Resistance to insulin-stimulated-glucose uptake in patients with hypertension

Insulin Resistance and High Blood Pressure: Mechanistic Insight on the Role of the Kidney

The metabolic effects of insulin predominate in skeletal muscle, fat, and liver where the hormone binds to its receptor, thereby priming a series of cell-specific and biochemically diverse intracellular mechanisms. In the presence of a good secretory reserve in the pancreatic islets, a decrease in insulin sensitivity in the metabolic target tissues leads to compensatory hyperinsulinemia. A large body of evidence obtained in clinical and experimental studies indicates that insulin resistance and the related hyperinsulinemia are causally involved in some forms of arterial hypertension. Much of this involvement can be ascribed to the impact of insulin on renal sodium transport, although additional mechanisms might be involved. Solid evidence indicates that insulin causes sodium and water retention, and both endogenous and exogenous hyperinsulinemia have been correlated to increased blood pressure. Although important information was gathered on the cellular mechanisms that are triggered by insulin in metabolic tissues and on their abnormalities, knowledge of the insulin-related mechanisms possibly involved in blood pressure regulation is limited. In this review, we summarize the current understanding of the cellular mechanisms that are involved in the pro-hypertensive actions of insulin, focusing on the contribution of insulin to the renal regulation of sodium balance and body fluids.

Hypertension and Type 2 Diabetes-The Novel Treatment Possibilities

Elevated blood pressure and hyperglycaemia frequently coexist and are both components of metabolic syndrome. Enhanced cardiovascular risk is strongly associated with diabetes and the occurrence of hypertension. Both hypertension and type 2 diabetes, if treated inappropriately, lead to serious complications, increasing the mortality of patients and generating much higher costs of health systems. This is why it is of great importance to find the missing link between hypertension and diabetes development and to simultaneously search for drugs influencing these two disorders or even drugs aimed at their pathological bases. Standard antihypertensive therapy mainly focuses on blood pressure reduction, while novel drugs also possess a wide range of pleiotropic modes of actions, such as cardio- and nephroprotective properties or body weight reduction. These properties are especially desirable in a situation when type 2 diabetes coexists with hypertension. This review describes the connections between diabetes and hypertension development and briefly summarises the current knowledge regarding attempts to define targets for the treatment of high blood pressure in diabetic patients. It also describes the standard hypotensive drugs preferred in patients with type 2 diabetes, as well as novel drugs, such as finerenone, esaxerenone, sodium-glucose co-transporter-2 inhibitors, glucagon-like peptide-1 analogues and sacubitril/valsartan.

Changes in Glucose Metabolism after Adrenalectomy or Treatment with a Mineralocorticoid Receptor Antagonist for Primary Aldosteronism

BACKGROUND

Data on the effects of excess aldosterone on glucose metabolism are inconsistent. This study compared the changes in glucose metabolism in patients with primary aldosteronism (PA) after adrenalectomy or treatment with a mineralocorticoid receptor antagonist (MRA).

METHODS

Overall, 241 patients were enrolled; 153 underwent adrenalectomy and 88 received an MRA. Fasting glucose, homeostatic model assessment of insulin resistance (HOMA-IR), and homeostatic model assessment of β-cell function (HOMA-β) were compared between the treatment groups after 1 year. Plasma aldosterone concentration (PAC) and factors determining HOMA-IR and PAC were evaluated.

RESULTS

No baseline differences were observed between the groups. Fasting insulin, HOMA-IR, and HOMA-β increased in both groups and there were no significant differences in fasting glucose following treatment. Multiple regression analysis showed associations between PAC and HOMA-IR (β=0.172, P=0.017) after treatment. Treatment with spironolactone was the only risk factor associated with PAC >30 ng/dL (odds ratio, 5.2; 95% confidence interval [CI], 2.7 to 10; P<0.001) and conferred a 2.48-fold risk of insulin resistance after 1 year compared with surgery (95% CI, 1.3 to 4.8; P=0.007).

CONCLUSION

Spironolactone treatment might increase insulin resistance in patients with PA. This strengthened the current recommendation that adrenalectomy is the preferred strategy for patient with positive lateralization test. Achieving a post-treatment PAC of <30 ng/dL for improved insulin sensitivity may be appropriate.

Relationship of reduced glomerular filtration rate with alterations in plasma free amino acids and uric acid evaluated in healthy control and hypertensive subjects

The potential association between altered levels of plasma free amino acids (PFAAs) and uric acid (UA) with estimated glomerular filtration rate (eGFR) remains unknown among patients with hypertension. A total of 2804 healthy controls and 2455 hypertensive patients were included in the current analysis. eGFR was defined as reduced when it was <60 ml/min/1.73 m². The associations between reduced eGFR and individual PFAAs and UA in the healthy control and hypertension groups were explored by logistic regression analyses adjusted for potential confounding variables. Results show that UA had a significant positive association with reduced eGFR in both healthy control and hypertension groups (P < 0.001). Among the PFAAs, citrulline, glycine and phenylalanine showed significant positive associations with reduced eGFR in both healthy control (P < 0.01 to 0.001) and hypertension (P < 0.001) groups. Moreover, alanine, asparagine and methionine achieved significant positive associations with reduced eGFR only in the hypertension group (P < 0.01 to 0.001). Conversely, serine showed significant inverse associations with reduced eGFR in the hypertension group only (P < 0.001). Our findings provide first evidence for a strong relationship between distinct patterns of PFAAs and elevated UA with reduced eGFR in hypertension. The findings may appear useful in developing effective strategies for the prevention or early detection and treatment of declined kidney function in hypertension.

Circulating bone morphogenetic protein-9 levels are associated with hypertension and insulin resistance in humans

It has been demonstrated that bone morphogenetic protein-9 (BMP-9) may have an important role in vascular development and stability. However, the association of circulating BMP-9 with essential hypertension (HTN) has not been established in humans. The objective of this study is to observe the changes of circulating BMP-9 levels in patients with HTN and to investigate the association of circulation BMP-9 and insulin resistance (IR) in a cross-sectional study. Two hundred twenty-five individuals, including 132 patients with hypertension, and 93 healthy controls, were included in the present study. Circulating BMP-9 concentrations were measured with an ELISA kit. The association of circulating BMP-9 with other parameters was analyzed. When compared with healthy subjects, circulating BMP-9 concentrations were markedly lower in HTN patients (46.20 [31.85-62.80] vs. 77.21 [39.33-189.15], P < .01) and correlated negatively with blood pressure and the homeostasis model assessment of insulin resistance (P < .05 or P < .01). Decreasing levels of BMP-9 were independently and markedly related to HTN. In a multiple linear regression analysis, only systolic blood pressure and free fatty acid concentrations were independently associated with circulating BMP-9. Our findings suggest that BMP-9 may be a serum biomarker for HTN and IR.

