The role of lipids in the development of diabetic microvascular complications: implications for therapy

Diabetic microvascular complications and associated factors in patients with type 2 diabetes in Southern Ethiopia

Background

Microvascular complications are long-term complications that affect small blood vessels, usually developed in diabetes, and are primary causes of end-stage renal disease, several painful neuropathies, and blindness. Thus, this study aimed to determine diabetic microvascular complications and factors associated with them among patients with type 2 diabetes.

Methods

An institution-based cross-sectional study was conducted among 378 type 2 diabetes patients. The presence of at least one diabetic microvascular complications diagnosed by physicians and found on the record was considered to have microvascular complications. The data was collected by reviewing the medical records of T2DM patients who were on follow-up from January 1, 2012, to December 31, 2021. The collected data was entered into EpiData version 3.1 and analyzed by Stata version 14. Bivariate and multivariable logistic regression were used to identify statistically significant risk factors for diabetic microvascular complications at p-value < 0.05.

Results

Patients with type 2 diabetes mellitus had a prevalence of diabetic microvascular complications of 26.5% (95% CI: 22.0%, 30.9%). Diabetic neuropathy was the highest (13.2%), followed by diabetic nephropathy (12.4%), and diabetic retinopathy (6.4%). Increasing age, poor glycemic control, hypertension comorbidity, anemia, positive proteinuria, a longer duration of type 2 diabetes mellitus, and hypercholesterolemia were significantly associated factors with diabetic microvascular complications.

Conclusion

Diabetic microvascular complications were highly prevalent. Therefore, the study suggests that interventional strategies should be taken for poor glycemic control, hypertension comorbidity, anemia, positive proteinuria, and hypercholesterolemia to control the development of diabetic microvascular complications in patients with type 2 diabetes.

Obesity, body fat distribution and eye diseases

BACKGROUND

The prevalence of obesity, a chronic disease, is increasing, and obesity is now considered a global epidemic. Eye diseases are also increasing worldwide and have serious repercussions on quality of life as well as increasingly high costs for the community. The relationships between obesity and ocular pathologies are not yet well clarified and are not pathologically homogeneous: they seem to be somehow linked to excess body fat, especially to the distribution of adipose tissue and its ectopic deposits.

PURPOSE

Our objective was to examine the associations between obesity and anthropometric indices, including body mass index (BMI), waist circumference (WC), and the waist/hip ratio (WHR), and the risk of most widespread eye diseases, with particular attention given to the most significant metabolic mechanisms.

METHODS

This article provides a narrative overview of the effect of obesity and anthropometric measurements of body fat on prevalent eye diseases. We used the MEDLINE/PubMed, CINAHL, EMBASE, and Cochrane Library databases from 1984 to 2024. In addition, we hand-searched references from the retrieved articles and explored a number of related websites. A total of 153 publications were considered.

RESULTS

There is significant evidence that obesity is associated with several eye diseases. Waist circumference (WC) and the waist/hip ratio (WHR) have been observed to have stronger positive associations with eye diseases than BMI.

CONCLUSIONS

Obesity must be considered a significant risk factor for eye diseases; hence, a multidisciplinary and multidimensional approach to treating obesity, which also affects ocular health, is important. In the prevention and treatment of eye diseases related to obesity, lifestyle factors, especially diet and physical activity, as well as weight changes, both weight loss and weight gain, should not be overlooked.

LEVEL OF EVIDENCE

Level V narrative review.

Adherence to a Healthy Lifestyle in Association With Microvascular Complications Among Adults With Type 2 Diabetes

IMPORTANCE

The association between an overall healthy lifestyle and the subsequent risk of microvascular complications among patients with diabetes remains unclear.

OBJECTIVE

To examine the association between adherence to a healthy lifestyle before and after diabetes diagnosis and the risk of subsequent microvascular complications among adults with diabetes.

DESIGN, SETTING, AND PARTICIPANTS

This prospective cohort study included incident patients with type 2 diabetes who were free of cardiovascular disease and cancer at the time of diabetes diagnosis and completed the diabetes supplementary questionnaires in the Nurses' Health Study (in 2000 and 2005) and the Health Professionals Follow-Up Study (in 2000, 2004, and 2008) in the US. Data were analyzed from April to August 2021.

EXPOSURES

Diet and lifestyle factors before and after diabetes diagnosis were assessed by validated questionnaires. A healthy lifestyle consisted of nonsmoking, having a healthy body weight (a body mass index of ≥18.5 or <25), engaging in moderate-to-vigorous physical activity (≥150 minutes per week), consuming a high-quality diet (top 40th percentile of the Alternative Healthy Eating Index), and moderate alcohol drinking (5-15 g/d for women and 5-30 g/d for men).

MAIN OUTCOMES AND MEASURES

Physician-diagnosed microvascular complications including diabetic neuropathy, retinopathy, nephropathy, and foot disorders were self-reported at questionnaire surveys.

