Effect of postprandial hypertriglyceridemia and hyperglycemia on circulating adhesion molecules and oxidative stress generation and the possible role of simvastatin treatment

Minor compounds of olive oil have postprandial anti-inflammatory effects

High postprandial levels of TAG may further induce endothelial dysfunction and inflammation in subjects with high fasting levels of TAG, an effect that seems to be related to oxidative stress. The present study investigated whether minor compounds of olive oil with antioxidant activity decrease postprandial levels of soluble isoforms of intercellular adhesion molecule 1 (sICAM-1) and vascular cell adhesion molecule 1 (sVCAM-1), as surrogate markers of vascular inflammation, after a high-fat meal. A randomized crossover and blind trial on fourteen healthy and fourteen hypertriacylglycerolaemic subjects was performed. The study involved a 1-week adaptation lead-in period on a National Cholesterol Education Program Step I diet supplemented with extra-virgin olive oil (EVOO) containing 1125 mg polyphenols/kg and 350 mg tocopherols/kg, or refined olive oil (ROO) with no polyphenols or tocopherols. After a 12 h fast, the participants ate a high-fat meal enriched in EVOO or ROO (50 g/m2 body surface area), which on average provided 3700 kJ energy with a macronutrient profile of 72 % fat, 22 % carbohydrate and 6 % protein. Blood samples drawn hourly over the following 8 h demonstrated a similar postprandial TAG response for both EVOO and ROO meals. However, in both healthy and hypertriacylglycerolaemic subjects the net incremental area under the curve for sICAM-1 and sVCAM-1 were significantly lower after the EVOO meal. In conclusion, the consumption of EVOO with a high content of minor antioxidant compounds may have postprandial anti-inflammatory protective effects.

Lack of an effect of pioglitazone or glipizide on lipoprotein-associated phospholipase A2 in type 2 diabetes

OBJECTIVE

To study the effects of pioglitazone, a peroxisome proliferator-activated receptor-y agonist with vascular beneficial effects, and glipizide, an insulin secretagogue, on novel inflammatory vascular risk markers in subjects with and without type 2 diabetes.

METHODS

We studied 11 subjects without diabetes and 19 matched subjects with diabetes. The subjects with diabetes were randomly assigned to receive either 45 mg daily of pioglitazone (N = 8) or 10 mg daily of glipizide (N = 11) (median dose) for 12 weeks. Lipoprotein-associated phospholipase A2 (LpPLA2), vascular cell adhesion molecule (VCAM-1), intracellular adhesion molecule (ICAM-1), and e-selectin were measured by established techniques before and after therapy with either agent. The subjects without diabetes were studied only once.

RESULTS

The study subjects with diabetes had higher (P<0.05) LpPLA2, e-selectin, and VCAM-1 levels than did those without diabetes. ICAM-1 levels tended to be higher (P = 0.07) in the study subjects with than in those without diabetes. Neither pioglitazone nor glipizide therapy significantly altered LpPLA2 or VCAM-1 concentrations. While pioglitazone therapy reduced (P<0.05) eselectin concentrations, glipizide therapy reduced (P<0.03) ICAM-1 concentrations.

CONCLUSION

Type 2 diabetes is associated with elevated concentrations of the novel vascular risk marker LpPLA2 and inflammatory risk markers e-selectin and VCAM-1. Neither pioglitazone nor glipizide significantly altered LpPLA2, VCAM-1, or highly sensitive C-reactive protein levels after 12 weeks of therapy. In study subjects with type 2 diabetes, e-selectin concentrations declined significantly with pioglitazone therapy, whereas ICAM-1 concentrations decreased significantly with glipizide therapy.

Meal amino acids with varied levels of arginine do not affect postprandial vascular endothelial function in healthy young men

Postprandial endothelial dysfunction is a key event mediating the effects of diet on early atherogenesis. The potential effects of protein intake have been overlooked in the past, although amino acids are precursors for homocysteine and nitric oxide (NO). Our objective was to study the effect of amino acids on postprandial vascular function, in relation to the utilization of meal arginine for NO production. In a crossover design, 9 men ingested 50 g of a complete amino acid mixture, trace-labeled with (13)C-glycine and (15)N(2)-arginine, without (meal A) or with (meal B) 3 g extra arginine. The postprandial utilization of meal arginine for NO production was determined from urinary (15)NO(3). We monitored endothelial function of the brachial artery, the stiffness of the common carotid artery, aortic pulse wave velocity and soluble markers related to endothelial function for 8 h. Meal A did not significantly increase plasma homocysteine and did not alter endothelial function markers. The amount of NO synthesized from meal arginine doubled after meal B (107.1 +/- 16.5% increase vs. meal A, P < 0.01) but was very low (271 +/- 84 ppm vs. 332 +/- 73 ppm, P < 0.05, respectively). After meal B, flow-mediated and nitroglycerine-induced dilation decreased but common carotid artery compliance, pulse wave velocity, plasma soluble intercellular adhesion molecule-1, and von Willebrand factor, and urinary cGMP did not differ when compared with meal A. Together, the data indicate that, in healthy men, meal amino acids do not adversely affect endothelial function, and meal arginine only slightly enters the NO pathway. Unexpectedly, arginine in physiological amounts may acutely lessen smooth muscle cell reactivity to a high dynamic NO release.

Hypothesis: the 'metabolic memory', the new challenge of diabetes

Large randomized studies have established that early intensive glycaemic control reduces the risk of diabetic complications, both micro- and macrovascular. However, epidemiological and prospective data support a long-term influence of early metabolic control on clinical outcomes. This phenomenon has recently been defined as 'metabolic memory.' Potential mechanisms for propagating this 'memory' are the non-enzymatic glycation of cellular proteins and lipids, and an excess of cellular reactive oxygen and nitrogen species, in particular originated at the level of glycated-mitochondrial proteins, perhaps acting in concert with one another to maintain stress signalling. Furthermore, the emergence of this 'metabolic memory' suggests the need for very early aggressive treatment aiming to 'normalize' glycaemic control and the addition of agents which reduce cellular reactive species and glycation in order to minimize long-term diabetic complications.

Effects of Insulin on Hepatic Inflammation Induced by Ethanol and Burn Injury in a Murine Model of Critical Illness

In recent, landmark clinical trials, insulin to maintain euglycemia in critically ill patients improved clinical outcomes, including decreased all-cause mortality. Novel antiinflammatory effects of insulin have recently been described. Thermal injury is an excellent model of critical illness. The addition of ethanol to the model is of great clinical relevance because nearly 50% of the patients admitted to hospitals for burn injuries have ethanol in their circulation. Utilizing a murine model of critical illness (ethanol and skin burn), we tested the hypothesis that insulin treatment in ethanol-exposed, burn-injured mice reduced hepatic inflammation, a potential mechanism for the benefit of insulin. Adult male C57BL/6 mice were given a single intraperitoneal injection of ethanol or saline, were given a 15% total body full-thickness skin burn, or were sham-burned and killed 24 hours later. In each group, half the animals were given subcutaneous injections of the long-lasting basal insulin glargine; the other half, the appropriate vehicle. Hepatic inflammatory markers, including polymorphonuclear infiltration, a chemokine, an important adhesion molecule, proinflammatory cytokines, and nuclear factor kappaB, were measured, and all were increased by ethanol and/or burn. These increases were prevented by insulin. An antiinflammatory cytokine was reduced by ethanol and/or burn. Insulin prevented this decrease. Thus, insulin has a substantial antiinflammatory effect, and this may underlie its dramatic clinical benefit in critical illness.

Effect of a single high-fat meal on endothelial function in patients with the metabolic syndrome: role of tumor necrosis factor-alpha

BACKGROUND AND AIMS

A single high-fat meal may induce endothelial activation and dysfunction in both normal subjects and in patients with type 2 diabetes. The aim of this study was to assess the effect of a high-fat meal on endothelial function in patients with the metabolic syndrome.

METHODS AND RESULTS

Twenty-five patients with the metabolic syndrome (ATP III criteria) were matched for sex, age and body mass index with 25 subjects without the metabolic syndrome. All subjects ate under supervision a high fat meal (760 calories) with 59% energy from fat, 12% energy from protein and 29% energy from carbohydrates. Compared with the control group, subjects with the metabolic syndrome had reduced endothelial function, as assessed with the l-arginine test, and higher circulating levels of TNF-alpha. Following the high-fat meal, both triglyceride and TNF-alpha levels increased more in subjects with the metabolic syndrome than in subjects without, while endothelial function decreased more in subjects with the metabolic syndrome. There was a significant relation between increases in TNF-alpha levels and decreases in endothelial function score in subjects with the metabolic syndrome (r=-0.39, P=0.03).

