Insulin resistance implications for type II diabetes mellitus and coronary heart disease

Dapagliflozin and sacubitril on myocardial microperfusion in patients with post-acute myocardial infarction heart failure and type 2 diabetes

BACKGROUND

Coronary heart disease and type 2 diabetes mellitus (T2DM) frequently coexist, creating a complex and challenging clinical scenario, particularly when complicated with acute myocardial infarction (AMI).

AIM

To examine the effects of dapagliflozin combined with sakubactrovalsartan sodium tablets on myocardial microperfusion.

METHODS

In total, 98 patients were categorized into control (n = 47) and observation (n = 51) groups. The control group received noxital, while the observation group was treated with dapagliflozin combined with noxital for 6 months. Changes in myocardial microperfusion, blood glucose level, cardiac function, N-terminal prohormone of brain natriuretic peptide (NT-proBNP) level, growth differentiation factor-15 (GDF-15) level, and other related factors were compared between the two groups. Additionally, the incidence of major adverse cardiovascular events (MACE) and adverse reactions were calculated.

RESULTS

After treatment, in the observation and control groups, the corrected thrombolysis in myocardial infarction frame counts were 37.12 ± 5.02 and 48.23 ± 4.66, respectively. The NT-proBNP levels were 1502.65 ± 255.87 and 2015.23 ± 286.31 pg/mL, the N-terminal pro-atrial natriuretic peptide (NT-proANP) levels were 1415.69 ± 213.05 and 1875.52 ± 241.02 ng/mL, the GDF-15 levels were 0.87 ± 0.43 and 1.21 ± 0.56 g/L, and the high-sensitivity C-reactive protein (hs-CRP) levels were 6.54 ± 1.56 and 8.77 ± 1.94 mg/L, respectively, with statistically significant differences (P < 0.05). The cumulative incidence of MACEs in the observation group was significantly lower than that in the control group (P < 0.05). The incidence of adverse reactions was 13.73% (7/51) in the observation group and 10.64% (5/47) in the control group, with no statistically significant difference (P > 0.05).

CONCLUSION

Dapagliflozin combined with nocinto can improve myocardial microperfusion and left ventricular remodeling and reduce MACE incidence in patients with post-AMI heart failure and T2DM. The underlying mechanism may be related to the reduction in the expression levels of NT-proANP, GDF-15, and hs-CRP.

The relationship between insulin sensitivity and serum antithrombin 3 activity in patients with type 2 diabetes

BACKGROUND

Antithrombin 3 (AT3) is a physiological inhibitor of thrombin, and serum AT3 activity was found to decrease at the status of type 2 diabetes (T2D). T2D was presented with an increased risk of thrombotic complications at the background of impaired insulin sensitivity. The aim of this study was to investigate the relationship between insulin sensitivity indices and serum AT3 activity in patients with T2D.

METHODS

We conducted a cross-sectional study in patients with T2D who consented to participate in the study at the Endocrinology Department of Affiliated 2 Hospital of Nantong University from January 2015 to June 2018. All patients received serum AT3 activity test and 75 g oral glucose tolerance test (OGTT). Basal and systemic insulin sensitivity were assessed by homeostasis model assessment of insulin resistance (HOMA-IR) and Matsuda index (ISIMatsuda), respectively, from the OGTT. And other relevant clinical data were also collected.

RESULTS

Total of 1612 patients with T2D were enrolled in the study, with a mean age of 58.67 ± 13.09 years and a median diabetes duration of 6 years (interquartile range, 1-10 years). Across ascending quartiles of serum AT3 activity, HOMA-IR progressively decreased, while ISIMatsuda progressively increased (all P for trend < 0.001). Moreover, serum AT3 activity was negatively correlated with HOMA-IR (r = -0.189, P < 0.001) and positively correlated with ISIMatsuda (r = 0.221, P < 0.001). After adjusting for other metabolic risk factors, hemostatic parameters and glucose-lowering therapies by multivariate linear regression analysis, HOMA-IR (β = -0.185, t = -5.960, P < 0.001) and ISIMatsuda (β = 0.197, t = 6.632, P < 0.001) remained independently associated with the serum AT3 activity in patients with T2D, respectively.

CONCLUSIONS

Reduced basal and systemic insulin sensitivity are associated with decreased serum AT3 activity in patients with T2D.

Effects of Stress Hyperglycemia on Short-Term Prognosis of Patients Without Diabetes Mellitus in Coronary Care Unit

Background: Diabetes mellitus (DM) has a high morbidity and mortality worldwide, and it is a risk factor for cardiovascular diseases. Non-diabetic stress hyperglycemia is common in severely ill patients, and it could affect prognosis. This study aimed to analyze the influence of different blood glucose levels on prognosis from the perspective of stress hyperglycemia by comparing them with normal blood glucose levels and those of patients with DM.

Methods: A retrospective study of 1,401 patients in coronary care unit (CCU) from the critical care database called Medical Information Mart for Intensive Care IV was performed. Patients were assigned to the following groups 1–4 based on their history of DM, random blood glucose, and HbA1c levels: normal blood glucose group, moderate stress hyperglycemia group, severe stress hyperglycemia group and DM group. The main outcome of this study was 30- and 90-day mortality rates. The associations between groups and outcomes were analyzed using Kaplan–Meier survival analysis, Cox proportional hazard regression model and competing risk regression model.

Results: A total of 1,401 patients in CCU were enrolled in this study. The Kaplan–Meier survival curve showed that group 1 had a higher survival probability than groups 3 and 4 in terms of 30- and 90-day mortalities. After controlling the potential confounders in Cox regression, groups 3 and 4 had a statistically significant higher risk of both mortalities than group 1, while no difference in mortality risk was found between groups 2 and 1. The hazard ratios [95% confidence interval (CI)] of 30- and 90-day mortality rates for group 3 were 2.77(1.39,5.54) and 2.59(1.31,5.12), respectively, while those for group 4 were 1.92(1.08,3.40) and 1.94(1.11,3.37), respectively.

Conclusions: Severe stress hyperglycemia (≥200 mg/dL) in patients without DM in CCU may increase the risk of short-term death, which is greater than the prognostic effect in patients with diabetes. Patients with normal blood glucose levels and moderate stress hyperglycemia (140 mg/dL ≤ RBG <200 mg/dL) had no effect on short-term outcomes in patients with CCU.

ICAM-1 and MKL-1 polymorphisms impose considerable impacts on coronary heart disease occurrence

This study was aimed to explore the correlation of intercellular adhesion molecule‐1 (ICAM‐1) K469E and megakaryoblastic leukaemia factor‐1 (MKL‐1) −184C/T polymorphisms with the susceptibility to coronary heart disease (CHD) in the Chinese Han population. 100 CHD patients and 91 healthy people that had no blood connection with each other were enrolled in this case‐control study. ICAM‐1 and MKL‐1 polymorphisms were genotyped by polymerase chain reaction‐restriction fragment length polymorphism (PCR‐RFLP) approach. Multiple logistic regression was used to analyse the correlation between polymorphisms of ICAM‐1 and MKL‐1 and CHD susceptibility. Differences of genotype and allele frequencies of the two SNPs between case and control groups were analysed by chi‐square test. Odds ratios (ORs) and 95% confidence intervals (CIs) were indicated relative susceptibility of CHD. The distributions of ICAM‐1 and MKL‐1 polymorphisms in each group conformed to Hardy‐Weinberg equilibrium (HWE). After adjusting for traditional risk factors, the TT genotype frequency of MKL‐1 −184C/T polymorphism was found significantly higher in case group than in control group (P < .05). Meanwhile, T allele frequency increased in case group compared with control group, and the differences had statistical significance (P = .04, OR = 2.34, 95% CI = 1.34‐5.26). Logistic regression analysis in this study proved that smoking, hypertension, diabetes and triglyceride (TG) were all risk factors for CHD ICAM‐1 K469E polymorphism has no association with the onset of CHD. But MKL‐1 −184C/T polymorphism is associated with the risk of CHD and T allele might be a susceptibility factor for CHD.