RESULTS

A total of 7077 patients with type 2 diabetes were included in the cohort (4982 women in NHS and 2095 men in HPFS, mean [SD] age 61 [8.8], 94.2% White). During follow-up, 2878 patients developed microvascular complications. After multivariable adjustment, adherence to a healthy lifestyle before and after diabetes diagnosis were both associated with a lower risk of developing microvascular complications. The relative risk (RR) for participants with 4 or more low-risk lifestyle factors before diabetes diagnosis compared with zero was 0.73 (95% CI, 0.60-0.91) for any microvascular complications, 0.71 (95% CI, 0.54-0.93) for diabetic neuropathy, 0.76 (95% CI, 0.57-1.01) for diabetic retinopathy, 0.42 (95% CI, 0.23-0.79) for diabetic nephropathy, and 0.60 (95% CI, 0.35-1.00) for diabetic foot disorders. Similar results were observed for adherence to a healthy lifestyle after diabetes diagnosis, with an RR of 0.68 (95% CI, 0.55-0.83) for any microvascular complications, 0.67 (95% CI, 0.51-0.88) for diabetic neuropathy, 0.65 (95% CI, 0.48-0.86) for diabetic retinopathy, 0.57 (95% CI, 0.34-0.98) for diabetic nephropathy, and 0.62 (95% CI, 0.37-1.05) for diabetic foot disorders. In addition, greater improvement in lifestyle factors from before to after diabetes diagnosis was also significantly associated with a lower risk of neuropathy or total microvascular complications. Each increment in number of low-risk lifestyle factors was associated with a 6% (RR, 0.94; 95% CI, 0.90-0.98) lower risk for any microvascular complications and a 9% (RR, 0.91; 95% CI, 0.86-0.96) lower risk for diabetic neuropathy. Consistent results were observed when analyses were stratified by age at diabetes diagnosis, sex/cohort, or lifestyle factors before diabetes diagnosis.

CONCLUSIONS AND RELEVANCE

In this cohort study, adhering to an overall healthy lifestyle was associated with a significantly lower risk of microvascular complications among individuals with diabetes. These findings suggest substantial reduction in the burden of microvascular complications associated with adopting a healthy lifestyle among patients with type 2 diabetes.

Regulation of glucose transporter-4 intervention with S. saman leaves extract in streptozotocin-induced diabetic rats

Diabetes mellitus is the leading disorder and affects more than millions of people worldwide. Nowadays, the usage of herbal drugs is said to control adiposity and hyperglycemia. The current research investigated the anti-adiposity and antidiabetic activity of S. saman leaf extract and bioactive compounds. Therefore, the results lower the sugar absorption into the blood and reveal the extract's antidiabetic properties. STZ-induced diabetic rats, Samanea saman methanolic extract show improvement in the parameters like fasting blood glucose levels, body weight, other biochemical parameters supported by the histopathological analysis, and an increase in serum levels in the experimental groups. The antioxidant plays a vital role by increasing SOD and catalase activity levels and decreasing lipid peroxidation levels. The methanolic extract protects the tissue from oxidation stress, which is responsible for the glycemic properties. According to the findings, diabetic-treated rats had overnight blood glucose levels lower and near standard biochemical markers. Histopathology of the liver, pancreas, kidneys, and adipose tissues supported the pharmacological observations. Further, we screened and documented S. saman extract used for in vitro and in vivo methods. In terms of effectiveness, the crude extracts exhibit 0.8-fold GLUT4 down-regulation. Consequently, this result contributes to clinical trials and develops antidiabetic therapy as a substitute for synthetic pharmaceuticals.

HDL cholesterol is a protective predictor in the development and progression of retinopathy in type 1 diabetes: A 15-year follow-up study

AIMS

To evaluate the 15-year incidence of development and progression of diabetic retinopathy (DR) in type 1 diabetic patients (T1DM) and determine the associated risk factors.

METHODS

123 T1DM were included in this prospective cohort study and followed for 15 years. Demographic, clinical, laboratory parameters, and retinal photographs were collected and analyzed. Risk factors for DR development and progression were identified using Cox regression analysis.

RESULTS

At baseline, 87 (71%) patients had no DR, and 36 (29%) had nonproliferative DR (NPDR). After 15 years, 54 patients (43.9%; 29.3/1000 person-years) developed NPDR or progressed to proliferative DR (PDR); 24 (27.6%) developed new NPDR, and 30 (83.3%) progressed to PDR. HbA₁c (HR = 1.48, p = 0.008) and urinary albumin excretion rate (AER) (HR = 1.58, p = 0.045) were associated with the risk of DR development and progression, and a protective association was found for HDL cholesterol (HR = 0.17, p = 0.021). The presence of DR at baseline (HR = 2.95, p = 0.023) was associated with the risk of its progression to PDR.

CONCLUSIONS

The 15-year incidence of DR development and progression in T1DM is still very high, which points to the need for close monitoring of T1DM, especially those with higher HbA₁c, higher AER, the initial presence of DR, and lower HDL cholesterol.

