Hyperinsulinemia, risk factors, and coronary heart disease. The Zutphen Elderly Study

The role of polysaccharides from natural resources to design oral insulin micro- and nanoparticles intended for the treatment of Diabetes mellitus: A review

Oral administration of insulin (INS) would represent a revolution in the treatment of diabetes, considering that this route mimics the physiological dynamics of endogenous INS. Nano- and microencapsulation exploiting the advantageous polysaccharides properties has been considered an important technological strategy to protect INS against harsh conditions of gastrointestinal tract, in the same time that improve the permeability via transcellular and/or paracellular pathways, safety and in some cases even selectivity for targeting delivery of INS. In fact, some polysaccharides also give to the systems functional properties such as pH-responsiveness, mucoadhesiveness under specific physiological conditions and increased intestinal permeability. In general, all polysaccharides can be functionalized with specific molecules becoming more selective to the cells to which INS is delivered. The present review highlights the advances in the past 10 years on micro- and nanoencapsulation of INS exploiting the unique natural properties of polysaccharides, including chitosan, starch, alginate, pectin, and dextran, among others.

Resting heart rate and impaired glucose regulation in middle-aged and elderly Chinese people: a cross-sectional analysis

Background

Elevated resting heart rate (RHR) has been reported to be associated with metabolic syndrome and type 2 diabetes. The aim of this study was to explore whether a positive relationship exists between RHR and impaired glucose regulation (IGR) among middle-aged and older Chinese individuals.

Methods

We conducted a cross-sectional analysis that included a total of 9898 subjects (3194 men and 6704 women) in a Chinese population. The RHRs were derived from ECG recordings, and the subjects were stratified based on RHR quartiles.

Results

RHR levels were significantly higher in the subjects with isolated impaired fasting glucose (i-IFG), isolated impaired glucose tolerance (i-IGT), IFG + IGT and diabetes than in those with normal glucose regulation. When multivariate logistic regression analyses were performed, the odds ratios were substantially higher for the subjects with IGR (odds ratio 2.19, 95% confidence interval 1.85–2.58) in the fourth RHR quartile compared with those in the first quartile after adjustment for potential confounding covariates, and the corresponding OR for the combined IGR and type 2 diabetes group was 2.56 (95% CI 2.20–2.98, p < 0.001). Multiple regression analyses demonstrated that RHR was significantly associated with fasting plasma glucose, 2-h OGTT plasma glucose and A1c.

Conclusions

Our cross-sectional findings provide evidence that high RHR is associated with existing IGR among middle-aged and older Chinese individuals.

The cutoff values of indirect indices for measuring insulin resistance for metabolic syndrome in Korean children and adolescents

PURPOSE

The prevalence rates of metabolic syndrome (MetS) and percentile distribution of insulin resistance (IR) among Korean children and adolescents were investigated. The cutoff values of IR were calculated to identify high-risk MetS groups.

METHODS

Data from 3,313 Korean subjects (1,756 boys and 1,557 girls, aged 10-18 years) were included from the Korean National Health and Nutrition Examination Survey conducted during 2007-2010. Three different sets of criteria for MetS were used. Indirect measures of IR were homeostasis model assessment (HOMA-IR) and triglyceride and glucose (TyG) index. The cutoff values of the HOMA-IR and TyG index were obtained from the receiver operation characteristic curves.

RESULTS

According to the MetS criteria of de Ferranti el al., Cook et al., and the International Diabetes Federation, the prevalence rates in males and females were 13.9% and 12.3%, 4.6% and 3.6%, and 1.4% and 1.8%, respectively. Uses these 3 criteria, the cutoff values of the HOMA-IR and TyG index were 2.94 and 8.41, 3.29 and 8.38, and 3.54 and 8.66, respectively. The cutoff values using each of the 3 criteria approximately corresponds to the 50th-75th, 75th, and 75th-90th percentiles of normal HOMA-IR and TyG index levels.

CONCLUSION

This study describes the prevalence rates of MetS in Korean children and adolescents, an index of IR, and the cutoff values for MetS with the aim of detecting high-risk groups. The usefulness of these criteria needs to be verified by further evaluation.

Stability of dietary patterns assessed with reduced rank regression; the Zutphen Elderly Study

Background

Reduced rank regression (RRR) combines exploratory analysis with a-priori knowledge by including risk factors in the model. Dietary patterns, derived from RRR analysis, can be interpreted by the chosen risk factor profile and give an indication of positive or adverse health effects for a specific disease. Our aim was to assess the stability of dietary patterns derived by RRR over time.

Methods

We used data from 467 men, aged 64–85 years, participating in the 1985 and 1990 examination rounds of the Zutphen Elderly Study. Backwards regression on risk factors and food groups was applied prior to the RRR analysis to exclude food groups with low predictability (from 36 to 19 food groups) for the chosen risk factor profile. For the final RRR analysis, dietary intake data from 19 food groups as predictor variables and 6 established risk factors for cardiovascular diseases (body mass index, systolic and diastolic blood pressure, high density lipoprotein and total cholesterol levels, and uric acid) were used.

Results

Three RRR dietary patterns were derived for both examination years: a “(low in) cereal fibre pattern”, an “alcohol pattern” and an “inconsistent pattern”. The “(low in) cereal fibre pattern” was most stable over time, with a correlation coefficient of 0.47 (95% CI: 0.38-0.53) between 1985 and 1990 measurements.

Conclusion

Dietary patterns as measured by RRR, after backwards regression, are reasonably stable over a period of five years. Thus, RRR appears to be an attractive method to measure long-term dietary exposure for nutritional epidemiological studies, with one dietary measurement at baseline.