A comparative pharmacogenomic analysis of three classic TCM prescriptions for coronary heart disease based on molecular network modeling

Traditional Chinese medicine (TCM) has evolved over several thousands of years, which has been shown to be efficacious in the treatment of ischemic heart disease. Three classical TCM prescriptions, namely Xuefu Zhuyu Decoction, Zhishi Xiebai Guizhi Decoction, and Gualou Xiebai Banxia Decoction, have been extensively used in the treatment of coronary heart disease (CHD). Based on molecular network modeling, we performed a comparative pharmacogenomic analysis to systematically determine the drug-targeting spectrum of the three prescriptions at molecular level. Wide-area target molecules of CHD were covered, which was a common feature of the three decoctions, demonstrating their therapeutic functions. Meanwhile, collective signaling involved metabolic/pro-metabolic pathways, driving and transferring pathways, neuropsychiatric pathways, and exocrine or endocrine pathways. These organized pharmacological disturbance was mainly focused on almost all stages of CHD intervention, such as anti-atherosclerosis, lipid metabolism, inflammation, vascular wall function, foam cells formation, platelets aggregation, thrombosis, arrhythmia, and ischemia-reperfusion injury. In addition, heterogeneity analysis of the global pharmacological molecular spectrum revealed that signaling crosstalk, cascade convergence, and key targets were tendentious among the three decoctions. After all, it is unadvisable to rank the findings on targeting advantages of the three decoctions. Comparative pharmacological evidence may provide an appropriate decoction scheme for individualized intervention of CHD.

Determinants of aspirin resistance in patients with type 2 diabetes

BACKGROUND

Cardiovascular disease is a leading cause of mortality among patients with type 2 diabetes mellitus (T2DM). Numerous patients with T2DM show resistance to aspirin treatment, which may explain the higher rate of major adverse cardiovascular events observed compared with non-diabetes patients, and it has recently been shown that aspirin resistance is mainly related to accelerated platelet turnover with persistent high platelet reactivity (HPR) 24h after last aspirin intake. The mechanism behind HPR is unknown. The aim of this study was to investigate the precise rate and mechanisms associated with HPR in a population of T2DM patients treated with aspirin.

METHODS

Included were 116 consecutive stable T2DM patients who had attended our hospital for their yearly check-up. HPR was assessed 24h after aspirin intake using light transmission aggregometry (LTA) with arachidonic acid (AA) and serum thromboxane B2 (TXB2) measurement. Its relationship with diabetes status, insulin resistance, inflammatory markers and coronary artery disease (CAD) severity, using calcium scores, were investigated.

RESULTS

Using LTA, HPR was found in 27 (23%) patients. There was no significant difference in mean age, gender ratio or cardiovascular risk factors in patients with or without HPR. HPR was significantly related to duration of diabetes and higher fasting glucose levels (but not consistently with HbA_1c), and strongly related to all markers of insulin resistance, especially waist circumference, HOMA-IR, QUICKI and leptin. There was no association between HPR and thrombopoietin or inflammatory markers (IL-6, IL-10, indoleamine 2,3-dioxygenase activity, TNF-α, C-reactive protein), whereas HPR was associated with more severe CAD. Similar results were found with TXB2.

CONCLUSION

Our results reveal that 'aspirin resistance' is frequently found in T2DM, and is strongly related to insulin resistance and severity of CAD, but weakly related to HbA_1c and not at all to inflammatory parameters. This may help to identify those T2DM patients who might benefit from alternative antiplatelet treatments such as twice-daily aspirin and thienopyridines.

The relationship between insulin sensitivity and heart rate-corrected QT interval in patients with type 2 diabetes

BACKGROUND

Reduced insulin sensitivity not only contributes to the pathogenesis of type 2 diabetes but is also linked to multiple metabolic risk factors and cardiovascular diseases (CVD). A prolonged heart rate-corrected QT interval (QTc interval) is related to ventricular arrhythmias and CVD mortality and exhibits a high prevalence among type 2 diabetes patients. The aim of the study was to investigate the relationship between insulin sensitivity and the QTc interval in patients with type 2 diabetes.

METHODS

This cross-sectional observational study recruited 2927 patients with type 2 diabetes who visited the Affiliated Haian Hospital and Second Affiliated Hospital of Nantong University. The insulin sensitivity index (Matsuda index, ISI_Matsuda) derived from 75-g OGTT and other metabolic risk factors were examined in all patients. The QTc interval was estimated using a resting 12-lead electrocardiogram, and an interval longer than 440 ms was considered abnormally prolonged.

RESULTS

The QTc interval was significantly and negatively correlated with the ISI_Matsuda (r = -0.296, p < 0.001), and when the multiple linear regression analysis was adjusted for anthropometric parameters, metabolic risk factors, and current antidiabetic treatments, the QTc interval remained significantly correlated with the ISI_Matsuda (β = -0.23, t = -12.63, p < 0.001). The proportion of patients with prolonged QTc interval significantly increased from 12.1% to 17.9%, 25.6% and 37.9% from the fourth to third, second and first quartile of the ISI_Matsuda, respectively. After adjusting for anthropometric parameters by multiple logistic regression analysis, the corresponding odd ratios (ORs) for prolonged QTc interval of the first, second and third quartiles versus the fourth quartile of ISI_Matsuda were 3.11 (95% CI 2.23-4.34), 2.09 (1.51-2.88) and 1.53 (1.09-2.14), respectively, and p for trend was <0.001.

CONCLUSIONS

Reduced insulin sensitivity is associated with an increase in the QTc interval in patients with type 2 diabetes.

Evaluating Pharmacological Effects of Two Major Components of Shuangdan Oral Liquid: Role of Danshensu and Paeonol in Diabetic Nephropathy Rat

Shuangdan oral liquid (SDO) containing radix Salviae miltiorrhizae (Chinese name Danshen) and cortex moutan (Chinese name Mudanpi) is a traditional Chinese medicine using for treating vascular diseases. Danshensu (DSS) is a main effective monomer composition derived from radix Salviae miltiorrhizae and paeonol (Pae) from cortex moutan. Although the two herbs are widely used in traditional Chinese medicine, the pharmacological functions of their active compositions were not reported. Therefore, the research of DSS and Pae in mechanisms and pharmacodynamics interaction can provide scientific evidence to support clinical application. The diabetic nephropathy (DN) rats which were induced by streptozotocin (STZ) were treated with SDO, DSS, Pae, and DSS+Pae for eight weeks. The positive effects on DN animal models were investigated by detection of physiological and biochemical indexes and oxidative stress markers, within five treatments: SDO, DSS, Pae, DSS+Pae and insulin group. Compared with the model group, the DSS+Pae group improved the renal function, blood lipid metabolism and blood viscosity, increased the vitality of T-SOD or T-AOC and decreased the level of MDA or NO after the treatment. The study was successfully showed that the DSS+Pae group could delay the process of DN, especially in the renal injury part of histopathology changes. Our results suggest that the co-administration of DSS and Pae significantly may play a protective role in DN rats through decreasing the oxidative stress and improving the blood lipid metabolism mechanisms.

Prospective evaluation of diabetic ischaemic heart disease by computed tomography: the PREDICT study

Coronary heart disease (CHD) is the main cause of morbidity and mortality in type 2 diabetic subjects. Electron beam computed tomography (EBCT) of the coronary arteries provides a non-invasive method of detecting and quantifying coronary calcification (coronary calcium score), which is known to be an early marker of coronary atheroma in non-diabetic subjects. 600 type 2 diabetic subjects aged between 50 and 70 years of either sex will undergo EBCT. They will be followed-up for a mean period of four years. Recruitment started in September 2000 and preliminary results are expected in 2004. The primary aim is to assess the predictive power of the coronary calcium score for coronary events specifically in type 2 diabetic subjects. Secondary aims are to assess the relationship between coronary calcium score in type 2 diabetes and conventional risk factors, with novel risk markers, plasma homocysteine and C-reactive protein, and with key genetic markers of CHD.

Lipidomic risk score independently and cost-effectively predicts risk of future type 2 diabetes: results from diverse cohorts

Background

Detection of type 2 diabetes (T2D) is routinely based on the presence of dysglycemia. Although disturbed lipid metabolism is a hallmark of T2D, the potential of plasma lipidomics as a biomarker of future T2D is unknown. Our objective was to develop and validate a plasma lipidomic risk score (LRS) as a biomarker of future type 2 diabetes and to evaluate its cost-effectiveness for T2D screening.