Investigating the molecular structure of plasma in type 2 diabetes mellitus and diabetic nephropathy by synchrotron Fourier-transform infrared microspectroscopy

Diabetes mellitus (DM) is associated with a high incidence of morbidity and mortality which, in many cases, is derived from the progressive kidney dysfunction due to diabetic nephropathy (DN). In this study, synchrotron-Fourier-transform infrared (SR-FTIR) microspectroscopy was used to identify molecular changes in the lipid and protein regions in the plasma of patients with different stages of DN (mild, moderate, severe and end-stage), and patients with type 2 diabetes mellitus (T2DM) without DN. Our results revealed different conformational changes in the proteins secondary structure between DN stages, and between DN and T2DM groups illustrated by peak shifts and intensity alterations. End-stage DN showed the highest CH₂/CH₃ ratio and intensity of the carbonyl group in protein-carbonyl region compared to other DN stages indicating high level of unsaturation and lipid peroxidation and oxidation conditions. Moreover, end-stage DN group was characterized by a decrease in amide I and amide II absorption signals which reflected a sign of hypoalbuminemia. When compared to T2DM, DN group demonstrated a higher oxidation state as confirmed via the high intensity of the carbonyl group and the high level of malondialdehyde. The current study highlights the promising role of SR-FTIR microspectroscopy as a new sensitive analytical approach that can be used to provide better understanding of the pathophysiology of DN, and guide the development of new preventive therapies and treatments.

Obesity and risk of age-related eye diseases: a systematic review of prospective population-based studies

BACKGROUND

Obesity is a public health challenge worldwide. The relationship between obesity and age-related eye diseases including cataract, glaucoma, age-related macular degeneration (AMD) and diabetic retinopathy (DR) have remained elusive.

DESIGN AND METHODS

We conducted a systematic review of three electronic databases for longitudinal population-based studies that described associations between measures of obesity including body mass index (BMI), waist-circumference (WC), and waist-to-hip ratio (WHR), and age-related eye diseases.

RESULTS

Our search yielded 1731 articles, of which 14, 10, 16 and 8 articles met our eligibility criteria for cataract, glaucoma, AMD and DR, respectively. BMI-defined obesity was positively associated with incident cataract, incident AMD and incident DR in Western populations, but in Asian populations associations for incident AMD were not significant and associations for incident DR were inverse. WC-defined obesity was associated with incident glaucoma in non-Western populations. WHR-defined obesity but not BMI-defined obesity was associated with the incidence or progression of AMD in two Western studies.

CONCLUSIONS

Overall, we found strong evidence supporting associations between obesity and age-related eye diseases. Further research on the association of abdominal obesity and effect of weight loss and physical activity on age-related eye diseases is warranted to support clinical and public health recommendations.

Reverse Cholesterol Transport Pathway and Cholesterol Efflux in Diabetic Retinopathy

Cholesterol esters, synthesized from cholesterol with long-chain fatty acids, are essential components of plasma lipoproteins and cell membranes that participate in various metabolic processes in the body. Cholesterol can be excreted through the cholesterol reverse transport (RCT) pathway when excessive cholesterol is produced in the extrahepatic cells, which is regulated by the liver X receptor (LXR) and its downstream regulators ATP-binding cassette subfamily A member 1 (ABCA1) and ATP-binding cassette subfamily G member 1 (ABCG1) genes. Abnormal cholesterol metabolism is closely associated with the development of diabetic retinopathy (DR). However, the precise underlying mechanism of the RCT pathway in the pathogenesis of DR is still not fully understood. This review focused on cholesterol metabolism, with a particular emphasis on the RCT pathway and its correlation with the development of DR. Particular attention has been paid to the key regulators of the RCT pathway: LXR, ABCA1, and ABCG1 genes and their potential therapeutic targets in the management of DR.

Relationship between triglyceride glucose index, retinopathy and nephropathy in Type 2 diabetes

Aims

To explore the relationship between TyG index, diabetic retinopathy (DR) and nephropathy.

Methods

This was a cross-sectional observational study that examined 1413 subjects with type 2 diabetes (both known and newly diagnosed). Subjects underwent a detailed standard evaluation to detect diabetic retinopathy (fundus photography) and nephropathy (defined as urinary albumin excretion ≥ 30 mg/24 h). The TyG index was calculated as ln (fasting triglycerides (mg/dL) × fasting glucose (mg/dL)/2) and stratified into 4 quartiles (TyG-Q). The baseline characteristics of the study population in the four TyG-Q (Q1 (≤7.3) n = 349, Q2 (>7.3 to ≤ 7.5) n = 358, Q3 (>7.5 to ≤ 8.0) n = 354, and Q4 (>8.0) n = 352) were analysed. Variables associated with the presence of DR and nephropathy were assessed using a stepwise binary logistic regression analysis.

Results

The presence of DR was associated with higher TyG index (OR = 1.453, P =.001) and longer duration of diabetes (OR = 1.085, P < .001). The presence of nephropathy was associated with a higher TyG index (OR = 1.703, P < .001), greater age (OR = 1.031, P < .001), use of insulin (OR = 1.842, P = .033), higher systolic BP (OR = 1.015, P < .001), and the presence of DR (OR = 3.052, P < .001). Higher TyG-Q correlated with the severity of DR (P = .024), presence of nephropathy (P = .001), age (P < .001) and diastolic blood pressure (P = .006).

