Targets for intervention in dyslipidemia in diabetes

Causal associations between age at diagnosis of diabetes and cardiovascular outcomes: a Mendelian randomization study

CONTEXT

Whether diabetes diagnosed at different age groups is causally associated with cardiovascular diseases (CVDs) is unknown.

OBJECTIVE

We conducted two-sample Mendelian randomization analyses to investigate the causal associations of diabetes by age at diagnosis with five type-specific CVDs and 11 cardiometabolic traits.

METHODS

We selected 208 single nucleotide polymorphisms (SNPs) for diabetes and 3, 21, 57, and 14 SNPs for diabetes diagnosed at <50, 50-60, 60-70, and >70 years, respectively, based on the GWAS (24,986 cases/187,130 controls) in the UK Biobank, and extracted genetic associations with stroke, myocardial infarction, heart failure, atrial fibrillation, and CVD mortality, as well as blood pressures, adiposity measurements, and lipids and apolipoproteins from corresponding European-descent GWASs. The inverse-variance weighted method was used as main analysis with several sensitivity analyses.

RESULTS

Diabetes diagnosed at all four age groups was causally associated with increased risks of stroke (5%-8%) and myocardial infarction (8%-10%), higher systolic blood pressure (0.56-0.94 mmHg) and waist-to-hip ratio (0.003-0.004), and lower body mass index (0.31-0.42 kg/m2), waist circumference (0.68-0.99 cm), and hip circumference (0.57-0.80 cm). Diabetes diagnosed at specific age groups was causally associated with increased risks of heart failure (4%) and CVD mortality (8%), higher diastolic blood pressure (0.20 mmHg) and triglycerides (0.06 SD), and lower high-density lipoprotein cholesterol (0.02 mmol/L). The effect sizes of genetically determined diabetes on CVD subtypes and cardiometabolic traits were comparable and the corresponding 95% confidence intervals largely overlapped across the four age groups.

CONCLUSION

Our findings provide novel evidence that genetically determined diabetes subgroups by age at diagnosis have similar causal effects on CVD and cardiometabolic risks.

Novel Indel Variation of NPC1 Gene Associates With Risk of Sudden Cardiac Death

Background and Aims: Sudden cardiac death (SCD) was defined as an unexpected death from cardiac causes during a very short duration. It has been reported that Niemann-Pick type C1 (NPC1) gene mutations might be related to cardiovascular diseases. The purpose of the study is to investigate whether common genetic variants of NPC1 is involved in SCD susceptibility.

Methods: Based on a candidate-gene-based approach and systematic screening strategy, this study analyzed an 8-bp insertion/deletion polymorphism (rs150703258) within downstream of NPC1 for the association with SCD risk in Chinese populations using 158 SCD cases and 524 controls. The association of rs150703258 and SCD susceptibility was analyzed using logistic regression. Genotype-phenotype correlation analysis was performed using public database including 1000G, expression quantitative trait loci (eQTL), and further validated by human heart tissues using PCR. Dual-luciferase assay was used to explore the potential regulatory role of rs150703258. Gene expression profiling interactive analysis and transcription factors prediction were performed.

Results: Logistic regression analysis exhibited that the deletion allele of rs150703258 significantly increased the risk of SCD [odds ratio (OR) = 1.329; 95% confidence interval (95%CI):1.03–1.72; p = 0.0289]. Genotype-phenotype correlation analysis showed that the risk allele was significantly associated with higher expression of NPC1 at mRNA and protein expressions level in human heart tissues. eQTL analysis showed NPC1 and C18orf8 (an adjacent gene to NPC1) are both related to rs150703258 and have higher expression level in the samples with deletion allele. Dual-luciferase activity assays indicate a significant regulatory role for rs150703258. Gene expression profiling interactive analysis revealed that NPC1 and C18orf8 seemed to be co-regulated in human blood, arteries and heart tissues. In silico analysis showed that the rs150703258 deletion variant may create transcription factor binding sites. In addition, a rare 12-bp allele (4-bp longer than the insertion allele) of rs150703258 was discovered in the current cohort.

Conclusion: In summary, our study revealed that rs150703258 might contribute to SCD susceptibility by regulating NPC1 and C18orf8 expression. This indel may be a potential marker for risk stratification and molecular diagnosis of SCD. Validations in different ethnic groups with larger sample size and mechanism explorations are warranted to confirm our findings.

Statin use for primary prevention in patients with type 2 diabetes: Can it benefit all ages? - A nationwide propensity-matched cohort study

AIMS

This study aims to investigate whether statin use is associated with a reduction in CVD and mortality in patients with type 2 diabetes without pre-existing CVD.

METHODS

A propensity score-matched cohort analysis using retrospective data was created. Statin users received at least a 90-day prescription, and never used statin before initiation of the study. Statin non-users never received statin throughout the study. Primary outcome was a composite of myocardial infarction (MI), stroke, and all-cause death, and secondary outcome was an individual event.

RESULTS

The propensity score matched cohort included 168,045 statin users and 168,045 non-users (mean age 57 years; median follow-up 5.0 years). Compared to statin non-users, the hazard ratio (HR) was 0.72 (95% confidence interval [CI] 0.70-0.73; P < 0.001) for composite outcomes, 0.80 (0.76-0.84; P < 0.001) for MI, 0.74 (0.71-0.76; P < 0.001) for stroke, and 0.68 (0.66-0.70; P < 0.001) for all-cause death in statin users. The risk reduction was most prominent in subjects aged 40-74 years, attenuated but significant in those aged ≥75 years, and not significant in those aged <40 years.

CONCLUSIONS

Statin showed a protective effect against CVD and all-cause death in type 2 diabetes; this effect was reduced beyond the age of 75 years and disappeared in young patients aged <40 years.

Epidemiology, risk factors across the spectrum of age-related metabolic diseases

BACKGROUND

Population aging is dynamic process of increasing proportion of older adults in the total population, which is an inescapable result of decline in fertility rate and extension in life expectancy. Inevitably, age-related metabolic diseases, for example obesity, type 2 diabetes, metabolic syndrome, dyslipidemia, and nonalcoholic fatty liver disease, are becoming epidemic globally along with the demographic transition.