Methods

Plasma LRS, based on significantly associated lipid species from an array of 319 lipid species, was developed in a cohort of initially T2D-free individuals from the San Antonio Family Heart Study (SAFHS). The LRS derived from SAFHS as well as its recalibrated version were validated in an independent cohort from Australia – the AusDiab cohort. The participants were T2D-free at baseline and followed for 9197 person-years in the SAFHS cohort (n = 771) and 5930 person-years in the AusDiab cohort (n = 644). Statistically and clinically improved T2D prediction was evaluated with established statistical parameters in both cohorts. Modeling studies were conducted to determine whether the use of LRS would be cost-effective for T2D screening. The main outcome measures included accuracy and incremental value of the LRS over routinely used clinical predictors of T2D risk; validation of these results in an independent cohort and cost-effectiveness of including LRS in screening/intervention programs for T2D.

Results

The LRS was based on plasma concentration of dihydroceramide 18:0, lysoalkylphosphatidylcholine 22:1 and triacyglycerol 16:0/18:0/18:1. The score predicted future T2D independently of prediabetes with an accuracy of 76 %. Even in the subset of initially euglycemic individuals, the LRS improved T2D prediction. In the AusDiab cohort, the LRS continued to predict T2D significantly and independently. When combined with risk-stratification methods currently used in clinical practice, the LRS significantly improved the model fit (p < 0.001), information content (p < 0.001), discrimination (p < 0.001) and reclassification (p < 0.001) in both cohorts. Modeling studies demonstrated that LRS-based risk-stratification combined with metformin supplementation for high-risk individuals was the most cost-effective strategy for T2D prevention.

Conclusions

Considering the novelty, incremental value and cost-effectiveness of LRS it should be used for risk-stratification of future T2D.

Electronic supplementary material

The online version of this article (doi:10.1186/s12944-016-0234-3) contains supplementary material, which is available to authorized users.

Insulin resistance caused by lipotoxicity is related to oxidative stress and endoplasmic reticulum stress in LPL gene knockout heterozygous mice

OBJECTIVE

To investigate the correlation of hypertriglyceridemia with abnormal glucose metabolism and insulin resistance.

METHODS

Lipid and glucose metabolism, whole-body and tissue-specific insulin sensitivity, genes and proteins related with oxidative stress and endoplasmic reticulum (ER) stress were compared between LPL+/- and control mice at different weeks of age.

RESULTS

16-50-week LPL+/- mice had increased body weight compared with their respective controls. Fat mass in visceral adipose tissue (VAT) of 16 and 28-week LPL+/- mice were twice more than their control littermates, and 50-week LPL+/- mice showed the same trend of increase. Plasma lipids were higher in 16-50-week LPL+/- mice. 28- and 50-week LPL+/- mice had elevated tissue lipid accumulation (liver, skeletal muscle, pancreas) and impaired glucose tolerance, while 16-week LPL+/- mice showed no differences. Homeostasis model assessment of insulin resistance for 28 and 50-week LPL+/- mice were twofold greater, whereas that for 16-week LPL+/- mice had no change. Insulin-stimulated phosphorylated Akt (Ser473) in VAT of 28-week LPL+/- mice decreased by 80.6% (p = 0.001), and that in liver and skeletal muscle decreased by 62.4% (P < 0.001) and 51.8% (p = 0.005) respectively. Then we found that plasma malondialdehyde and reactive oxygen species levels in liver and skeletal muscle of LPL+/- mice were elevated. Increased ER stress biomarkers were also detected in liver and VAT of 28-week LPL+/- mice.

CONCLUSIONS

Systemic LPL deletion results in impaired glucose tolerance, whole-body and tissue-specific insulin resistance, which is associated with tissue lipid deposition in various insulin target tissues. Furthermore, the activation of oxidative stress and ER stress may play an important role in the development of tissue-specific and systemic insulin resistance.

Association of dietary acid load with cardiovascular disease risk factors in patients with diabetic nephropathy

OBJECTIVE

An association between dietary acid load and cardiovascular disease risk has been reported in epidemiologic studies; however, there are no reports to our knowledge of this association in patients with diabetic nephropathy (DN). Therefore, the aim of this study was to examine the association between dietary acid load, based on potential renal acid load (PRAL) and protein:potassium ratio (Pro:K) scores, and cardiovascular disease risk factors in individuals with DN.

METHODS

In this cross-sectional study, we randomly enrolled 547 patients with DN. Dietary intake was assessed using a validated food frequency questionnaire. Biochemical and anthropometric measures were assessed using standard methods.

RESULTS

Participants had a mean age of 66.8 y and body mass index of 24 kg/m(2). After controlling for potential confounders, participants in the low PRAL group had lower hemoglobin (Hb)A1c (5.7% ± 0.5% versus 7.8% ± 0.5%; P = 0.01), triacylglycerols (246.9 ± 2.3 mg/dL versus 257.4 ± 2.3 mg/dL; P = 0.006), systolic blood pressure (103.6 ± 0.7 mm Hg versus 106.1 ± 0.7 mm Hg; P = 0.03), and lower creatinine and fasting blood sugar compared with the high PRAL group. Pro:K was positively related to HbA1c (5.8% ± 0.5% versus 7.6% ± 0.5%; P = 0.03), but inversely associated with low-density lipoprotein and waist circumference.

CONCLUSIONS

We found that both PRAL and Pro:K were positively related to HbA1c in the setting of DN, whereas other biochemical and kidney-related markers varied with PRAL and Pro:K status. Future studies are warranted to clarify the clinical outcomes of dietary acid load in older populations as well as in patients with chronic kidney disease.

High plasma ghrelin protects from coronary heart disease and Leu72Leu polymorphism of ghrelin gene from cancer in healthy adults during the 19 years follow-up study

The aim of our investigation was to find out if ghrelin concentrations or polymorphisms predict the future risk for cardiovascular diseases and cancer in a population-based cohort initiated in 1991 (491 hypertensive and 513 control subjects). Total mortality and hospital events were followed up for 19 years. Fasting total ghrelin concentrations were determined and Arg51Gln, Leu72Met and -501 A > C polymorphisms identified. Cox regression analysis was performed. The mean value in the control cohort was 674 pg/ml whereas in the hypertensive cohort it was 661 pg/ml. The associations found suggest that in the controls the highest ghrelin quartile protected from CHD (coronary heart disease). The results were significant without or with adjustments for age, sex, smoking, systolic blood pressure and LDL cholesterol, BMI, type 2 diabetes or QUICK index. C/C variant of the promoter associated with the prevention of IHD (ischemic heart disease) in the hypertensive group (p<0.05). The controls with the Leu72Leu genotype had less cancer (p<0.05). In conclusion, high plasma ghrelin concentration was related to protection from CHD and Leu72Leu genotype to prevention of cancer in healthy adults during the 19 years follow-up. C/C promoter protects from IHD in the hypertensive subjects.

Pharmacological effects of the water fraction of key components in the traditional Chinese prescription Mai Tong Fang on 3T3-L1 adipocytes and ob/ob diabetic mice

Mai Tong Fang (MTF), a Chinese herbal combination, has been used for the treatment of diabetic nephropathy in traditional medical clinics in China. However, the anti-adipogenic and anti-hyperglycemic effects of MTF have not been fully elucidated, so this study explored these pharmacological activities in 3T3-L1 adipocytes and ob/ob mice, respectively, of the water fraction of milkvetch root, salviae miltiorrhizae and mulberry as key components of MTF. MTF was found to inhibit adipogenesis and triglyceride accumulation in 3T3-L1 adipocytes. Oral administration of MTF in ob/ob mice for 8 weeks, exhibited positive controls on blood glucose and body weight, and further improved glucose tolerance according to an oral glucose tolerance test. Importantly, MTF extract alleviated fat deposition and ballooning degeneration in liver tissue and blocked the increase of adipocyte size in adipose tissue from treated ob/ob mice. These results indicated that the extract of key components in the traditional Chinese prescription MTF continue a potent anti-adipogenic and glucose-lowering agent.