Urokinase receptor mediates osteogenic differentiation of mesenchymal stem cells and vascular calcification via the complement C5a receptor

Vascular calcification is a severe consequence of several pathological processes with a lack of effective therapy. Recent studies suggest that circulating and resident mesenchymal stem cells (MSC) contribute to the osteogenic program of vascular calcification. Molecular mechanisms underlying MSC osteogenic potential and differentiation remain, however, sparsely explored. We investigated a role for the complement receptor C5aR in these processes. We found that expression of C5aR was upregulated upon differentiation of human MSC to osteoblasts. C5aR inhibition by silencing and specific antagonist impaired osteogenic differentiation. We demonstrate that C5aR expression upon MSC differentiation was regulated by the multifunctional urokinase receptor (uPAR). uPAR targeting by siRNA resulted in complete abrogation of C5aR expression and consequently in the inhibition of MSC-osteoblast differentiation. We elucidated the NFκB pathway as the mechanism utilized by the uPAR-C5aR axis. MSC treatment with the NFκB inhibitor completely blocked the differentiation process. Nuclear translocation of the p65 RelA component of the NFκB complex was induced under osteogenic conditions and impaired by the inhibition of uPAR or C5aR. Dual-luciferase reporter assays demonstrated enhanced NFκB signaling upon MSC differentiation, whereas uPAR and C5aR downregulation lead to inhibition of the NFκB activity. We show involvement of the Erk1/2 kinase in this cascade. In vivo studies in a uPAR/LDLR double knockout mouse model of diet-induced atherosclerosis revealed impaired C5aR expression and calcification in aortic sinus plaques in uPAR(-/-)/LDLR(-/-) versus uPAR(+/+)/LDLR(-/-) control animals. These results suggest that uPAR-C5aR axis via the underlying NFκB transcriptional program controls osteogenic differentiation with functional impact on vascular calcification in vivo.

Responsive materials for self-regulated insulin delivery

With diabetes mellitus becoming an important public health concern, insulin-delivery systems are attracting increasing interest from both scientific and technological researchers. This feature article covers the present state-of-the-art glucose-responsive insulin-delivery system (denoted as GRIDS), based on responsive polymer materials, a promising system for self-regulated insulin delivery. Three types of GRIDS are discussed, based on different fundamental mechanisms of glucose-recognition, with: a) glucose enzyme, b) glucose binding protein, and c) synthetic boronic acid as the glucose-sensitive component. At the end, a personal perspective on the major issues yet to be worked out in future research is provided.

Plasma albumin and platelet function: relevance to atherogenesis and thrombosis

Two papers published in this journal(1,2) during the past year remind us that plasma albumin concentrations can influence platelet function. These publications, together with epidemiological evidence showing that low plasma concentrations of albumin predict mortality from cardiovascular disease(3,4) have prompted this review.

Oral delivery of therapeutic protein/peptide for diabetes--future perspectives

Diabetes is a metabolic disease and is a major cause of mortality and morbidity in epidemic proportions. A type I diabetic patient is dependent on daily injections of insulin, for survival and also to maintain a normal life, which is uncomfortable, painful and also has deleterious effects. Extensive efforts are being made worldwide for developing noninvasive drug delivery systems, especially via oral route. Oral route is the most widely accepted means of administration. However it is not feasible for direct delivery of peptide and protein drugs. To overcome the gastro-intestinal barriers various types of formulations such as polymeric micro/nanoparticles, liposomes, etc. are investigated. In the recent years lot of advances have taken place in developing and understanding the oral peptide delivery systems. Simultaneously, the development and usage of other peptides having anti-diabetic potentials are also considered for diabetes therapy. In this review we are focusing on the advances reported during the past decade in the field of oral insulin delivery along with the possibility of other peptidic incretin hormones such as GLP-1, exendin-4, for diabetes therapy.

Effect of high-fat diets on body composition, lipid metabolism and insulin sensitivity, and the role of exercise on these parameters

Dietary fat composition can interfere in the development of obesity due to the specific roles of some fatty acids that have different metabolic activities, which can alter both fat oxidation and deposition rates, resulting in changes in body weight and/or composition. High-fat diets in general are associated with hyperphagia, but the type of dietary fat seems to be more important since saturated fats are linked to a positive fat balance and omental adipose tissue accumulation when compared to other types of fat, while polyunsaturated fats, omega-3 and omega-6, seem to increase energy expenditure and decrease energy intake by specific mechanisms involving hormone-sensitive lipase, activation of peroxisome proliferator-activated receptor α (PPARα) and others. Saturated fat intake can also impair insulin sensitivity compared to omega-3 fat, which has the opposite effect due to alterations in cell membranes. Obesity is also associated with impaired mitochondrial function. Fat excess favors the production of malonyl-CoA, which reduces GLUT4 efficiency. The tricarboxylic acid cycle and beta-oxidation are temporarily uncoupled, forming metabolite byproducts that augment reactive oxygen species production. Exercise can restore mitochondrial function and insulin sensitivity, which may be crucial for a better prognosis in treating or preventing obesity.

Worksite health screening programs for predicting the development of Metabolic Syndrome in middle-aged employees: a five-year follow-up study

BACKGROUND

Metabolic syndrome (MetS) management programs conventionally focus on the adults having MetS. However, risk assessment for MetS development is also important for many adults potentially at risk but do not yet fulfill MetS criteria at screening. Therefore, we conducted this follow-up study to explore whether initial screening records can be efficiently applied on the prediction of the MetS occurrence in healthy middle-aged employees.

METHODS

Utilizing health examination data, a five-year follow-up observational study was conducted for 1384 middle-aged Taiwanese employees not fulfilling MetS criteria. Data analyzed included: gender, age, MetS components, uric acid, insulin, liver enzymes, sonographic fatty liver, hepatovirus infections and lifestyle factors. Multivariate logistic regression was used to estimate the adjusted odds ratios (OR) and 95% confidence interval (CI) of risk for MetS development. The synergistic index (SI) values and their confidence intervals of risk factor combinations were calculated; and were used to estimate the interacting effects of coupling MetS components on MetS development.

RESULTS

Within five years, 13% (175 out of 1384) participants fulfilled MetS criteria. The ORs for MetS development among adults initially having one or two MetS components were 2.8 and 7.3, respectively (both p < 0.01), versus the adults having zero MetS component count at screening. Central obesity carried an OR of 7.5 (p < 0.01), which far exceeded other risk factors (all ORs < 2.7). Synergistic effects on MetS development existed between coupling MetS components: 1. High blood pressure plus low-HDL demonstrated an OR of 11.7 (p < 0.01) for MetS development and an SI of 4.7 (95% CI, 2.1-10.9). 2. High blood pressure plus hyperglycemia had an OR of 7.9 (p < 0.01), and an SI of 2.7 (95% CI, 1.2-6.4).