Insulin resistance: potential role of the endogenous nitric oxide synthase inhibitor ADMA

The insulin resistance syndrome (IRS) is considered to be a new target of risk-reduction therapy. The IRS is a cluster of closely associated and interdependent abnormalities and clinical outcomes that occur more commonly in insulin-resistant/hyperinsulinemic individuals. This syndrome predisposes individuals to type 2 diabetes, cardiovascular diseases, essential hypertension, certain forms of cancer, polycystic ovary syndrome, nonalcoholic fatty liver disease, and sleep apnea. In patients at high risk for cardiovascular diseases, endothelial dysfunction is observed in morphologically intact vessels even before the onset of clinically manifest vascular disease. Indeed, there are several lines of evidence that indicate that endothelial function is compromised in situations where there is reduced sensitivity to endogenous insulin. It is well established that a decreased bioavailability of nitric oxide (NO) contributes to endothelial dysfunction. Furthermore, NO may modulate insulin sensitivity. Activation of NO synthase (NOS) augments blood flow to insulin-sensitive tissues (i.e. skeletal muscle, liver, adipose tissue), and its activity is impaired in insulin resistance. Inhibition of NOS reduces the microvascular delivery of nutrients and blunts insulin-stimulated glucose uptake in skeletal muscle. Furthermore, induction of hypertension by administration of the NOS inhibitor NG-monomethyl-L-arginine is also associated with insulin resistance in rats. Increased levels of asymmetric dimethylarginine (ADMA) are associated with endothelial vasodilator dysfunction and increased risk of cardiovascular diseases. An intriguing relationship exists between insulin resistance and ADMA. Plasma levels of ADMA are positively correlated with insulin resistance in nondiabetic, normotensive people. New basic research insights that provide possible mechanisms underlying the development of insulin resistance in the setting of impaired NO bioavailability will be discussed.

Review: The metabolic syndrome as an endocrine disease: is there an effective pharmacotherapeutic strategy optimally targeting the pathogenesis?

The metabolic syndrome (MetS) represents a combination of cardiovascular risk determinants such as obesity, insulin resistance and lipid abnormalities such as hypertriglyceridemia, increased free fatty acids, low high-density-cholesterol and hypertension. As a multiple component condition it imparts a doubling of relative risk for atherosclerotic cardiovascular disease (ASCVD). It is currently controversial which component of the syndrome carries what weight. There is even a considerable debate whether the risk for ASCVD is greater in patients diagnosed with MetS than that by the individual risk factors. At present, no unifying pathogenetic mechanism can explain the metabolic syndrome and there is no unique treatment for it. This review summarizes and critically reviews the currently available clinical and scientific evidence for the concept that the MetS is causally an endocrine disease and discusses pharmacotherapeutic strategies targeting the pathogenesis rather than single symptoms of the cluster.

Metabolic markers associated with insulin resistance predict type 2 diabetes in Koreans with normal blood pressure or prehypertension

Background

Questions remain as to the association between essential hypertension and increased incidence of type 2 diabetes (T2DM). The premise of this analysis is that insulin resistance/compensatory hyperinsulinemia is a major predictor of T2DM, and the greater the prevalence of insulin resistance within any population, normotensive or hypertensive, the more likely T2DM will develop. The hypothesis to be tested is that surrogate estimates of insulin resistance will predict incident T2DM to a significant degree in persons with normal blood pressure or prehypertension.

Methods

Analysis of data from a population-based survey of 10, 038 inhabitants of rural and urban areas of Korea, ≥40 years-old, initiated in 2001, with measures of demographic and metabolic characteristics at baseline and 8-years later. Participants were classified as having normal blood pressure or prehypertension, and three simple manifestations of insulin resistance related to the pathophysiology of T2DM used to predict incident T2DM: (1) glycemia (plasma glucose concentration 2-hour after 75 g oral glucose challenge = 2-hour PG); (2) hyperinsulinemia (plasma insulin concentration 2-hour after 75 g oral glucose challenge = 2-hour PI); and (3) dyslipidemia (ratio of fasting plasma triglyceride/high/density lipoprotein cholesterol concentration = TG/HDL-C ratio).

Results

Fully adjusted hazard ratios (HR, 95 % CI) for incident T2DM were highest (P < 0.001) in the quartile of individuals with the highest 2-hour PG concentrations, ranging from 5.84 (3.37–10.1) in women with prehypertension to 12.2 (7.12–21.00) in men with normal blood pressure. T2DM also developed to a significantly greater degree in subjects within the highest quartile of TG/HDL-C ratios, with HRs varying from 2.91 (1.63–2.58) in women with prehypertension (P < 0.001) to 1.77 (1.12–2.81, P < 0.05) in men with prehypertension. The least predictive index of insulin resistance was the 2-hour PI concentration. Subjects with normal blood pressure in the highest quartile of 2-hour PI concentrations were significantly associated with incident T2DM, with HRs of 1.5 (1.02–2.20, P = 0.25) and 2.02 (1.35–3.02, P < 0.001), in men and women, respectively. Finally, incidence of T2DM in the highest quartile was somewhat greater in patients with prehypertension, irrespective of predictor.

Conclusions

Metabolic variables associated with insulin resistance (glycemia, insulinemia, and dyslipidemia) predict the development of T2DM in patients with either normal blood pressure or prehypertension.

Electronic supplementary material

The online version of this article (doi:10.1186/s12933-016-0368-7) contains supplementary material, which is available to authorized users.

Correlated analysis and pathological study on insulin resistance and cardiovascular endocrine hormone in elderly hypertension patients

AIMS

The correlated analysis and pathological study on insulin resistance and cardiovascular endocrine hormone in elderly hypertension patients was investigated by clinical observation and physical experiments in my hospital.

MATERIALS AND METHODS

Randomly enrolled 300 subjects seen at hospital from January 2011 to January 2013, which included 150 hypertension patients and 150 non-hypertension of healthy people, while 150 cases of hypertension patients as the experimental group, 150 cases of healthy people without hypertension acts as the control group. The t-PA of serum (plasma), activity of PAI, ANP, IS, ET were determined in this 300 subjects, and it studied on the correlation and pathological effect between insulin resistance and cardiovascular endocrine hormone in elderly hypertension patients.

RESULTS

The levels of PAI, ANP, ET are apparently higher in hypertension patients than in healthy control group (p<0.05), while the t-PA, IS are obviously lower in hypertensive patients than in healthy control group (p>0.05).

CONCLUSION

This study has shown that there is a significant correlation and pathological effect between insulin resistance and cardiovascular endocrine hormone in hypertensive patients, and which plays an important role in genesis and development of hypertension in elderly people.