Risk factors for type 2 diabetes mellitus preceded by β-cell dysfunction, insulin resistance, or both in older adults: the Cardiovascular Health Study

Insulin resistance (IR) and pancreatic β-cell dysfunction lead to type 2 diabetes mellitus (DM). We tested whether risk factors would differ for DM that was preceded predominantly by IR, β-cell dysfunction, or both among 4,384 older adults (mean age, 72.7 (standard deviation, 5.6) years) in the Cardiovascular Health Study, which was conducted in North Carolina, California, Maryland, and Pennsylvania (1989-2007). When evaluating established risk factors, we found older age, greater adiposity, higher systolic blood pressure, a lower high-density lipoprotein cholesterol level, a higher triglyceride level, and a lower alcohol intake to be independently associated with greater IR but, conversely, with better β-cell function (P < 0.001). The prospective associations between some risk factors and incident DM varied significantly depending on whether DM was preceded predominantly by IR, β-cell dysfunction, or both. For example, obesity and lower high-density lipoprotein cholesterol levels were positively associated with DM preceded predominantly by IR (hazard ratio (HR) = 5.02, 95% confidence interval (CI): 2.81, 9.00; and HR = 1.97, 95% CI: 1.32, 2.93, respectively), with a significant association with and an insignificant trend toward a lower risk of DM preceded predominantly by β-cell dysfunction (HR = 0.33, 95% CI: 0.14, 0.80; and HR = 0.78, 95% CI: 0.43, 1.39, respectively). In conclusion, among older adults, DM risk factors were differentially associated with DM preceded predominantly by IR or β-cell dysfunction. Biologic and clinical implications of putative subtypes of DM require further investigation.

Chromium Therapy for Insulin Resistance Associated with HIV-Disease

OBJECTIVE

With the advent of highly active anti-retroviral therapy, HIV disease has become a chronic condition, but with a number of metabolic complications including insulin resistance and diabetes mellitus, dyslipidemia and hypertension and an increased incidence of atherosclerosis. The aim of the current study was to test the safety and efficacy of chromium picolinate for HIV- associated insulin resistance.

MATERIALS/METHODS

The study was a randomized, double-blind, placebo-controlled trial with subjects receiving 500μg of chromium picolinate or placebo twice daily for two months. HIV- infected subjects were selected based on a fasting concentration of plasma glucose greater than 5.5mmol/L or a plasma glucose concentration of greater than 7.7mmol/L (but less than 11mmol/L) 2h after oral ingestion of 75g of glucose. Insulin sensitivity was assessed with a hyper-insulinemic-euglycemic clamp and glucose tolerance was assessed with the oral glucose tolerance test. Subjects were monitored closely for alterations in viral load, CD4+ cells, hemoglobin and hematocrit, kidney and liver function, and fasting lipid profiles.

RESULTS

Forty-three subjects were enrolled and 39 completed the protocol (20 in the chromium-supplemented and 19 in the placebo arm). Following chromium-supplementation, there were no significant changes in either insulin sensitivity or glucose tolerance. There was a significant improvement in serum HDL cholesterol concentration in the group supplemented with chromium.

CONCLUSIONS

Chromium picolinate supplementation at this level was well-tolerated, but overall was not an effective therapy for insulin resistance in these HIV-infected subjects.

Association of H. pylori infection with insulin resistance and metabolic syndrome among Lebanese adults

BACKGROUND

Several epidemiological studies proposed an association between Helicobacter pylori ( H. pylori) infection with insulin resistance (IR) and metabolic syndrome (MetS). However, up to date there is no conclusive evidence regarding this association.

OBJECTIVES

To investigate the prevalence and correlates of H. pylori infection among Lebanese adults and to evaluate its association with IR and MetS.

MATERIALS AND METHODS

Stored blood samples of adults participating in the national Nutrition and Non-Communicable Diseases Risk factors survey conducted in Lebanon were used for this study (n = 308). H. pylori-specific immunoglobulin G antibody titers were measured by ELISA. Data available included, in addition to anthropometric measurements, sociodemographic and lifestyle characteristics, blood pressure, and biochemical indices (serum insulin, HDL, LDL, TAG, glucose). A HOMA -IR level was used to assess insulin resistance. The International Diabetes Federation criteria were used to classify study participants with MetS.

RESULTS

The prevalence of H. pylori infection in the study sample was 52% (95% CI, 46.43-57.57). A higher crowding index was associated with a 50% increase in the odds of infection (OR, 1.41; CI, 1.08-2.27). Blood pressure, waist circumference, serum HDL, LDL, TAG, and glucose levels were comparable between H. pylori positive and negative subjects. The odds of IR and MetS were not significantly different between the two groups.

CONCLUSION

Prevalence of H. pylori infection in Lebanon is comparable to other developing countries. Furthermore, our findings suggested no association of H. pylori infection with IR or MetS. Eradication of H. pylori infection to prevent IR or MetS is not warranted.

The hypoglycemic effects of American red ginseng (Panax quinquefolius L.) on a diabetic mouse model

American ginseng (Panax quinquefolius L.) root health benefits include treatment of type 2 diabetes and this study evaluated the hypoglycemic effects of American red ginseng (ARG). ARG roots have increased bioactive phenolic contents, such as cinnamic acid and ferulic acid during the steaming process. The antihyperglycemic effects of methanol fraction extract of ARG, ferulic acid, and cinnamic acid were examined using a type 2 diabetic mouse model. The ARG treated group presented relatively lower blood glucose levels than the control group (P < 0.05). In addition, the glycogen and high density lipoprotein (HDL) contents were significantly increased while levels of plasma cholesterol and low density lipoprotein (LDL) concentration were significantly decreased in the ARG treated group. The groups treated with ferulic and cinnamic acids showed similar effects as those found in the ARG treated group. Thus, it is suggested that ARG roots, ferulic acid, and cinnamic acid have hypoglycemic effects in an animal model.

PRACTICAL APPLICATION

This study was conducted to elucidate the hypoglycemic effects of American red ginseng (ARG) using a type 2 diabetic mouse model. ARG showed an enhanced antioxidant capacity and higher antihyperglycemia effect. The glycogen and high density lipoprotein (HDL) contents were significantly increased while levels of plasma cholesterol and low density lipoprotein (LDL) concentration were significantly decreased in the ARG treated group. It is suggested that ARG has a potential to be used for human diabetic treatment.

Improvement of Insulin Resistance and Early Atherosclerosis in Patients after Gastric Banding

OBJECTIVE

To evaluate the effect of massive weight loss on insulin sensitivity, soluble adhesion molecules, and markers of the insulin resistance syndrome (IRS).

RESEARCH METHODS AND PROCEDURES

Eighteen morbidly obese patients underwent gastric banding and were evaluated before and 6 and 12 months after surgery. Total insulin secretion, hepatic insulin extraction, and insulin sensitivity were analyzed by oral glucose-tolerance test model analysis. In addition, soluble intercellular adhesion molecule-1, vascular cell adhesion molecule-1, E-selectin, leptin, high-sensitivity C-reactive protein, plasminogen activating factor-1 (PAI-1), and tissue plasminogen activator were measured.

RESULTS

BMI dropped from 45.22 +/- 5.62 to 36.99 +/- 4.34 kg/m(2) after 6 months and 33.72 +/- 5.55 kg/m(2) after 12 months (both p < 0.0001). This intervention resulted in a significant reduction of blood pressure (p < 0.00001), triglycerides (p < 0.01), fasting blood glucose (p = 0.03), basal insulin (p < 0.001), and basal C-peptide (p = 0.008) levels. Total insulin secretion decreased (p < 0.05), whereas hepatic insulin extraction (p < 0.05) and oral glucose insulin sensitivity index (p < 0.0001) increased compared with baseline. Leptin (p < 0.0001) and E-selectin levels decreased significantly after 6 and 12 months (p = 0.05), whereas significantly lower levels of intercellular adhesion molecule-1 and PAI-1 were only seen after 6 months. Subclinical inflammation, measured by high-sensitivity C-reactive protein, was lowered to normal ranges. No changes were observed in vascular cell adhesion molecule-1 and tissue plasminogen activator levels.

DISCUSSION

Although gastric banding ameliorates several features of the IRS, including 29.05% improvement in insulin sensitivity and blood pressure and reduction of soluble adhesion molecules and PAI-1, considerable weight loss did not normalize all components of the IRS in morbidly obese patients.

