Lipoprotein(a) in type 2 diabetic subjects and its relationship to diabetic microvascular complications

Association between Lipoprotein(a) and diabetic nephropathy in patients with type 2 diabetes

Background

Diabetic nephropathy (DN) is one of the most prevalent and severe microvascular complications of type 2 diabetes (T2DM). However, little is currently known about the pathogenesis and its associated risk factors in DN. The present study aims to investigate the potential risk factors of DN in patients with T2DM.

Methods

A total of 6,993 T2DM patients, including 5,089 participants with DN and 1,904 without DN, were included in this cross-sectional study. Comparisons between the two groups (DN vs. non-DN) were carried out using Student's t-test, Mann-Whitney U-test, or Pearson's Chi-squared test. Spearman's correlation analyses were performed to assess the correlations of serum lipids and indicators of renal impairment. Logistic regression models were applied to assess the relationship between blood lipid indices and the presence of DN.

Results

T2DM patients with DN were older, and had a longer duration of diagnosed diabetes compared to those without DN. Of note, the DN patients also more likely develop metabolic disorders. Among all serum lipids, Lipoprotein(a) [Lp(a)] was the most significantly correlated indicators of renal impairment. Moreover, univariate logistic regression showed that elevated Lp(a) level was associated with an increased risk of DN. After adjusted for confounding factors, including age, gender, duration of T2DM, BMI, SBP, DBP and lipid-lowering drugs usage, Lp(a) level was independently positively associated with the risk of DN [odds ratio (OR):1.115, 95% confidence interval (CI): 1.079-1.151, P=6.06×10-11].

Conclusions

Overall, we demonstrated that serum Lp(a) level was significantly positively associated with an increased risk of DN, indicating that Lp(a) may have the potential as a promising target for the diagnosis and treatment of diabetic nephropathy.

Lipoprotein (a) as a predictor of diabetic retinopathy in patients with type 2 diabetes: A systematic review

BACKGROUND

Lipoprotein a (LP(a)), an LDL-like lipoprotein, known as a risk factor for cardiovascular diseases, has a controversial association with diabetic retinopathy in patients with type 2 diabetes-the current systematic review aimed to critically assess the association between LP(a) and diabetic retinopathy.

METHODS

A systematic review of relevant studies was conducted after a thorough search in PubMed, Scopus, and Google Scholar electronic databases. We used English observational, case-control, and prospective cohort studies published up to August 2022, including type 2 diabetic patients as the population, diabetic retinopathy as the outcome, and LP(a) as the intervention.

RESULT

17 relevant studies, including 4688 patients with diabetes, were included in this systematic review. While in 13 studies, Lipoprotein(a) was recognized as a risk factor for diabetic retinopathy, only three studies reported no evidence of a relationship between the two. Also, another study showed a mixed outcome of the relationship between LP(a) and diabetic retinopathy.

CONCLUSION

High serum lipoprotein(a) in patients with type 2 diabetes is considered a risk factor for diabetic retinopathy. However, further large-scaled cohort studies are still required to validate this finding.

Serum Lipoprotein(a) and High-Density Lipoprotein Cholesterol Associate with Diabetic Nephropathy: Evidence from Machine Learning Perspectives

Purpose

Diabetic nephropathy (DN) is a common complication of type 2 diabetes mellitus (T2DM) that significantly impacts the quality of life for affected patients. Dyslipidemia is a known risk factor for developing cardiovascular complications in T2DM patients. However, the association between serum lipoprotein(a) (Lp(a)) and high-density lipoprotein cholesterol (HDL-C) with DN requires further investigation.

Patients and Methods

For this cross-sectional study, we randomly selected T2DM patients with nephropathy (DN, n = 211) and T2DM patients without nephropathy (T2DM, n = 217) from a cohort of 142,611 patients based on predefined inclusion and exclusion criteria. We collected clinical data from the patients to identify potential risk factors for DN using binary logistic regression and machine learning. After obtaining the feature importance score of clinical indicators by building a random forest classifier, we examined the correlations between Lp(a), HDL-C and the top 10 indicators. Finally, we trained decision tree models with top 10 features using training data and evaluated their performance with independent testing data.

Results

Compared to the T2DM group, the DN group had significantly higher serum levels of Lp(a) (p < 0.001) and lower levels of HDL-C (p = 0.028). Lp(a) was identified as a risk factor for DN, while HDL-C was found to be protective. We identified the top 10 indicators that were associated with Lp(a) and/or HDL-C, including urinary albumin (uALB), uALB to creatinine ratio (uACR), cystatin C, creatinine, urinary ɑ1-microglobulin, estimated glomerular filtration rate (eGFR), urinary β2-microglobulin, urea nitrogen, superoxide dismutase and fibrinogen. The decision tree models trained using the top 10 features and with uALB at a cut-off value of 31.1 mg/L showed an average area under the receiver operating characteristic curve (AUC) of 0.874, with an AUC range of 0.870 to 0.890.