CONCLUSION

MetS component count and combination can be used in predicting MetS development for participants potentially at risk. Worksite MetS screening programs simultaneously allow for finding out cases and for assessing risk of MetS development.

Antiatherogenic properties of flavonoids: implications for cardiovascular health

Epidemiological studies suggest that higher flavonoid intake from fruits and vegetables is associated with decreased risk for the development of cardiovascular disease. The mechanisms explaining this observation remain unclear, but current evidence suggests that flavonoids may exert their effects through the improvement of cardiovascular risk factors. The present review summarizes data suggesting that flavonoids improve endothelial function. inhibit low-density lipoprotein oxidation, decrease blood pressure and improve dyslipidemia. A large number of studies have reported the impact of consuming flavonoid-rich foods on biomarkers of cardiovascular disease risk in healthy volunteers or at-risk individuals. Most studies have focused on cocoa, soy, and green and black tea. Recent evidence suggests that some polyphenols in their purified form, including resveratrol, berberine and naringenin, have beneficial effects on dyslipidemia in humans and/or animal models. In a mouse model of cardiovascular disease, naringenin treatment, through correction of dyslipidemia, hyperinsulinemia and obesity, attenuated atherosclerosis. Therefore, the beneficial effects of flavonoids on multiple risk factors may explain, in part, the observed beneficial effects of flavonoids on cardiovascular disease.

Associations of apolipoprotein B with pulse pressure and glucose in Chinese families with familial combined hyperlipidemia

Familial combined hyperlipidemia (FCHL), with a marked elevation of apolipoprotein B (apoB), is estimated to cause 10-20% of premature coronary artery disease. However, little data are available to demonstrate the associations of apoB with pulse pressure and glucose levels in FCHL families in China. This study was to investigate the potential influence factors for blood pressure and glucose phenotypes in FCHL families by multiple linear regression analysis. We recruited 147 FCHL relatives and 90 spouses, aged 30 to 60 years, from 42 Chinese families with FCHL. Our results showed that triglyceride and low density lipoprotein cholesterol were associated with fasting glucose levels (all P<0.05). Body mass index and glucose significantly correlated to systolic blood pressure, diastolic blood pressure, and mean arterial pressure, respectively (all P<0.05). Furthermore, apoB was significantly related to pulse pressure and glucose in FCHL families (all P<0.05). Thus, this study demonstrates that apoB is significantly associated with pulse pressure and glucose levels in FCHL families. Accordingly, our data suggest that apoB may be a candidate risk marker for pulse pressure and glucose in FCHL populations.

Consequences of food energy excess and positive energy balance

This paper discusses possible consequences of energy excess throughout the life cycle. Firstly we consider the effects of foods on hunger, satiety and satiation. Also, the changes in food availability and consumption in relation to changes in social and economic determinants of energy excess. The relationship between physical activity and energy intake (EI) is also considered. Secondly we explore the definition of energy excess and the metabolic effects of macronutrients (mainly in relation to fuel partitioning oxidation/storage) on energy balance. The cellular and molecular regulation determined by specific genes involved in lipogenesis, fuel partitioning and/or in energy dissipation are explored. Thirdly, we examine the main consequences induced by energy excess and positive energy balance, starting with the alterations in glucose utilisation (insulin resistance) leading to type 2 diabetes and the linkage of energy excess with other non-communicable diseases (NCDs). Biological, social and psychological consequences during perinatal, childhood and adolescence periods are specifically analysed. Fourthly, the transition from energy deficit to excess, under the optic of a developing country is analysed with country examples drawn from Latin America. The possible role of supplementary food programmes in determining positive energy balance is discussed especially in relation to pre-school and school feeding programmes. Fifthly, we deal with the economic costs of energy excess and obesity related diseases. Finally, some areas where further research is needed are described; biological and genetic determinants of individual and population energy requirements, foods and food preparations as actually consumed, consumer education and research needs on social determinants of energy imbalances.

Clustering of haemostatic variables and the effect of high cashew and walnut diets on these variables in metabolic syndrome patients

We investigated the effect of a high walnut and cashew diet on haemostatic variables in people with the metabolic syndrome. Factor analysis was used to determine how the haemostatic variables cluster with other components of the metabolic syndrome and multiple regression to determine possible predictors. This randomized, control, parallel, controlled-feeding trial included 68 subjects who complied with the Third National Cholesterol Education Program Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol criteria. After a 3-week run-in following the control diet, subjects were divided into three groups receiving either walnuts or cashews (20 energy%) or a control diet for 8 weeks. The nut intervention had no significant effect on von Willebrand factor antigen, fibrinogen, factor VII coagulant activity, plasminogen activator inhibitor 1 activity, tissue plasminogen activator activity or thrombin activatable fibrinolysis inhibitor. Statistically, fibrinogen clustered with the body-mass-correlates and acute phase response factors, and factor VII coagulant activity clustered with high-density lipoprotein cholesterol (HDL-C). Tissue plasminogen activator activity, plasminogen activator inhibitor 1 activity and von Willebrand factor antigen clustered into a separate endothelial function factor. HDL-C and markers of obesity were the strongest predictors of the haemostatic variables. We conclude that high walnut and cashew diets did not influence haemostatic factors in this group of metabolic syndrome subjects. The HDL-C increase and weight loss may be the main focus of dietary intervention for the metabolic syndrome. Furthermore, diet composition may have only limited effects if weight loss is not achieved.