The impact of effective continuous positive airway pressure on homeostasis model assessment insulin resistance in non-diabetic patients with moderate to severe obstructive sleep apnea

Previous studies on the effects of continuous positive airway pressure (CPAP) on homeostasis model assessment insulin resistance (HOMA-IR) in obstructive sleep apnea patients have yielded conflicting results. Therefore, we conducted this meta-analysis to evaluate the impact of effective CPAP on HOMA-IR in non-diabetic patients with moderate to severe obstructive sleep apnea. We searched PubMed, HighWire Press, Ovid Medline (R), Cochrane library and EMBASE before December 2011 on original English language studies. The data on HOMA-IR and body mass index (BMI) were extracted from these studies. As compared with baseline values, 8 to 24 weeks of effective CPAP (>4 h/night) treatment significantly reduced HOMA-IR by an average of 0.75(95% CI, from -0.96 to -0.53; p < 0.001). However, in subjects with irregular CPAP (<4 h/night), this effect was not observed (-0.22; 95%CI, from -2.24 to 1.80; p = 0.83). There were no intervention-related changes in BMI in both regular and irregular CPAP. Our analysis showed that 8 to 24 weeks of effective CPAP could significantly improve HOMA-IR in non-diabetic patients with moderate to severe obstructive sleep apnea, while no significant changes in BMI were detected. Further large scale, randomized and controlled trials are needed to evaluate the longer treatment and its possible effects on weight control and cardiovascular disease.

Steam-dried ginseng berry fermented with Lactobacillus plantarum controls the increase of blood glucose and body weight in type 2 obese diabetic db/db mice

This study examined whether steam-dried ginseng berries fermented with Lactobacillus plantarum (FSGB) could improve the indices of type 2 diabetes mellitus (T2DM) in obese db/db mice. FSGB was shown to have an effect on body weight and blood glucose/serum parameters when administered at a dose of 0.5 g/kg. In the intraperitoneal glucose tolerance test (IPGTT) and insulin tolerance test (ITT), FSGB was clearly shown to improve insulin tolerance and glucose tolerance. Moreover, FSGB was shown to enhance immune activities by increasing the immune cell population, and glucose transpoter 1 (GLUT1) mRNA expression in L6 cells was up-regulated, suggesting that FSGB can increase glucose transport activity in target cells. These results indicate that steam- and dry-processed ginseng berries fermented with L. plantarum can be used to effectively control blood sugar metabolism via improving insulin and glucose tolerance and body weight gain in db/db mice.

Optimal waist circumference cutoff value reflecting insulin resistance as a diagnostic criterion of metabolic syndrome in a nondiabetic Korean population aged 40 years and over: the Chungju Metabolic Disease Cohort (CMC) study

PURPOSE

We aimed at determining the cutoff value of waist circumference with respect to its ability to reflect insulin resistance in a Korean population.

MATERIALS AND METHODS

A total of 8,817 subjects aged 40 years and over were analyzed. Insulin resistant individuals were defined as those who had the highest quartile value of the homeostasis model assessment of insulin resistance (HOMA-IR) in a non-diabetic population. Receiver operating characteristic (ROC) curve analysis and multiple logistic regression analysis were applied.

RESULTS

The cutoff value of waist circumference reflecting insulin resistance from the ROC analysis was 84.4 cm for men and 80.6 cm for women. Sensitivity and specificity were 70.0% and 54.2% in men and 71.1% and 59.3% in women, respectively. After being controlled for other covariates, the odds ratio for the risk of insulin resistance using < 70 cm of waist circumference as a reference increased significantly in the category of 85.0-89.9 cm for men and 80.0-84.9 cm for women. In addition, statistically significant associations were consistently observed over the category of 85.0-89.9 cm for men and 80.0-84.9 cm for women.

CONCLUSION

The optimal cutoff value for waist circumference reflecting insulin resistance is considered to be 85 cm for men and 80 cm for women, suggesting that the Asian criterion of abdominal obesity (90 cm for men and 80 cm for women) as a component of metabolic syndrome (MetS) might not be applicable for middle-aged to older men in Korea.

Current issues in the treatment of type 2 diabetes. Overview of newer agents: where treatment is going

Impaired insulin secretion (beta-cell), increased hepatic glucose production (liver), and decreased peripheral (muscle) glucose utilization constitute the traditional primary defects responsible for the development and progression of type 2 diabetes mellitus. beta-Cell failure, ultimately leading to decreased insulin secretion, is now known to occur much earlier in the natural history of type 2 diabetes than originally believed. Additionally, a better understanding of the pathophysiology of type 2 diabetes reveals other etiologic mechanisms beyond the classic triad, now referred to as the ominous octet. In addition to the beta-cell, liver, and muscle, other pathogenic mechanisms include adipocyte insulin resistance (increased lipolysis), reduced incretin secretion/sensitivity (gastrointestinal), increased glucagon secretion (alpha-cell), enhanced glucose reabsorption (kidney), and central nervous system insulin resistance resulting from neurotransmitter dysfunction (brain). Currently, the management of type 2 diabetes focuses on glucose control via lowering of blood glucose (fasting and postprandial) and hemoglobin A(1c). However, the goal of therapy should be to delay disease progression and eventual treatment failure. Treatment should target the known pathogenic disturbances of the disease (i.e., reducing the deterioration of beta-cell function and improving insulin sensitivity). In recent years, treatment strategies have focused on the development of novel therapeutic options that affect many of the defects contributing to type 2 diabetes and that provide durable glucose control through a blunting of disease progression. Optimal management of type 2 diabetes should include early initiation of therapy using multiple drugs, with different mechanisms of action, in combination.

Glucose intolerance and decreased early insulin response in mice with severe hypertriglyceridemia

Hypertriglyceridemia (HTG) is one of the key features of dyslipidemia in type 2 diabetes, caused by the overproduction and/or decreased clearance of triglyceride (TG)-rich lipoproteins, and significantly promotes the development of cardiovascular diseases in diabetes. However, the effect of severe HTG on glucose metabolism has not previously been determined. Lipoprotein lipase (LPL) deficiency results in severe HTG in humans. By using LPL-deficient mice with severe HTG, we assessed the impact of severe HTG on insulin secretion and glucose tolerance in the present study. While young LPL-deficient mice (4 months of age) showed higher fasting blood glucose (7.42 ± 0.84 versus 4.8 ± 0.80 mmol/L, P < 0.01) and lower insulin concentrations (0.16 ± 0.03 versus 0.48 ± 0.14 ng/mL, P < 0.05), old mice (12 months of age) had higher insulin (1.70 ± 0.35 versus 0.77 ± 0.04 ng/mL, P < 0.05) but normal fasting blood glucose concentrations. Both young and old mice had elevated free fatty acid (FFA) concentrations and exhibited decreased early insulin response; however, only old mice showed impaired glucose tolerance, as compared with wild-type mice of a similar age. Morphological assessment showed enlarged islets in old LPL-deficient mice. These findings suggest that different tests for glucose homeostasis may be needed for patients with LPL deficiency and severe HTG, even though their glucose concentrations are normal at initial screening.

Helicobacter pylori infection as a risk factor for insulin resistance

This study aimed to determine the relation between Helicobacter pylori infection and insulin resistance in healthy subjects. In a cross-sectional case control study between January and April 2007, a total of 71 healthy subjects without the exclusion criteria completed the study. Forty-three (60.6%) patients were H. pylori positive and 28 (39.4%) patients were H. pylori negative. Age and body mass index of the patients were not significantly different between the two groups (32.2 +/- 14.2 vs. 33 +/- 8.05 years and 23.15 +/- 4.5 vs. 24.04 +/- 3.2 kg/m(2), respectively). H-pylori-positive patients had significantly higher HOMA-IR level compared to H-pylori-negative patients (3.54 +/- 2.2 vs. 2.46 +/- 1.9, respectively) (P < 0.05). Fasting serum insulin level was significantly higher in the H-pylori-positive group compared with the H-pylori-negative group (19.41 +/- 3.08 vs. 16.57 +/- 2.02 microU/ml, respectively) (P < 0.05). Our findings suggest recognition of H. pylori infection as a risk factor for insulin resistance.