CONTENT

The review examines the literatures related to: 1) the epidemiology of age related metabolic diseases including obesity, type 2 diabetes, metabolic syndrome, dyslipidemia, and nonalcoholic fatty liver disease; and 2) the risk factors of age related metabolic diseases including genetic factors, diet, smoking, Physical activity, intestinal microbiota and environmental factors.

CONCLUSION

Population aging is becoming epidemic worldwide, resulting in increasing incidence and prevalence of a serious of age-related metabolic diseases. Both genetic and environmental factors contribute to the diseases, thus interventions targeting on these factors may have beneficial effect on the development of age-related metabolic diseases.

Prescribing pattern of statins for primary prevention of cardiovascular diseases in patients with type 2 diabetes: insights from Ethiopia

Objective

Although most clinical practice guidelines endorsed statin use in type 2 diabetes (T2D) patients for reducing cardiovascular diseases (CVD), little is known about statin utilization in case of Ethiopia. Hence, this study was aimed to evaluate prescribing pattern of statins for primary prevention of CVD in T2D patients. A retrospective study conducted in T2D patients with the age group of 40–75 years. Prescriptions were audited for details of statin use and dose intensity. Descriptive analysis was performed using SPSS version 22.0.

Results

We included a total of 323 study subjects. Of those, 55.7% study subjects were found to be received statin for their primary prevention of CVD. Commonly prescribed type of statins was simvastatin (37.2%), atorvastatin (32.8%) and rosuvastatin (15.6%). Low, moderate and high intensive dose of statins were prescribed in 27.8%, 46.1%, and 26.1%, respectively. Of those subjects received statin, 60.6% had on target cholesterol level. Overall, a significant percentage of subjects did not receive their recommended statin for primary prevention of CVD which is below the guidelines’ recommendation. Therefore, adherence to guidelines may help to promote the use of statins for primary prevention of CVD in T2D and advance interventions to improve statin prescribing should be considered.

Electronic supplementary material

The online version of this article (10.1186/s13104-019-4423-9) contains supplementary material, which is available to authorized users.

Antidiabetic Activity of Sargassum hystrix Extracts in Streptozotocin-Induced Diabetic Rats

The objective of this research was to determine the potential effects of Sargassum hystrix extracts (SHE) on the glucose levels, lipid profile, and pancreas of streptozotocin (STZ)-induced diabetic rats. SHE at 200, 300, and 400 mg/kg was administered orally to STZ-induced diabetic rats once daily for 15 days. Glucose levels, lipid profile, and weight of rats were measured in the normal state and on the 15th day. The histology of the pancreas was observed on the 15th day. The results showed that the preprandial and postprandial glucose levels in the group treated with SHE at 300 mg/kg were significantly reduced compared with those of the diabetes group. Additionally, the levels of triglycerides and cholesterol in the 300 mg/kg SHE group were significantly different from those in the diabetes group. However, the levels of high-density lipoprotein cholesterol and low-density lipoprotein cholesterol across the treatment groups did not have significant differences. Necrosis was found in all STZ-induced rats. SHE at a dose of 300 mg/kg had the best capability to lower the levels of preprandial and postprandial glucose and to prevent necrosis in diabetic rats.

Pharmacological inhibition of diacylglycerol acyltransferase-1 and insights into postprandial gut peptide secretion

AIM

To examine the role that enzyme Acyl-CoA:diacylglycerol acyltransferase-1 (DGAT1) plays in postprandial gut peptide secretion and signaling.

METHODS

The standard experimental paradigm utilized to evaluate the incretin response was a lipid challenge. Following a lipid challenge, plasma was collected via cardiac puncture at each time point from a cohort of 5-8 mice per group from baseline at time zero to 10 h. Incretin hormones [glucagon like peptide-1 (GLP-1), peptide tyrosine-tyrosine (PYY) and glucose dependent insulinotropic polypeptide (GIP)] were then quantitated. The impact of pharmacological inhibition of DGAT1 on the incretin effect was evaluated in WT mice. Additionally, a comparison of loss of DGAT1 function either by genetic ablation or pharmacological inhibition. To further elucidate the pathways and mechanisms involved in the incretin response to DGAT1 inhibition, other interventions [inhibitors of dipeptidyl peptidase-IV (sitagliptin), pancreatic lipase (Orlistat), GPR119 knockout mice] were evaluated.

RESULTS

DGAT1 deficient mice and wildtype C57/BL6J mice were lipid challenged and levels of both active and total GLP-1 in the plasma were increased. This response was further augmented with DGAT1 inhibitor PF-04620110 treated wildtype mice. Furthermore, PF-04620110 was able to dose responsively increase GLP-1 and PYY, but blunt GIP at all doses of PF-04620110 during lipid challenge. Combination treatment of PF-04620110 and Sitagliptin in wildtype mice during a lipid challenge synergistically enhanced postprandial levels of active GLP-1. In contrast, in a combination study with Orlistat, the ability of PF-04620110 to elicit an enhanced incretin response was abrogated. To further explore this observation, GPR119 knockout mice were evaluated. In response to a lipid challenge, GPR119 knockout mice exhibited no increase in active or total GLP-1 and PYY. However, PF-04620110 was able to increase total GLP-1 and PYY in GPR119 knockout mice as compared to vehicle treated wildtype mice.

CONCLUSION

Collectively, these data provide some insight into the mechanism by which inhibition of DGAT1 enhances intestinal hormone release.

Effect of fenugreek on hyperglycaemia and hyperlipidemia in diabetes and prediabetes: A meta-analysis

ETHNOPHARMACOLOGICAL RELEVANCE

Fenugreek is a widely used herb for the treatment of diabetes mellitus (DM) but the effects in randomized controlled trials (RCTs) were controversial. Therefore, a meta-analysis was conducted to estimate the overall effects of fenugreek on hyperglycaemia and hyperlipidemia in diabetes and prediabetes.