Conclusion

Our findings indicate that serum Lp(a) and HDL-C are associated with DN and we have provided a decision tree model with uALB as a predictor for DN.

Circulating level of homocysteine contributes to diabetic retinopathy associated with dysregulated lipid profile and impaired kidney function in patients with type 2 diabetes mellitus

BACKGROUND

To test the hypothesis that elevated plasma levels of homocysteine (Hcy) and lipoprotein (a) (LPA) contribute to diabetic retinopathy (DR) associated with dysregulated lipid profile, dyslipidaemia, and kidney function.

METHODS

A total of 83 patients with type 2 diabetes mellitus (T2DM) were enrolled in this prospective case-control study. Patients were categorized into those with no DR (DM), non-proliferative DR (NPDR), and proliferative DR (PDR). Age and sex-matched individuals with no diabetes were included in the control group. Biochemical tests, including fasting blood glucose (FBG), glycated hemoglobin (HbA1c), Hcy, LPA, lipid profile, and urine microalbumin (UMA), were evaluated.

RESULTS

Hcy was negatively correlated with high-density lipoprotein-cholesterol (HDL-C) (p < 0.05), but positively correlated with [total cholesterol (TC)-HDL-C)/HDL-C] (p < 0.05), low-density lipoprotein cholesterol (LDL-C)/HDL-C (p < 0.05), and UMA (p < 0.05). Traditional risk factors, Hcy, arteriosclerosis-associated plasma indices, and UMA, resulted as the independent risk factors for the occurrence of DM and DR. After controlling for age, sex, duration of DM, and FBG, a multiple ordinal logistic regression model showed that LPA [OR = 2.90, 95% confidence interval (95% CI) 1.16-7.23, p = 0.023)], LDL-C (OR = 4.28, 95% CI 1.24-14.79, p = 0.021), and (TC-HDL-C)/HDL-C (OR = 1.92, 95% CI 1.05-3.53, p = 0.035) were risk factors for DM and DR.

CONCLUSIONS

Hcy and LPA contributed to DM and DR. Hcy was positively correlated with kidney dysfunction and the ratios of lipid profiles, and negatively with HDL-C, LPA, LDL-C, and (TC-HDL-C)/HDL-C resulted as predictors of the occurrence of DM and severity of DR.

Clinical investigation of lipoprotein (a) levels in type 2 diabetics for cariovascular diseases prediction and prognosis

OBJECTIVES

We aimed to evaluate the levels of serum lipoprotein a, LP (a), in Jordanian patients with type 2 diabetes mellitus (DM); and to examine its relation to glycemic control, metabolic syndrome (MS) and duration of DM. The LP (a) is considered one of the independent risk factors for coronary artery disease (CAD) in the general population.

METHODS

Fasting blood samples were drawn from 51 diabetic patients with type 2 DM and 31 non-diabetic age and sex control subjects. Serum LP (a) was measured along with other parameters, including triglycerides (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-c), low-density lipoprotein cholesterol (LDL-c) and glycosylated haemoglobin (HbA_1c). Correlation analyses were performed between LP (a) and the various variables measured.

RESULTS

LP (a) measurement showed a skewed distribution towards the lower levels in both groups. Mean LP (a) levels showed a statistically insignificant difference between the two groups. No correlations of LP (a) were observed with age, sex or body mass index (BMI). No correlations of LP (a) with LDL-c, HDL-c, TG, TC, MS, DM duration or HbA_1c were observed. The LP (a) serum levels were significantly higher in type 2 diabetic patients with retinopathy.

CONCLUSIONS

LP (a) serum levels are not increased in type 2 diabetic patients; so, LP (a) may not be a reliable marker for early therapeutic interventions in DM patients, even in high-risk for thrombosis groups.

Lipoprotein(a) plasma levels are not associated with incident microvascular complications in type 2 diabetes mellitus

AIMS/HYPOTHESIS

Microvascular disease in type 2 diabetes is a significant cause of end-stage renal disease, blindness and peripheral neuropathy. The strict control of known risk factors, e.g. lifestyle, hyperglycaemia, hypertension and dyslipidaemia, reduces the incidence of microvascular complications, but a residual risk remains. Lipoprotein (a) [Lp(a)] is a strong risk factor for macrovascular disease in the general population. We hypothesised that plasma Lp(a) levels and the LPA gene SNPs rs10455872 and rs3798220 are associated with the incident development of microvascular complications in type 2 diabetes.

