AT1R antagonist, was given to 4-week-old obese db/db mice for a period of 8 weeks. UCP2-driven oxidative damage and apoptosis were then analyzed in isolated islets. Losartan selectively inhibited oxidative stress via downregulation of NADPH oxidase; this in turn suppressed UCP2 expression, thus improving beta-cell insulin secretion and decreasing apoptosis-induced beta-cell mass loss in db/db mouse islets. These data indicate that islet AT1R activation in young diabetic mice can generate progressive islet beta-cell failure through UCP-driven oxidative damage.

The metabolic syndrome: role of skeletal muscle metabolism

Skeletal muscle constitutes the largest insulin-sensitive tissue in the body and is the primary site for insulin-stimulated glucose utilization. Skeletal muscle resistance to insulin is fundamental to the metabolic dysregulation associated with obesity and physical inactivity, and contributes to the development of the metabolic syndrome (MS). The inability to efficiently take up and store fuel, and to transition from fat to glucose as the primary source of fuel during times of caloric abundance (high insulin) or scarcity (low insulin) has been termed metabolic inflexibility which contributes to a whole body metabolic dysregulation and cardiovascular risk. Potential mechanisms contributing to reduced insulin signaling and action in skeletal muscle includes adipose tissue expansion and increased inflammatory adipokines, increased renin-angiotensin-aldosterone system (RAAS) activity, decreases in muscle mitochondrial oxidative capacity, increased intramuscular lipid accumulation, and increased reactive oxygen species. Future research is focused upon understanding these and other potential mechanisms in order to identify therapeutic targets for reducing MS risk. Strategies will include adequate physical activity and maintaining a healthy weight, but may also require specific pharmacologic interventions.