Conclusions

A higher TyG index is associated with the presence of retinopathy and nephropathy in individuals with diabetes and could be used for monitoring metabolic status in clinical settings.

High-Density Lipoprotein Cholesterol in Age-Related Ocular Diseases

There is limited understanding of the specific role of high-density lipoprotein cholesterol (HDL-C) in the development of various age-related ocular diseases, despite it being a common measurable biomarker in lipid profiles. This literature review summarizes current knowledge of the role of HDL-C, if any, in pathogenesis and progression of four age-related ocular diseases, namely age-related macular degeneration (AMD), age-related cataract, glaucoma, and diabetic retinopathy (DR), and will primarily discuss epidemiological and genetic evidence.

Microvascular and macrovascular complications in type 2 diabetes Ghanaian residents in Ghana and Europe: The RODAM study

AIMS

To compare microvascular and macrovascular complication rates among Ghanaians with type 2 diabetes (T2D) living in Ghana and in three European cities (Amsterdam, London and Berlin).

METHODS

Data from the multicenter Research on Obesity and Diabetes among African Migrants (RODAM) study were analyzed. 650 Ghanaian participants with T2D (206 non-migrant and 444 migrants) were included. Logistic regression analyses were used to determine the association between migrant status and microvascular (nephropathy and retinopathy) and macrovascular (coronary artery disease (CAD), peripheral artery disease (PAD) and stroke) complications with adjustment for age, gender, socioeconomic status, alcohol, smoking, physical activity, hypertension, BMI, total-cholesterol, and HbA1c.

RESULTS

Microvascular and macrovascular complications rates were higher in non-migrant Ghanaians than in migrant Ghanaians (nephropathy 32.0% vs. 19.8%; PAD 11.2% vs. 3.4%; CAD 18.4% vs. 8.3%; and stroke 14.5% vs. 5.6%), except for self-reported retinopathy (11.0% vs. 21.6%). Except nephropathy and stroke, the differences persisted after adjustment for the above-mentioned covariates: PAD (OR 7.48; 95% CI, 2.16-25.90); CAD (2.32; 1.09-4.93); and retinopathy (0.23; 0.07-0.75).

CONCLUSIONS

Except retinopathy, the rates of microvascular and macrovascular complications were higher in non-migrant than in migrant Ghanaians with T2D. Conventional cardiovascular risk factors did not explain the differences except for nephropathy and stroke.

Prevalence of and factors related to microvascular complications in patients with type 2 diabetes mellitus in Tianjin, China: a cross-sectional study

Background

Since chronic hyperglycemia-related damage to small blood vessels results in complications, patients with longer durations of type 2 diabetes mellitus (T2DM) are more likely to develop microvascular complications, such as retinopathy, neuropathy and nephropathy, which are very harmful to the health of humans. Therefore, this study aimed to assess the prevalence of diabetes-related microvascular complications and to explore their risk factors in patients with T2DM in Tianjin, China.

Methods

This observational, cross-sectional study was conducted at 8 hospitals in urban and suburban regions of Tianjin, China. The information collected from the subjects mainly included demographic characteristics, anthropometric measurements and clinical information. Univariate and multivariate logistic regression was used to identify the possible risk factors for microvascular complications (retinopathy, neuropathy and nephropathy).

Results

A total of 4,490 patients with T2DM from 8 hospitals in Tianjin, China were selected from November 2015 to January 2016. Of the study subjects, 2,270 (50.6%) were males. The median age was 64.0±13.0 years. The percentage of patients with T2DM who had at least one microvascular complication was 34.5%. The prevalence rates of neuropathy, retinopathy, and nephropathy were 23.5%, 17.4%, and 10.8%, respectively. The results of the multivariate logistic regression showed that the duration of diabetes, insulin use, and the presence of hypertension and dyslipidemia were the main risk factors for developing microvascular complications of T2DM.

Conclusions

The incidence of diabetes complications in Tianjin is high. Increasing the control of risk factors can reduce the occurrence of complications to reduce the disease burden and improve the quality of life of patients.

Correlations between SIRT1 gene polymorphisms and diabetic kidney disease

To investigate the correlations between SIRT1 gene polymorphisms and diabetic kidney disease (DKD). There were 150 patients with DKD in the observation group (urinary albumin excretion rate (UAER) ≥ 300 mg 24 h-1), and 160 patients with a more than 10 year history of type 2 diabetes but without retinopathy and DKD (UAER < 30 mg 24 h-1) in the control group. Genotypes of three tagged single-nucleotide polymorphism loci (rs3818292, rs4746720 and rs10823108) in the SIRT1 gene in the two groups were detected. Risks of DKD for patients with the GG and GG + AG genotype in the rs10823108 locus of the SIRT1 gene were 2.96 and 2.92 times higher than that for AA genotype carriers, respectively. The risk of DKD for patients with the GG genotype in the rs3818292 locus was 0.23 times and 0.21 times higher than that for AA and for AA + AG genotype carriers, respectively, and the risk of DKD for patients with allele G was 0.66 times higher than that for allele A carriers. There was no significant difference in genotype frequency of rs4746720 locus gene polymorphisms between the observation and control groups. The SIRT1 gene is a genetic susceptibility gene of DKD. Mutation genotype GG and GG + AG in the rs10823108 locus can increase the risk of DKD. Mutation genotype GG and allele G in the rs3818292 locus can decrease the risk of DKD.