Waist circumference alone predicts insulin resistance as good as the metabolic syndrome in elderly women

BACKGROUND

Insulin resistance (IR) is a risk factor for diabetes and atherosclerotic diseases. The metabolic syndrome (MetS) reflects IR. Waist circumference (WC) is the most easily registered component of MetS. The objective was to compare WC alone with MetS as defined by the National Cholesterol Education Program (NCEP) and the International Diabetes Federation (IDF) for their abilities to predict IR in elderly without known diabetes.

METHODS

The study included 223 women and 210 men comprising 70% of a random sample of 75-year-olds from a general population. IR was conventionally defined as the gender-specific upper quartile of the Homeostasis Model Assessment-Insulin Resistance (HOMA-IR) index in individuals without known diabetes.

RESULTS

1) The positive association between WC and IR is stronger in women than in men. 2) WC >88 cm alone is nearly as good as MetS, using NCEP criteria, in predicting IR in women. 3) According to the ROC curve, the optimal cut-off point for WC predicting IR was between 96 and 97 cm (men) and between 88 and 89 cm (women). The relative risk of IR was 5.6 (95% CI: 3.1-11.9) for women with WC >88 cm and 1.9 (1.5-2.8) for men with WC >96 cm. 4) The NCEP criteria predicts IR significantly better than the IDF criteria.

CONCLUSION

WC >88 cm in women indicates a high likelihood of IR and is almost as good as MetS defined using the NCEP criteria in predicting IR. MetS defined using the NCEP criteria predicts IR better than MetS defined using the IDF criteria.

Chromium picolinate for insulin resistance in subjects with HIV disease: a pilot study

AIM

Multidrug regimens in HIV disease are associated with an increased incidence of insulin resistance, by as much as 50%. Not only does insulin resistance predisposes subjects to diabetes but also it is associated with the metabolic syndrome and increased risk of cardiovascular disease. Previous studies suggest that chromium picolinate can improve insulin resistance in patients with type 2 diabetes. The objective was to study the efficacy and safety of chromium picolinate as a treatment of insulin resistance in subjects infected with HIV.

METHODS

The ability of chromium picolinate (1000 mug/day) to improve insulin sensitivity, determined with a hyperinsulinaemic-euglycaemic insulin clamp, was determined in eight HIV-positive subjects on highly active antiretroviral therapy.

RESULTS

The mean rate of glucose disposal during the clamp was 4.41 mg glucose/kg lean body mass (LBM)/min (range 2.67-5.50), which increased to 6.51 mg/kg LBM/min (range 3.19-12.78, p = .03), an increase of 25% after 8 weeks of treatment with chromium picolinate. There were no significant changes in blood parameters, HIV viral burden or CD4+ lymphocytes with chromium picolinate treatment. Two subjects experienced abnormalities of liver function during the study. Another subject experienced an elevation in blood urea nitrogen.

CONCLUSIONS

The study shows that chromium picolinate therapy improves insulin resistance in some HIV-positive subjects, but with some concerns about safety in this population.

The pathophysiology of cardiovascular disease in diabetes mellitus and the future of therapy

Diabetes mellitus is a complex disease with several metabolic abnormalities leading to varied, interconnected endothelial and vascular dysfunction and resulting in accelerated atherosclerosis. Cardiovascular disease is the main cause of mortality in patients with diabetes. Apart from traditional therapy for control of hyperglycemia and other associated comorbidities, various newer therapies are being investigated to fight atherosclerosis at a molecular level. In this review, the authors briefly describe the pathophysiology of cardiovascular disease in patients with diabetes mellitus and the future of therapy.

Novel mutations of the lipoprotein lipase gene associated with hypertriglyceridemia in members of type 2 diabetic pedigrees

Increased plasma triglyceride and free fatty acid levels are frequently associated with type 2 diabetes mellitus (T2DM). To test the hypothesis that LPL gene mutations contribute to the hypertriglyceridemia observed in members of T2DM pedigrees, we screened the LPL gene in 53 hypertriglyceridemic members of 26 families. Four known and three novel mutations were identified. All three novel mutations, Lys312insC, Thr361insA, and double mutation Lys312insC + Asn291Ser, are clinically associated with hypertriglyceridemia. In vitro mutagenesis and expression studies confirm that these variants are associated with a significant reduction in LPL activity. The modeled structures displaying the Lys312insC and Thr361insA mutations showed loss of the activity-related C-terminal domain in the LPL protein. Another novel double mutation, Lys312insC + Asn291Ser, resulted in the loss of the catalytic ability of LPL attributable to the complete loss of the C-terminal domain and alteration in the heparin association site. Thus, these novel mutations of the LPL gene contribute to the hypertriglyceridemia observed in members of type 2 diabetic pedigrees.

Changes in pattern of use, clinical characteristics and persistence rate of hormone replacement therapy among postmenopausal women after the WHI publication

The WHI was stopped prematurely because of an increased risk of breast cancer, stroke and cardiovascular diseases (CVD) in the hormone replacement therapy (HRT) arm of the trial. Changes in the use of HRT are expected.

OBJECTIVE

To assess the impact of the Women's Health Initiative (WHI) publication on the rate of HRT prescription, and the clinical characteristics and persistence rate of new users and its determinants.

METHODS

From the RAMQ databases, the total numbers of HRT prescriptions, and of new HRT's users were calculated between 2 January 1998 and 31 May 2003. To assess the clinical characteristics of women, two retrospective cohorts of new HRT's users were constructed before (pre-WHI) and after (post-WHI) the WHI study publication. The persistence rate after 1 year of follow-up was estimated using a Kaplan-Meier analysis. Cox regression models were used to estimate the rate ratio of HRT cessation.

RESULTS

The total numbers of HRT users and of new users declined respectively by 28% and 50% in post-WHI. The standard dosage of HRT was significantly less used, while the proportion of women with risk factors of CVD or at very high risk of coronary artery disease (CAD) did not change. The rate of persistence in the pre-WHI cohort was 59% compared to 45% in the post-WHI (p < 0.0001), and women with risk factors of CVD or at very high risk of CAD were less likely to cease their HRT.

CONCLUSION

One year after publication, significant changes had already occurred in the trends of use, women's characteristics and estrogen dosage. No change in the proportion of new users with CVD risk factors or at very high risk of CAD was seen.

Whole-grain foods do not affect insulin sensitivity or markers of lipid peroxidation and inflammation in healthy, moderately overweight subjects

High intakes of whole grain foods are inversely related to the incidence of coronary heart diseases and type 2 diabetes, but the mechanisms remain unclear. Our study aimed to evaluate the effects of a diet rich in whole grains compared with a diet containing the same amount of refined grains on insulin sensitivity and markers of lipid peroxidation and inflammation. In a randomized crossover study, 22 women and 8 men (BMI 28 +/- 2) were given either whole-grain or refined-grain products (3 bread slices, 2 crisp bread slices, 1 portion muesli, and 1 portion pasta) to include in their habitual daily diet for two 6-wk periods. Peripheral insulin sensitivity was determined by euglycemic hyperinsulinemic clamp tests. 8-Iso-prostaglandin F(2alpha) (8-iso PGF(2alpha)), an F(2)-isoprostane, was measured in the urine as a marker of lipid peroxidation, and highly sensitive C-reactive protein and IL-6 were analyzed in plasma as markers of inflammation. Peripheral insulin sensitivity [mg glucose . kg body wt(-1) . min(-1) per unit plasma insulin (mU/L) x 100] did not improve when subjects consumed whole-grain products (6.8 +/- 3.0 at baseline and 6.5 +/- 2.7 after 6 wk) or refined products (6.4 +/- 2.9 and 6.9 +/- 3.2, respectively) and there were no differences between the 2 periods. Whole-grain consumption also did not affect 8-iso-PGF(2alpha) in urine, IL-6 and C-reactive protein in plasma, blood pressure, or serum lipid concentrations. In conclusion, substitution of whole grains (mainly based on milled wheat) for refined-grain products in the habitual daily diet of healthy moderately overweight adults for 6-wk did not affect insulin sensitivity or markers of lipid peroxidation and inflammation.