CONCLUSION

TNF-alpha levels are increased in subjects with the metabolic syndrome; moreover, a high-fat meal produces further increase in its levels associated with endothelial dysfunction.

Effects of low- and high-advanced glycation endproduct meals on macro- and microvascular endothelial function and oxidative stress in patients with type 2 diabetes mellitus

BACKGROUND

An advanced glycation endproducts (AGEs)-rich diet induces significant increases in inflammatory and endothelial dysfunction markers in type 2 diabetes mellitus (T2DM).

OBJECTIVE

The aim was to investigate the acute effects of dietary AGEs on vascular function in T2DM patients.

DESIGN

Twenty inpatients with T2DM [x (+/-SEM) age: 55.4 +/- 2.2 y; glycated hemoglobin: 8.8 +/- 0.5%] were investigated. In a randomized crossover design, the effects of a low-AGE (LAGE) and high-AGE (HAGE) meal on macrovascular [by flow-mediated dilatation (FMD)] and microvascular (by Laser-Doppler flowmetry) function, serum markers of endothelial dysfunction (E-selectin, intracellular adhesion molecule 1, and vascular cell adhesion molecule 1), oxidative stress, and serum AGE were assessed. The meals had identical ingredients but different AGE amounts (15.100 compared with 2.750 kU AGE for the HAGE and LAGE meals, respectively), which were obtained by varying the cooking temperature and time. The measurements were performed at baseline and 2, 4, and 6 h after each meal.

RESULTS

After the HAGE meal, FMD decreased by 36.2%, from 5.77 +/- 0.65% (baseline) to 3.93 +/- 0.48 (2 h), 3.70 +/- 0.42 (4 h), and 4.42 +/- 0.54% (6 h) (P<0.01 for all compared with baseline). After the LAGE meal, FMD decreased by 20.9%, from 6.04 +/- 0.68% (baseline) to 4.75 +/- 0.48% (2 h), 4.69 +/- 0.51% (4 h), and 5.62 +/- 0.63% (6 h), respectively (P<0.01 for all compared with baseline; P<0.001 for all compared with the HAGE meal). This impairment of macrovascular function after the HAGE meal was paralleled by an impairment of microvascular function (-67.2%) and increased concentrations of serum AGE and markers of endothelial dysfunction and oxidative stress.

CONCLUSIONS

In patients with T2DM, a HAGE meal induces a more pronounced acute impairment of vascular function than does an otherwise identical LAGE meal. Therefore, chemical modifications of food by means of cooking play a major role in influencing the extent of postprandial vascular dysfunction.

The role of hypertriglyceridemia in atherosclerosis

Atherosclerosis is a chronic disease associated with accumulation of lipids in lesions along blood vessels, leading to the occlusion of blood flow. Much of the focus has been on the role of low-density lipoprotein (LDL), and of oxidatively modified LDL, in the initiation and progression of this disease. LDL is in fact a metabolic end-product of the triglyceride-rich lipoproteins (ie, very-low density lipoproteins). Over the years, univariate analyses have implicated triglycerides as a contributor in atherosclerosis. However, depending on the studies, the significance of this relationship is either reduced or nullified when other co-variates are taken into account. This review summarizes more recent data that support the role of triglyceride-rich lipoproteins in the atherosclerotic process, both in the fasted as well as in the postprandial state.

Inflammation in metabolic syndrome and type 2 diabetes: Impact of dietary glucose

Chronic overnutrition combined with a lack of exercise is the main cause for the rapidly increasing prevalence of overweight and obesity. It seems accepted that adipositis (macrophage infiltration and inflammation of adipose tissue in obesity) and systemic low grade inflammation affect the pathogenesis of the metabolic syndrome or type 2 diabetes mellitus (T2DM). Therefore, modern weight reduction programs additionally focus on strategies to attenuate the inflammation state. Exercise is one major factor, which contributes to the reduction of both the incidence of T2DM and inflammation, and the immunomodulatory effects of exercise are supported by similarly beneficial effects of dietary changes. In this context, glucose is the most extensively studied nutrient and current investigations focus on postprandial glucose-induced inflammation, one possible reason why hyperglycemia is detrimental. Indeed, glucose may modulate the mRNA expression and serum concentrations of immune parameters but these alterations rapidly normalize in normoglycemic subjects. In case of an impaired metabolic state, however, postprandial hyperglycemia increases magnitude and duration of systemic inflammatory responses, which probably promotes the development of T2DM and of cardiovascular disease.

Cardiovascular disease in diabetic nephropathy patients: cell adhesion molecules as potential markers?

Cardiovascular disease is a major complication of diabetes mellitus, especially for patients with diabetic nephropathy. The underlying factor or pathogenic mechanism that links diabetic nephropathy with cardiovascular disease is not known. The endothelial cell adhesion molecules, intercellular adhesion molecule-1 or vascular cell adhesion molecule-1, play a crucial role in the initiation of atherosclerosis. Levels of both cell adhesion molecules are raised by the diabetic and kidney disease states. This review focuses on these important cell adhesion molecules and their role in the pathogenesis of cardiovascular disease in diabetes and diabetic nephropathy.

A high-fat meal is accompanied by increased plasma interleukin-6 concentrations

BACKGROUND AND AIM

Enhanced and prolonged postprandial lipaemia is associated with coronary heart disease (CHD). However, the mechanisms linking postprandial lipaemia to the increased risk of atherosclerosis and CHD remain to be determined. The aim of the present study was to examine the effects of a high-fat meal on plasma levels of the pro-inflammatory cytokine interleukin-6 (IL-6) and cellular adhesion molecules in CHD patients and control subjects.

METHODS AND RESULTS

Forty-one middle-aged men with premature CHD and 26 healthy male controls were investigated. The plasma triglyceride response to the high-fat meal was significantly greater among cases than controls. The oral fat load induced a twofold increase in plasma concentrations of IL-6, an increase that was similar in CHD patients and control subjects. No changes could be detected in plasma concentrations of cellular adhesion molecules in response to postprandial lipaemia in either CHD patients or control subjects.

CONCLUSION

The results of the present study suggest that a high-fat meal affects mechanisms that induce increased inflammatory activity, which is recognised as a key modulator in the development of atherosclerosis and CHD. However, the increased levels of plasma IL-6 appear not to be determined by the magnitude of the postprandial triglyceridaemia.

Prevalence-dependent decision limits for the early detection of type 2 diabetes mellitus in venous blood, venous plasma and capillary blood during glucose challenge

BACKGROUND

The glycemia decision limits recommended by WHO/ADA for type 2 diabetes detection are derived from clinical signs in advanced stages of the disease. Since insulin secretion patterns and sensitivitity are impaired at the beginning of type 2 diabetes, this stage may be better suited to identify decision limits with higher diagnostic efficiency than those currently applied.

METHODS

Oral glucose tolerance tests were performed in 300 subjects. Glucose concentrations were measured at 30-min intervals in venous plasma, venous blood and capillary blood. Insulin concentrations in venous plasma, an insulin sensitivity index and body mass index were used to indicate a type 2 diabetic state. A multiple logistic regression procedure was "trained" using only subjects "clearly" considered to be non-diseased or diseased based on an oral glucose tolerance test according to WHO criteria. This insulin algorithm was applied to the whole study group, leading to definitive classification into the non-diseased or the diseased group. This a posteriori classification was used to identify cutoff values with the highest diagnostic efficiency.

RESULTS

The diagnostic efficiency was significantly higher when decision limits lower than the WHO recommendations for glucose concentrations were applied in a preselected subpopulation and in all three sample systems tested, e.g., 9.49 mmol/L (171 mg/dL) for venous plasma and 8.94 mmol/L (161 mg/dL) for capillary blood in the 2-h post-load state. The optimized and WHO 2-h cutoff values corresponded to a disease prevalence of 28% and approximately 5% (20% in the fasting state), respectively. Diagnostic efficiency was higher in the 2-h post-load than in the fasting state. Combining fasting values with 2-h post-load values did not further improve the diagnostic efficiency. Glucose concentrations determined from capillary blood were as efficient as those from venous blood or plasma. The number of diabetic subjects detected differed considerably between capillary blood and venous plasma for the WHO/ADA cutoff values, but not for the optimized cutoff values.

CONCLUSIONS

The efficiency of type 2 diabetes diagnosis can be improved by optimizing cutoff values according to disease prevalence. Unexpectedly, the optimized 2-h post-load cutoff was lower for capillary blood than for venous plasma. It is proposed to identify a risk group e.g., by characteristics of the metabolic syndrome in which the 2-h post-challenge concentration is determined using lower cut-off values than presently recommended.