Variability of triglyceride levels and incidence of microalbuminuria in type 2 diabetes

BACKGROUND

Experimental and clinical studies have shown a strong association between hypertriglyceridemia and diabetic nephropathy. A variability of triglyceride (TG) levels has been reported in diabetes.

OBJECTIVES

To investigate the relationship of TG variability with the incidence of microalbuminuria (albumin excretion rate > 20 μg/min), in patients with type 2 diabetes.

METHODS

A longitudinal, retrospective, observational study was performed on a consecutive series of 457 normoalbuminuric outpatients, with measurements of HbA1c, lipids and microalbuminuria thrice per year with 6.8-year follow-up. TG variability, defined as standard deviation of TG (TG-SD) and TG-SD adjusted for the number of visits was calculated. A nested case-control sensitivity analysis was performed to validate the results of the primary cohort study.

RESULTS

Incident microalbuminuria (N = 124, 27.1%) was associated with higher median TG-SD (33.6 mg/dL vs 29.0 mg/dL, P < .05) and TG-SD adjusted for the number of visits (31.4 mg/dL vs 26.7 mg/dL, P < .05). At multivariate (Cox) analysis, logTG-SD and adj-logTG-SD were significant predictors of incident microalbuminuria (hazard ratio 2.1 [1.1-4.2], P = .028 and 1.5 [1.1-3.3], P = .042, respectively). In the case-control analysis, time spent with TG > 150 mg/dL during the follow-up was significantly higher in cases vs controls (27.2 ± 19 vs 16.7 ± 12.5 months, P < .05) with hazard ratio 2.0 (1.1-5.1), P < .05, for adj-logTG-SD.

CONCLUSIONS

A higher intraindividual TG variability is a predictor of incident microalbuminuria in type 2 diabetes. In addition, time of exposure to elevated TG levels (>150 mg/dL) predicts incident microalbuminuria.

Association between plasma triglycerides and high-density lipoprotein cholesterol and microvascular kidney disease and retinopathy in type 2 diabetes mellitus: a global case-control study in 13 countries

BACKGROUND

Microvascular renal and retinal diseases are common major complications of type 2 diabetes mellitus. The relation between plasma lipids and microvascular disease is not well established.

METHODS AND RESULTS

The case subjects were 2535 patients with type 2 diabetes mellitus with an average duration of 14 years, 1891 of whom had kidney disease and 1218 with retinopathy. The case subjects were matched for diabetes mellitus duration, age, sex, and low-density lipoprotein cholesterol to 3683 control subjects with type 2 diabetes mellitus who did not have kidney disease or retinopathy. The study was conducted in 24 sites in 13 countries. The primary analysis included kidney disease and retinopathy cases. Matched analysis was performed by use of site-specific conditional logistic regression in multivariable models that adjusted for hemoglobin A1c, hypertension, and statin treatment. Mean low-density lipoprotein cholesterol concentration was 2.3 mmol/L. The microvascular disease odds ratio increased by a factor of 1.16 (95% confidence interval, 1.11-1.22) for every 0.5 mmol/L (≈1 quintile) increase in triglycerides or decreased by a factor of 0.92 (0.88-0.96) for every 0.2 mmol/L (≈1 quintile) increase in high-density lipoprotein cholesterol. For kidney disease, the odds ratio increased by 1.23 (1.16-1.31) with triglycerides and decreased by 0.86 (0.82-0.91) with high-density lipoprotein cholesterol. Retinopathy was associated with triglycerides and high-density lipoprotein cholesterol in matched analysis but not significantly after additional adjustment.

CONCLUSIONS

Diabetic kidney disease is associated worldwide with higher levels of plasma triglycerides and lower levels of high-density lipoprotein cholesterol among patients with good control of low-density lipoprotein cholesterol. Retinopathy was less robustly associated with these lipids. These results strengthen the rationale for studying dyslipidemia treatment to prevent diabetic microvascular disease.

The impact of serum lipids on risk for microangiopathy in patients with type 2 diabetes mellitus

Background

Few large-scale, real-world studies have assessed the relative associations of lipid fractions with diabetic microvascular events. The main objective of this study was to evaluate the association of the lipid profile components, high density lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C), triglycerides (TG), and non-high density lipoprotein cholesterol (non-HDL-C) with microvascular complications (MVCs) in type 2 diabetes mellitus (T2DM) patients.