Spectrum of insulin sensitivity in the Korean population

The aims of the present study were to (1) examine the range of values for insulin sensitivity measures such as fasting serum insulin, homeostasis model assessment (HOMA), and quantitative insulin sensitivity check index (QUICKI) and (2) to identify cutoffs for indirect indexes of insulin sensitivity such as insulin, HOMA, and QUICKI that confer increased risk of metabolic syndrome in a large sample of Korean adults. The total number of study subjects involved was 83186. All of them presented for a routine health status checkup at the Kangbuk Samsung Hospital between January 2003 and December 2004, and none of them was currently taking medication for hypertension, diabetes, or dyslipidemia. We used 3 measures of insulin sensitivity: the fasting serum insulin, the HOMA, and the QUICKI. The age- and sex-adjusted prevalence of metabolic syndrome was examined by tenths of the distribution of each index of insulin. The fasting serum insulin, HOMA, and QUICKI were compared by using receiver operating characteristic curves. The fasting serum insulin ranged from 1.71 to 70.40 microU/mL, with the 25th percentile = 5.97, the median = 7.69, and the 75th percentile = 9.82. The HOMA ranged from 0.34 to 17.72, with the 25th percentile = 1.33, the median = 1.74, and the 75th percentile = 2.27. The QUICKI ranged from 0.112 to 0.202, with the 25th percentile = 0.146, the median = 0.152, and the 75th percentile = 0.158. The insulin, HOMA, and QUICKI values at the point on the receiver operating characteristic curve closest to the ideal of 100% sensitivity and 100% specificity for detecting the presence of metabolic syndrome were 9.7 microU/mL, 2.43, and 0.145, respectively. In conclusion, these findings describe the spectrum of insulin sensitivity in Korean adults. This study is the first attempt to determine cutoff values for indirect indexes of insulin sensitivity such as insulin, HOMA, and QUICKI that confer an increased risk of metabolic syndrome. These findings may be useful for evaluating insulin resistance, particularly in epidemiological studies.

Two measures of insulin sensitivity provided similar information in a U.S. population

BACKGROUND AND OBJECTIVE

Two methods for measuring insulin sensitivity, fasting plasma insulin (FPI) and homeostasis model assessment (HOMA) have been proposed for use in large epidemiological research and clinical practice. This project describes the range of observed values of the HOMA and FPI in a large sample of the U.S. population.

METHODS

We used fasting plasma glucose and insulin values from the Third National Health and Nutrition Survey (NHANES III) to identify the FPI and HOMA values. For both FPI and HOMA, higher values indicate lower insulin sensitivity.

RESULTS

Among 6,511 participants without treated diabetes mellitus, FPI ranged from 1.8 to 175.8 microU/mL, with 25th percentile=6.7, median=9.3, 75th percentile=13.3, and mean+/-1 SD=11.2+/-7.5; HOMA ranged from 0.3 to 52.6 (mmol)(microU)/L(2), with 25th percentile=1.5, median=2.2, 75th percentile=3.3, and mean+/-SD=2.8+/-2.4.

CONCLUSION

These findings describe the spectrum of insulin sensitivity and may be useful in helping physicians develop a clinical understanding of the dynamic range of both FPI and HOMA measures.

Hemostatic risk factors and insulin sensitivity, regional body fat distribution, and the metabolic syndrome

Disturbances in the thrombotic and fibrinolytic systems are a feature of insulin resistance, obesity, and the metabolic syndrome. However, there are few studies in which these relationships have been explored in mainly asymptomatic individuals using sophisticated measures of insulin sensitivity and regional adiposity. Variables of the hemostatic system were measured in 106 men (aged 32-68 yr; body mass index, 20-34 kg/m(2)). Insulin sensitivity was measured by minimal model analysis and regional adiposity by dual energy x-ray absorptiometry. Clustering of intercorrelated variables was assessed by the statistical technique of factor analysis. Plasma levels of procoagulant factors VII and X, anticoagulant proteins C and S, and plasminogen activator inhibitor-1 correlated positively with total and percent central body fat (r = 0.25-0.38; P < 0.05) and negatively with insulin sensitivity (except protein S; r = -0.24 to -0.35; P < 0.05). On factor analysis, procoagulant factors VII and X, proteins C and S, and plasminogen activator inhibitor-1 were components of the cluster of variables that explained the greatest proportion of the variance in the data (39.2%). Other variables included in this cluster were those typical of the metabolic syndrome and also serum gamma-glutamyl transferase activity. These results suggest that factors VII and X and proteins C and S are features of the intercorrelated disturbances of the metabolic syndrome. Associations with adiposity and liver enzyme activity suggest the involvement of hepatic fat deposition.

Impact of adiponectin gene polymorphisms on plasma lipoprotein and adiponectin concentrations of viscerally obese men

The aim of this study was first to examine the relationships between adiponectin gene (Apm1) polymorphisms and anthropometric indices as well as plasma adiponectin and lipoprotein/lipid levels, and then to investigate whether the presence of visceral obesity or insulin resistance may modulate the impact of these polymorphisms on metabolic risk variables. Molecular screening of the Apm1 gene was achieved, and a sample of 270 unrelated men recruited from the greater Quebec City area and selected to cover a wide range of body fatness values was genotyped. Sequencing of the Apm1 gene revealed two previously reported polymorphisms (c.45T>G and c.276G>T) as well as two newly identified genetic variations (-13752delT and -13702G>C). Carriers of the c.276T allele had higher LDL-cholesterol and lower HDL-triglyceride concentrations than did 276G/G homozygotes (P=0.02 and P=0.01, respectively). Carriers of the c.45G allele exhibited higher plasma adiponectin concentrations than did 45T/T homozygotes (P=0.04). After dividing each genotype group into subgroups for visceral AT, homozygotes for the normal allele at position -13752delT, carriers of the c.45G allele, and carriers of the c.276T allele had similar total apolipoprotein B (apoB) concentrations, whether they were viscerally obese or not. These results suggest that some Apm1 gene polymorphisms influence plasma adiponectin concentrations and lipoprotein/lipid levels. In addition, the impact of these polymorphisms is modulated by the presence of visceral obesity.

Control of postprandial plasma glucose by an oral insulin product (HIM2) in patients with type 2 diabetes

OBJECTIVE

The objectives of this exploratory study were to assess the postprandial glucose-lowering effects and evaluate the safety and tolerability of single, escalating doses of an oral insulin product, hexyl-insulin monoconjugate 2 (HIM2), in patients with type 2 diabetes. Subcutaneous insulin and oral placebo were also administered for comparison.

