Domenico Galzerano

Daily vitamin E supplements improve metabolic control but not insulin secretion in elderly type II diabetic patients

OBJECTIVE To investigate the potential metabolic benefits deriving from daily vitamin E administration in type II diabetic patients. RESEARCH DESIGN AND METHODS Twenty-five type II diabetic patients were invited to randomly take placebo or vitamin E (d-α-tocopherol; 900 mg/day) along a similar 3-mo period in a double-blind, crossover procedure. A wash-out period of 30 days separated the two treatment periods. At the end of each treatment period blood samples were drawn for plasma metabolites determination, and an intravenous glucose tolerance test (25 g of glucose as bolus in 3 min) was performed. During this study oral hypoglycemic agents were not discontinued or changed in their dosage. RESULTS Chronic vitamin E administration reduced plasma glucose (8.3 ± 0.3 vs. 7.5 ± 0.2 mM, P > 0.05), triglycerides (2.27 ± 0.08 vs. 1.67 ± 0.09 mM, P < 0.02), free fatty acids (786 ± 116 vs. 483 ± 64 mM), total cholesterol (6.74 ± 0.09 vs. 5.50 ± 0.10 mM, P < 0.05), low-density lipoprotein cholesterol (4.73 ± 0.11 vs. 3.67 ± 0.07 mM, P < 0.04), and apoprotein B (1.7 ± 0.3 vs. 1.0 ± 0.1 g/L) levels but did not affect β-cell response to glucose. HbA1 levels (7.8 ± 0.3 vs. 7.1 ± 0.5%, P < 0.05) were also significantly lowered after chronic vitamin E administration. CONCLUSIONS Daily vitamin E supplements seem to produce a minimal but significant improvement in the metabolic control in type II diabetic patients. More studies are necessary before conclusions can be drawn about the safety of vitamin E during long-term administration.

Total-body and myocardial substrate oxidation in congestive heart failure

Congestive heart failure is a condition associated with increased plasma norepinephrine levels, which have been demonstrated to impair glucose handling. In the present study, 10 patients suffering from congestive heart failure and 10 healthy age- and body mass index-matched subjects were submitted to a hyperinsulinemic (insulin infusion rate, 0.5 mU/kg.min-1) glucose clamp, while simultaneous D-3H-glucose infusion and indirect calorimetry allowed for determination of glucose turnover parameters and substrate oxidation, respectively. On a separate day, basal local (myocardial) indirect calorimetry was also performed. Our data demonstrate that in congestive heart failure, fasting myocardial glucose oxidation (Gox) was inhibited with a simultaneous increase in lipid oxidation (Lox). In our patients, a significant decrease in total-body insulin-stimulated glucose metabolism (31.0 +/- 0.5 v 20.3 +/- 0.4 mumol/kg.min-1, P < .01) and nonoxidative glucose metabolism (18.9 +/- 1.1 v 11.0 +/- 0.5 mumol/kg.min-1, P < .05) was also found. Such latter changes were also associated with a simultaneous overdrive of Lox (0.4 +/- 0.2 v 1.9 +/- 0.2 mumol/kg.min-1, P < .02) that was correlated with an enhanced availability of plasma free fatty acids (FFAs).

Evidence for a relationship between oxidative stress and insulin action in non-insulin-dependent (type II) diabetic patients