Type 2 diabetes and hearing loss in personnel of the Self-Defense Forces

The association of type 2 diabetes with hearing loss was evaluated in middle-aged male personnel of the Self-Defense Forces (SDFs). Hearing loss was defined as the pure-tone average (PTA) of the thresholds frequency at 0.5, 1, 2, and 4 kHz greater than 25 dB hearing levels (HL) in the worse ear. Diabetes status was determined by self-report of physician-diagnosed diabetes or by oral glucose tolerance test (OGTT). Of 699 subjects studied (age 52.9+/-1.0 years), 103 subjects were classified as having type 2 diabetes. Fasting plasma glucose of diabetic subjects was 120+/-19 mg/dl. Hearing loss levels were (worse) higher among diabetic subjects compared with subjects with normal glucose tolerance (NGT) (30.7+/-13.0 dB versus 27.4+/-12.3 dB, P=0.014). Hearing loss was more prevalent among diabetic subjects than among subjects with normal glucose tolerance (60.2% versus 45.2%, P=0.006). The odds ratio (OR) of type 2 diabetes for the presence of hearing loss was 1.87 (95% confidence interval 1.20-2.91, P=0.006) in a logistic regression analysis adjusted for age, rank, cigarette smoking and ethanol consumption. These results suggest that type 2 diabetes is associated with hearing loss independently of lifestyle factors in middle-aged men.

Arteries, inflammation and insulin resistance

Inflammation plays a role in all stages of atherosclerosis from the formation to the rupture of the plaque. Guided by inflammatory mediators, monocytes bind to an endothelium damaged by cardiovascular risk factors, and then migrate towards the intima where, after incorporating oxidized low-density lipoprotein particles, they are transformed into foam cells. The lipid streak forms and develops as an atherosclerotic plaque, which is susceptible to erosion and rupture. Inflammation fed by excess adipose tissue decreases insulin sensitivity, which is the central feature of the metabolic syndrome. Inflammation therefore appears to be a common factor of atherosclerosis and the metabolic syndrome. The factors triggering this inflammation have yet to be determined. One line of thought would appear to point to diet.

Premeal insulin lispro plus bedtime NPH or twice-daily NPH in patients with type 2 diabetes: acute postprandial and chronic effects on glycemic control and cardiovascular risk factors

OBJECTIVE

Two insulin regimens were used to explore acute and chronic postprandial changes in glycemia, lipemia, and metabolic markers associated with increased risk of cardiovascular disease.

METHODS

An open-label, randomized, two-period crossover study (12 weeks/period) compared a prandial regimen [premeal insulin lispro+bedtime neutral protamine Hagedorn (NPH)] with a basal regimen (twice-daily NPH). There were 30 patients (12 women and 18 men; mean age=61 years) with type 2 diabetes mellitus (mean duration=16 years) who were randomized after a 2-month lead-in with twice-daily NPH treatment. A standard lunch test meal developed according to each patient's caloric needs was administered at the end of each treatment period.

RESULTS

Insulin lispro was associated with significantly lower postprandial glucose (area under the curve0-5 h=43.54 vs. 57.65 mM/h; P<.001), elevated insulin concentrations, and acutely altered lipid fractions that included an early decrease followed by an increase in free fatty acids, lower triglycerides, elevated total cholesterol, elevated low-density lipoprotein cholesterol (LDL), and elevated high-density lipoprotein cholesterol. After 12 weeks of treatment, insulin lispro+bedtime NPH reduced hemoglobin A1c (HbA1c; mean+/-SE=7.6+/-0.2 vs. 8.2+/-0.2%; P<.001) without increasing hypoglycemia or insulin dose as compared with twice-daily NPH. Furthermore, treatment with the prandial insulin regimen resulted in lower total cholesterol, lower LDL cholesterol, and lower oxidized LDL.

CONCLUSION

Improved postprandial glycemic control, as observed in a regimen containing both prandial insulin lispro and NPH as the basal insulin, is associated with significantly lower HbA1c and acute modulation of lipid fractions after a test meal. These biochemical modifications may potentially have a favorable impact on cardiovascular risk in patients with type 2 diabetes mellitus.

Circulating oxidised low-density lipoprotein and intercellular adhesion molecule-1 and risk of type 2 diabetes mellitus: the Atherosclerosis Risk in Communities Study

AIMS/HYPOTHESIS

To evaluate the role of oxidative stress and inflammation in the aetiology of type 2 diabetes, we examined the association of oxidised LDL (ox-LDL) and soluble intercellular adhesion molecule-1 (sICAM-1) levels with type 2 diabetes incidence over 9 years in the Atherosclerosis Risk in Communities Study.

MATERIALS AND METHODS

In a large, prospective, case-cohort design, ox-LDL and sICAM-1 were measured in stored plasma samples collected at baseline in stratified samples of 581 diabetes cases and 572 non-cases selected from 10,275 middle-aged men and women without prevalent diabetes at baseline.

RESULTS

Compared with non-cases, diabetes cases had significantly higher mean baseline levels of ox-LDL and sICAM-1. Elevated ox-LDL and sICAM-1 were both associated with increased risk of incident diabetes after adjustment for age, sex, race and centre, with hazard ratios for the highest vs lowest tertiles of 1.68 (95% CI 1.25-2.24) and 1.91 (95% CI 1.45-2.50), respectively. After additional adjustment for fasting glucose, waist circumference, HDL-cholesterol, triacylglycerol, hypertension and C-reactive protein, only sICAM-1 remained an independent predictor of incident diabetes (hazard ratio 1.50; 95% CI 1.02-2.23).

CONCLUSIONS/INTERPRETATION

In this community-based cohort of middle-aged US adults, elevated plasma ox-LDL and sICAM-1 levels were associated with increased risk of type 2 diabetes. Measurement of ICAM-1 or ox-LDL, or other measures related to inflammation or oxidative stress, may be helpful in identifying those patient populations in which to test whether novel therapies that inhibit specific pathways related to inflammation or oxidative stress are beneficial in the prevention of diabetes in humans.

The metabolic syndrome sensitizes leukocytes for glucose-induced immune gene expression

Definitions of the metabolic syndrome (MetS) include obesity, dyslipidemia, elevated levels of fasting blood glucose, and blood pressure as criteria, but it is also known that the MetS is associated with chronic, subclinical inflammation. Hyperglycemia (fasting and postprandial) may be important in exacerbating this proinflammatory state. We aimed to assess the impact of oral glucose challenge and in vitro glucose-stimulation on gene expression and secretion of inflammatory parameters in peripheral blood leukocytes and to investigate whether presence of the MetS could "prime" leukocytes to up-regulate proinflammatory markers in response to glucose. Using quantitative real-time PCR, we could show that the expression of intercellular adhesion molecule 1 (ICAM-1), tumor necrosis factor alpha (TNF-alpha), and interleukin 6 (IL-6) significantly increased in peripheral blood leukocytes from "MetS" subjects (n=39) compared to "no MetS" subjects (n=35) 2 h after an oral glucose tolerance test (ICAM-1 +52%, TNF-alpha +107%, and IL-6 +38%) and also in vitro after 72 h cultivation in high-glucose medium (ICAM-1 +74%, TNF-alpha +71%, and IL-6 +44%). Using ELISA and Luminex technique, we further observed a trend towards increased immune mediator concentrations in the corresponding cell culture supernatants from MetS patients (ICAM-1 +21%, TNF-alpha +31%, and IL-6 +175%). Thus, the MetS may support peripheral inflammation by sensitizing leukocytes to up-regulate proinflammatory markers in response to glucose, which in turn increases the risk for type-2 diabetes mellitus and cardiovascular disease.

Inflammation affects lipid metabolism during recovery from hyperinsulinaemia

BACKGROUND

Inflammation is an established contributor in atherosclerosis and several other common diseases including diabetes. Therefore the study was to investigate how inflammatory factors affect lipid metabolism during recovery from hyperinsulinaemia in healthy individuals.

MATERIALS AND METHODS

A total of 22 healthy subjects [aged 27.7 +/- 1.8 years; body mass index (BMI) 24.1 +/- 0.8 kg m(-2)] participated in the study. After a 4-h euglycaemic hyperinsulinaemia (55.9 +/- 2.2 mU L(-1)) insulin infusion was stopped and baseline blood samples were taken. Glucose infusion at a decreasing rate continued for 120 min to maintain euglycaemia throughout the study.