Methods

This observational cohort study queried the HealthCore Integrated Research Database (HIRD^SM) for newly-diagnosed (Index Date) 18-64-year-old patients with diabetes mellitus between 01/01/2005-06/30/2010. Inclusion required ≥12 months pre-index continuous health plan eligibility and ≥1 pre-index lipid profile result. Patients with polycystic ovary syndrome and prior MVCs were excluded. Incident complications were defined as the earliest occurrence of diabetic retinopathy, peripheral neuropathy, and/or nephropathy post-index. Cox proportional models and Kaplan-Meier (KM) curves were used to evaluate associations among variables.

Results

Of the patients (N = 72,267), 50.05 % achieved HDL-C, 64.28 % LDL-C, 59.82 % TG, and 56.79 % non-HDL-C American Diabetes Association goals at baseline. During follow-up (mean, 21.74 months), there were 5.21 microvascular events per 1,000 patient-months. A 1-mg/dL increase in HDL-C was associated with 1 % decrease in any MVC risk (P < .0001), but for LDL-C, TG, and non-HDL-C, 1-mg/dL increase resulted in increases of 0.2 % (P < .0001), 0.1 % (P < 0.001) and 0.3 % (P < 0.001) in MVC risk. Patients achieving HDL-C goals had a 11 % lower risk of MVC versus non-achievers (RR 0.895, [95 % CI, 0.852-0.941], P < .0001). Similarly, TG goal attainment was associated with a lowered risk for any MVC (RR 0.849, [95 % CI, 0.808-0.892], P < .0001). Evaluation of KM survival curves demonstrated no significant difference in the risk of MVCs between patients achieving vs. not achieving LDL-C goals, but did demonstrate a difference in MVC risk between patients achieving vs. not achieving non-HDL-C goals.

Conclusion

This study demonstrates significant independent associations among lipid fractions and risk for microangiopathy. These findings suggest that attaining established ADA goals for HDL-C, TG, and non-HDL-C may reduce risk for microvascular events among patients with diabetes.

The protective effect of berberine on β-cell lipoapoptosis

AIMS

To evaluate the protective effect of berberine on β-cell lipoapoptosis induced by palmitate and to explore the possible underlying mechanisms.

MATERIALS AND METHODS

HIT-T15 pancreatic β-cells were divided into the following treatment groups: untreated controls; 100 μM berberine; 0.5 mM palmitate; 0.5 mM palmitate + 0.1 μM berberine; 0.5 mM palmitate + 1 μM berberine; 0.5 mM palmitate + 10 μM berberine; and 0.5 mM palmitate + 100 μM berberine. After 48 h, cell apoptosis was assessed by flow cytometry and the Hoechst 33258 fluorescent assay. Basal and glucose-stimulated insulin levels in culture medium were measured by radioimmunoassay. Peroxisome proliferator- activated receptor-γ (PPAR-γ) mRNA and protein levels were determined by real-time PCR and immunocytochemistry, respectively.

RESULTS

Apoptosis was significantly increased upon treatment with palmitate as compared to the untreated controls (p<0.0001). In addition, glucose-stimulated insulin secretion (GSIS), PPAR-γ mRNA and protein expression were significantly reduced in response to palmitate (p<0.0001); however, palmitate-induced apoptosis and reduction in PPAR-γ expression were reversed in response to berberine in a dose-dependent manner (p<0.05). Furthermore, there was a non-significant increase in GSIS with increasing berberine dose.

CONCLUSION

Palmitate exerted lipotoxic effects on HIT-T15 cells, inducing apoptosis and reducing GSIS. Berberine reduced palmitate-induced lipoapoptosis and tended to increase GSIS in HIT-T15 cells, possibly through increased PPAR-γ expression.

Microangiopathy and visual deficits characterize the retinopathy of a spontaneously hypertensive rat model with type 2 diabetes and metabolic syndrome

Retinopathy has been increasing in prevalence as a consequence of type 2 diabetes and a cluster of coexisting risk factors characterized as the metabolic syndrome. However, the combined effects of these conditions on the retina are poorly understood. Therefore, we focused on the spontaneously hypertensive corpulent rat (SHR/N-cp), a model with type 2 diabetes, obesity and features of the metabolic syndrome to characterize retinal changes at a structural and functional level. SHR/N-cp males at 4 and 8 months of age were used in this study. Metabolic parameters and blood pressure were measured by standard methods. Morphology was investigated by histological techniques supplemented by nicotinamide adenine dinucleotide phosphate-diaphorase staining of whole mounts and fluorescein angiography to analyze the retinal vasculature. The in vivo function of the retina was examined by electroretinography (ERG). Obese SHR/N-cp rats were hypertensive and showed significant increases in body weight, serum levels of glucose, triglycerides, total cholesterol and urinary glucose excretion compared with lean controls (P < 0.01 for each). Histology indicated an overall intact integrity of the retina and aspects of microangiopathy in obese SHR/N-cp rats. ERG revealed intact processing of light signals but significantly decreased amplitudes of b-waves for all (P < 0.01) and of a-waves for some examined light intensities (P < 0.05). Oscillatory potentials were significantly protracted (P < 0.01), whereas amplitudes were not reduced. Microangiopathy and electroretinographic deficits combine to produce an early non-proliferative retinopathy phenotype in the obese SHR/N-cp rats. Thus, this model represents a valuable experimental tool to obtain further insights into the mechanisms of retinopathy in the context of obesity, type 2 diabetes and metabolic syndrome.