Ten healthy subjects and 30 non-insulin-dependent (type II) diabetic patients matched for age, gender ratio, body mass index, lean body mass (LBM), waist to hip ratio, and arterial blood pressure volunteered for the study. In all subjects, fasting plasma free radical (O2-) levels and basal membrane lipid fluidity (MLF) and protein mobility (MPM) were determined. The whole group of subjects underwent a euglycemic hyperinsulinemic glucose clamp with simultaneous indirect calorimetry for substrate oxidation determination. Diabetic patients versus controls displayed higher fasting plasma glucose (8.3 +/- 0.4 v 5.1 +/- 0.4 mmol/L, P +/- .001), O2- (0.48 +/- 0.02 v 0.16 +/- 0.02 mumol/L x min), and hemoglobin A1c ([HbA1C] 7.9% +/- 0.4% v 5.7% +/- 0.3%, P < .03) levels and a stronger reduction in basal MLF (0.243 +/- 0.006 v 0.318 +/- 0.009, P < .003) and basal MPM (0.348 +/- 0.003 v 0.518 +/- 0.010, P < .002). Whole-body glucose disposal (WBGD) and oxidative and nonoxidative glucose metabolism were also significantly lower in diabetics than in controls. In diabetic patients (n = 30), plasma O2- levels correlated with basal MLF (r = -.59, P < .005), basal MPM (r = -.84, P < .001), fasting plasma insulin level (r = .51, P < .004), WBGD (r = -.53, P < .002), and nonoxidative (r = -.45, P < .01) glucose metabolism. In conclusion, our results demonstrate that a relationship between plasma O2- levels and insulin action occurs in non-insulin-dependent diabetics.

Evidence for a relationship between free radicals and insulin action in the elderly

In forty healthy subjects with normal glucose tolerance divided by age into four groups (group A, subjects with mean age < 25 years [n = 10]; group B, subjects with mean age < 40 years [n = 9]; group C, subjects with mean age < 60 years [n = 11]; group D, subjects with mean age > 75 years [n = 10]) and were matched for body mass index (BMI), lean body mass (LBM), mean arterial blood pressure, and sedentary life style, we determined the plasma O2- production, reduced to oxidized glutathione level ratio (GSH/GSSG), and plasma membrane microviscosity. Euglycemic hyperinsulinemic (1 mU/kg.min-1 for 120 minutes) glucose clamp with simultaneous D-3-H glucose infusion and indirect calorimetry allowed determination of glucose turnover parameters and substrate oxidation. In the oldest group of subjects, a significant increase in plasma O2-production and membrane microviscosity associated with a significative reduction in glucose disappearance rate (Rd), total body glucose disposal (TBGD), and nonoxidative glucose metabolism was found. In group D subjects (n = 10), all of these changes were correlated with one another. In a multiple regression analysis of the pooled data from all study subjects (n = 40), only plasma O2- production levels displayed a statistically significant relation with TBGD and nonoxidative glucose metabolism. In conclusion, in aged patients a significant relationship between free radical production and insulin action seems to exist.

Myocardial Wall Thickness and Left Ventricular Geometry in Hypertensives: Relationship With Insulin

In hypertensive patients the presence of left ventricular (LV) hypertrophy has been associated with a more severe degree of insulin resistance. Whether myocardial wall thickness or LV geometry are associated with a different degree of insulin resistance is still unknown in essential hypertensives. For this reason 26 men with new diagnosed essential hypertension were enrolled. All patients underwent echocardiographic examination and euglycemic hyperinsulinemic glucose clamp combined with indirect calorimetry. According to LV mass and relative wall thickness data, all patients were categorized in four groups: 1) patients with a normal geometric LV pattern (n = 8) (PAT = 0); 2) patients with concentric remodeling LV mass (n = 8) (PAT = 1); 3) patients with eccentric LV hypertrophy (n = 3) (PAT = 2); and 4) patients with concentric LV hypertrophy (n = 7) (PAT = 3). All groups were similar for anthropometric characteristics. Patients with normal echocardiographic LV pattern (PAT = 0) had higher whole body glucose disposal (WBGD), oxidative and nonoxidative glucose metabolism, and lower lipid oxidation than patients with abnormal echocardiographic LV patterns (PAT = 1 to 3). Nevertheless, no significant differences among the groups with abnormal echocardiographic patterns were found. After controlling for age, body mass index (BMI), waist/hip ratio (WHR), and mean arterial blood pressure, only sum of the wall thickness was significantly correlated with fasting plasma insulin (r = -0.38, P < .05), WBGD (r = - 0.50, P < .009), and NOGM (r = - 0.48, P < .02). In multivariate analysis, a model made by age, BMI, WHR, systolic and diastolic blood pressure, and WBGD explained 38% of the echocardiographic pattern variability. In this model, WBGD (P < .02) was significantly and independently associated with echocardiographic patterns explaining 19% of the echocardiographic pattern variability. In conclusion, our data demonstrate that in arterial hypertension hyperinsulinemia/insulin resistance mainly affects myocardial wall thickness, whereas only a trivial association with LV geometry occurs.