MATERIALS AND METHODS

PubMed, EMBASE, web of science, Chinese Biomedical Literature database (CBM), the Cochrane library, China Doctor Dissertations Full-text Database (CDFD), Wan Fang medical database, China Proceedings of Conference Full-text Database (CPCD), China national knowledge internet (CNKI) and China Master's Theses Full-text Database (CMFD) were searched to find the available literatures. RCTs with regard to the efficacy and safety of fenugreek on prediabetes or DM were included. The data of fasting blood glucose (FBG), postprandial 2h blood glucose (2hBG), glycosylated hemoglobin (HbA1c), triglyceride (TG), total cholesterol (TC), low density lipoprotein cholesterol (LDL-c) and high density lipoprotein cholesterol (HDL-c) were extracted to appraise the net change with fixed or randomized effect model.

RESULTS

A total of 10 articles (12 studies) were included in the analysis. Pooled results showed fenugreek significantly decreased the levels of FBG (MD -0.84mmol/L; 95% CI -1.38 to -0.31; p=0.002), 2hBG (MD -1.30mmol/L; 95% CI -1.78 to -0.83; p<0.0001), HbA1c (MD -1.16; 95% CI -1.23 to -1.09; p<0.00001) and TC (MD -0.30mmol/L; 95% CI-0.56 to -0.03; p=0.03). In spite of the reductive trends in the TG or LDL-c levels and incremental trends of HDL-c, these results were not statistically significant or need further verification for fenugreek in the treatment of DM and prediabetes. Some studies were of low quality. No liver and kidney toxicity were found in all included studies, and the main side effects were gastrointestinal discomfort.

CONCLUSIONS

The results suggest fenugreek has the hypoglycaemic and TC-lowering efficacy; however, the effects on TG, LDL-c and HDL-c need further confirmations.

Effect of breviscapine injection on clinical parameters in diabetic nephropathy: A meta-analysis of randomized controlled trials

Diabetic nephropathy (DN) is currently a major public health problem worldwide. The objective of the present study was to evaluate the clinical effect of breviscapine injections in patients with DN. A meta-analysis was performed using the following databases to obtain published reports in any language: PubMed/MEDLINE, Embase, China National Knowledge Infrastructure, Chinese Evidence-Based Medicine, Wanfang Digital Periodicals, Chinese Academic Journals Full-text Database, Chinese Biological and Medical Database, China Doctoral and Masters Dissertations Full-text Database and the Chinese Proceedings of Conference Full-text Database. Two assessors independently reviewed each trial. A total of 35 randomized controlled trials, which performed studies on a total of 2,320 patients (1,188 in treatment groups and 1,132 in control groups), were included in the present meta-analysis. Data were analyzed using Stata version 11.0 for Windows. The results from the analysis demonstrated that breviscapine injections have greater therapeutic effects in patients with DN in comparison with the control group, including renal protective effects (reducing urine protein, serum creatinine and blood urea nitrogen) and adjustment for dyslipidemia (affecting levels of cholesterol, triglycerides and high density lipoproteins). These effects indicate that breviscapine injections are beneficial to patients with DN. Further studies are required to determine the mechanisms underlying the therapeutic effects of breviscapine.

Exercise improved lipid metabolism and insulin sensitivity in rats fed a high-fat diet by regulating glucose transporter 4 (GLUT4) and musclin expression

This study aimed to evaluate the effects of exercise training on triglyceride deposition and the expression of musclin and glucose transporter 4 (GLUT4) in a rat model of insulin resistance. Thirty male Sprague-Dawley rats (8 weeks old, weight 160±10 g) were fed a high-fat diet (40% calories from fat) and randomly divided into high-fat control group and swimming intervention group. Rats fed with standard food served as normal control. We found that 8-week swimming intervention significantly decreased body weight (from 516.23±46.27 to 455.43±32.55 g) and visceral fat content (from 39.36±2.50 to 33.02±2.24 g) but increased insulin sensitivity index of the rats fed with a high-fat diet. Moreover, swimming intervention improved serum levels of TG (from 1.40±0.83 to 0.58±0.26 mmol/L) and free fatty acids (from 837.80±164.25 to 556.38±144.77 μEq/L) as well as muscle triglycerides deposition (from 0.55±0.06 to 0.45±0.02 mmol/g) in rats fed a high-fat diet. Compared with rats fed a standard food, musclin expression was significantly elevated, while GLUT4 expression was decreased in the muscles of rats fed a high-fat diet. In sharp contrast, swimming intervention significantly reduced the expression of musclin and increased the expression of GLUT4 in the muscles of rats fed a high-fat diet. In conclusion, increased musclin expression may be associated with insulin resistance in skeletal muscle, and exercise training improves lipid metabolism and insulin sensitivity probably by upregulating GLUT4 and downregulating musclin.

Dyslipidemia in young patients with type 1 diabetes mellitus

OBJECTIVE

The association between type 1 diabetes mellitus (T1D) and dyslipidemia (DLP) increases the risk of cardiovascular disease (CVD). The aim of this study was to evaluate the presence of dyslipidemia in young T1D patients.

MATERIALS AND METHODS

The study design was cross-sectional and descriptive. We reviewed medical records of T1D patients followed at an endocrinology service, from 1998-2012.

DATA COLLECTED

gender, actual age and age at diagnosis, duration of T1D since diagnosis, body mass index (BMI), pubertal stage, glycemic control (GC) determined by glycated hemoglobin (HbA1c), total cholesterol (TC), HDL, LDL, triglycerides (TG). To analyze lipid profile and metabolic control, we used the Brazilian Society of Diabetes Guidelines.