Reducing lipids for CV protection in CKD patients-current evidence

Lipid parameters are altered in the earliest stages of primary kidney disease, some even when measured glomerular filtration rate (GFR) is still normal. The main problem is that routinely measured lipid parameters are deceivingly normal except low high-density lipoprotein (HDL) and moderately elevated triglycerides (TGs) (>150 mg per 100 ml). Behind this unimpressive spectrum, serious anomalies are hidden: increased very low-density lipoprotein (VLDL) and chylomicron remnants, accumulation of delipidated small dense low-density lipoprotein (LDL), post translational modification of lipoproteins, abnormal concentrations of Lp(a) and nonprotective HDL. A routine parameter with some predictive value is the concentration of non-HDL cholesterol. Several of these abnormal lipoprotein particles stimulate cellular free oxygen radical formation which in turn induce inflammation and impact on endothelial function.A bone of contention is the indication for treatment with statins in endstage renal disease. Poor survival is paradoxically predicted by low cholesterol. This appears to be the result of confounding by microinflammation. One controlled interventional study in hemodialysed type 2 diabetics, the 4-D study, failed to show a significant benefit on the primary cardiovascular endpoint. We discuss potential explanations for this 'negative' outcome and the implications for statin treatment.

Microvascular complications of diabetes mellitus: renal protection accompanies cardiovascular protection

The microvascular complications of diabetes mellitus confer substantial morbidity and impair patient quality of life. Dyslipidemia and prolonged hyperglycemia promote an increase in oxidative stress, inflammation, and vascular damage, which together promote endothelial dysfunction and are associated with macrovascular and microvascular complications. Microalbuminuria is an early marker of diabetic nephropathy and an independent risk factor for cardiovascular disease. Diabetic nephropathy is the most common cause of end-stage renal disease in developed countries, and its prevalence is increasing. Preventing or limiting the progression of diabetic nephropathy, as demonstrated in the Fenofibrate Intervention and Event Lowering in Diabetes (FIELD) trial, may prevent or delay renal complications, as well as convey important cardioprotective benefits in patients with type 2 diabetes.

A review of the current status of the management of mixed dyslipidemia associated with diabetes mellitus and metabolic syndrome

Current treatment guidelines recommend lowering elevated low-density lipoprotein (LDL) cholesterol levels with a statin as the primary lipid-modifying intervention to reduce cardiovascular risk in patients with type 2 diabetes mellitus or metabolic syndrome. However, even with high-dose statin therapy or the combination of statin plus ezetimibe, many patients remain at substantial risk of a cardiovascular event. Increasingly, there is recognition of the importance of treating all components of the atherogenic dyslipidemic profile associated with both conditions, specifically low high-density lipoprotein cholesterol and elevated triglyceride levels, in addition to lowering LDL cholesterol. Both niacin (nicotinic acid) and fibrates are recommended as options for combination with a statin in this setting. Data from ongoing prospective outcomes studies are needed to evaluate the efficacy and safety of these combinations.

Lipid-lowering therapy in patients with type 2 diabetes: the case for early intervention

Chronic complications of type 2 diabetes, in particular, macrovascular complications, confer substantial morbidity and mortality and adversely affect a patient's quality of life. Early intensive intervention to control cardiovascular risk factors is essential in clinical management. Atherogenic dyslipidaemia characterized by elevated triglycerides, a low level of high-density lipoprotein cholesterol (HDL-C), and an increase in the preponderance of small, dense low-density lipoprotein (LDL) particles, is a key modifiable risk factor for macrovascular diabetic complications. Lowering low-density lipoprotein cholesterol (LDL-C) with a statin (or the combination of statin and ezetimibe) is the main focus for reducing cardiovascular risk in patients with diabetes. However, statins fail to address the residual cardiovascular risk associated with low HDL-C. Fibrates are effective against all components of the atherogenic dyslipidaemia associated with type 2 diabetes. Secondary analyses of the Fenofibrate Intervention and Event Lowering in Diabetes (FIELD) study suggest a role for early treatment with fenofibrate in improving cardiovascular risk reduction in type 2 diabetes and provide safety data supporting the use of fenofibrate in combination with a statin. Data from the FIELD study suggest that fenofibrate may also have potential to impact on microvascular diabetic complications associated with type 2 diabetes. Data are awaited from the ongoing Action to Control Cardiovascular Risk in Diabetes (ACCORD) study to evaluate the outcome benefits of combining fenofibrate with a statin in patients with type 2 diabetes. Finally, in view of divergent study results and outstanding data, assessment of the risk of the individual with type 2 diabetes is mandatory to assist clinical decision-making when initiating lipid therapy.