The wrong white crystals: not salt but sugar as aetiological in hypertension and cardiometabolic disease

Cardiovascular disease is the leading cause of premature mortality in the developed world, and hypertension is its most important risk factor. Controlling hypertension is a major focus of public health initiatives, and dietary approaches have historically focused on sodium. While the potential benefits of sodium-reduction strategies are debatable, one fact about which there is little debate is that the predominant sources of sodium in the diet are industrially processed foods. Processed foods also happen to be generally high in added sugars, the consumption of which might be more strongly and directly associated with hypertension and cardiometabolic risk. Evidence from epidemiological studies and experimental trials in animals and humans suggests that added sugars, particularly fructose, may increase blood pressure and blood pressure variability, increase heart rate and myocardial oxygen demand, and contribute to inflammation, insulin resistance and broader metabolic dysfunction. Thus, while there is no argument that recommendations to reduce consumption of processed foods are highly appropriate and advisable, the arguments in this review are that the benefits of such recommendations might have less to do with sodium-minimally related to blood pressure and perhaps even inversely related to cardiovascular risk-and more to do with highly-refined carbohydrates. It is time for guideline committees to shift focus away from salt and focus greater attention to the likely more-consequential food additive: sugar. A reduction in the intake of added sugars, particularly fructose, and specifically in the quantities and context of industrially-manufactured consumables, would help not only curb hypertension rates, but might also help address broader problems related to cardiometabolic disease.

Renal Denervation

Resistant hypertension, defined as failure to reach blood pressure (BP) goals despite treatment with ≥3 antihypertensive agents, one of which is a diuretic, bears a significant risk of cardiovascular complications. Strong evidence exists, implicating the overactivation of the sympathetic nervous system (SNS) in the pathogenesis of resistant hypertension through complex neurohormonal interactions. Renal denervation is a novel attractive option to achieve adequate blockade of the sympathetic system, with subsequent BP reductions in patients with resistant hypertension. Data have shown promising results regarding the efficacy of the procedure, maintaining a favorable safety profile. As such, the paradigm of resistant hypertension has expanded in other conditions involving a hyperadrenergic state such as the metabolic syndrome, heart failure, arrhythmias, sleep apnea, and renal failure. This review focuses on the pathophysiological rationale of modifying SNS tone and the evidence of the benefits of such intervention beyond BP control.

C-reactive protein and glucose regulation in familial longevity

Earlier, we showed that the offspring from exceptionally long-lived families have a more favorable glucose metabolism when compared with controls. As chronic low-grade inflammation has been regarded as a strong risk factor for insulin resistance, we evaluated if and to what extent the favorable glucose metabolism in offspring from long-lived families could be explained by differences in subclinical inflammation, as estimated from circulating levels of C-reactive protein. We found no difference between the two groups in C-reactive protein levels or in the distribution of C-reactive protein haplotypes. However, among controls higher levels of C-reactive protein were related to higher glucose levels, whereas among offspring levels of C-reactive protein were unrelated to glucose levels. It is a limitation of the current study that its cross-sectional nature does not allow for assessment of cause-effect relationships. One possible interpretation of these data is that the offspring from long-lived families might be able to regulate glucose levels more tightly under conditions of low-grade inflammation. To test this hypothesis, our future research will be focused on assessing the robustness of insulin sensitivity in response to various challenges in offspring from long-lived families and controls.

Relationship of insulin resistance in chronic haemodialysis patients with inflammatory indicators, malnutrition, echocardiographic parameters and 24 hour ambulatory blood pressure monitoring

OBJECTIVE

The relationship between malnutrition, echocardiographic parameters, 24 h ambulatory blood pressure (ABP) parameters and decreased insulin sensitivity index (ISI-S) in chronic haemodialysis patients was investigated.

MATERIAL AND METHODS

ISI-S and inflammatory indicators were measured. The nutritional state was assessed by malnutrition score. Echocardiography and 24 h ABP were performed 1 day before the second haemodialysis session of the week.

RESULTS

ISI-S was inversely correlated with the night-time mean blood pressure (BP)/day-time mean BP ratio (p = 0.021) and malnutrition score (p < 0.01). High-sensitivity C-reactive protein, night-time mean BP/day-time mean BP and vena cava collapse index were independent risk factors affecting ISI-S (p < 0.001; beta = 0.412, p = 0.025; beta = -0.204, p < 0.001; beta = -0.465).

CONCLUSIONS

The decrease in ISI-S along with the hypervolaemia suggests that volume overload is a contributory factor in the pathogenesis of insulin resistance in patients with chronic renal failure. This study indicates that, in addition to the traditional cardiovascular risk factors in these patients, insulin resistance can be regarded as a risk factor, but not an independent one, mainly a reflection of the underlying culprit, hypervolaemia.

Positive relationship between plasma leptin level and hypertension

Leptin is an adipose tissue-derived hormone shown to be related to metabolic, inflammatory, and hemostatic factors involved in hypertension development. Animal studies suggest that higher leptin levels may activate the sympathetic nervous system and cause elevations in blood pressure (BP). However, few studies have examined the association between leptin and hypertension in humans. Also it is not clear whether this association is present among women as well as men. Therefore, we examined the association between plasma leptin levels and hypertension in a representative sample of US adults. We examined the third National Health and Nutrition Examination Survey participants >20 years of age (n=5599; 54.7% women). Plasma leptin levels were categorized into quartiles (women: <7.68, 7.68 to 13.18, 13.19 to 21.70, >21.70 fg/L; men: <2.64, 2.64 to 4.36, 4.37 to 7.12, >7.12 fg/L). Hypertension was defined as BP-reducing medication use or having systolic BP ≥140 mm Hg and/or diastolic BP ≥90 mm Hg. We found that higher plasma leptin levels were positively associated with hypertension after adjusting for age, sex, race/ethnicity, education, smoking, alcohol intake, body mass index, diabetes mellitus, serum cholesterol, and C-reactive protein. Compared with quartile 1 of leptin (referent), the odds ratio (95% CI) of hypertension associated with quartile 4 was 1.89 (1.24 to 2.09; P for trend=0.0036). Subgroup analyses examining the relation between leptin and hypertension by sex and body mass index categories also showed a consistent positive association. In conclusion, higher plasma leptin levels are associated with hypertension both among women as well as men in a representative sample of US adults.

Aortic elastic properties in nonalcoholic fatty liver disease

BACKGROUND

Recent studies have shown that patients with nonalcoholic fatty liver disease (NAFLD) have an increased risk of developing cardiovascular disease. Aortic stiffness, an early marker of arteriosclerosis, is associated with cardiovascular mortality. In this study, the aortic elastic properties of nondiabetic, normotensive NAFLD patients were evaluated.

METHODS

Thirty-five patients with NAFLD and 30 age-matched and sex-matched healthy controls were enrolled. Aortic distensibility, aortic strain, aortic stiffness index (ASI), left ventricular mass index (LVMI), homeostasis model assessment of insulin resistance (HOMA-IR) and fasting lipid parameters were assessed in both the groups.