RESULTS

The free fatty acid (FFA) concentration at the 120-min time-point was associated with baseline alpha-1-acid glycoprotein (A1GP) (r = 0.57, P < 0.01), C-reactive protein (CRP) (r = 0.54, P < 0.02) and serum amyloid A (r = 0.53, P < 0.02); in total they accounted for 54% of the variation in FFA concentration at the 120-min time-point. Baseline A1GP was also associated with the triglyceride concentration at the 120-min time-point (r = 0.66, P < 0.001). Insulin sensitivity was the most important factor associated with glucose disposal at the 120-min time-point, thus explaining 30% of the variation (P < 0.01). Interleukin-6 (positive correlation) and fibrinogen (negative correlation) increased the proportion to 48% (P < 0.01). There was no significant change in the most acute-phase proteins between baseline and the 120-min time-point.

CONCLUSION

Inflammation is an important contributor to lipid and glucose metabolism during recovery from hyperinsulinaemia.

Almonds decrease postprandial glycemia, insulinemia, and oxidative damage in healthy individuals

Strategies that decrease postprandial glucose excursions, including digestive enzyme inhibition, and low glycemic index diets result in lower diabetes incidence and coronary heart disease (CHD) risk, possibly through lower postprandial oxidative damage to lipids and proteins. We therefore assessed the effect of decreasing postprandial glucose excursions on measures of oxidative damage. Fifteen healthy subjects ate 2 bread control meals and 3 test meals: almonds and bread; parboiled rice; and instant mashed potatoes, balanced in carbohydrate, fat, and protein, using butter and cheese. We obtained blood samples at baseline and for 4 h postprandially. Glycemic indices for the rice (38 +/- 6) and almond meals (55 +/- 7) were less than for the potato meal (94 +/- 11) (P < 0.003), as were the postprandial areas under the insulin concentration time curve (P < 0.001). No postmeal treatment differences were seen in total antioxidant capacity. However, the serum protein thiol concentration increased following the almond meal (15 +/- 14 mmol/L), indicating less oxidative protein damage, and decreased after the control bread, rice, and potato meals (-10 +/- 8 mmol/L), when data from these 3 meals were pooled (P = 0.021). The change in protein thiols was also negatively related to the postprandial incremental peak glucose (r = -0.29, n = 60 observations, P = 0.026) and peak insulin responses (r = -0.26, n = 60 observations, P = 0.046). Therefore, lowering postprandial glucose excursions may decrease the risk of oxidative damage to proteins. Almonds are likely to lower this risk by decreasing the glycemic excursion and by providing antioxidants. These actions may relate to mechanisms by which nuts are associated with a decreased risk of CHD.

Elevation of plasma concentration of adhesion molecules in late-life depression

OBJECTIVES

Late-life depression may be associated with vascular disease. The purpose of the study was to investigate this association by determining the levels of soluble adhesion molecules (sICAM-1 and sVCAM-1) which represent markers of ischemia-induced inflammation in elderly individuals with depression.

METHODS

Blood samples were obtained from 33 subjects with depression selected from a community-dwelling population after screening with the Geriatric Depression Scale, and 33 matched controls. Serum concentrations of sICAM-1 (ng/mL) and sVCAM-1 (ng/mL) were measured in both groups.

RESULTS

Depressed patients (Group A) possessed significantly higher sICAM-1 levels compared to healthy controls (Group B) (674.94 +/- 166.90 ng/ml vs 467.05 +/- 231.26 ng/ml, respectively, p < 0.01). Similarly the same groups demonstrated elevated sVCAM-1 levels compared to controls (572.14 +/- 182.20 ng/ml vs 449.04 +/- 285.27 ng/ml, p < 0.05); a difference that in both cases remained significant after adjustment for potential confounders (gender, smoking, presence of metabolic syndrome).

CONCLUSION

These findings indicate an association between high serum levels of VCAM-1, and ICAM-1 and depression in the elderly and further support the vascular depression hypothesis, which has important implications for the understanding and management of late-life depression.

Controlling oxidative stress as a novel molecular approach to protecting the vascular wall in diabetes

PURPOSE OF REVIEW

In diabetes, oxidative stress plays a key role in the pathogenesis of vascular complications; therefore an antioxidant therapy would be of great interest in this disease.

RECENT FINDINGS

Hyperglycemia directly promotes an endothelial dysfunction--inducing process of overproduction of superoxide at the mitochondrial level. This is the first and key event able to activate all the pathways involved in the development of vascular complications of diabetes. It has recently been shown that statins, angiotensin-converting enzyme inhibitors, angiotensin II type 1 blockers, calcium channel blockers, and thiazolidinediones have a strong intracellular antioxidant activity.

SUMMARY

Classic antioxidants, such as vitamin E, failed to show beneficial effects on diabetic complications probably because their action is only "symptomatic". The preventive activity against hyperglycemia-induced oxidative stress shown by statins, angiotensin-converting enzyme inhibitors, angiotensin II type 1 blockers, calcium channel blockers, and thiazolidinediones justifies use of these compounds for preventing complications in patients with diabetes, in whom antioxidant defences have been shown to be defective.

Postprandial hyperglycaemia and cardiovascular complications of diabetes: an update

Type 2 diabetes is characterised by a gradual decline in insulin secretion in response to nutrient loads; hence, it is primarily a disorder of postprandial glucose (PPG) regulation. However, physicians continue to rely on fasting plasma glucose (FPG) and glycosylated haemoglobin (HbA1c) levels as indicators for disease management. There is a linear relationship between the risk of cardiovascular disease (CVD) and the two-hour oral glucose tolerance test (OGTT), while a recent study confirms postprandial hyperglycaemia as an independent risk factor for CVD in type 2 diabetes. At the same time, several intervention studies have shown that treating postprandial hyperglycaemia may reduce the incidence of new cardiovascular events. Evidence supports the hypothesis that postprandial hyperglycaemia may be linked to CVD through the generation of oxidative stress. Furthermore, clinical data suggest that postprandial hyperglycaemia is a common phenomenon, even in patients who may be considered in 'good metabolic control'. Therefore, in addition to HbA1c and FPG, physicians should consider monitoring and targeting PPG in patients with type 2 diabetes.

Postprandial modulation of serum paraoxonase activity and concentration in diabetic and non-diabetic subjects

OBJECTIVES

To analyse the HDL associated anti-oxidant enzyme paraoxonase-1, during postprandial hyperlipaemia.

METHODS AND RESULTS

Type 2 diabetic patients (n=72), glucose intolerant patients (n=10) and controls (n=38) consumed a high fat:high carbohydrate meal. Blood samples were collected up to 4h and analysed for lipids and paraoxonase-1. In vitro studies examined HDL function with respect to the enzyme. There were significant postprandial increases in serum triglycerides. Paraoxonase-1 activity decreased significantly throughout the postprandial phase. Concentrations of the enzyme initially decreased significantly, but returned to fasting concentrations at 4h. Specific activities were significantly lower at 4h, compared to fasting. The decrease in specific activity was linked to the dynamic phase of postprandial lipoprotein metabolism. Apo AI limited loss of paraoxonase-1. HDL isolated after being subjected to postprandial conditions in vitro had reduced capacity to associate with and stabilise PON1.

CONCLUSIONS

Postprandial hyperlipaemia was associated with changes to serum paraoxonase-1, consistent with a reduced anti-oxidant potential of HDL. No differences were observed between diabetic and non-diabetic patients, suggesting that the effect was linked to postprandial hyperlipaemia. Modifications to paraoxonase-1 could contribute to increased risk of vascular disease associated with postprandial lipaemia, particularly in diabetic patients, who are already deficient in serum paraoxonase-1.

Targeting postprandial hyperglycemia

In healthy individuals, blood glucose levels in the fasting state are maintained by the continuous basal-level insulin secretion. After a meal, the rise in postprandial glucose (PPG) is controlled by the rapid pancreatic release of insulin, stimulated by both glucose and the intestinal production of the incretins glucose-dependent insulinotropic polypeptide and glucagon-like peptide 1. In diabetic individuals, postprandial insulin secretion is insufficient to suppress an excessive rise in PPG. There is increasing evidence that elevated PPG exerts a more deleterious effect on the vascular system than elevation of fasting plasma glucose. In particular, individuals with normal fasting plasma glucose but impaired glucose tolerance have significantly increased risk of cardiovascular events. With the recognition of the importance of PPG and the availability of new pharmacologic options, management of diabetes will shift to greater attention to PPG levels. The prototype for such an approach is in the treatment of gestational diabetes and diabetic pregnancies where PPG is the primary target of efforts at glycemic control. These efforts have been extremely successful in improving the outlook for diabetic pregnant women. There are many approaches to reduction of PPG; dietary management and promotion of exercise are very effective. Sulfonylureas, meglitinides, metformin, thiazolidinediones, and disaccharidase inhibitors all counteract PPG elevation. The development of glucagon-like peptide 1 agonists such as exendin and dipeptidyl peptidase IV inhibitors such as vildagliptin offers a new approach to suppression of PPG elevation. New semisynthetic insulin analogues permit a more aggressive response to postprandial glucose elevation, with lower risk of hypoglycemia, than with regular insulin. Inhaled insulin also has a rapid onset of action and offers benefits in PPG control. It is proposed that an aggressive treatment approach focusing on PPG, similar to the current standards for diabetic pregancies, be directed at individuals with diabetes and impaired glucose tolerance.