Ethnicity and cardiovascular disease prevention in the United Kingdom: a practical approach to management

The United Kingdom is a diverse society with 7.9% of the population from black and minority ethnic groups (BMEGs). The causes of the excess cardiovascular disease (CVD) and stroke morbidity and mortality in BMEGs are incompletely understood though socio-economic factors are important. However, the role of classical cardiovascular (CV) risk factors is clearly important despite the patterns of these risk factors varying significantly by ethnic group. Despite the major burden of CVD and stroke among BMEGs in the UK, the majority of the evidence on the management of such conditions has been based on predominantly white European populations. Moreover, the CV epidemiology of African Americans does not represent well the morbidity and mortality experience seen in black Africans and black Caribbeans, both in Britain and in their native African countries. In particular, atherosclerotic disease and coronary heart disease are still relatively rare in the latter groups. This is unlike the South Asian diaspora, who have prevalence rates of CVD in epidemic proportions both in the diaspora and on the subcontinent. As the BMEGs have been under-represented in research, a multitude of guidelines exists for the 'general population.' However, specific reference and recommendation on primary and secondary prevention guidelines in relation to ethnic groups is extremely limited. This document provides an overview of ethnicity and CVD in the United Kingdom, with management recommendations based on a roundtable discussion of a multidisciplinary ethnicity and CVD consensus group, all of whom have an academic interest and clinical practice in a multiethnic community.

Peroxisome proliferator-activated receptor-gamma agonists for management and prevention of vascular disease in patients with and without diabetes mellitus

Inflammation is known to have a pathogenic role in atherosclerosis and the genesis of acute coronary syndromes. The peroxisome proliferator-activated receptor (PPAR)-gamma, which is expressed in many constituent cells of atheromatous plaques, inhibits the activation of several proinflammatory genes responsible for atheromatous plaque development and maturation. Agonists of this receptor, such as rosiglitazone and pioglitazone, are currently available for the treatment of type 2 diabetes mellitus, and several lines of evidence have shown that these drugs have antiatherogenic effects. Insulin resistance is associated with inflammation and has a key role in atherogenesis. The antiatherogenic and insulin sensitizing effects of the thiazolidinediones in patients with type 2 diabetes mellitus may be associated with this action. However, in recent years there has been growing evidence that the antiatherogenic effects of PPAR-gamma agonists are not confined to patients with diabetes mellitus. PPAR-gamma agonists have been shown to downregulate the expression of endothelial activation markers, reduce circulating platelet activity, improve flow-mediated dilatation and attenuate atheromatous plaque progression in patients without diabetes mellitus. These effects of PPAR-gamma agonists appear to result from both insulin sensitization and a direct modulation of transcriptional activity in the vessel wall. This review summarizes the current understanding of the role of PPAR-gamma agonists in atherogenesis and discusses their potential role in the treatment of coronary artery disease in patients with type 2 diabetes mellitus and in nondiabetic patients.

Fruit and vegetable intakes, C-reactive protein, and the metabolic syndrome

BACKGROUND

Limited data on the relation between the risk of the metabolic syndrome and fruit and vegetable intakes and inflammatory marker concentrations are available.

OBJECTIVE

We evaluated the relation between fruit and vegetable intakes and C-reactive protein (CRP) concentrations and the prevalence of the metabolic syndrome.

DESIGN

Fruit and vegetable intakes were assessed with the use of a validated semiquantitative food-frequency questionnaire in a cross-sectional study of 486 Tehrani female teachers aged 40-60 y. Anthropometric measurements were made and blood pressure was assessed according to standard methods. Fasting blood samples were taken for biochemical measurements. The metabolic syndrome was defined on the basis of the National Cholesterol Education Program Adult Treatment Panel III guidelines.

RESULTS

The reported mean daily fruit and vegetable intakes were 228 +/- 79 and 186 +/- 88 g/d, respectively. Both fruit and vegetable intakes were inversely associated with plasma CRP concentrations. After statistical control for age, body mass index, and waist circumference, mean plasma CRP concentrations across increasing quintile categories of fruit intakes were 1.94, 1.79, 1.65, 1.61, and 1.56 mg/L and of vegetable intakes were 2.03, 1.82, 1.58, 1.52, and 1.47 mg/L (P for trend < 0.01 for both). These inverse associations remained significant after additional control for other potential confounding variables and dietary factors. After control for potential confounders, persons in the highest quintile of fruit intake had a 34% (95% CI: 20%, 46%) lower and those in the highest quintile of vegetables intake had a 30% (95% CI: 16%, 39%) lower chance of having the metabolic syndrome than did those in the lowest quintiles.

CONCLUSIONS

Higher intakes of fruit and vegetables are associated with a lower risk of the metabolic syndrome; the lower risk may be the result of lower CRP concentrations. These findings support current dietary recommendations to increase daily intakes of fruit and vegetables as a primary preventive measure against cardiovascular disease.

Menopause, insulin resistance, and risk factors for cardiovascular disease

OBJECTIVE

In this retrospective analysis of the European Group for the Study of Insulin Resistance database, a clamp data pooling project, a cardiovascular risk score (CVS) was assessed to verify whether hyperinsulinemia and/or insulin resistance were independent cardiovascular risk factors and to investigate how menopause affected CVS and insulin resistance.

DESIGN

Information was obtained on whole-body glucose uptake (M), determined by the euglycemic hyperinsulinemic clamp technique, normalized by fat-free mass (FFM), and insulin concentration (I) at a steady state. Body composition was estimated using a labeled water technique or bioimpedance. Other parameters measured included blood pressure, lipid levels, and waist-to-hip ratio. CVS was computed using a structural equation model that included age, body mass index, blood lipids, and blood pressure. The study population included 523 normal and overweight patients. Women were grouped according to fertility status, and men, according to age (cutoff 50 y).

RESULTS

M/kg(FFM)/I significantly decreased after menopause (12.41 +/- 3.40 vs 10.96 +/- 3.68; P < 0.01) and in men 50 years and older (11.39 +/- 3.47 vs 10.32 +/- 3.77 micromol x min(-1) x kg(-1) x microUI/mL; P < 0.02). CVS was lowest in fertile women (-0.414 +/- 0.57 vs 0.107 +/- 0.43; P < 0.0001) and highest in men 50 years and older (0.045 +/- 0.455 vs 0.257 +/- 0.51; P < 0.001). CVS significantly correlated with M/kg(FFM)/I in men 49 years and younger (r(o) = -0.27, P < 0.0001) and 50 years and older (r(o) = -0.38, P < 0.0001) and with fasting insulin in fertile women (r(o) = -0.29, P < 0.01) and in the other groups (r(o) ranging from 0.37 to 0.45, P < 0.0001).

CONCLUSIONS

Menopause does not seem to strictly relate to a decrease in insulin sensitivity as postmenopausal women had the same insulin sensitivity as age-matched men. In the population studied, the best predictor of CVS was fasting insulin rather than insulin sensitivity.

A systematic review and meta-analysis of the relationship between lipoprotein lipase Asn291Ser variant and diseases

This systematic review attempted to summarize the associations between the Asn291Ser variant in the lipoprotein lipase (LPL) gene and dyslipidemia, the risk of type 2 diabetes mellitus (T2DM), and coronary heart disease (CHD). In addition, the relationships between the Asn291Ser variant and other metabolic diseases such as obesity and high blood pressure were also investigated in this systematic review. We systematically reviewed the literature by means of a meta-analysis. Twenty-one articles, including 19,246 white subjects, were selected for this meta-analysis. The summary standardized mean difference (SMD) of plasma triglyceride (TG) for carriers compared with noncarriers of the Asn291Ser variant was 3.23 (P < 0.00001). The summary SMD of plasma HDL-cholsterol (HDL-C) for carriers compared with noncarriers of the Asn291Ser variant was -3.42 (P < 0.0001). The summary SMD of the association of the Asn291Ser variant with plasma TG increased with increasing age and weight gain. Significant interactions between the LPL Asn291Ser variant and fasting glucose, T2DM, and CHD were seen (P = 0.02, 0.04, and 0.01, respectively). No significant interactions were seen between the LPL Asn291Ser variant and body mass index, waist-hip ratio, and blood pressure (P > 0.05). This meta-analysis indicates that the Asn291Ser variant in the LPL gene is a risk factor for dyslipidemia, characterized by hypertriglyceridemia and low HDL-C levels. And the Asn291Ser variant in the LPL gene predisposes to more severe dyslipidemia with increasing age and weight gain. Also, this meta-analysis shows that the LPL Asn291Ser variant is associated with CHD and T2DM.