RESULTS

ASI was higher in NAFLD patients (7.1+/-2.0) than in the control group (3.8+/-1.0) (P<0.01). Aortic distensibility and aortic strain were also significantly decreased in NAFLD patients as compared with the control group (2.9+/-0.7 cm/dyn vs. 6.3+/-2.4 cm/dyn, P<0.0001 and 7.1+/-1.7 vs. 14.5+/-4.0, P<0.0001, respectively). Although ASI was significantly correlated with age, HOMA-IR, waist circumference, body mass index and LVMI, a stepwise multiple linear regression analysis showed that HOMA-IR and LVMI were the only variables associated with ASI index [(standardized beta coefficient= 0.41, P=0.004, overall R=0.17) and (standardized beta coefficient=0.31, P=0.02, overall R=0.10), respectively].

CONCLUSION

Our data suggest that aortic elasticity is significantly impaired and is also associated with insulin resistance and LVMI in NAFLD patients, which may contribute to the relationship between NAFLD and the increased risk of cardiovascular disease among these patients.

Early left ventricular mechanics abnormalities in prehypertension: a two-dimensional strain echocardiography study

BACKGROUND

Prehypertension predicts established hypertension. In this study, the aim was to analyze left ventricular (LV) mechanics in borderline prehypertensive (pre-HT) and hypertensive (HT) subjects through two-dimensional (2D)-strain echocardiography and then evaluate possible relations between cardiac parameters and insulin metabolism (homeostasis model assessment of insulin resistance (HOMA(IR)).

METHODS

Seventy-four consecutive newly diagnosed, untreated HT were divided, on the basis of their office blood pressure (BP) measurements, confirmed by ambulatory BP monitoring (ABPM), in 41 borderline pre-HT (ABPM: 122.5 +/- 6.7/76.2 +/- 5.2 mm Hg) and 33 never-treated mild HT (ABPM: 138.3 +/- 7.3/87.6 +/- 7.1 mm Hg). Thirty-three healthy normotensive (NT) controls (ABPM: 114.8 +/- 6.3/73.1 +/- 6.1 mm Hg) (P < 0.0001) were also studied (NT). All subjects performed 2D color Doppler and pulsed-wave tissue Doppler imaging (PW-TDI).

RESULTS

Left ventricular mass (LVM) was significantly higher in pre-HT (39.2 +/- 8.7 g/m(2.7)) and in HT (43.6 +/- 8.5 g/m(2.7)) compared with NT (30.9 +/- 7.4 g/m(2.7)) (P < 0.0001). A mild LV diastolic dysfunction was found both with Doppler mitral flow velocity and PW-TDI at mitral annulus level analysis. Longitudinal 2D strain in pre-HT (-18.9% +/- 3.4) and in HT (-18.0% +/- 3.3) was significantly lower than in NT (-23.9% +/- 3.0) (P < 0.002). These LV abnormalities were associated with systolic ABPM, LVM, and HOMA(IR).

CONCLUSIONS

Early abnormalities of LV longitudinal systolic deformation were found both in pre-HT and HT, together with a mild LV diastolic dysfunction. In both groups this early cardiac systolic and diastolic dysfunction is associated to insulin resistance, systolic pressure load, and cardiac remodeling.

Comparative evaluation of whole body and hepatic insulin resistance using indices from oral glucose tolerance test in morbidly obese subjects with nonalcoholic Fatty liver disease

Nonalcoholic Fatty Liver Disease (NAFLD) is the hepatic manifestation of metabolic syndrome and is a marker of Insulin Resistance (IR). Euglycemic-hyperinsulinemic clamp is the gold standard for measuring whole body IR (hepatic + peripheral IR). However, it is an invasive and expensive procedure. Homeostasis Model Assessment Index for Insulin Sensitivity (HOMA-IS), Quantitative Insulin Sensitivity Check Index (QUICKI) for hepatic IR and Insulin Sensitivity Index (ISI(0,120)), and Whole Body Insulin Sensitivity Index (WBISI) for whole body IR are the indices calculated after Oral Glucose Tolerance Test (OGTT). We used these indices as noninvasive methods of IR (inverse of insulin sensitivity) estimation and compared hepatic/peripheral components of whole body IR in NAFLD. Methods. 113 morbidly obese, nondiabetic subjects who underwent gastric bypass surgery and intraoperative liver biopsy were included in the study. OGTT was performed preoperatively and the indices were calculated. Subjects were divided into closely matched groups as normal, fatty liver (FL) and Non-Alcoholic Steatohepatitis (NASH) based on histology. Results. Whole body IR was significantly higher in both FL and NASH groups (NAFLD) as compared to Normal, while hepatic IR was higher only in NASH from Normal. Conclusions. FL is a manifestation of peripheral IR but not hepatic IR.

High prevalence of impaired fasting glucose in Chinese children and adolescents with prehypertension/hypertension

AIM

To assess the prevalence of impaired fasting glucose among Chinese children and adolescents with prehypertension/hypertension (PHP/HP), overweight/obesity (OW/OB) or both in the general population.

METHODS

In total, 3409 children and adolescents among the age group of 10-18 years were enrolled. These subjects were then divided into four groups: OW/OB, PHP/HP, OW/OB + PHP/HP and a control group. Fasting plasma glucose (FPG) and lipid levels were measured in children with a body mass index > or =85th percentile and/or blood pressure > or =90th percentile and in 100 subjects randomly selected from the control group. The oral glucose tolerance test was performed in all the subjects with fasting glucose > or =5.6 mmol/L.

RESULTS

Eighty-one impaired fasting glucose subjects and one girl with type 2 diabetes were identified. The prevalence of impaired fasting glucose in PHP/HP (7.03%) was not significantly different from that in the OW/OB + PHP/HP group (8.59%), but was higher than that in the OW/OB group (3.31%).

CONCLUSION

Although the American Diabetes Association does not recommend the FPG test for children and adolescents with PHP/HP, in this study, we found that children and adolescents with PHP/HP have a higher prevalence of impaired fasting glucose than those with OW/OB. Further validation of these findings is warranted and a type 2 diabetes screening protocol for Chinese children and adolescents needs to be established.

Impact of body mass index on blood pressure levels in patients with polycystic ovary syndrome

As there is controversy about the prevalence of hypertension in patients with polycystic ovary syndrome (PCOS) and, up to the present moment, no studies have evaluated the impact of body mass index (BMI) on blood pressure levels (BP) in these patients, we studied retrospectively sixty-nine patients with PCOS, with BMI of 29.0 ± 6.7 kg/m² and aged 25.6 ± 5.6 yr, subdivided into three groups according to BMI (normal, overweight and obese) and evaluated regarding BP (mercury sphygmomanometer), basal hormonal profile, fasting glucose, and insulin sensitivity (HOMA-IR). Mean systolic blood pressure (SBP) and diastolic blood pressure (DBP) were normal (118.1 ± 17.0 and 74.7 ± 11.5 mmHg, respectively), with a hypertension prevalence of 20.3%. Of these patients, 78.6% were obese and 21.4% were overweight. When the groups were compared according to BMI, a significant increase in SBP and DBP was observed (higher in overweight and obese patients for SBP and higher in obese for DBP), as well as a significant progressive increase in glucose, insulin, homeostatic model assessment, and a significant progressive decline in LH levels. When the patients were subdivided as normotensive or hypertensive, a significant difference was observed only for BMI (28.2 ± 6.1 and 34.7 ± 8.6 kg/m², respectively; p = 0.007). In conclusion, we observed a significant and progressive impact of BMI on blood pressure levels in our patients with polycystic ovary syndrome.