Apolipoprotein CIII induces expression of vascular cell adhesion molecule-1 in vascular endothelial cells and increases adhesion of monocytic cells

BACKGROUND

Activation of vascular endothelial cells (ECs) plays an important role in atherogenesis and plaque instability. Lipoproteins containing apolipoprotein CIII (apoCIII) predict coronary heart disease (CHD). We recently reported that apoCIII has a proinflammatory effect on human monocytes. In this study, we looked for a direct effect of apoCIII on EC expression of adhesion molecules, leading to monocytic cell adhesion.

METHODS AND RESULTS

Treatment of ECs with apoCIII or apoCIII-rich VLDL caused human monocytic THP-1 cells to adhere to them under static condition or under laminar sheer stress (1.0 dyne/cm2). ApoCIII increased EC expression of vascular cell adhesion molecule-1 (VCAM-1) protein and intercellular cell adhesion molecule-1 (ICAM-1) protein (4.9 +/- 1.5-fold and 1.4 +/- 0.5-fold versus control, respectively). Furthermore, apoCIII remarkably increased membrane-bound protein kinase C (PKC) beta in ECs, indicating activation. A selective inhibitor of PKCbeta prevented the rise in VCAM-1 and THP-1 cell adhesion to ECs. Moreover, exposure of ECs to apoCIII induced nuclear factor-kappaB (NF-kappaB) activation. PKCbeta inhibition abolished apoCIII-induced NF-kappaB activation, and NF-kappaB inhibition reduced expression of VCAM-1, each resulting in reduced THP-1 cell adhesion. ApoCIII-rich VLDL also activated PKCbeta and NF-kappaB in ECs and increased expression of VCAM-1. Pretreatment of ApoCIII-rich VLDL with anti-apoCIII neutralizing antibody abolished its effect on PKCbeta activation.

CONCLUSIONS

Our findings provide the first evidence that apoCIII increases VCAM-1 and ICAM-1 expression in ECs by activating PKCbeta and NF-kappaB, suggesting a novel mechanism for EC activation induced by dyslipidemia. Therefore, apoCIII-rich VLDL may contribute directly to atherogenesis by activating ECs and recruiting monocytes to them.

Effects of rosiglitazone and metformin on postprandial paraoxonase-1 and monocyte chemoattractant protein-1 in human immunodeficiency virus-infected patients with lipodystrophy

Highly active antiretroviral therapy in Human Immunodeficiency Virus (HIV) has been associated with lipodystrophy, insulin resistance and atherosclerosis. We investigated the effects of rosiglitazone or metformin on fasting and postprandial inflammatory and antioxidant variables in HIV-infected males with lipodystrophy. Thirty-one patients were randomly assigned to receive either rosiglitazone (4 mg twice daily) or metformin (1 g twice daily) for 26 weeks. At baseline and after treatment, standardized 10-h oral fat loading tests were performed. Before treatment, inflammatory variables remained unchanged but there was a postprandial decrease in high density lipoprotein (HDL)-cholesterol and paraoxonase (PON1) activity. Rosiglitazone and metformin reduced homeostasis model assessment index (HOMA) similarly (-34% and -37%, respectively, P<0.05 for each). Both treatments increased fasting and postprandial PON1 activity and decreased postprandial monocyte chemoattractant protein 1 (MCP-1) concentrations. However, plasma C-reactive protein (CRP) and Interleukin-6 (IL-6) concentration did not change throughout the study. To decrease insulin resistance results in a higher anti-oxidant and consequent lower pro-inflammatory action of HDL. This may confer protection against accelerated atherosclerosis in these patients.

Short-term hyperglycemia in surgical patients and a study of related cellular mechanisms

OBJECTIVE

To examine cellular mechanisms by which short-term elevations of glucose or insulin impair leukocyte functions and to assess the occurrence of perioperative hyperglycemia in surgical patients.

SUMMARY BACKGROUND DATA

A major factor in the contemporary management of the critically ill surgical patient is the progressively exact control of blood glucose. However, the separate role of insulin and underlying immunologic mechanisms are not well understood.

METHODS

Venous blood samples of 20 healthy volunteers were exposed for 24 hours to various glucose and insulin concentrations. Lipopolysaccharide (LPS) was added at 1 ng/mL for up to 16 hours and the monocytes' ability to express CD14 and HLA-DR assessed as an index of the monocyte's capability to present antigen. To evaluate the clinical importance of the observed experimental results, a prospective evaluation of perioperative blood glucose values in 5285 surgical patients in Kentucky was performed.

RESULTS

Both exposure to high glucose (400 mg/dL) and insulin (100 muU/mL) led to an independent and additive impairment of monocyte HLA-DR expression after 24 hours (P < 0.01). Perioperative blood glucose exceeded 200 mg/dL in 21% of all cardiothoracic patients and in 31% of diabetic patients undergoing common major operations.

CONCLUSIONS

Both short-term hyperglycemia and hyperinsulinemia are associated with significantly decreased monocyte HLA-DR expression, a parameter correlating with infectious complications and patient mortality. This may provide a mechanism by which high glucose and insulin impair innate immunity. It also appears that perioperative maintenance of normoglycemia will become a valid performance measure for practicing surgical specialists.

Soluble semicarbazide-sensitive amine oxidase (SSAO) activity is related to oxidative stress and subchronic inflammation in streptozotocin-induced diabetic rats

Diabetes is known to increase the risk of Alzheimer's disease (AD) and vascular dementia via oxidative stress and inflammation. There are speculations that SSAO activity might be related to the development of AD. Our aim was to investigate whether changes of soluble SSAO activity, oxidative stress and inflammation markers are related to each other in diabetes. Soluble and tissue-bound SSAO activities (from serum and aorta, respectively) were determined in streptozotocin (STZ)-induced diabetic rats without insulin treatment, receiving insulin once, or twice daily compared to control animals. After three weeks of treatment soluble and tissue-bound SSAO activities (seSSAO and aoSSAO, respectively), serum total antioxidant status (TAS), high sensitivity C-reactive protein (hsCRP), fructose amine levels and routine laboratory parameters were determined. SeSSAO activity significantly increased in the diabetic groups without treatment and receiving insulin once daily, and a marked decrease in aoSSAO activity was seen in all diabetic groups. Increased oxidative stress was correlated with hsCRP elevation, while hsCRP and seSSAO activity were also significantly correlated. In all groups seSSAO and aoSSAO activities were in negative correlation with each other. Our results support the view that poor metabolic control leads to increased oxidative stress, which in turn may cause the elevation of hsCRP levels. Soluble SSAO on the one hand acts as an adhesion molecule--thus possibly being a factor responsible for the late complications of diabetes--and on the other hand, it may contribute to oxidative stress. Our parsimonious conclusion is that there is a relation between the risk factors of AD and vascular dementia (diabetes, oxidative stress and chronic inflammation) and SSAO activity, which may originate from the vessel wall.

An alpha-glucosidase inhibitor, voglibose, reduces oxidative stress markers and soluble intercellular adhesion molecule 1 in obese type 2 diabetic patients

Postprandial hyperglycemia and hyperlipidemia are considered risk factors for cardiovascular disease. This study was designed to elucidate whether improving the postprandial state by voglibose, an alpha-glucosidase inhibitor, leads to the reduction of oxidative stress markers and soluble adhesion molecules in obese type 2 diabetic patients. A total of 30 Japanese obese type 2 diabetic patients were randomly assigned and treated for 3 weeks with either diet alone (the control group) or diet plus voglibose (0.9 mg daily) (the voglibose group) (n=15 each). Analysis of the diurnal metabolic profiles revealed a significant reduction of postprandial hyperglycemia and hyperlipidemia in the voglibose group relative to the control group (P<.05), despite the similar improvement in body mass index and hemoglobin A(1c) in both groups. Voglibose also decreased significantly the plasma levels of soluble intercellular adhesion molecule 1 and urinary excretion of 8-iso-prostaglandin F(2)alpha and 8-hydroxydeoxyguanosine (P<.01) and C-reactive protein (P<.05) relative to the control group. In conclusion, this study represents the first demonstration that voglibose reduces oxidative stress generation and soluble intercellular adhesion molecule 1 in parallel with the reduction of postprandial hyperglycemia and hyperlipidemia in obese type 2 diabetic patients.