RESEARCH DESIGN AND METHODS

Eighteen patients with type 2 diabetes were enrolled in this randomized, single-blind, placebo-controlled, three-way crossover, dose-escalation study. A single dose of each of the following study drugs was administered to each patient on 3 separate days: oral HIM2 (at one of three dose levels: 0.375, 0.5, or 1.0 mg/kg), subcutaneous regular insulin (8 units Humulin R), and oral placebo. At 30 min after dosing, patients ingested a standardized test meal (16 oz/720 calories of Boost Plus). Serial blood samples were collected for determination of plasma glucose and insulin concentrations during the 4-h postdose period.

RESULTS

The mean glucose area under the curve for 0 to 240 min (AUC(0-240)) values were lower following administration of 0.5 and 1.0 mg/kg HIM2 vs. placebo (1,097.1 vs. 1,196.9 and 801.1 vs. 992.1 mg x h(-1) x dl(-1), respectively). This difference was statistically significant at the 1.0-mg/kg HIM2 dose level. Insulin exposure, as measured by insulin AUC(0-240) values, for the 0.375-, 0.5-, and 1.0-mg/kg dose levels of HIM2 were 169.9, 193.1, and 230.8 micro U x h(-1) x ml(-1), respectively; insulin AUC(0-240) values for placebo were 165.8, 196.1, and 169.2 micro U x h(-1) x ml(-1), respectively. The mean glucose AUC(0-240) values were similar following administration of 0.5 and 1.0 mg/kg HIM2 vs. subcutaneous insulin (1,097.1 vs. 1,048.0 and 801.1 vs. 875.2 mg x h(-1) x dl(-1), respectively). For pooled data from the 0.5- and 1.0-mg/kg dose groups, the HIM2/subcutaneous insulin ratios for the 2-h postprandial glucose concentration (0.97, 95% CI 0.90-1.06), maximum postprandial glucose concentration (0.99, 95% CI 0.93-1.06), and glucose AUC(0-240) (0.98, 95% CI 0.9-1.06) were within 10% of unity, implying glucodynamic equivalence. Although HIM2 (0.5 and 1.0 mg/kg) and subcutaneous insulin (8 units) provided comparable control of postprandial plasma glucose concentrations, HIM2 resulted in peripheral insulin concentrations that were lower than subcutaneous insulin (mean insulin AUC(0-240) of 193.1 vs. 233.6 and 230.8 vs. 270.3 micro U x h(-1) x ml(-1), respectively).

CONCLUSIONS

Single, oral doses of HIM2 were safe and well tolerated. HIM2 (0.5 and 1.0 mg/kg) was more effective than placebo and as effective as subcutaneous regular insulin (8 units) at controlling postprandial glycemia with respect to the following parameters: 2-h postprandial glucose concentration, maximum glucose concentration, and glucose AUC(0-240). This occurred even though peripheral insulin concentrations were lower following the administration of HIM2 (0.5 and 1.0 mg/kg) than subcutaneous insulin. Thus, HIM2 therapy may control postprandial glycemia without causing peripheral hyperinsulinemia in patients with type 2 diabetes.

Comparison of modifiable determinants of lipids and lipoprotein levels among African-Americans, Hispanics, and Non-Hispanic Caucasians > or =65 years of age living in New York City

Information on determinants of plasma lipids and lipoproteins and how these factors would differ among race/ethnic groups in elderly populations is scarce. We studied cross-sectionally the distribution and predictors of lipids and lipoproteins in 1,118 free-living elderly subjects (> or =65 years of age), in a multiethnic urban community (22% non-Hispanic Caucasian, 34% African-American, and 44% Hispanic). Mean levels of total cholesterol, total/high-density lipoprotein (HDL) cholesterol ratio, and triglycerides decreased with increasing age (p <0.001). Low-density lipoprotein cholesterol and total cholesterol were lower among men, whereas women had higher levels of HDL cholesterol (p <0.001). Hispanics had lower low-density lipoprotein cholesterol, total cholesterol, and HDL cholesterol levels, whereas African-Americans had a lower total/HDL cholesterol ratio and triglyceride levels along with higher HDL cholesterol levels (p <0.001). Diabetes was more prevalent among Hispanics and African-Americans (p = 0.002), and body mass index was higher in African-Americans (p = 0.009). Hispanics were less likely to drink alcohol (p <0.0001), but more likely to drink larger amounts of coffee (p <0.0001). A greater proportion of African-Americans were active smokers (p <0.001). In multivariate regression models, body mass index was a significant independent predictor of total cholesterol (beta = 0.74, p <0.001). Waist circumference predicted lower HDL cholesterol levels (0.57 mg/dl lower per inch, p <0.001) and a higher total/HDL cholesterol ratio (beta = 0.05, p <0.001). Alcohol intake (>2 g/day) predicted higher HDL cholesterol (beta = 6.20, p <0.001). Diabetic status predicted lower HDL cholesterol (beta = -2.47, p <0.05), higher total/HDL cholesterol ratio (beta = 0.35, p <0.001), and triglycerides (beta = 37.10, p <0.001). Physical activity, coffee intake, and a calorie-adjusted atherogenicity index did not show independent predictive value. These findings indicate that obesity, alcohol intake, and diabetes mellitus are potentially modifiable independent determinants of lipids and lipoprotein levels in an elderly multiethnic population.

Effect of short-term exercise training on insulin-stimulated PI 3-kinase activity in middle-aged men

The purpose of this study was to determine whether the improved insulin action with short-term exercise training in middle-aged individuals is associated with enhanced phosphatidylinositol (PI) 3-kinase activity in skeletal muscle. Nine men of ages 50-70 yr were studied before and after 7 consecutive days of supervised exercise (60 min/day, 70% peak O2 consumption). Insulin sensitivity was measured with a euglycemic hyperinsulinemic glucose clamp in the sedentary condition and 15-17 h after the final exercise session. Anti-phosphotyrosine-associated PI 3-kinase activity was determined from muscle samples obtained in the fasted condition and after 60 min of insulin infusion during the clamp. With exercise, the glucose infusion rate increased (P < 0.001) by 33%, indicating enhanced insulin action (mean +/- SE, 6.6 +/- 0.6 vs. 8.7 +/- 0.8 mg x kg(-1) x min(-1)). Short-term exercise training did not, however, increase insulin-stimulated (insulin stimulated/fasting) PI 3-kinase activity (1.8 +/- 0.8 vs. 1.8 +/- 0.7-fold stimulation with insulin pre- vs. posttraining, respectively). There was also no change in insulin-stimulated protein kinase B activity (1.3 +/- 0.1 vs. 1.4 +/- 0.2-fold stimulation with insulin) with training. These data suggest that insulin action is enhanced with short-term exercise training via an adaptation distal to PI 3-kinase in middle-aged, insulin-resistant individuals.