Evaluation of Insulin Resistance and Sodium Sensitivity in Normotensive Offspring of Hypertensive Individuals

BACKGROUND

Sodium sensitivity (SS) and insulin resistance (IR) might be a common link in the pathogenesis of essential hypertension. The aim of the present study is to investigate the relationship, if any, between SS and IR in a population with a family predisposition to develop hypertension.

METHODS

Twenty normotensive subjects aged 20 to 40 years with a family history of hypertension (1 or both parents hypertensive) and no other risk factor (group A) and 10 normotensive subjects aged 20 to 40 years without a family history of hypertension (group B) were enrolled. SS and IR were estimated using the euglycemic clamp technique and correlated in both groups. Blood pressure, mean blood pressure (MAP), and biochemical control were recorded.

RESULTS

The frequency of SS was equal in offspring of hypertensive subjects and the control group. Individuals with a family history of hypertension had a tendency to develop IR (45%) compared with the control group (20%). This group had a greater MAP at both salt-loading and salt-deprivation periods. Increased IR was associated with increased MAP. No significant relationship was found between SS and IR in either the entire sample or the subgroup of individuals with a family history of hypertension. Serum urea and total cholesterol levels were significantly greater in group A. Age, sex, and body mass index were not related to the presence of IR or SS in either group.

CONCLUSION

SS and IR do not relate in young normotensive adults or offspring of hypertensive parents. However, the latter may comprise a high-risk group, currently normotensive, who have an increased possibility to present or develop IR in early adolescent life. Moreover, the increased IR is related to the greater MAP in group A. Thus, they are subject to increased cardiovascular risk because of the subsequent disturbed glucose and lipid metabolism.

Diagnosing abnormal glucose tolerance in hypertensive women: are we making the best choice?

Essential hypertension is a condition of peripheral insulin resistance; thus, fasting plasma glucose level (FPG) alone may not identify glucose tolerance abnormalities. To evaluate the value of an FPG of 100 mg/dL in the detection of these abnormalities in hypertensive women and to identify clinical markers of a high risk of glucose intolerance indicative of further investigation, the authors studied 313 hypertensive women, without known diabetes, in whom an oral glucose tolerance test (OGTT) was performed. The authors demonstrated that FPG alone was not sufficient to identify 27.6% of hypertensive women with glucose intolerance. In this subgroup, the association of waist circumference >or=97 cm and FPG >or=100 mg/dL increased the risk of glucose intolerance with an odds ratio of 6.97. The authors suggest that OGTT should be performed in hypertensive women with normal FPG but with FPG >or=90 mg/dL or waist circumference >or=97 cm.

Assessment and mathematical modeling of glucose turnover and insulin sensitivity in lean and obese cats

Insulin sensitivity (SI) of glucose disposal can be quantified with the euglycemic hyperinsulinemic clamp (EHC) with tracer glucose infusion. True steady state is, however, difficult to achieve, and non-steady state analysis of EHC data is preferred. This analysis requires information on glucose kinetics that can be obtained from bolus injection of cold and tracer glucose. The aim of this study was to assess glucose kinetics in cats. Mathematical modeling and non-steady state analysis was applied to assess effects of obesity on glucose turnover, glycolysis/glycogen synthesis, SI, and inhibition of endogenous glucose production (EGP) in lean cats (L) and obese cats (O). D-[3-(3)H]-glucose kinetics and 3H-H2O production were analyzed in 4 L and 4 O with three-compartment modeling. Frequently sampled insulin-modified intravenous glucose tolerance tests (FSIGT) with minimal model analysis were performed in 5L and 3 O to assess glucose kinetics and SI. EHC was performed in 10 L and 10 O with primed-constant infusion of 3H-glucose. Data were analyzed with a modified minimal model segregating suppression of EGP by insulin using a non-linear mixed-effects population approach. FSIGT provided estimates of SI, glucose effectiveness SG, and distribution volume. EHC provided estimates of SI, SG, glycolysis, and suprabasal insulin concentration for 50% EGP inhibition. Obesity appears to affect glucose distribution but not utilization at basal insulin, and reduces SI estimated by FSIGT and EHC. Differences in SI between FSIGT and EHC depend on different descriptions of EGP inhibition by insulin. Finally, glucose disposal at basal insulin appears to occur entirely through glycolysis, whereas significant amounts of glucose are sequestrated from oxidation during EHC.

Insulin resistance: potential role of the endogenous nitric oxide synthase inhibitor ADMA

The insulin resistance syndrome (IRS) is considered to be a new target of risk-reduction therapy. The IRS is a cluster of closely associated and interdependent abnormalities and clinical outcomes that occur more commonly in insulin-resistant/hyperinsulinemic individuals. This syndrome predisposes individuals to type 2 diabetes, cardiovascular diseases, essential hypertension, certain forms of cancer, polycystic ovary syndrome, nonalcoholic fatty liver disease, and sleep apnea. In patients at high risk for cardiovascular diseases, endothelial dysfunction is observed in morphologically intact vessels even before the onset of clinically manifest vascular disease. Indeed, there are several lines of evidence that indicate that endothelial function is compromised in situations where there is reduced sensitivity to endogenous insulin. It is well established that a decreased bioavailability of nitric oxide (NO) contributes to endothelial dysfunction. Furthermore, NO may modulate insulin sensitivity. Activation of NO synthase (NOS) augments blood flow to insulin-sensitive tissues (i.e. skeletal muscle, liver, adipose tissue), and its activity is impaired in insulin resistance. Inhibition of NOS reduces the microvascular delivery of nutrients and blunts insulin-stimulated glucose uptake in skeletal muscle. Furthermore, induction of hypertension by administration of the NOS inhibitor NG-monomethyl-L-arginine is also associated with insulin resistance in rats. Increased levels of asymmetric dimethylarginine (ADMA) are associated with endothelial vasodilator dysfunction and increased risk of cardiovascular diseases. An intriguing relationship exists between insulin resistance and ADMA. Plasma levels of ADMA are positively correlated with insulin resistance in nondiabetic, normotensive people. New basic research insights that provide possible mechanisms underlying the development of insulin resistance in the setting of impaired NO bioavailability will be discussed.