Left ventricular hypertrophy is associated with a stronger impairment of non-oxidative glucose metabolism in hypertensive patients

Abstract. Hypertensive patients with left ventricular hypertrophy (LVH) have a higher degree of hyper‐insulinaemia than hypertensive patients without LVH. Obese patients with LVH have also been demonstrated to have a very low glucose disappearance rate after an intravenous glucose bolus. No studies have investigated the difference in insulin action and substrate oxidation in hypertensive patients with and without LVH. For this reason 36 subjects were enrolled for our study: (1) healthy control subjects (n=10); (2) hypertensive patients without LVH (n= 12); and (3) hypertensive patients with LVH (n= 14). All subjects underwent an oral glucose tolerance test (OGTT, 75 g of glucose) and a euglycaemic hyperinsulinaemic glucose clamp (insulin infusion rate, 71 pmol(kgmin)‐1 for 120min). In this latter test indirect calorimetry allowed substrate oxidation determination. Echocardiographic methods allowed LVH assessment. Hypertensive patients with LVH had the lowest insulin‐mediated nonoxidative glucose metabolism compared to hypertensive patients without LVH (P<0.01) and to healthy subjects (P< 0.001). In the whole group of hypertensive patients (n= 26), partial correlations showed left ventricular mass index (LVMI) associated with fasting plasma insulin levels (r= 0.44 P<0.005), insulin‐mediated whole body glucose disposal (r= ‐0.41 P<0.01) and nonoxidative glucose metabolism (r= ‐0.33 P<0.04) independently of age, body weight, systolic blood pressure and plasma catechola‐mines levels. In conclusion, our data provide evidence that LVH in hypertensive patients is associated with a worsening in nonoxidative glucose metabolism.

New standards in hypertension and cardiovascular risk management: focus on telmisartan.

Blockade of the renin–angiotensin system is an important approach in managing high blood pressure, and has increasingly been shown to affect cardiovascular disease processes mediated by angiotensin II throughout the cardiovascular and renal continua. Telmisartan is an angiotensin II receptor blocker (ARB) displaying unique pharmacologic properties, including a longer half life than any other ARB, that result in large and sustained reductions of blood pressure. In patients with mild-to-moderate hypertension, telmisartan has proved superior to other antihypertensive agents (valsartan, losartan, ramipril, perindopril, and atenolol) in controlling blood pressure particularly towards the end of the dosing interval. There is also clinical evidence that telmisartan reduces left ventricular hypertrophy, reduces arterial stiffness and the recurrence of atrial fibrillation, and confers renoprotection. The ONgoing Telmisartan Alone and in combination with Ramipril Global Endpoint Trial (ONTARGET®) study has demonstrated that telmisartan has similar cardiovascular protective effects to ramipril in a large, high-risk patient population but was better tolerated. The powerful and sustained blood pressure control apparent in clinical trials, together with cardiovascular protection and tolerability demonstrated in ONTARGET® means that telmisartan may be a preferred option for patients with hypertension.