RESULTS

Were included 239 T1D patients, 136 (56.9%) females; mean ± SD: actual age 15.7 ± 5.0 years and at T1D diagnosis 7.3 ± 3.9; T1D duration 10.6 ± 6.4 years, 86.6% puberty, 15.1% overweight. The prevalence of DLP was 72.5%, 63.3% females, 86.6% puberty, mean ± SD: actual age 15.4 ± 4.8 years and at T1D diagnosis 7.2 ± 4.1 years, duration of T1D 10.7 ± 6.1 years. We found high-CT in 56.7%, low-HDL = 21.7%, high LDL = 44.0%, high-TG = 11.8%. Between females with DLP, 83.5% was in puberty. We find correlation between the presence of DLP, a poor GC and BMC.

CONCLUSION

We found a high prevalence of DLP in young patients with T1D, particularly in puberty females. Programs targeting the prevention of dyslipidemia should be adopted, especially for this group, in order to prevent/delay chronic complications and cardiovascular disease.

Alterations of intestinal lipoprotein metabolism in diabetes mellitus and metabolic syndrome

Diabetes and metabolic syndrome are associated with abnormal postprandial lipoprotein metabolism, with a significant delay in the clearance of many lipid parameters, including triglycerides and chylomicrons. Abnormal concentrations of plasma lipids can result from changes in the production, conversion, or catabolism of lipoprotein particles. Whereas the liver is involved in controlling serum lipid levels through synthesis of liver derived triglyceride-rich lipoproteins and low-density lipoprotein metabolism, the intestine also has a major role in lipoprotein production. Postprandial lipemia results from increases in apoB-48 availability, lipogenesis, and the synthesis and absorption of cholesterol in the enterocytes. Increased intestinal lipoprotein production prolongs postprandial lipemia in patients with diabetes and MetS, and may contribute directly to atherogenesis in these patients.

Simvastatin-ezetimibe combination therapy is associated with a lower rate of major adverse cardiac events in type 2 diabetics than high potency statins alone: A population-based dynamic cohort study

BACKGROUND

Recent trials have shown a reduction in the risk of major adverse cardiac events (MACE) with simvastatin-ezetimibe therapy in patients with acute coronary syndrome. The potential benefits of simvastatin-ezetimibe for patients at a lower risk of MACE are unclear. This study aimed to investigate the differences of MACE risk between patients with type 2 diabetes mellitus (DM) using simvastatin-ezetimibe or high potency statins.

METHODS

This population-based dynamic cohort study used data from the Taiwan National Health Insurance Database. The study subjects were patients with type 2 DM, aged between 40 and 75 years. The simvastatin-ezetimibe group took simvastatin-ezetimibe only, and the statin group took atorvastatin or rosuvastatin but not simvastatin or ezetimibe. The two groups were matched for age, gender, medication date, DM diagnosis date, hypertension, and cardiovascular complications. The outcome variable was new-onset MACE. Univariate and multivariate survival analyses were performed.

RESULTS

A total of 20,485 patients (53% male; 4099 in the simvastatin-ezetimibe group and 16,396 in the statin group) were included, with a mean age of 59.1 years. In a total of 37,388 person-years, 1100 patients developed new-onset MACE. The annual incidence rate of new-onset MACE was lower in the simvastatin-ezetimibe group (2.61%) than that in the statin group (3.02%) (p=0.0476). After Cox regression analysis, simvastatin-ezetimibe use was independently associated with a lower risk of MACE (HR, 0.77; 95% confidence interval 0.66-0.90).

CONCLUSIONS

Compared to high potency statins alone, simvastatin-ezetimibe therapy was associated with a lower incidence of MACE in patients with type 2 DM.

Desaturation index versus isotopically measured de novo lipogenesis as an indicator of acute systemic lipogenesis

BACKGROUND

High carbohydrate feeding is known to increase plasma triglycerides as well as hepatic de novo lipogenesis (DNL) and may be implicated in the development of hepatic insulin resistance and fatty liver. Unfortunately, it is technically challenging to determine what proportion of circulating plasma triglycerides have been derived from the newly synthesized fatty acids in the postprandial period. The aims of this study were to 1) characterize the changes in the plasma postprandial total fatty acid pool in beagles following the consumption of meals containing 44% (Control) and 74% (High Sucrose) carbohydrate and 2) determine if changes in plasma fatty acid concentration and delta-9 desaturation index (DI) would be useful as simple and easy to measure biomarkers of systemic DNL.

FINDINGS

No differences in plasma total palmitic acid (16:0), stearic acid (18:0) and oleic acid (18:1) concentrations or delta-9 DI for the total 18:0 and 18:1 pools between High Sucrose and Controls were observed. However, newly synthesized 16:0 (2.6 ± 0.2% vs. 8.8 ± 2.0%; p = 0.016), 18:0 (0.93 ± 0.2% vs. 4.1 ± 1.7%; p = 0.007) and 18:1 (0.29 ± 0.09% vs. 3.5 ± 1.2%; p = 0.017) were higher in High Sucrose versus Control animals, respectively. Also, the delta-9 DI for the newly synthesized 18:0 and 18:1 pools was higher at 2 and 6 hours postprandial, with a pattern of change which supports the increased stearoyl-CoA desaturase (SCD-1) activity following high carbohydrate feeding followed by a down regulation of this enzyme.

CONCLUSIONS

Our data show that high sucrose meals increase the relative contribution of systemic DNL produced fatty acids to the total postprandial plasma fatty acid pool. These data also show that a different pattern of both fatty acid synthesis and disposal occurs depending on energy and macronutrient profile of the meal. These changes are in spite of no observable changes in the plasma concentrations or ratios of the total fatty acid pool opposed to the observed changes in the newly synthesized fatty acid pool.

The hypertriglyceridemia is associated with isolated impaired glucose tolerance in subjects without insulin resistance

AIM OF THE STUDY

The objective of this study was to determine if hypertriglyceridemia is associated with isolated impaired glucose tolerance in subjects without insulin resistance.