The metabolic syndrome: is this diagnosis necessary?

Values of insulin-mediated glucose disposal vary continuously throughout a population of apparently healthy persons, and a difference of > or = 600% exists between the most insulin-sensitive and the most insulin-resistant persons. Approximately 50% of this variability can be attributed to differences in adiposity (25%) and fitness (25%), with the remaining 50% likely of genetic origin. The more insulin-resistant a person, the more likely that he or she will develop some degree of glucose intolerance, high triacylglycerol and low HDL concentrations, essential hypertension, and procoagulant and proinflammatory states, all of which increase the risk of cardiovascular disease (CVD). To identify persons at greater CVD risk because of these abnormalities, the World Health Organization, the Adult Treatment Panel III, and the International Diabetes Federation created a new diagnostic category, the metabolic syndrome. Although the components of the 3 versions of the metabolic syndrome are similar, the specific values for those components that define an abnormality are somewhat different, and the manner in which the abnormalities are used to make a positive diagnosis varies dramatically from version to version. This review will summarize the similarities in and differences between the 3 versions of the metabolic syndrome, point out that the clustering of components that make up all 3 definitions of the metabolic syndrome is not accidental and occurs only in insulin-resistant persons, develop the argument that diagnosing the metabolic syndrome in a person has neither pedagogical nor clinical utility, and suggest that the clinical emphasis should be on treating effectively any CVD risk factor that is present.

Insulin resistance--a common link between type 2 diabetes and cardiovascular disease

Evidence suggests that diabetes and cardiovascular disease (CVD) may share an underlying cause(s), a theory known as the 'common soil' hypothesis. Insulin resistance is central both to the progression from normal glucose tolerance to type 2 diabetes and to a constellation of cardiovascular risk factors known as the metabolic syndrome. These risk factors include visceral obesity and dyslipidaemia characterized by low levels of high-density lipoprotein cholesterol, hypertriglyceridaemia and raised small dense low-density lipoprotein particle levels. Changes in adipose tissue mass and metabolism may link insulin resistance and visceral obesity, a condition that is common in type 2 diabetes. Furthermore, weight reduction, increased physical activity, metformin and acarbose have been shown to reduce the development of type 2 diabetes in genetically predisposed subjects and may decrease the high cardiovascular risk of patients with diabetes. Some fatty acid derivatives can affect energy metabolism by activating peroxisome proliferator-activated receptors (PPARs), nuclear receptors that play a key role in energy homeostasis. These receptors represent an ideal therapeutic target for reducing cardiovascular risk, because they are involved in the regulation of both insulin action and lipid metabolism. In addition to lifestyle changes, PPARgamma agonists such as thiazolidinediones are frequently beneficial and have been shown to ameliorate insulin resistance, while activation of PPARalpha (e.g. by fibrates) can lead to improvements in free fatty acid oxidation and lipid profile, and a reduction in cardiovascular events. The development of agents with both PPARalpha and PPARgamma activity promises added benefits with amelioration of insulin resistance, delayed progression to and of type 2 diabetes and a reduction of CVD.

Ethanolic extract of Spirulina maxima alters the vasomotor reactivity of aortic rings from obese rats

BACKGROUND

Aortic rings with endothelium excised from fructose-fed obese rats develop more tension in response to phenylephrine and relax less in response to carbachol than corresponding rings from lean rats. This altered vascular reactivity is prevented when Spirulina maxima is added to the fructose-rich diet. In the present study the effects of a raw ethanolic extract of Spirulina maxima on the vasomotor responses of aorta rings from sucrose-fed obese hypertensive rats were analyzed.

METHODS

The experiments were performed on aorta rings from sucrose-fed obese male rats. For each experiment, a pair of rings from the same aorta (one with intact endothelium, the other without a functional endothelium) was used. In this study we analyzed, in vitro, the effects of the ethanolic extract of Spirulina maxima on the reactivity of the aortic rings to phenylephrine and to carbachol.

RESULTS

On rings with endothelium, the extract produced the following effects: a) a concentration-dependent (0.06-1.0 mg/mL) decrease of the contractile response to phenylephrine; b) a rightward shift and a decrease in maximal developed tension, of the concentration-response curve to phenylephrine; c) a concentration-dependent relaxation of phenylephrine-precontracted rings. These effects persisted in the presence of indomethacin but were prevented by L-NAME. The extract had no effect on the concentration-response curve of phenylephrine-precontracted rings to carbachol. On endothelium-denuded rings the extract caused a significant rightward shift of the concentration response curve to phenylephrine without any effect on maximal tension development.

CONCLUSIONS

These results suggest that, in rings from obese rats, the extract, in addition to increasing the synthesis/release of NO, also inhibits the synthesis/release of a cyclooxygenase-dependent vasoconstrictor metabolite of arachidonic acid, which is increased in obesity.

Glucose metabolism in patients with essential hypertension

PURPOSE

Arterial hypertension is an insulin-resistant condition that has been associated with an increased incidence of diabetes. We assessed the prevalence of glucose abnormalities in a population of patients with essential hypertension.

METHODS

In this cross-sectional study, 420 consecutively referred essential hypertensive patients were studied at 16 hypertension clinics in university and community hospitals of Spain. Fasting and 2-hour plasma glucose and insulin levels were determined in nondiabetic patients.

RESULTS

An abnormal glucose metabolism was diagnosed in 68.5% (95% confidence interval [CI], 63.7%-72.9%) of the patients. Isolated insulin resistance, defined by a homeostasis model assessment-estimated insulin resistance (HOMA-IR) equal to or above 3.8, was shown in 9.3% (95% CI, 6.7%-12.5%); impaired fasting glucose in 11.2% (95% CI, 8.6%-14.7%); impaired glucose tolerance in 22.5% (95% CI, 18.5%-26.9%); silent undiagnosed type 2 diabetes in 11.5% (95% CI, 8.6%-14.5%); and known diabetes mellitus in 13.9% (95% CI, 10.4%-17.2%) of the patients. According to the European Group for the Study of Insulin Resistance and the Adult Treatment Program III criteria, the metabolic syndrome was diagnosed in 41.5% (95% CI, 35.9%-47.3%) and 47.9% (95% CI, 43.1%-52.8%) of the patients, respectively. The prevalence of left ventricular hypertrophy (defined by a left ventricular mass index [LVMI] >125 g/m2 was 44.2%. The relation between HOMA-IR and LVMI was statistically nonsignificant, and the LVMI values in the HOMA-IR quartiles were similar. Only 27 patients (6.4%) showed good control of cardiovascular risk factors. In most patients (273, 65%; 95% CI, 60.3%-69.4%) 2 or more cardiovascular risk factors were identified as not being under control.

CONCLUSIONS

Two thirds of the patients attending hypertension clinics with essential hypertension show an abnormal glucose metabolism. The metabolic syndrome can be identified in a substantial number of these patients, and 2 or more cardiovascular risk factors are not controlled in the majority of patients.