Indices of low-grade chronic inflammation correlate with early cognitive deterioration in an elderly Greek population

Elevated serum levels of adhesion molecules (AM) reflect low-grade chronic inflammation and have been associated with several conditions of neuronal damage. The aim of the present study was the investigation of possible correlation between early cognitive decline and inflammatory processes in the elderly as indicated by plasma C-reactive protein (CRP) and AM levels. Thirty-seven subjects with dementia were selected from a community-dwelling, genetically isolated, geriatric population (above 60 years of age) based on the Mini Mental State Examination scale (MMSE) and the Diagnostic and Statistical Manual (DSM-IV) criteria. In parallel, a group of 33 age-matched healthy controls were selected from the same population. The levels of CRP (mg/l), sICAM-1 (ng/ml) and sVCAM-1 (ng/ml) were measured in the serum samples of both groups. Serum concentrations of all three molecules sICAM-1, sVCAM-1 and CRP were significantly higher in the dementia group when compared to controls (656.78 +/- 161.51 versus 467.05 +/- 231.26, p < 0.01; 631.64 +/- 149.76 versus 449.04 +/- 285.27, p < 0.01; 1.53 +/- 0.97 versus 0.7221 +/- 0.61, p < 0.01, respectively). Furthermore, a positive correlation was observed between the three molecules studied and the degree of severity of cognitive impairment. The findings of this study enhance the hypothesis of the presence of an underlying inflammatory process leading to cognitive deterioration and predisposing dementia in the elderly. The present work supports the evaluation of inflammatory molecules as early indicators of cognitive decline in elderly individuals.

Effects of rosiglitazone on postprandial leukocytes and cytokines in type 2 diabetes

OBJECTIVE

We postulated that in type 2 diabetes, the postprandial phase is a pro-inflammatory state that can be modulated by PPAR-gamma agonists. For this purpose, we determined the effects of rosiglitazone (8 mg/d) on postprandial leukocyte counts and pro-inflammatory cytokines (IL-6 and IL-8) in patients with type 2 diabetes.

METHODS AND RESULTS

A randomized, 8-week, cross-over, placebo-controlled, double-blind clinical trial was performed in 19 patients with type 2 diabetes. Standardized 6-h oral fat-loading tests were performed after each treatment period. During placebo treatment, blood leukocytes increased to a maximum 6-h postprandially, due to significant increases in neutrophils and lymphocytes. Concomitant postprandial increases were observed for IL-6 and IL-8, the major chemokines responsible for leukocyte recruitment. Rosiglitazone reduced the incremental area under the curves (dAUCs) for IL-6 (-63%, p<0.01) and IL-8 (-16%, p<0.05). The dAUC for leukocytes decreased with 37% (p<0.05), due to a specific reduction of neutrophils (-39%, p<0.05).

CONCLUSIONS

Rosiglitazone attenuated the postprandial increases of neutrophils, IL-6 and IL-8 in patients with type 2 diabetes. Since inflammation is a major force driving atherosclerosis, and man lives in a postprandial period most part of the day, a reduced inflammatory response after a meal may delay progression of atherosclerosis.

CONDENSED ABSTRACT

We postulated that in type 2 diabetes, the postprandial phase is a pro-inflammatory state that can be modulated by PPAR-gamma agonists. Rosiglitazone attenuated the postprandial increases of neutrophils, IL-6 and IL-8 in patients with type 2 diabetes. These effects may contribute to cardiovascular risk reduction.

Oxidative stress in type 2 diabetes: the role of fasting and postprandial glycaemia

Oxidative stress, through the production of reactive oxygen species (ROS), has been proposed as the root cause underlying the development of insulin resistance, beta-cell dysfunction, impaired glucose tolerance and type 2 diabetes mellitus (T2DM). It has also been implicated in the progression of long-term diabetes complications, including microvascular and macrovascular dysfunction. Excess nourishment and a sedentary lifestyle leads to glucose and fatty acid overload, resulting in production of ROS. Additionally, reaction of glucose with plasma proteins forms advanced glycation end products, triggering production of ROS. These ROS initiate a chain reaction leading to reduced nitric oxide availability, increased markers of inflammation and chemical modification of lipoproteins, all of which may increase the risk of atherogenesis. With the postulation that hyperglycaemia and fluctuations in blood glucose lead to generation of ROS, it follows that aggressive treatment of fasting and postprandial hyperglycaemia is important for prevention of micro and macrovascular complications in T2DM.

Meal-induced platelet activation in Type 2 diabetes mellitus: effects of treatment with repaglinide and glibenclamide

AIMS

To compare the effects of treatment with repaglinide and glibenclamide on platelet function and endothelial markers in patients with Type 2 diabetes mellitus, before and after a standardized meal.

METHODS

Fifteen patients with Type 2 diabetes were investigated on three occasions: at baseline without oral hypoglycaemic drug treatment, and after 6 weeks' treatment with repaglinide or glibenclamide, respectively, in an open randomized cross-over study. Agonist-induced platelet P-selectin expression and platelet aggregation, urinary thromboxane, soluble P-selectin, von Willebrand factor (VWF), soluble E-selectin, intercellular adhesion molecule (ICAM-1) and C-reactive protein (CRP) were measured. In addition, pre-meal data were compared with non-diabetic control subjects (n = 15), matched for sex, age and BMI.

RESULTS

Adenosine diphosphate (ADP)-induced platelet P-selectin expression increased post-meal in Type 2 diabetic patients both at baseline and after treatment with repaglinide and glibenclamide (P < 0.01 for all; repeated measures anova). Repaglinide treatment reduced fasting ADP-induced P-selectin expression compared with baseline (P = 0.01), but did not influence meal-induced platelet hyper-reactivity (P = 0.32). No significant anti-platelet effects of glibenclamide treatment were found. Plasma concentrations of VWF and ICAM-1 were elevated in patients with Type 2 diabetes compared with control subjects (P < 0.05 for both) and were reduced during treatment with repaglinide (P < 0.01 for both) but did not change during glibenclamide treatment.

CONCLUSIONS

The post-meal state is associated with enhanced platelet reactivity in patients with Type 2 diabetes mellitus. Pre-meal treatment with repaglinide or glibenclamide does not inhibit postprandial platelet activation, but repaglinide treatment is associated with attenuated platelet and endothelial activity in the fasting state.

Diabetes treatments have differential effects on nontraditional cardiovascular risk factors

OBJECTIVE

The aim of this study was to determine the effect of basal insulin, alone or with a sensitizer, or a combination of oral agents on nontraditional risk factors for cardiovascular disease (CVD).

RESEARCH DESIGN AND METHODS

We randomized 57 patients with T2DM to either (1) continuous subcutaneous basal Lispro insulin at a single rate using an insulin pump (basal insulin) or (2) basal insulin and oral pioglitazone 30 mg daily (basal insulin +Pio) or (3) a sulfonylurea and metformin (SU+M). We measured glycosylated hemoglobin (HbA1c), plasma high-sensitivity C-reactive protein (hs-CRP), plasminogen activator inhibitor-1 (PAI-1), 8-epi-prostaglandin F2 alpha (PGF2alpha), serum lipoprotein (a) [Lp (a)], and lipoprotein profile at baseline and after 20 weeks of treatment.

RESULTS

HbA1c decreased by >or=2% (P<.001) and to comparable levels (P=NS) in all groups. Despite improved glycemia, hsCRP did not change in any group, whereas plasma PAI-1 fell with basal insulin +Pio (P<.02) and SU+M (P<.01). PGF2alpha declined with basal insulin (P<.02) and SU+M (P<.001). High-density lipoprotein cholesterol (HDL-C) increased only with basal insulin +Pio (18.2%, P<.05). Lp (a) increased with basal insulin therapy alone (P<.01). Data were pooled from all groups to determine the overall effect of glycemic control-there was a significant (P<.001) decline in HbA1c, PAI-1, and PGF2alpha and an increase in HDL-C (P<.001). There was no correlation between HbA1c reduction and changes in these parameters.