MATERIALS AND METHODS

A total of 365 apparently healthy individuals aged 20-65 years were enrolled in a population-based cross-sectional study. Subjects were allocated into the groups with and without hypertriglyceridemia. Age, gender, body mass index, and waist circumference were matched criteria. Individuals with impaired fasting glucose, impaired fasting glucose+impaired glucose tolerance, diabetes, homeostasis model assessment of insulin resistance index ≥ 2.5, and/or chronic illnesses such as renal disease or malignancy were excluded. Hypertriglyceridemia was defined by triglycerides levels ≥ 150 mg/dL. Impaired glucose tolerance was defined by plasma glucose concentration 2-h post-load glucose ≥ 140 mg/dL <200 mg/dL. Subjects with impaired glucose tolerance were required to have fasting plasma glucose levels <100 mg/dL. Logistic regression analysis was used to compute the odds ratio between hypertriglyceridemia (independent variable) and impaired glucose tolerance (dependent variable).

RESULTS

A total of 132 and 233 subjects were allocated into the groups with and without hypertriglyceridemia, respectively. The frequency of impaired glucose tolerance was 13.6% and 5.6% in the individuals with and without hypertriglyceridemia, p = 0.01. The logistic regression analysis adjusted by gender, blood pressure, and high-density lipoprotein cholesterol showed that hypertriglyceridemia is significantly associated with impaired glucose tolerance (OR 2.34; 95% CI: 1.02-5.32, p = 0.04).

CONCLUSION

Results of this study indicate that hypertriglyceridemia is independently associated with isolated impaired glucose tolerance in subjects without insulin resistance.

Effect of sitagliptin on lipid profile in patients with type 2 diabetes mellitus

BACKGROUND

Animal studies have demonstrated that an inhibition of DPP-4 has an impact on the secretion of cholesterol and apoB by the small intestine. However, there is no consensus about the changes of the lipid profile following administration of sitagliptin.

METHODS

Accordingly, we treated patients who had type 2 diabetes complicated by dyslipidemia with sitagliptin and evaluated its effects on the profile of lipid parameters. A total of 248 outpatients with type 2 diabetes complicated by dyslipidemia were treated with sitagliptin at a daily dose of 50 mg. The levels and percent changes of lipid and glucose metabolism markers were measured at baseline and at 12 weeks after the initiation of treatment.

RESULTS

Both plasma glucose and HbA1c were significantly decreased. Among the lipid parameters, total cholesterol (TC) and non-high-density lipoprotein cholesterol (non-HDL-C) showed a significant decrease (TC 3.6±15.6%, non-HDL-C 2.9±19.7%; P < 0.05). Stratified analysis revealed a significant decrease of TC, low-density lipoprotein cholesterol (LDL-C) and non-HDL-C in the high triglyceride (TG) group (≥ 150 mg/dL) (P < 0.05). Analysis stratified by demographic factors demonstrated significant differences in the changes of TC, LDL-C and non-HDL-C. Multivariate analysis showed a significant decrease of the TC, LDL-C and non-HDL-C levels in the high TG group (≥ 150 mg/dL), as well as a significant decrease of TC and LDL-C in patients using strong statins.

CONCLUSIONS

The results suggested that sitagliptin caused a significant decrease of TC, LDL-C and non-HDL-C, particularly in patients with high baseline TG levels and those using strong statins.

Aberrant promoter methylation profile of Niemann-pick type C1 gene in cardiovascular disease

BACKGROUND

The protein of Niemann-pick type C1 (NPC1) gene promotes the egress of cholesterol from late endosomes and lysosomes to other cellular compartments and contributes to a process known as reverse cholesterol transport. This study aimed to examine whether promoter methylation of NPC1 is associated with risk of cardiovascular disease (CVD).

METHODS

Fifty CVD patients and 50 healthy subjects as the control group were recruited in this study. Promoter methylation of NPC1 gene was defined using a nested-methylation specific polymerase chain reaction method. Statistical analyses were done using the chi-square, t-test or ANOVA tests.

RESULTS

Our study showed that the frequency of semi-methylated promoter (methylated/unmethylated status) was significantly higher in CVD patients than that in controls (OR = 6.521, 95% CI = 2.211-19.215, P = 0.008). However, a completely methylated promoter (methylated/methylated status) was not detected in any subjects in either of the two groups tested. Additionally, the analysis of clinical data according to the methylation status of NPC1 gene demonstrated that serum levels of total cholesterol, total triglycerides, high low-density lipoprotein cholesterol (LDL-C) and low high-density lipoprotein cholesterol (HDL-C) are influenced by NPC1 methylation, so that subjects with a completely unmethylated promoter (Unmethylated/unmethylated status) held lower levels of total triglycerides, total cholesterol, LDL-C and higher levels of HDL-C.

CONCLUSION

Our findings propose that the NPC1 promoter methylation is a probable mechanism that can result in reduced/impaired NPC1 expression/activity and may thus contribute to progression of CVD.

Pharmacological inhibition to examine the role of DGAT1 in dietary lipid absorption in rodents and humans

Alterations in fat metabolism, in particular elevated plasma concentrations of free fatty acids and triglycerides (TG), have been implicated in the pathogenesis of Type 2 diabetes, obesity, and cardiovascular disease. Acyl-CoA:diacylglycerol acyltransferase 1 (DGAT1), a member of the large family of membrane-bound O-acyltransferases, catalyzes the final step in triacylglycerol formation. In the intestine, DGAT1 is one of the acyltransferases responsible for the reesterficiation of dietary TG. Following a single dose of a selective pharmacological inhibitor of DGAT1, PF-04620110, a dose-dependent inhibition of TG and vitamin A absorption postprandially was demonstrated in rodents and human subjects. In C57/BL6J mice, acute DGAT1 inhibition alters the temporal and spatial pattern of dietary lipid absorption. To understand the impact of DGAT1 inhibition on enterocyte lipid metabolism, lipomic profiling was performed in rat intestine and plasma as well as human plasma. DGAT1 inhibition causes an enrichment of polyunsaturated fatty acids within the TG class of lipids. This pharmacological intervention gives us insight as to the role of DGAT1 in human dietary lipid absorption.

Hyperlipidemia in patients with schizophrenia: a national population-based study

OBJECTIVE

The objective was to examine hyperlipidemia among Taiwanese patients with schizophrenia.