Insulin resistance in hypertension quantified by oral glucose tolerance test: comparison of methods

Four methods reported in the literature for evaluation of insulin sensitivity indexes from oral glucose tolerance tests (OGTTs) were analyzed and compared in order to test their ability to discriminate the insulin-resistant state in hypertension. To this aim, 15 normoglycemic subjects, not affected by metabolic syndrome, underwent a 22-sample, 300-minute OGTT. Eight subjects were normotensive (mean age, 47.0 +/- 4.2 years) and 7 were hypertensive (mean age, 53.6 +/- 1.6 years). The following insulin sensitivity indexes were computed and compared: (a) 2 indexes, ISIE22/300 and ISIE8/180, provided by an integral equation (IE) method applied to the full OGTT and to a reduced 8-sample, 180-minute data subset, respectively; (b) 2 indexes, ISOGIS180 and ISOGIS120, computed by the oral glucose, insulin sensitivity (OGIS) method, which only requires 3 blood samples taken within 180 and 120 minutes, respectively; (c) an index, ISISI, which considers fasting and mean insulinemia and glycemia measured during a 5-sample, 120-minute OGTT; and (d) an index, ISMCR, which considers body mass index and requires 2 blood samples taken within 120 minutes. Except the ISOGIS180, all other indexes were able to detect a significant reduction (unpaired Student t test, P < .05) of insulin sensitivity in our hypertensive group compared with the normotensive group. Failure of ISOGIS180 was explained by the fact that this index did not capture the information portrayed by the peak of insulinemia in hypertensive patients, which occurred around the 90th minute. Intraclass correlation coefficients higher than 0.89 demonstrated a substantial agreement between ISIE22/300 and ISIE8/180 indexes. These are the only indexes characterized by units of measure consistent with the definition of insulin sensitivity as the ability of insulin to enhance glucose effectiveness.

The Cardiometabolic Syndrome as a Cardiovascular Risk Factor

The cardiometabolic syndrome (CMS) is associated with cardiovascular disease (CVD) and includes a constellation of risk factors such as central obesity, hypertension, insulin resistance, dyslipidemia, microalbuminuria, and hypercoagulability. Collectively, these risk factors increase CVD endpoints such as stroke, congestive heart failure, chronic kidney disease (CKD), and overall mortality. The CMS is associated with endothelial dysfunction, inflammation, abnormal thrombolysis, and increased oxidative stress that accentuate progression of CVD. We will review how the varying components of the CMS relate to an increased CVD and renal disease risk.

Rosiglitazone effects on blood pressure and metabolic parameters in nondipper diabetic patients

The class of antidiabetic drugs called thiazolidinediones (TZD), possesses as its main feature, the ability to ameliorate insulin sensitivity. As diabetes and hypertension share common ground in insulin resistance, the aim of this study was to evaluate if Rosiglitazone (RSG) may exert antihypertensive properties. Diabetic patients selected for the study were free from complications and/or other diseases. They were not known hypertensives, not on any antihypertensive treatment and they were on up to 2550 mg of metformin per day. Twenty-four hour blood pressure (24-h BP) measurements were recorded and monitored. Thirty-eight patients with a nocturnal decline in BP less than 10% (nondippers) participated in the study. Patients were randomly assigned to metformin+placebo (19 patients: group A) or to metformin+RSG 4 mg b.i.d. (19 patients: group B). Patients from both groups continued to take the same dosage of metformin during the study period. After 12 months of treatment, 24-h BP measurements were recorded. Fasting blood glucose, insulin, HbA1c, total cholesterol and trigliceryde levels were taken at the beginning and again at the end of the study. After 12 months of treatment with RSG+metformin we observed an amelioration of metabolic parameters (reduction of HOMA index, glucose, insulin, HbA1c, total cholesterol and triglycerides); an increase in body weight and BMI; a significant reduction of systolic and diastolic BP values both during the day and night and variations in the HOMA index were positively related to the reduction of diurnal and nocturnal BP (HOMA index versus diurnal systolic BP (P<0.001; r2=0.727); versus diastolic BP (P<0.001; r2=0.757); versus nocturnal systolic BP (P<0.001; r2=0.842), versus diastolic BP (P<0.001; r2=0.773)). These findings indicate firstly that RSG is able to induce a reduction of BP and secondly the amelioration of insulin sensitivity is associated with the reduction of BP.

Diagnosis of impaired glucose tolerance in hypertensive patients in daily clinical practice

Many patients with hypertension suffer from impaired glucose tolerance or type 2 diabetes mellitus. Although these diagnoses are generally simple and reliable, it is more difficult to diagnose impaired glucose tolerance. As the gold standard (oral glucose tolerance test (OGTT)) is complicated to perform, a simpler alternative would be useful. The aims of the Pre-Diabetes Score study are to correlate demographic and/or laboratory parameters that are clinically simple to determine with the results of the OGTT and to determine the diagnostic significance of the combinations of parameters with regard to impaired glucose tolerance. A total of 260 patients were included in the evaluation; 39% had impaired glucose tolerance and 12% had diabetes mellitus. A combination of HbA1c of > or =6%, a venous fasting glucose of > or =110 mg/dl, an age of > or =55 years, a systolic blood pressure of > or =140 mmHg and an enlarged waist size is highly predictive of impaired glucose tolerance.

Insulin resistance in spontaneously hypertensive rats is associated with endothelial dysfunction characterized by imbalance between NO and ET-1 production

Insulin stimulates production of NO in vascular endothelium via activation of phosphatidylinositol (PI) 3-kinase, Akt, and endothelial NO synthase. We hypothesized that insulin resistance may cause imbalance between endothelial vasodilators and vasoconstrictors (e.g., NO and ET-1), leading to hypertension. Twelve-week-old male spontaneously hypertensive rats (SHR) were hypertensive and insulin resistant compared with control Wistar-Kyoto (WKY) rats (systolic blood pressure 202 +/- 11 vs. 132 +/- 10 mmHg; fasting plasma insulin 5 +/- 1 vs. 0.9 +/- 0.1 ng/ml; P < 0.001). In WKY rats, insulin stimulated dose-dependent relaxation of mesenteric arteries precontracted with norepinephrine (NE) ex vivo. This depended on intact endothelium and was blocked by genistein, wortmannin, or N(omega)-nitro-l-arginine methyl ester (inhibitors of tyrosine kinase, PI3-kinase, and NO synthases, respectively). Vasodilation in response to insulin (but not ACh) was impaired by 20% in SHR (vs. WKY, P < 0.005). Preincubation of arteries with insulin significantly reduced the contractile effect of NE by 20% in WKY but not SHR rats. In SHR, the effect of insulin to reduce NE-mediated vasoconstriction became evident when insulin pretreatment was accompanied by ET-1 receptor blockade (BQ-123, BQ-788). Similar results were observed during treatment with the MEK inhibitor PD-98059. In addition, insulin-stimulated secretion of ET-1 from primary endothelial cells was significantly reduced by pretreatment of cells with PD-98059 (but not wortmannin). We conclude that insulin resistance in SHR is accompanied by endothelial dysfunction in mesenteric vessels with impaired PI3-kinase-dependent NO production and enhanced MAPK-dependent ET-1 secretion. These results may reflect pathophysiology in other vascular beds that directly contribute to elevated peripheral vascular resistance and hypertension.