Is insulin resistance or diabetes mellitus associated with stroke? An 18-year follow-up study

Insulin resistance and/or diabetes are risk factors for coronary artery disease. However, it is still controversial whether they are associated with the development of stroke. A total of 304 Japanese men and women, aged 20-69 years, were selected on the basis of casual high blood glucose concentrations from 2732 participants of a population-based health examination in 1980. They all underwent a 50 g oral glucose tolerance test in 1981. Homa IR (index of insulin resistance) and Homa beta-cells (index of beta-cell function) were calculated from their fasting insulin and glucose using the formulas for the homeostasis model. They were followed-up for 18 years. Incidence of stroke was investigated by computed tomography. During 18 years, 28 subjects had a stroke; 21 had ischemic and nine had hemorrhagic strokes (two had both). Baseline variables, which showed an independent association with the incidence of stroke in the Cox proportional hazard model, were blood pressure, use of anti-hypertensive medications, and Homa beta-cell index (inversely) after adjustments for age and sex. After further adjustment for blood pressure using a step-forward method, Homa beta-cell was significantly related to the incidence of stroke (Hazard ratio: 0.65, 95% confidence interval: 0.44-0.95). In addition to hypertension, diabetes but not insulin resistance, is a risk factor for stroke.

Age-related insulin resistance: is it an obligatory finding? The lesson from healthy centenarians

It is widely known that advancing age is associated with impaired glucose handling. A unifying hypothesis explaining the relationship between aging and insulin resistance might encompass four main pathways, namely: (a) anthropometric changes (relative and absolute increase in body fat combined with a decline in fat free mass) which could be the anatomic substrate for explaining the reduction in active metabolic tissue; (b) environmental causes, mainly diet style and physical activity; (c) neuro-hormonal variations [decline in plasma dehydroepandrosterone sulphate (DHEAS) and IGF-1]; and finally (d) the rise in oxidative stress. Indeed previous studies have also investigated the occurrence and the degree of insulin resistance in healthy centenarians. Such data demonstrated that age-related insulin resistance is not an obligatory finding in the elderly and that healthy centenarians have a preserved insulin action compared to aged subjects. Why insulin action is preserved in centenarians is still not known. Nevertheless, a possible approach to the question is to outline the centenarians' anthropometric, endocrine and metabolic characteristics in order to design a clinical picture of such metabolic "successful aging". According to the remodeling theory of age, the preserved insulin action in centenarians might be the net result of the continuous adaptation of the body to the deleterious changes that occur over time. Nevertheless, only future longitudinal studies specifically designed to investigate the relationship between extreme old age and degree of insulin sensitivity will provide a conclusive answer with regard to the pathophysiology of adaptive metabolic changes occurring in the elderly.

Cardiovascular disease and fiber: is insulin resistance the missing link?

Multiple mechanisms are likely for any effect of fiber on cardiovascular disease risk. One component that is described is the hypocholesterolemic activity of soluble fibers as they bind bile acids. New epidemiologic evidence indicates that fiber's modulation of insulin secretion and resistance deserves additional attention.

Metabolic age modelling: the lesson from centenarians

Evolutionary theories of ageing, and data emerging from cellular and molecular biology of ageing, suggested that animals and humans capable of reaching an age close to the extreme limit of the life span should be equipped with a very efficient network of anti-ageing mechanisms. Indeed several evidences have demonstrated that starting from young to very old subjects, ageing is associated with a progressive remodelling. Thus, a new paradigm, the remodelling theory of age, was proposed. This theory, focusing on the human immune system, suggested that immunosenescence is the net result of the continuous adaptation of the body to the deteriorative changes occurring over time. According to this hypothesis, body resources are continuously optimized, and immunosenescence must be considered a very dynamic process including both loss and gain. Whether the metabolic pathways and the endocrine functions are also part of the age remodelling is not investigated. The aim of this review is to focus on the age-related changes in metabolic pathways and endocrine functions and to demonstrate that healthy centenarians (HC) represent the best living example of successful age-remodelling in whom the age remodelling has occurred without problems. In order to design the clinical picture of such successful ageing, anthropometric, endocrine and metabolic characteristics of healthy centenarians (HC), compared with aged subject, have been outlined.

Age-related changes in coagulation, fibrinolysis, and platelet aggregation in male WBN/Kob rats

We investigated the age-related changes in blood coagulation, fibrinolysis, and platelet aggregation in male WBN/Kob rats, animals that exhibit spontaneously diabetes mellitus at more than 6 months of age. The rats aged 6 months or more showed significant hyperglycemia, hypoinsulinemia, and hyperlipidemia. As changes in coagulation parameters, the data indicated significant increases in factors II, V, VII, VIII, IX, X, and XII activities; a significant decrease in antithrombin III activity in rats more than 6 months of age; significant increases in fibrinogen level and factor XI activity; and significant decreases in prothrombin time and activated partial thromboplastin time in those more than 9 months of age. As changes in fibrinolytic parameters, the animals showed significant decreases in plasminogen and tissue-type plasminogen activator, and significant increases in alpha2-plasmin inhibitor and plasminogen activator inhibitor at more than 6 months of age. In addition, there were significant correlations between the plasma levels of coagulation/fibrinolytic markers and the 4-hour fasting glucose or lipids. Furthermore, they displayed significant increases in ADP- or collagen-induced platelet aggregation and in cholesterol/phospholipid molar ratio in platelets at more than 9 months of age. The increase in cholesterol/phospholipid ratio may be responsible for hyperaggregation of platelets in diabetic animals. These findings suggest that WBN/Kob rats are suitable for research on blood coagulation abnormalities in diabetes. However, further studies are needed to clarify the details of the mechanisms involved.