METHODS

We obtained a random sample of 766,427 subjects aged ≥18 years in 2005. Subjects with at least one primary diagnosis of schizophrenia and with a primary or secondary diagnosis of hyperlipidemia or medication for hyperlipidemia were identified. We compared the prevalence and incidence of hyperlipidemia in schizophrenic patients with the general population.

RESULTS

The prevalence of hyperlipidemia in patients with schizophrenia was higher than that in the general population (8.15% vs. 8.10%; odds ratio 1.17; 95% confidence interval, 1.04-1.31) in 2005. Compared with the general population, schizophrenic patients had a higher prevalence of hyperlipidemia in individuals aged <50 years, among those with higher insurance amount, and among persons living in northern and central regions and in urban areas. The average annual incidence of hyperlipidemia in schizophrenic patients with second-generation antipsychotic use from 2006 to 2008 was higher than that in the general population (1.57% vs. 1.29%; odds ratio 1.31; 95% confidence interval, 1.11-1.55).

CONCLUSIONS

Patients with schizophrenia had a much higher prevalence of hyperlipidemia in young adulthood than that in the general population. Schizophrenic patients with second-generation antipsychotic exposure had a higher incidence of hyperlipidemia than individuals in the general population.

Current treatments and strategies for type 2 diabetes: can we do better with GLP-1 receptor agonists?

Abstract Diet, lifestyle modification, and pharmacotherapy with metformin are appropriate initial treatments for many patients with type 2 diabetes (T2DM). However, most individuals do not maintain glycemic control with metformin alone. Addition of other oral antidiabetes drugs (OADs), including sulfonylurea, meglitinide, or thiazolidinedione, is often the next step. Newer options, including incretin-based glucagon-like peptide-1 (GLP-1) receptor agonists (RAs) and dipeptidyl peptidase-4 (DPP-4) inhibitors, offer important benefits as monotherapies or in combination with OADs, with low risk for hypoglycemia. Reductions in glycated hemoglobin (A1C) have been reported among patients treated with GLP-1 RAs (exenatide, -0.8 to -1.1%; liraglutide, -0.8 to -1.6%), as has weight loss (exenatide, -1.6 to -3.1 kg; liraglutide, -1.6 to -3.2 kg). GLP-1 RAs also stimulate β-cell responses and have positive effects on cardiovascular risk factors often present in patients with T2DM. The most common adverse events associated with GLP-1 RAs are nausea, which diminishes over time, and hypoglycemia (when used in combination with a sulfonylurea). A large number of trials demonstrated benefits of GLP-1 RAs, suggesting they could provide suitable treatment options for patients with T2DM.

Lipid profile and nutritional intake in children and adolescents with Type 1 diabetes improve after a structured dietician training to a Mediterranean-style diet

AIM

To evaluate if nutritional intakes and lipid profile fulfill international guidelines and recommendations before and after a structured dietician training to a Mediterranean- style diet in an Italian pediatric population with Type 1 diabetes.

METHODS

A 6-month prospective cohort study. Baseline and after-intervention nutritional intakes, lipid profile, glycated hemoglobin (HbA(1c)), and clinical parameters of 96 children and adolescents with Type 1 diabetes were assessed. A comparative computerized system which was approved and validated by the Italian Diabetologist Association was used to define the amounts of nutrients.

RESULTS

At baseline mean daily dietary intakes of carbohydrates, proteins, and lipids were respectively (mean ± SEM) 51.8 ± 0.5, 15.9 ± 0.2, 33.8 ± 0.6%, with a contribution of cholesterol of 248.7 ± 12.5 mg/day. Fiber assumption was 18.0 ± 0.4 g/day. The 64.5% and 29.1% (p<0.0001) of subjects had at least one lipid parameter higher than 75(th) and 95(th) percentiles, respectively, of selected cut points (American Diabetes Association guidelines for total and LDL-cholesterol and American Academy of Pediatrics standards for HDL-cholesterol and triglycerides). Six months after the dietician intervention, dietary lipids and cholesterol decreased (p<0.0001) while fibers (p<0.0001) increased. LDL-cholesterol, non-HDL-cholesterol, and total cholesterol:HDL-cholesterol ratios significantly decreased (p<0.001) with a reduction of rate of subjects with at least one pathological lipid parameter (p<0.01) independently by weight and glucose control.

CONCLUSIONS

Italian pediatric subjects with Type 1 diabetes present a balanced diet with exception of lipids intake and a suboptimal lipid profile. A structured dietician training to a Mediterranean-style diet improves the quality of nutrient intakes being followed by a reduction of LDL-cholesterol, non- HDL-cholesterol, and total cholesterol:HDL-cholesterol ratios.

The TALLYHO mouse as a model of human type 2 diabetes

The TALLYHO/Jng (TH) mouse is an inbred polygenic model for type 2 diabetes (T2D) with moderate obesity. Both male and female TH mice are characterized by increased body and fat pad weights, hyperleptinemia, hyperinsulinemia, and hyperlipidemia. Glucose intolerance and hyperglycemia are exhibited only in males. Reduced 2-deoxy-glucose uptake occurs in adipose tissue and skeletal muscle of male TH mice. While both sexes of TH mice exhibit enlarged pancreatic islets, only males have degranulation and abnormal architecture in islets. Endothelial dysfunction and considerably decreased bone density are also observed in male TH mice. The blood pressure of male TH mice is normal. Genetic outcross experiments with non-diabetic strains revealed multiple susceptibility loci (quantitative trait loci) for obesity, hypertriglyceridemia, hypercholesterolemia, and hyperglycemia. In conclusion, TH mice encompass many aspects of polygenic human diabetes and are a very useful model for T2D.