CONCLUSIONS

We conclude that excellent glycemic control per se does not impact nontraditional risk factors for CVD equally, but various diabetes medications have different effects on these risk factors. These findings may have implications for making appropriate therapeutic choices for patients with Type 2 diabetes, although larger studies with more appropriate treatment comparisons may be necessary.

The hOGG1 Ser326Cys gene polymorphism is associated with decreased insulin sensitivity in subjects with normal glucose tolerance

Increased oxidative stress has been observed to contribute the development of insulin resistance. Oxidative stress is known to increase the conversion of deoxyguanosine (dG) to 8-hydroxy-2'-deoxyguanosine (8-OHdG). Human 8-oxoguanine glycosylase (hOGG1) is the key component responsible for the removal of 8-OHdG from oxidatively damaged DNA. The repair activity of the hOGG1 Ser326Cys gene variant has been demonstrated to be lower than that of the hOGG1 Ser/Ser genotype. Therefore, the possible association of the hOGG1 Ser326Cys gene variant with insulin sensitivity was investigated in 279 normal glucose-tolerant subjects without history of cancer. Allele frequency was 21.5% for the Ser/Ser genotype (n = 60), 45.9% for the Ser/Cys genotype (n = 128), and 32.6% for the Cys/Cys genotype (n = 91). Subjects carrying the Cys/Cys genotype had significantly lower insulin sensitivity levels, assessed by homeostasis model assessment-insulin resistance (HOMA-IR), compared with the Ser/Ser and Ser/Cys genotypes (P < 0.001 and P < 0.001, respectively). In a multiple linear regression analysis, the Cys/Cys genotype was a significant determinant of HOMA-IR, independent of age, sex, body mass index, fasting plasma cholesterol, triglyceride, HDL cholesterol, LDL cholesterol, or hypertension. The present study indicates that the hOGG1 gene Cys/Cys variant is associated with a significant decrease in insulin sensitivity in subjects with normal glucose tolerance.

Emerging risk factors and early atherosclerosis indices in subjects with impaired glucose tolerance

AIM

To evaluate the response to an oral lipid overload, inflammatory markers and carotid intima-media thickness in subjects with impaired glucose tolerance.

METHODS

54 subjects, both sexes, 58 y-old average were submitted to 1) Clinical evaluation 2) Glucose tolerance test with 75 g glucose; classified as normal (2 h plasma glucose<140 mg/dl, n=37) or IGT (2 h G 140-200 mg/dl, n=17), 3) 12 h fasting sample (plasma glucose, lipids, C-reactive protein, fibrinogen and HOMA-IR calculation); 4 and 6 h after the oral lipid overload (1000 kcal, lipids 65 g) glycemia, fibrinogen and triglycerides were reevaluated. Intima-media thickness was calculated by the average of 6 measurements (3 highest of each carotid) evaluated by ultrasonography (7 MHZ transducer).

RESULTS

The IGT group had higher (P<0.001) fasting plasma glucose (89.4 +/- 13 vs 104.4 +/- 8 mg/dl), HOMA-IR (1.69 +/- 1.2 vs 2.93 +/- 2.2) and waist (91 +/- 14 vs 101 +/- 9 cm), similar fasting lipids, intima-media thickness (P=0.58) and post-oral lipid overload triglycerides (P=0.74), but higher fibrinogen (284.3 +/- 6 and 305 +/- 10 mg/dl, P=0.05) and C-reactive protein (2.11 +/- 0.33 and 4.19 +/- 0.65 mg/l, P=0.003). C-reactive protein was positively correlated with HOMA-IR (r=0.45, P=0.001), fasting plasma glucose (r=0.43, P=0.002) and waist (r=0.45, P=0.0006), but not with postprandial lipids.

CONCLUSION

A higher C-reactive protein in IGT, and its positive correlation with insulin resistance indices, but not with postprandial lipaemia, suggests that the clustering of these factors, characteristic of the metabolic syndrome, occurs earlier than postprandial lipid abnormalities.

Extracts of monascusus purpureus beyond statins —Profile of efficacy and safety of the use of extracts of monascus purpureus

Extracts of Monascus purpureus have always been considered a natural source of lovastatin, the precursor of the world's largest selling class of drugs. In actual fact, the fungus contains many other substances (flavonoids, polyunsaturated fats, pyrrolinic compounds etc.) with a wide variety of other actions. The most recent studies have shown that it has an action on the glycemic metabolism, and on the mechanisms of adipogenesis, also an effects on the endothelium and on postprandial vasodilation. These effects are more extensive and complex than those of statins alone. And new strains of Monascus purpureus have recently been patented where the presence of statins is only one of the therapeutic components of the fungus. In particular, the increase in secondary components, such as flavonoids, which coincides with a more complex therapeutic action, probably making the new extracts of Monascus purpureus, the ideal candidate for the treatment of the metabolic syndrome.

Nateglinide--current and future role in the treatment of patients with type 2 diabetes mellitus

Therapy for type 2 diabetes mellitus should aim to control not only fasting, but also postprandial glucose levels. Nateglinide, a d-phenylalanine derivative, restores postprandial early phase insulin secretion in a transient and glucose-sensitive manner without affecting basal insulin levels. As nateglinide is administered immediately before meals it provides greater lifestyle flexibility than agents that require patients to eat to avoid hypoglycemic events (e.g. long-acting sulfonylureas). In randomised, double-blind trials in patients with type 2 diabetes, nateglinide monotherapy (mealtime treatment of 120 mg three times daily) significantly improved long-term glycaemic control by significantly reducing glyated haemoglobin (HbA 1c) and preventing mealtime glucose spikes. The combination of nateglinide with insulin-sensitising agents, for example, metformin and thiazolidinediones, addresses the dual defects of loss of insulin secretion and insulin resistance to provide optimal management of type 2 diabetes, and more patients achieve HbA 1c goal with nateglinide combination therapy rather than with monotherapy with other oral agents. Nateglinide also restores early insulin secretion and reduces postprandial hyperglycaemia in prediabetic subjects with impaired glucose tolerance (IGT) and appears similarly effective in elderly and non-elderly populations with type 2 diabetes. It has an excellent safety and tolerability profile, with a low propensity to cause hypoglycaemia due to its transient, selective effect on early phase insulin secretion. Nateglinide as monotherapy or combination therapy is an effective option to reduce mealtime glucose in patients with type 2 diabetes. The results of ongoing research into its potential role in delaying progression to overt diabetes, and protecting against cardiovascular events, in prediabetic patients with IGT are awaited.

Glycated and oxidized protein degradation products are indicators of fasting and postprandial hyperglycemia in diabetes

OBJECTIVE

To assess the relative importance of fasting and postprandial hyperglycemia to vascular dysfunction in diabetes, we have measured indicators of glycation, oxidative and nitrosative stress in subjects with type 1 diabetes, and different postprandial glucose patterns.

RESEARCH DESIGN AND METHODS

Plasma and urinary levels of specific arginine- and lysine-derived advanced glycation end products, as well as oxidative and nitrosative products, were measured by liquid chromatography with triple quadrupole mass spectrometric detection (LC-MS/MS) after 2 months of treatment with insulin lispro or human regular insulin in 21 subjects participating in a cross-over study. Hb-bound early glycation (Amadori) products were also measured after each treatment period by high-performance liquid chromatography (fructosyl-valine Hb or HbA1c [A1C]:Diamat) and fructosyl-lysine Hb by LC-MS/MS (A1C:fructosyl-lysine).

RESULTS

In diabetic patients, the concentrations of protein glycation and oxidation-free adducts increased up to 10-fold, while urinary excretion increased up to 15-fold. Decreasing postprandial hyperglycemia with lispro gave 10-20% decreases of the major free glycation adducts, hydroimidazolones derived from methylglyoxal and 3-deoxyglucosone, and glyoxal-derived Nepsilon-carboxymethyl-lysine. No differences were observed in A1C:Diamat or A1C:fructosyl-lysine with lispro or regular insulin therapy in spite of significant decreases in postprandial glycemia with lispro.

CONCLUSIONS

We conclude that the profound increases in proteolytic products of proteins modified by advanced glycation endproducts in diabetic patients are responsive to changes in mean hyperglycemia and also show responses to changes in postprandial hyperglycemia.

Metabolic and vascular effects of tumor necrosis factor-alpha blockade with etanercept in obese patients with type 2 diabetes

OBJECTIVE

The pro-inflammatory cytokine tumor necrosis factor-alpha (TNF-alpha) impairs insulin action in insulin-sensitive tissues, such as fat, muscle and endothelium, and causes endothelial dysfunction. We hypothesized that TNF-alpha blockade with etanercept could reverse vascular and metabolic insulin resistance.