Rationale, design, and methods for glycemic control in the Bypass Angioplasty Revascularization Investigation 2 Diabetes (BARI 2D) Trial

A major therapeutic question in considering accelerated atherogenesis in patients with type 2 diabetes mellitus is whether reducing insulin resistance, as a proximal defect of a host of proatherogenic abnormalities including hyperglycemia, will be superior for decreasing mortality and coronary artery disease (CAD) risk compared with treating hyperglycemia to overcome insulin resistance with insulin-providing agents. This question is highly relevant, since earlier targeted glycemic control trials utilizing conventional glucose-lowering strategies that increase insulin levels have generally failed to reduce CAD risk despite markedly reducing microvascular risk. The Bypass Angioplasty Revascularization Investigation 2 Diabetes (BARI 2D) trial seeks to determine whether primarily using an insulin-sensitizing strategy for treatment of type 2 diabetes is superior when compared with primarily using an insulin-providing strategy with regard to cardiovascular outcomes. This article presents the rationale, design, and methods being used to test the glycemic control hypothesis in BARI 2D.

The effect of Helicobacter pylori on insulin resistance

Helicobacter pylori causes a lifelong infection in the stomach after exposure. H. pylorihas been shown to be associated with peptic ulcer and gastric cancer development. Moreover, it is held responsible for some other nongastric diseases. Among them, coronary heart disease attracts much debate. Many studies have demonstrated a close relationship between insulin resistance and atherosclerosis. Chronic inflammation and alterations in counter-regulatory hormones are deemed responsible for the etiology of insulin resistance. We aimed to examine the effect of H. pylori on insulin resistance. Sixty-three patients were enrolled in the study. Patients were divided into two groups according to H. pylori presence. HOMA-IR (homeostasis model assessment of insulin resistance) level was used to assess insülin resistance. Thirty-six patients were H. pylori positive and 27 were H. pylori negative. There was no difference between the two groups with regard to age, gender, or body mass index. HOMA-IR level was 1.73+/- 1.1 in the H. pylori-negative group, whereas it was 2.56 +/- 1.54 in the H. pylori-positive group (P < 0.05). This study provides the first direct evidence for an association between chronic H. pylori infection and insulin resistance.

Insulin resistance and the endothelium

Type 2 diabetes is a cardiovascular disease equivalent that is associated with accelerated atherosclerosis and significant mortality. However, the metabolic syndrome and prediabetes are associated with increased cardiovascular mortality, indicating that atherogenic vascular changes begin prior to the onset of overt diabetes. At the core of diabetes and the metabolic syndrome is insulin resistance (IR), which sets the stage for dyslipidemia, hypertension, and inflammation. Endothelial dysfunction is the first stage of the atherosclerosis process and results from exposure to cardiovascular risk factors, such as IR and diabetes. IR and atherosclerosis follow parallel paths as they progress in severity. Thiazolidinediones, angiotensin-converting enzyme inhibitors, angiotensin receptor-AT1 blockers, and statins are widely used in the treatment of diabetes. Emerging evidence indicates that these pharmacologic agents have added mechanisms of action, especially on the endothelium and in the prevention of diabetes.

Whole-grain consumption and the metabolic syndrome: a favorable association in Tehranian adults

BACKGROUND

Although dietary guidelines recommend increased intake of grain products to prevent chronic diseases, epidemiologic data regarding whole-grain intake association with metabolic syndrome are sparse.

OBJECTIVE

To evaluate the relationship between whole-grain intakes, metabolic syndrome and metabolic risk factors in Tehranian adults.

DESIGN

Population-based cross-sectional study.

SETTING

Tehran, the capital of Iran.

SUBJECTS

A representative sample of 827 subjects (357 men and 470 women) aged 18-74 y.

METHODS

Usual dietary intake was assessed using a food frequency questionnaire. The procedure developed by Jacobs et al was used to classify grain products into whole and refined grains. Weight and height were measured according to standard protocols and body mass index was calculated. Fasting blood samples were taken for biochemical measurements and blood pressure was assessed according to standard methods. Hypertriglyceridemia, hypercholestrolemia, high LDL, low HDL and metabolic syndrome were defined according to ATP III guidelines and hypertension based on JNC VI. Diabetes was defined as fasting plasma glucose level of > or = 126 mg/dl or 2-h postchallenge blood glucose level of > or = 200 mg/dl. Subjects were categorized based on quartile cut-points of whole- and refined-grain intake.

RESULTS

Mean (+/-s.d.) consumptions of whole and refined grains were 93+/-29 and 201+/-57 g/day, respectively. Both men and women reported higher intakes of refined grain than of whole grains. Compared with subjects in the lower quartile category, those in the upper category of whole-grain intake had lower prevalence of metabolic risk factors. Conversely, those in the higher category of refined-grain intake had higher prevalence of metabolic risk factors, except for diabetes. After controlling for confounders, a significantly decreasing trend was observed for the risk of having hypertriglyceridemia (odds ratios among quartiles: 1.00, 0.89, 0.74, 0.61, respectively), hypertension (1.00, 0.99, 0.93, 0.84) and metabolic syndrome (1.00, 0.84, 0.76, 0.68). Higher consumption of refined grains was associated with higher odds of having hypercholestrolemia (1.00, 1.07, 1.19, 1.23), hypertriglyceridemia (1.00, 1.17, 1.49, 2.01), hypertension (1.00, 1.22, 1.48, 1.69) and metabolic syndrome (1.00, 1.68, 1.92, 2.25).

CONCLUSION

Whole-grain intake is inversely and refined-grain intake is positively associated with the risk of having metabolic syndrome. Recommendations to increase whole-grain intake may reduce this risk.

Pathogenesis and management of diabetic dyslipidemia

Patients with diabetes mellitus have a 2- to 4-fold increased risk of atherosclerotic cardiovascular, peripheral vascular, and cerebrovascular disease, which are the leading causes of morbidity and mortality in this population. Several epidemiological studies have shown an association between diabetic dyslipidemia, which is characterized by hypertriglyceridemia, low levels of high density lipoprotein-cholesterol, postprandial lipemia and small, dense low density lipoprotein-cholesterol (LDL-C) particles, and the occurrence of cardiovascular disease. Other studies have established the beneficial effects of lipid lowering on the reduction of major coronary events in diabetic patients. The recent National Cholesterol Education Program (NCEP) Adult Treatment Panel III (ATP III) guidelines emphasize diabetes as a coronary heart disease risk equivalent. The NCEP ATP III states that elevated LDL-C is a major risk factor for coronary heart disease, and the primary goal of risk-reduction therapy is the reduction of LDL-C levels to 100 mg/dL. This article defines and describes diabetic dyslipidemia and its etiology and pathogenesis, as well as reviewing guidelines and recommendations for treatment of this disorder. Treatment of diabetic dyslipidemia includes 1) lifestyle modifications: physical activity and a diet low in saturated fats and cholesterol and high in complex carbohydrates and fiber; and 2) pharmacological treatment with (i) oral antihyperglycemic agents: metformin and thiazolidinediones; (ii) weight reduction drugs: orlistat and sibutramine and; (iii) lipid-lowering drugs: HMG-CoA reductase inhibitors, fibric acid derivatives, nicotinic acid, and bile acid sequestrants.

C-Peptide utilization in clinical practice: effect on treatment and outcome of diabetes in a series of cases

OBJECTIVE

To emphasize that measurement of a C-peptide level can be critical in the diagnosis and appropriate management of patients with diabetes mellitus.

METHODS

We present a series of clinical cases in which glycemic control proved challenging, and we discuss the underlying pathophysiologic features of type 1 versus type 2 diabetes.

RESULTS

In a series of 12 illustrative cases, suboptimal control of blood glucose levels in patients with diabetes prompted further investigation. Assessment of C-peptide levels helped determine a precise diagnosis of type 1 or type 2 diabetes, information that was pivotal in choosing treatment options and improving the outcome. These examples show that the age of the patient at the time of diagnosis of diabetes does not necessarily indicate the type of diabetes that is present.

CONCLUSION

Clinicians should be aware of the importance of establishing whether patients have type 1 or type 2 diabetes mellitus and the implications of that distinction on the effectiveness of therapeutic strategies.