A multicentre, randomized study of telmisartan versus carvedilol for prevention of atrial fibrillation recurrence in hypertensive patients

Introduction: Atrial remodelling, leading to atrial fibrillation (AF), is mediated by the renin–angiotensin–aldosterone system. Methods: Mild hypertensive outpatients (systolic/diastolic blood pressure 140–159/90–99 mmHg) in sinus rhythm who had experienced ≥ 1 electrocardiogram (ECG)-documented AF episode in the previous six months received randomly telmisartan 80 mg/day or carvedilol 25 mg/day. Blood pressure and 24-hour ECG were monitored monthly for one year; patients were asked to report symptomatic AF episodes and to undergo an ECG as early as possible. Results: One hundred and thirty-two patients completed the study (telmisartan, n=70; carvedilol, n=62). Significantly fewer AF episodes were reported with telmisartan versus carvedilol (14.3% vs. 37.1%; p<0.003). Left atrial diameter, assessed by echocardiography, was similar with telmisartan and carvedilol (3.4±2.3 cm vs. 3.6±2.4 cm). At study end, both regimes significantly reduced mean left ventricular mass index, but the reduction obtained with telmisartan was significantly greater than with carvedilol (117.8±10.7 vs. 124.7±14.5; p<0.0001). Mean blood pressure values were not significantly different between the groups (telmisartan 154/97 to 123/75 mmHg; p<0.001; carvedilol 153/94 to 125/78 mmHg; p<0.001). Conclusions: Telmisartan was significantly more effective than carvedilol in preventing recurrent AF episodes in hypertensive AF patients, despite a similar lowering of blood pressure.

Slowing of mitral valve annular calcium in systemic hypertension by nifedipine and comparisons with enalapril and atenolol

Mitral annular calcium (MAC) is a condition that often occurs in patients with systemic hypertension. To evaluate the effectiveness of nifedipine in preventing MAC, 223 patients with systemic hypertension of recent onset and without MAC were selected and randomly enrolled in 3 groups: group 1 (76 patients) received nifedipine; group 2 (72 patients) received enalapril; and group 3 (75 patients) received atenolol. After 5 years, these treatments significantly reduced systolic (p < 0.001) and diastolic (p < 0.05) blood pressure (BP) in 3 treated groups. M-mode echocardiography revealed MAC only in 2 patients in the nifedipine group (2.6%), in 13 in the enalapril group (18%) and in 15 in the atenolol group (20%). The degree of MAC was mild (< 5 mm) in the 2 patients in group 1, in 5 of the 13 in group 2, and in 6 of the 15 in the group 3, whereas it was severe (> 5 mm) in the remaining 8 in the enalapril group and in the other 9 in the atenolol group. There was also a significant correlation in the degree of MAC, left atrial enlargement and mitral regurgitation. In addition, atrial fibrillation and atrioventricular conduction defects were associated with severe MAC. These results indicate that nifedipine is an effective drug both in the long-term management of systemic hypertension and in preventing or delaying MAC.

Do we need more than just powerful blood pressure reductions? New paradigms in end-organ protection.

Antihypertensive therapy can lower the risk of cardiovascular morbidity and mortality. Yet, partly because of inadequate dosing, wrong pharmacological choices, and poor patient adherence, hypertension control remains suboptimal in the majority of hypertensive patients. Achieving greater blood pressure control requires a multifaceted approach that raises awareness of hypertension, uses effective therapies, and improves adherence. Particular classes of antihypertensive therapy have beneficial actions beyond blood pressure and studies have evaluated differences in cardiovascular protection among classes. The LIFE and HOPE studies showed between-class differences that may be due to effects other than blood pressure-lowering. In the ONTARGET study, telmisartan and ramipril provided similar cardiovascular protection but adherence was higher with telmisartan, which was better tolerated. This difference in compliance is likely to be important for long-term therapy. The selection of an agent for cardiovascular protection should depend on an appreciation of its composite properties, including any beneficial effects on tolerability and increased patient adherence, as these are likely to be advantageous for the long-term management of hypertension. This review examines the evidence that the effects beyond blood pressure provided by some antihypertensive agents can also lower the risk of cardiovascular, cerebrovascular, and renal events in patients with hypertension.