Insulin and hypertension in the NHLBI Family Heart Study: a sibpair approach to a controversial issue

The association between insulin and hypertension remains equivocal. We therefore investigated insulin levels in 3037 normotensive and 1067 hypertensive subjects from the National Heart, Lung and Blood Institute (NHLBI) Family Heart Study (FHS) by two different approaches. First, we compared insulin levels between normotensive and 275 untreated hypertensive subjects. Insulin levels unadjusted as well as adjusted for age, sex, and center were significantly higher in hypertensives. After adjustment for body mass index (BMI), insulin remained significantly higher only in the diastolic hypertensive group (mean +/- SD 77.0 +/-36.7 pmol/L, P < .01) but not in the isolated systolic hypertensive group (67.0 +/- 38.2 pmol/L) when compared to normotensives (63.2 +/- 29.1 pmol/L). A sibpair analysis was then used that compared the intra-sibpair differences in insulin concentrations to the intra-sibpair differences in blood pressure (BP) levels. This approach was intended to control for the effects of genetic and residual shared environmental variance upon insulin levels. The intra-sibpair difference in insulin concentrations between concordant (diastolic and systolic deltaBP < 5 mm Hg) and discordant sibpairs (diastolic and systolic deltaBP > 15 and > 20 mm Hg, respectively) was no longer significantly different when adjusted for BMI (2.7 v 5.9 pmol/L for diastolic and -1.7 v -1.8 pmol/L for systolic BP). Even the random selection of one sibpair from each of the 326 families independently of insulin and BP levels did not result in a significant correlation between the intrasibpair differences in insulin and BP. Using an insulin resistance index instead of insulin did not change our findings. Our investigation in the FHS sample of families suggests that there is only a small, if any, influence of insulin levels on BP after adjustment for obesity-related sources of variation.

Advancing age and insulin resistance: new facts about an ancient history

The relationship between advancing age and insulin resistance is widely known, but the cause(s) of such association are less well understood. Age-related changes in anthropometric characteristics and environmental factors (changes in diet habits and decline in physical activity) have been hypothesized as being among the main causes. More recently, the role of plasma insulin-like growth factor I (IGF-I), dehydroepiandrosterone sulphate (DHEAS) and tumour necrosis factor alpha (TNF-alpha) concentrations as well as the degree of oxidative stress have also been evaluated. As far as the anthropometric changes are concerned, a decline in fat-free mass and a relative or absolute increase in fat mass are common findings in aged subjects. Such changes are combined with a decline in plasma DHEAS and IGF-I concentration and a rise in plasma TNF-alpha concentrations and oxidative stress, which, in turn, may interact with the anthropometric changes determining the worsening in insulin-mediated glucose uptake. Finally, age-related environmental factors (changes in diet quality and decline in the degree of physical activity) might be a common factor allowing anthropometric factors and age-related remodelling to accelerate their negative impact on insulin action.

Metabolic effects of temocapril in hypertensive patients with diabetes mellitus type 2

Compared with other angiotensin-converting enzyme (ACE) inhibitors, the elimination of temocapril is less dependent on renal function. To investigate the metabolic and antihypertensive effects of temocapril in diabetic hypertensives, 30 patients with diabetes mellitus type 2 and mild to moderate hypertension [diastolic blood pressure (BP) 90-115 mm Hg] and without azotemia (plasma creatinine < 180 microM) were evaluated in a prospective randomized double-blind placebo-controlled study. After a 4-week placebo run-in, they received temocapril, 20 mg daily (n = 19), or placebo (n = 11) for 6 weeks. Insulin sensitivity index (SI), determined by the Minimal Model method of Bergman, serum lipoproteins, plasma renin activity, fibrinogen, and microalbuminuria were assessed at the end of the placebo run-in phase and the double-blind treatment phases. Temocapril but not placebo administration produced a significant decrease in supine BP (152/92+/-5/3 vs. 162/98+/-5/2 mm Hg; p < 0.01) and increase in plasma renin (p < 0.05). Variation of SI during temocapril treatment did not reach statistical significance (0.95+/-0.2 before vs. 1.44+/-0.4 x 10(-4)/min/mU/L after treatment). During administration of temocapril or placebo, no significant changes in fasting plasma glucose, insulin, and serum levels of total triglycerides, cholesterol, lipoprotein cholesterol fractions, or fibrinogen were observed. Microalbuminuria decreased significantly on temocapril treatment (49+/-10 vs. 79+/-17 mg/24 h; p < 0.01) but not on placebo. These findings demonstrate that in hypertensive patients with diabetes mellitus type 2, short-term treatment with temocapril is neutral to insulin sensitivity, lipoprotein metabolism, and fibrinogen, and significantly reduces microalbuminuria.

Will new diagnostic criteria for diabetes mellitus change phenotype of patients with diabetes? Reanalysis of European epidemiological data. DECODE Study Group on behalf of the European Diabetes Epidemiology Study Group

OBJECTIVE

To evaluate the impact of the revised diagnostic criteria for diabetes mellitus adopted by the American Diabetes Association on prevalence of diabetes and on classification of patients. For epidemiological purposes the American criteria use a fasting plasma glucose concentration >=7.0 mmol/l in contrast with the current World Health Organisation criteria of 2 hour glucose concentration >=11.1 mmol/l.

DESIGN

Data were collected from 13 populations and three occupational based studies from eight European countries. All studies used a 75 g oral glucose tolerance test to measure fasting and 2 hour glucose concentrations.

SUBJECTS

17 881 men; 8309 women; age range 17-92 years.

MAIN OUTCOME MEASURES

Classification of diabetes according to both sets of criteria.

RESULTS

The application of the American criteria on European populations induced changes in prevalence of diabetes ranging from a reduction of 4.0% to an increase of 13.2%. A total of 1517 previously undiagnosed individuals had diabetes according to either the WHO or the American criteria. Among 1044 with diabetes according to American criteria, only 45% had 2 hour values fulfilling the WHO criteria. The risk of disagreement of classification decreased with increasing body mass index (P<0.00001) and increasing age (P<0.0001); the impact of sex was not significant (P=0.08).