Effects of DPP-4 inhibition on cardiac metabolism and function in mice

Type 2 diabetes is associated with an increased risk of cardiac complications. Inhibitors of dipeptidylpeptidase 4 (DPP-4) are novel drugs for the treatment of patients with type 2 diabetes. The effect of DPP-4 inhibitors on myocardial metabolism has not been studied in detail. In wild-type C57Bl6-mice, 3weeks of treatment with sitagliptin had no effect on body weight and glucose tolerance nor on phosphorylation of AMP-activated protein kinase (AMPK) and acetyl-CoAcarboxylase (ACC), phosphofructokinase-2 (PFK2) or tuberin-2 (TSC2) in the left ventricular myocardium. However, in 10week old db/db-/- mice, a model of diabetes and obesity, sitagliptin potently reduced plasma glucose rise in peritoneal glucose tolerance tests and reduced weight increase. The myocardium of untreated db/db-/- mice exhibited a marked increase of the phosphorylation of AMPK, ACC, TSC2, expression of p53 and fatty acid translocase (FAT/CD36) membrane expression. These changes were reduced by DPP-4 inhibition. Sitagliptin showed no effect on cardiomyocyte size but prevented myocardial fibrosis in the 10week old db/db-/- mice and reduced expression of TGF-β1, markers of oxidative stress and the accumulation of advanced glycation end products in cardiomyocytes. Working heart analyses did not show an effect of sitagliptin on parameters of systolic cardiac function. In animals with diabetes and obesity, sitagliptin improved glucose tolerance, reduced weight gain, myocardial fibrosis and oxidative stress. Furthermore the study provides evidence that treatment with sitagliptin decreases elevated myocardial fatty acid uptake and oxidation in the diabetic heart. These observations show beneficial myocardial metabolic effect of DPP-4 inhibition in this mouse model of diabetes and obesity.

DPP-4 inhibitor des-F-sitagliptin treatment increased insulin exocytosis from db/db mice β cells

Incretin promotes insulin secretion acutely. Recently, orally-administered DPP-4 inhibitors represent a new class of anti-hyperglycemic agents. Indeed, inhibitors of dipeptidyl peptidase-IV (DPP-4), sitagliptin, has just begun to be widely used as therapeutics for type 2 diabetes. However, the effects of sitagliptin-treatment on insulin exocytosis from single β-cells are yet unknown. We therefore investigated how sitagliptin-treatment in db/db mice affects insulin exocytosis by treating db/db mice with des-F-sitagliptin for 2 weeks. Perfusion studies showed that 2 weeks-sitagliptin treatment potentiated insulin secretion. We then analyzed insulin granule motion and SNARE protein, syntaxin 1, by TIRF imaging system. TIRF imaging of insulin exocytosis showed the increased number of docked insulin granules and increased fusion events from them during first-phase release. In accord with insulin exocytosis data, des-F-sitagliptin-treatment increased the number of syntaxin 1 clusters on the plasma membrane. Thus, our data demonstrated that 2-weeks des-F-sitagliptin-treatment increased the fusion events of insulin granules, probably via increased number of docked insulin granules and that of syntaxin 1 clusters.

Genetic and genomic analysis of hyperlipidemia, obesity and diabetes using (C57BL/6J × TALLYHO/JngJ) F2 mice

BACKGROUND

Type 2 diabetes (T2D) is the most common form of diabetes in humans and is closely associated with dyslipidemia and obesity that magnifies the mortality and morbidity related to T2D. The genetic contribution to human T2D and related metabolic disorders is evident, and mostly follows polygenic inheritance. The TALLYHO/JngJ (TH) mice are a polygenic model for T2D characterized by obesity, hyperinsulinemia, impaired glucose uptake and tolerance, hyperlipidemia, and hyperglycemia.

RESULTS

In order to determine the genetic factors that contribute to these T2D related characteristics in TH mice, we interbred TH mice with C57BL/6J (B6) mice. The parental, F1, and F2 mice were phenotyped at 8, 12, 16, 20, and 24 weeks of age for 4-hour fasting plasma triglyceride, cholesterol, insulin, and glucose levels and body, fat pad and carcass weights. The F2 mice were genotyped genome-wide and used for quantitative trait locus (QTL) mapping. We also applied a genetical genomic approach using a subset of the F2 mice to seek candidate genes underlying the QTLs. Major QTLs were detected on chromosomes (Chrs) 1, 11, 4, and 8 for hypertriglyceridemia, 1 and 3 for hypercholesterolemia, 4 for hyperglycemia, 11 and 1 for body weight, 1 for fat pad weight, and 11 and 14 for carcass weight. Most alleles, except for Chr 3 and 14 QTLs, increased phenotypic values when contributed by the TH strain. Fourteen pairs of interacting loci were detected, none of which overlapped the major QTLs. The QTL interval linked to hypercholesterolemia and hypertriglyceridemia on distal Chr 1 contains Apoa2 gene. Sequencing analysis revealed polymorphisms of Apoa2 in TH mice, suggesting Apoa2 as the candidate gene for the hyperlipidemia QTL. Gene expression analysis added novel information and aided in selection of candidates underlying the QTLs.

CONCLUSIONS

We identified several genetic loci that affect the quantitative variations of plasma lipid and glucose levels and obesity traits in a TH × B6 intercross. Polymorphisms in Apoa2 gene are suggested to be responsible for the Chr 1 QTL linked to hypercholesterolemia and hypertriglyceridemia. Further, genetical genomic analysis led to potential candidate genes for the QTLs.

Effects of combined ezetimibe and simvastatin therapy as compared with simvastatin alone in patients with type 2 diabetes: a prospective randomized double-blind clinical trial

OBJECTIVE

To assess the effects of inhibited gastrointestinal cholesterol absorption in statin-treated dyslipidemic patients.

RESEARCH DESIGN AND METHODS

In a multicenter prospective randomized double-blind placebo-controlled trial, we primarily compared by ANCOVA the effect of 2-month ezetimibe (10 mg/day) or placebo therapy on LDL cholesterol serum levels in 108 type 2 diabetic patients with albuminuria <200 microg/min and total cholesterol concentrations >135 mg/dl despite simvastatin treatment (40 mg/day).