METHOD AND RESULTS

Twenty obese patients with type 2 diabetes were randomized to etanercept treatment (25 mg subcutaneously twice weekly for 4 weeks) or used as controls in an open parallel study. Forearm blood flow and glucose uptake were measured during intra-arterial infusions of serotonin, sodium nitroprusside and insulin co-infused with serotonin. Beta-cell function was assessed with oral and intra-venous glucose tolerance tests and whole-body insulin sensitivity by hyperinsulinemic euglycemic clamps. Plasma levels of C-reactive protein and interleukin-6 decreased significantly with etanercept (C-reactive protein from 9.9 +/- 3.1 to 4.8 +/- 1.4 mg l(-1), p = 0.04; interleukin-6 from 3.1 +/- 0.4 to 1.9 +/- 0.2 ng l(-1), p = 0.03). Vasodilatory responses to serotonin and sodium nitroprusside infusions remained unchanged. Insulin effect on vasodilatation and on whole-body and forearm glucose uptake remained unchanged as well. Beta-cell function tended to improve.

CONCLUSION

Although short-term etanercept treatment had a significant beneficial effect on systemic inflammatory markers, no improvement of vascular or metabolic insulin sensitivity was observed.

Plasma nitrotyrosine levels, antioxidant vitamins and hyperglycaemia

AIMS

Studies on plasma nitrotyrosine (NT) levels, a measure of oxidative injury, in diabetes are limited and discordant; the amount of antioxidants might represent a possible explanation for the discordant results. The aim of this paper is to evaluate the association between plasma NT levels and glucose tolerance status, according to antioxidant vitamin intakes.

METHODS

In three hundred men randomly selected from a population-based cohort, NT levels were measured and dietary intake assessed by a food-frequency questionnaire. Results NT values were similar in patients with diabetes (n = 34), impaired fasting glucose (n = 77) and normoglycaemic subjects (n = 189). However, in subjects with lower than recommended daily intakes of antioxidant vitamins C and A, NT levels were significantly higher in the diabetic patients. In a multiple regression model, after adjustments for age, body mass index (BMI) and smoking habits, NT levels were significantly associated with fasting glucose in patients with lower intakes of vitamin C (beta = 11.4; 95% CI 1.3-21.5) and vitamin A (beta = 14.9; 95% CI 3.9-25.9), but not in subjects with lower intake of vitamin E.

CONCLUSION

A significant positive correlation between NT levels and fasting glucose is evident only in the presence of a reduced intake of some antioxidant vitamins. These findings might explain, at least in part, the discrepant results of previous studies and, if confirmed by further studies, suggest a simple measure (a balanced diet) to alleviate the increased oxidative stress of diabetes.

Effects of S21403 (mitiglinide) on postprandial generation of oxidative stress and inflammation in type 2 diabetic patients

AIM/HYPOTHESIS

Evidence suggests that postprandial hyperglycaemia may be a cardiovascular risk factor in diabetes. Oxidative stress and inflammation are involved in the pathogenesis of diabetic complications and previous studies have shown increased oxidative stress and inflammation in the postprandial phase in diabetic patients. The aim of the present study was to evaluate whether controlling postprandial hyperglycaemia with S21403 (mitiglinide) is accompanied by a reduced generation of oxidative stress and inflammation.

SUBJECTS AND METHODS

Forty type 2 diabetic patients participated in the study. Two different breakfast-tests were performed in each patient, with placebo or S21403. Plasma nitrotyrosine, plasma malondialdehyde (MDA), oxidised LDL (oxLDL), plasma total radical-trapping antioxidant parameter (TRAP), IL-6, IL-18, TNF-alpha, plasma glucose and insulin were measured.

RESULTS

After the administration of S21403, 40 mg, a rapid stimulation of insulin secretion was observed, accompanied by a reduction of postprandial hyperglycaemia. With S21403, a significant decrease of either nitrotyrosine, MDA and oxLDL levels, and a preservation of plasma TRAP compared with placebo was found. Significant decreases of IL-6, IL-18 and TNF-alpha were also observed with S21403 compared with placebo.

CONCLUSIONS/INTERPRETATION

This study shows that controlling postprandial hyperglycaemia with S21403 significantly improves the cluster of oxidative stress and inflammation markers that are increased in the postprandial state in diabetic patients.

Acute hyperglycemia and the innate immune system: clinical, cellular, and molecular aspects

OBJECTIVE

To extract from the biomedical literature the reported effects of acute hyperglycemia on the major components of the innate immune system and to describe the clinical benefits of strict blood glucose control in certain patients.

DATA SOURCE AND SELECTION

A Medline/PubMed search (1966 to July 2004) with manual cross-referencing was conducted, including all relevant articles investigating the effects of acutely elevated glucose levels on innate immunity. All publication types, languages, or subsets were searched.

DATA EXTRACTION AND SYNTHESIS

Original and selected review articles, short communications, letters to the editor, and chapters of selected textbooks were extracted. Most recent and relevant clinical trials were reviewed for the introductory section to provide the clinical background to this topic. The selected bench laboratory articles were then divided into three main categories based on the timing of events: a) the early phase of the innate immune reaction; b) the cytokine network; and c) the phagocytic phase. The most obvious findings related to hyperglycemia included reduced neutrophil activity (e.g., chemotaxis, formation of reactive oxygen species, phagocytosis of bacteria), despite accelerated diapedesis of leukocytes into peripheral tissue, as well as specific alterations of cytokine patterns with increased concentrations of the early proinflammatory cytokines tumor necrosis factor-alpha and interleukin-6. Furthermore, a reduction of endothelial nitric oxide formation takes place, thus decreasing microvascular reactivity to dilating agents such as bradykinin, and complement function (e.g., opsonization, chemotaxis) is impaired, despite elevations of certain complement factors.

CONCLUSIONS

Acute, short-term hyperglycemia affects all major components of innate immunity and impairs the ability of the host to combat infection, even though certain distinctive proinflammatory alterations of the immune response can be observed under these conditions.

Contributions of basal and post-prandial hyperglycaemia to micro- and macrovascular complications in people with type 2 diabetes

BACKGROUND

People with Type 2 diabetes mellitus are at high risk of cardiovascular disease and microvascular complications. A number of epidemiological studies have shown a strong relationship between the prevalence of vascular complications and raised levels of plasma glucose and glycated haemoglobin (HbA(1c)). Accumulating evidence supports the superior independent prognostic importance of the post-challenge glucose level, measured either 1 or 2 h after a glucose load. Thus, data from studies conducted in Europe, the USA, and particularly the Pacific rim and South Asia suggest that 2-h glucose is a better predictor of cardiovascular and all-cause mortality than pre-breakfast glucose, both in people with diabetes and those with pre-diabetic impaired glucose tolerance (IGT). Pathophysiological studies suggest that post-prandial rises in hyperglycaemia can trigger endothelial damage through multiple mechanisms, including increased oxidative stress and the increased expression of atherogenic circulating adhesion molecules and inflammatory cytokines that induce and regulate cell recruitment, migration, growth, and proliferation. Optimal pharmacological control of meal-time glucose levels can help to lower the HbA(1c) and thus may reduce the incidence of vascular complications in many people with diabetes. Moreover, emerging evidence suggests that reducing meal-time hyperglycaemia may delay the progression from pre-diabetic states toward overt diabetes.

SCOPE

This review (based on MEDLINE searches, 1980-2005) examines the evidence linking the microvascular and macrovascular complications of diabetes and glycaemic control, assesses the relative contributions of basal and meal-time concentrations, and considers the implications for optimal treatment for people with Type 2 diabetes or with prediabetic IGT.

An immune origin of type 2 diabetes?

Subclinical, low-grade systemic inflammation has been observed in patients with type 2 diabetes and in those at increased risk of the disease. This may be more than an epiphenomenon. Alleles of genes encoding immune/inflammatory mediators are associated with the disease, and the two major environmental factors the contribute to the risk of type 2 diabetes-diet and physical activity-have a direct impact on levels of systemic immune mediators. In animal models, targeting of immune genes enhanced or suppressed the development of obesity or diabetes. Obesity is associated with the infiltration and proinflammatory activity of macrophages in adipose tissue, and immune mediators may be important regulators of insulin resistance, mitochondrial function, ectopic lipid storage and beta cell dysfunction or death. Intervention studies targeting these pathways would help to determine the contribution of an activated innate immune system to the development of type 2 diabetes.