Oxidised, glycated LDL selectively influences tissue inhibitor of metalloproteinase-3 gene expression and protein production in human retinal capillary pericytes

AIMS/HYPOTHESIS

Matrix metalloproteinases (MMPs) and their natural inhibitors, tissue inhibitor of metalloproteinases (TIMPs), regulate important biological processes including the homeostasis of the extracellular matrix, proteolysis of cell surface proteins, proteinase zymogen activation, angiogenesis and inflammation. Studies have shown that their balance is altered in retinal microvascular tissues in diabetes. Since LDLs modified by oxidation/glycation are implicated in the pathogenesis of diabetic vascular complications, we examined the effects of modified LDL on the gene expression and protein production of MMPs and TIMPs in retinal pericytes.

METHODS

Quiescent human retinal pericytes were exposed to native LDL (N-LDL), glycated LDL (G-LDL) and heavily oxidised and glycated LDL (HOG-LDL) for 24 h. We studied the expression of the genes encoding MMPs and TIMPs mRNAs by analysis of microarray data and quantitative PCR, and protein levels by immunoblotting and ELISA.

RESULTS

Microarray analysis showed that MMP1, MMP2, MMP11, MMP14 and MMP25 and TIMP1, TIMP2, TIMP3 and TIMP4 were expressed in pericytes. Of these, only TIMP3 mRNA showed altered regulation, being expressed at significantly lower levels in response to HOG- vs N-LDL. Quantitative PCR and immunoblotting of cell/matrix proteins confirmed the reduction in TIMP3 mRNA and protein in response to HOG-LDL. In contrast to cellular TIMP3 protein, analysis of secreted TIMP1, TIMP2, MMP1 and collagenase activity indicated no changes in their production in response to modified LDL. Combined treatment with N- and HOG-LDL restored TIMP3 mRNA expression to a level comparable with that after N-LDL alone.

CONCLUSIONS/INTERPRETATION

Among the genes encoding for MMPs and TIMPs expressed in retinal pericytes, TIMP3 is uniquely regulated by HOG-LDL. Reduced TIMP3 expression might contribute to microvascular abnormalities in diabetic retinopathy.

Hyperglycemia and loss of ovarian hormones mediate atheroma formation through endothelial layer disruption and increased permeability

The overall goal of this project was to examine the interactions of hyperglycemia and loss of ovarian hormones on the artery wall in a type I diabetic mouse model. Intact or ovariectomized (OVX) female BALB/C mice were fed a high-cholesterol diet. Half the animals were treated with steptozotocin to induce insulin-deficient diabetes mellitus, generating four treatment groups: control, intact; control, ovariectomized; diabetic, intact; diabetic, ovariectomized (DOVX). We examined arterial structure and function and found that 1) diabetes and ovariectomy additively increased endothelial layer permeability, 2) arterial stiffening was increased in DOVX, 3) DOVX synergistically increased atheroma formation, and 4) ultrastructural evaluation revealed that the basal lamina was often multilayered and formed convoluted aggregates separating endothelium from the internal elastic lamina in diabetic, but not control arteries or arteries from OVX mice. Endothelium overlying these regions formed thin cytoplasmic extensions between these aggregates and was often separated from the basal lamina by electron lucent spaces. Our studies showed that diabetes and loss of ovarian function have additive and synergistic effects to worsen arterial pathophysiology by disrupting the arterial endothelial layer with increased permeability and increased atheroma formation.

The prevention of diabetic microvascular complications of diabetes: is there a role for lipid lowering?

The role of hyperglycemia in the development of microvascular complications of diabetes, such as nephropathy, retinopathy and neuropathy, has been well documented. Evidence is accumulating to support the concept that dyslipidemia can also contribute to the development of these complications. Lipid-lowering agents, such as statins, have been shown to prevent cardiovascular events in patients with diabetes. However, in addition to preventing macrovascular diseases, statins may also be able to retard the progression of microvascular complications of diabetes. Indeed, in addition to reducing lipid levels, these agents can improve endothelial function and reduce oxidative stress, which can improve microvascular function. These findings would provide further support for the use of lipid-lowering agents in patients with diabetes.

Role of lipid control in diabetic nephropathy

Patients with diabetic nephropathy are known to be associated with many lipoprotein abnormalities, including higher plasma levels of very low-density lipoprotein, low-density lipoprotein and triglycerides, and lower levels of high-density lipoprotein. Many studies have reported that lipids may induce both glomerular and tubulointerstitial injury through mediators such as cytokines, reactive oxygen species, chemokines, and through hemodynamic changes. Clinical studies in patients with diabetic nephropathy showed that lipid control can be associated with an additional effect of reduction in proteinuria. Experimental studies demonstrated that lipid-lowering agents exerted a certain degree of renoprotection, through both indirect effects from lipid lowering and a direct effect on cell protection. Therefore, lipid control appears to be important in the prevention and treatment of diabetic nephropathy. Diabetic nephropathy has become the leading cause of end-stage renal failure in many countries, including Taiwan. One of the major risk factors for the development and progression of diabetic nephropathy is dyslipidemia. In this paper we will review the role of lipid in mediating renal injury and the beneficial effects of lipid control in diabetic nephropathy.