CONCLUSIONS

This shift in strategy from using 2 hour to fasting plasma glucose will cause an increase in the prevalence of diabetes in some European populations. A high degree of disagreement in the classification was observed between the two recommendations. Prospective data are needed to evaluate whether the WHO or the American criteria best identify individuals at risk of developing microvascular complications and cardiovascular disease. Wider implementation of revised diagnostic criteria should await prospective data.

Relationships between fasting plasma insulin, anthropometrics, and metabolic parameters in a very old healthy population. Associazione Medica Sabin

Several studies have shown that insulin resistance and hyperinsulinemia are associated with many metabolic disorders predisposing to coronary heart disease (CHD). This syndrome has been termed syndrome X. However, it is not completely known whether these relationships are still present in the elderly, or whether other factors such as age, gender, and body fat distribution modulate them. Therefore, we investigated the relationship between fasting plasma insulin, total and regional adiposity, fasting plasma glucose and lipids, plasma plasminogen activator inhibitor-1 (PAI-1), fibrinogen, and coagulation factor VII in a sample of 100 healthy free-living octogenarians-nonagenarians (52 men and 48 women) who were disability-free according to the Katz index. By univariate analysis, fasting insulin correlated positively with all anthropometric measures except the waist to hip ratio (WHR) in women. There was a positive correlation between fasting insulin and fasting glucose (r=.40, P < .01), plasma triglycerides ([TGs] r=.21, P < .05), and PAI-1 levels (r=.33, P < .01), whereas a negative relation was found with high-density lipoprotein cholesterol (HDL-C) and apolipoprotein, A-I (apo A-I) levels (r=-.22 and =-.24, respectively, P < .05). These relationships were weaker and less significant in women. In pooled data, stepwise multiple regression analysis showed an independent relationship of both the body mass index (BMI) and fasting insulin level with TGs (R2=.14), while gender and fasting insulin were the best predictors of HDL-C variance (R2=.17). Furthermore, fasting insulin was the only variable independently related to PAI-1 (R2=.12). Our findings support the existence of a metabolic syndrome even in very old age by showing that high insulin levels are related to various metabolic and hemostatic disorders.

Does fasting plasma insulin increase by age in the general elderly population?

The aim of this study was to examine the association of fasting plasma insulin with age. Insulin levels are influenced by obesity, physical inactivity, and medications, e.g., thiazide diuretics and beta adrenergic blockers. Further, comorbidity and pre-terminal conditions may confound the age-association of insulin. 1197 random subjects from four birth cohorts of the general aged population in southern Finland were examined, and followed for five years. Insulin levels at baseline tended to increase in men to the age of 75 years (mean 15.1 mU/L, SE 2.18), and in women to the age of 80 years (mean 15.9 mU/L, SE 1.14). The same association was seen among survivors in a five-year follow-up. These associations remained significant after controlling for obesity, physical inactivity and hyperinsulinogenic medications.

Elevated fasting plasma insulin in a general aged population: an innocent companion of cardiovascular diseases

OBJECTIVE

Although high insulin levels have been linked to cardiovascular disease, the role of insulin as an independent risk factor has been questioned. Our objective was to examine the association of fasting plasma insulin with cardiovascular disease as well as to investigate the prognostic value of insulin with respect to survival.

DESIGN

A 5-year follow-up of random samples from four birth cohorts age 65 (n = 660), 75 (n = 194), 80 (n = 179), and 85 (n = 162) years at baseline.

SETTING

Two urban communities in southern Finland.

MEASUREMENTS

Clinical and laboratory investigation at base line with collection of date and cause of death information during follow-up.

RESULTS

Subjects with cardiovascular disease generally had higher levels of fasting plasma insulin than did subjects without cardiovascular disease (13.9 mU/L vs 11.2 mU/L, P < .001). Heart failure and hypertension were associated with significant 30 to 80% elevations of insulin levels in all but the oldest group. In the 65-year-old group, all vascular diseases were associated with significantly elevated insulin. The associations were generally not explained by body mass index or by use of diuretics or beta-blockers. During the follow-up insulin was generally not associated with an impaired survival. On the contrary, in subjects with manifest cardiovascular disease, high insulin was associated with a rather favorable 5-year survival prognosis. Exclusion of subjects who died during the first 500 days of follow-up did not change these associations.

CONCLUSION

Albeit fasting plasma insulin appeared to be secondarily associated with cardiovascular disease in this general aged population, it was related to a fair or favorable survival prognosis.

Correlates of uric acid and its association with asymptomatic carotid atherosclerosis: the ARIC Study. Atherosclerosis Risk in Communities

The correlates of serum uric acid and the association of uric acid with carotid intimal-medial thickness (an early measure of atherosclerosis) were investigated in participants of the baseline examination of the Atherosclerosis Risk in Communities (ARIC) Study. The study sample included 6522 women (74% white) and 4966 men (79% white) who were aged 45 to 64 years at baseline (1986-1989). Those with prevalent coronary heart disease or previous stroke and those taking uricosuric medication were excluded. The mean (SD) uric acid concentration was 5.9 (1.5) mg/dL. It was highest among black men 45-54 years old (6.9 [1.5] mg/dL), and lowest in white women aged 45-54 years old (5.0 [1.2] mg/dL). The uric acid level was positively correlated in both sexes with a variety of health-related factors, most notably body mass index, creatinine, triglycerides, diuretic use, alcohol intake, hypertension, diabetes, and insulin levels. In a linear regression model adjusting for age and ARIC center, the level of uric acid was directly and significantly associated with B-mode ultrasound carotid intimal-medial thickness in women and white men (but not in black men). However, when known risk factors for atherosclerotic disease and relevant behavioral and biological correlates of uric acid were controlled for in multivariate analysis, the association of uric acid with this early measure of atherosclerosis became negligible in white women and much weaker and not statistically significant in black women and white men. Thus, uric acid itself may not be a risk factor for atherosclerosis. Future analysis of cardiovascular events in the ARIC Study will further elucidate the role of uric acid in atherosclerotic disease.