Why Syndrome X? From Harold Himsworth to the insulin resistance syndrome

Although the concept of Syndrome X was introduced in the Banting Medal address of 1988 (Reaven, 1988), the notion that led to its genesis had started approximately 50 years earlier. In this short history, an attempt will be made to trace the two paths of scientific discovery that were formally merged in New Orleans in 1988 to form the scientific foundation of Syndrome X. In addition, the developments in the last 16 years that have led from the notion of Syndrome X to the broader concept of an Insulin Resistance Syndrome (IRS) will be briefly summarized.

Akt mediates the cross-talk between beta-adrenergic and insulin receptors in neonatal cardiomyocytes

Upregulation of the sympathetic nervous system plays a key role in the pathogenesis of insulin resistance. Although the heart is a target organ of insulin, few studies have examined the mechanisms by which beta-adrenergic stimulation affects insulin sensitivity in cardiac muscle. In this study, we explored the molecular mechanisms involved in the regulation of the cross-talk between beta adrenergic and insulin receptors in neonatal rat cardiomyocytes and in transgenic mice with cardiac overexpression of a constitutively active mutant of Akt (E40K Tg). The results of this study show that beta-adrenergic receptor stimulation has a biphasic effect on insulin-stimulated glucose uptake. Short-term stimulation induces an additive effect on insulin-induced glucose uptake, and this effect is mediated by phosphorylation of Akt in threonine 308 through PKA/Ca2+-dependent and PI3K-independent pathway, whereas insulin-evoked threonine phosphorylation of Akt is exclusively PI3K-dependent. On the other hand, long-term stimulation of beta-adrenergic receptors inhibits both insulin-stimulated glucose uptake and insulin-induced autophosphorylation of the insulin receptor, and at the same time promotes threonine phosphorylation of the insulin receptor. This is mediated by serine 473 phosphorylation of Akt through PKA/Ca2+ and PI3K-dependent pathways. Under basal conditions, E40K Tg mice show increased levels of threonine phosphorylation of the beta subunit of the insulin receptor and blunted tyrosine autophosphorylation of the beta-subunit of the insulin receptor after insulin stimulation. These results indicate that, in cardiomyocytes, beta-adrenergic receptor stimulation impairs insulin signaling transduction machinery through an Akt-dependent pathway, suggesting that Akt is critically involved in the regulation of insulin sensitivity.

A novel approach to treatment of hypertension in diabetic patients - a multicenter, double-blind, randomized study comparing the efficacy of combination therapy of Eprosartan versus Ramipril with low-dose Hydrochlorothiazide and Moxonidine on blood pressure levels in patients with hypertension and associated diabetes mellitus type 2 - rationale and design [ISRCTN55725285]

Hypertension and diabetes mellitus are closely interrelated and coexist in as many as two-thirds of patients with type 2 diabetes. The consequent risk of such an association is an accelerated development of atherosclerotic cardiovascular disease and nephropathy complications.In choosing an antihypertensive agent, effectiveness needs to be accompanied by favourable metabolic, cardioprotective, and nephroprotective properties. Given the multifactorial nature of hypertension, the approach that has gained widespread agreement is treatment with more than one agent. Agents with different mechanisms of action increase antihypertensive efficacy because of synergistic impacts on the cardiovascular system. Combination therapy allows the use of lower doses of each antihypertensive agent which accounts for the excellent tolerability of combination products.The aim of the present study is to quantify the efficacy of combination therapy of Eprosartan 600 mg respectively Ramipril 5 mg with low-dose Hydrochlorothiazide and Moxonidine on blood pressure levels in patients with essential hypertension and associated diabetes mellitus type 2.The use of monotherapy (Eprosartan or Ramipril) followed by addition of low-dose Hydrochlorothiazide as second agent and of Moxonidine as a third agent will be individualized to the severity of hypertension in the particular patient and to his/her degree of response to current treatment.

The metabolic syndrome: one step forward, two steps back

Individuals with insulin resistance are at increased risk of glucose intolerance, dyslipidaemia and essential hypertension. In 1988, it was proposed that this cluster of abnormalities associated with insulin resistance identifies individuals at increased risk for cardiovascular disease. Recently, in an effort to raise awareness of this problem, both the World Health Organisation (WHO) and the Adult Treatment Panel III (ATP III) of the National Cholesterol Education Program have suggested a set of clinical criteria to diagnose individuals with what they both refer to as the metabolic syndrome. Although using the same term, the two groups have different goals for creating this diagnosis and different criteria to identify individuals, which relate to their different institutional goals. This review critically evaluates the similarities and differences between the two groups' concepts of the metabolic syndrome and questions the clinical utility of making the diagnosis with either set of definitions.

Effects of cardiac rehabilitation on exercise capacity in Type 2 diabetic patients with coronary artery disease

AIM

To determine whether Type 2 diabetic patients with coronary disease can obtain, after cardiac rehabilitation, a similar benefit on exercise capacity to non-diabetic coronary individuals.

RESEARCH DESIGN AND METHODS

Fifty-nine Type 2 diabetic patients and 36 age-matched non-diabetic patients were enrolled in a 2-month cardiac rehabilitation programme, after an acute coronary event. At the beginning and at the end of the cardiac rehabilitation programme, each subject underwent a cardiopulmonary exercise test to assess exercise capacity as measured by peak workload, duration of test, maximal heart rate, peak VO2 and anaerobic threshold. The two groups of patients were not different in age, sex ratio, type of coronary event or left ventricular ejection fraction.

RESULTS

The baseline exercise capacity parameters were not different between diabetic and non-diabetic subjects. After cardiac rehabilitation, improvement of exercise capacity was significantly less in patients with diabetes compared with those without diabetes: peak workload (19% vs. 29%, P = 0.022), peak VO2 (13% vs. 30%, P = 0.002), anaerobic threshold (12% vs. 31%, P = 0.017). In the diabetic patients, a significant inverse relation between fasting blood glucose and change in peak VO2 was observed on both univariate (r = -0.40, P = 0.002) and multivariate (P = 0.001) analyses.

CONCLUSIONS

The benefit of cardiac rehabilitation, after an acute ischaemic heart event, in exercise capacity is significantly lower in Type 2 diabetic patients. The response to cardiac rehabilitation in those with diabetes appears to be influenced by blood glucose levels.