RESULTS

Unlike placebo, ezetimibe decreased LDL cholesterol from 99 +/- 31 to 66 +/- 22 mg/dl, total cholesterol from 162 +/- 36 to 124 +/- 30 mg/dl, and apolipoprotein B from 83 +/- 22 to 64 +/- 18 mg/dl (P < 0.0001 for all changes versus placebo). A total of 72 and 17% of patients on ezetimibe or placebo achieved LDL levels <70 mg/dl, respectively (P < 0.0001). Treatment was well tolerated.

CONCLUSIONS

Adding ezetimibe to simvastatin therapy helps to improve the pro-atherogenic lipoprotein profile in type 2 diabetic patients who fail to reach recommended lipid targets with statin therapy alone.

Fatty acid- and cholesterol transporter protein expression along the human intestinal tract

Background

Protein distribution profiles along the human intestinal tract of transporters involved in the absorption of cholesterol and long-chain fatty acids (LCFA) have been scarcely evaluated.

Methodology/Principal Findings

In post-mortem samples from 11 subjects, intestinal transporter distribution profiles were determined via Western Blot. Differences in transporter protein levels were statistically tested using ANOVA and Tukey's Post Hoc comparisons. Levels in all segments were expressed relative to those in duodenum. Except for ABCG5 and FATP4, levels (mean±SEM) were the highest in the ileum. For ABCA1, ileal levels (1.80±0.26) differed significantly from those in duodenum (P = 0.049) and proximal colon (0.92±0.14; P = 0.029). ABCG8 levels in ileum (1.91±0.30) differed from those in duodenum (P = 0.041) and distal colon (0.84±0.22; P = 0.010) and jejunum (1.64±0.26) tended to be higher than distal colon (0.84±0.22; P = 0.087). Ileal NPC1L1 levels (2.56±0.51) differed from duodenum levels (P = 0.019) and from distal colon (1.09±0.22; P = 0.030). There was also a trend (P = 0.098) for higher jejunal (2.23±0.37) than duodenal NPC1L1 levels. The levels of ABCG5 did not correlate with those of ABCG8. FAT/CD36 levels in ileum (2.03±0.42) differed from those in duodenum (P = 0.017), and proximal and distal colon (0.89±0.13 and 0.97±0.15 respectively; P = 0.011 and P = 0.014). FABPpm levels in ileum (1.04±0.13) differed from proximal (0.64±0.07; P = 0.026) and distal colon (0.66±0.09; P = 0.037).

Conclusions/Significance

The distribution profiles showed a bell-shape pattern along the GI-tract with the highest levels in ileum for ABCA1, ABCG8, NPC1L1, FATCD36 and FABPm, suggesting a prominent role for ileum in transporter-mediated uptake of cholesterol and LCFAs.

Combining a dipeptidyl peptidase-4 inhibitor, alogliptin, with pioglitazone improves glycaemic control, lipid profiles and beta-cell function in db/db mice

BACKGROUND AND PURPOSE

Alogliptin, a highly selective dipeptidyl peptidase-4 (DPP-4) inhibitor, enhances incretin action and pioglitazone enhances hepatic and peripheral insulin actions. Here, we have evaluated the effects of combining these agents in diabetic mice.

EXPERIMENTAL APPROACH

Effects of short-term treatment with alogliptin alone (0.01%-0.1% in diet), and chronic combination treatment with alogliptin (0.03% in diet) and pioglitazone (0.0075% in diet) were evaluated in db/db mice exhibiting early stages of diabetes.

KEY RESULTS

Alogliptin inhibited plasma DPP-4 activity up to 84% and increased plasma active glucagon-like peptide-1 by 4.4- to 4.9-fold. Unexpectedly, alogliptin alone lacked clear efficacy for improving glucose levels. However, alogliptin in combination with pioglitazone clearly enhanced the effects of pioglitazone alone. After 3-4 weeks of treatment, combination treatment increased plasma insulin by 3.8-fold, decreased plasma glucagon by 41%, both of which were greater than each drug alone, and increased plasma adiponectin by 2.4-fold. In addition, combination treatment decreased glycosylated haemoglobin by 2.2%, plasma glucose by 52%, plasma triglycerides by 77% and non-esterified fatty acids by 48%, all of which were greater than each drug alone. Combination treatment also increased expression of insulin and pancreatic and duodenal homeobox 1 (PDX1), maintained normal beta-cell/alpha-cell distribution in islets and restored pancreatic insulin content to levels comparable to non-diabetic mice.

CONCLUSIONS AND IMPLICATIONS

These results indicate that combination treatment with alogliptin and pioglitazone at an early stage of diabetes improved metabolic profiles and indices that measure beta-cell function, and maintained islet structure in db/db mice, compared with either alogliptin or pioglitazone monotherapy.

The effect of antidiabetic drugs on genes regulating lipid metabolism

PURPOSE OF REVIEW

Hyperglycaemia and dyslipidaemia are closely linked, yet, there has been difficulty in demonstrating that lowering blood sugar reduces cardiovascular events. The pathways linking abnormalities in fatty acid metabolism, insulin resistance and diabetes with abnormalities in cholesterol metabolism are being rapidly unravelled with new understandings of the effect of antidiabetic drugs on lipoprotein metabolism. The purpose of this review is to explore the recent literature.

RECENT FINDINGS

Postprandial lipoproteins are now firmly established as a postprandial risk factor. Both insulin resistance and diabetes are associated with abnormalities in chylomicron production, and clearance and regulatory genes have been identified. Metformin, the most commonly used drug in type 2 diabetes, has multiple actions affecting numerous genes. The peroxisome proliferator-activated receptor-gamma regulation of insulin sensitivity and the important effects on lipoproteins are described. The entero-insulin axis and glucagon-like peptide-1 agonists, together with inhibitors of dipeptidyl peptidase 4 may have lipoprotein implications, but the evidence at present is sparse even though glucagon-like peptide-1 is found in high concentrations in the lymph.

SUMMARY

Although antidiabetic drugs affect lipid metabolism, there is little evidence to suggest that these drugs can prevent atherosclerosis in diabetes and some may promote atherosclerosis through their adverse effect on lipoproteins.