METHODS

Analyses were performed of data from the DiaGene study, a prospective study for complications of type 2 diabetes, collected in the city of Eindhoven, the Netherlands (n = 1886 individuals with type 2 diabetes, mean follow-up time = 6.97 years). To assess the relationship between plasma Lp(a) levels and the LPA SNPs with each newly developed microvascular complication (retinopathy n = 223, nephropathy n = 246, neuropathy n = 236), Cox proportional hazards models were applied and adjusted for risk factors for microvascular complications (age, sex, mean arterial pressure, non-HDL-cholesterol, HDL-cholesterol, BMI, duration of type 2 diabetes, HbA_1c and smoking).

RESULTS

No significant associations of Lp(a) plasma levels and the LPA SNPs rs10455872 and rs3798220 with prevalent or incident microvascular complications in type 2 diabetes were found. In line with previous observations the LPA SNPs rs10455872 and rs3798220 did influence the plasma Lp(a) levels.

CONCLUSIONS/INTERPRETATION

Our data show no association between Lp(a) plasma levels and the LPA SNPs with known effect on Lp(a) plasma levels with the development of microvascular complications in type 2 diabetes. This indicates that Lp(a) does not play a major role in the development of microvascular complications. However, larger studies are needed to exclude minimal effects of Lp(a) on the development of microvascular complications.

Lipoprotein(a) and Apolipoproteins as Predictors for Diabetic Retinopathy and Its Severity in Adults With Type 2 Diabetes: A Case-Cohort Study

OBJECTIVES

Our aim in this study was to assess the relationship between serum lipoprotein(a) [Lp(a)] and apolipoproteins and the risk of developing diabetic retinopathy (DR).

METHODS

One thousand fifty-seven patients with type 2 diabetes were divided into 2 main groups and followed for 5 years: 637 patients without DR and 420 patients with DR. A group of patients with DR were then divided into 2 subgroups: 162 patients with nonproliferative DR (NPDR) and 163 patients with proliferative DR (PDR). The association between serum Lp(a) and apolipoproteins with NPDR and PDR was assessed using univariate and multivariate regression analyses. Receiver-operating characteristic curve analysis was performed based on the new cutoff values.

RESULTS

There was a positive relationship between Lp(a) and the presence of DR as well as a negative correlation between ApoA and DR (p<0.001 and p=0.03, respectively). We also found a positive association between ApoB and the severity of DR (p=0.008). ApoA1 had an area under the curve of 55.0% for the prediction of DR. The calculated cutoff values of ApoB/ApoA1 ratio (0.58 g/L) and ApoB (77.5 g/L) in detection of DR were lower than their standard cutoff values of 0.8 and 90 g/L, respectively. Also, the sensitivity of new cutoff values for ApoB and ApoB/ApoA1 ratio was higher than the standard value, but the specificity of the standard cutoff values for both was higher than our new cutoff value.

CONCLUSIONS

Serum Lp(a) and ApoA1 levels were independently associated with DR, and serum ApoB correlated with severity of DR. These measurements can be used for assessment and early treatment of this vision-threatening complication of diabetes.

Serum Lipoprotein (a) Levels in Black South African Type 2 Diabetes Mellitus Patients

Lipoprotein (a) (Lp(a)) which is a low-density lipoprotein-like particle containing apo(a) is considered as an emergent cardiovascular risk factor. Type 2 diabetes mellitus (T2DM) is associated with a two- to threefold increase in the risk of cardiovascular disease (CVD). The aim of this study was to investigate the levels of Lp(a) in Black South African T2DM patients and its association with other metabolic factors. 67 T2DM patients and 48 healthy control participants were recruited for the cross-sectional study. The Lp(a) level was determined by ELISA and the result was analyzed using SPSS. The Lp(a) level in diabetics was found to be significantly increased (P = 0.001) when compared to the normal healthy group. In the diabetic group, the Lp(a) levels correlated significantly with the duration of diabetes (P = 0.008) and oxidized LDL (ox-LDL) levels (P = 0.03) and decreased total antioxidant capacity (P = 0.001). The third tertile of Lp(a) was significantly correlated with increased ox-LDL, C-reactive protein, and triglycerides and decreased total antioxidant capacity.

Serum lipoprotein(a) levels and diabetic nephropathy among Japanese patients with type 2 diabetes mellitus

AIMS

We aimed to evaluate the association between serum lipoprotein(a) [Lp(a)] levels and diabetic nephropathy among Japanese patients with type 2 diabetes mellitus.

METHODS

This study included 581 patients with type 2 diabetes mellitus. Serum Lp(a) levels were divided into four groups; the cut-off points were at the 30th, 60th, and 90th percentile values on the basis of the distribution for all subjects. Diabetic nephropathy was defined as present when the urinary albumin-creatinine ratio was ≥33.9mg/mmol creatinine and/or the estimated glomerular filtration rate was <30ml/min/1.72m(2). Adjustment was made for age, sex, body mass index, hemoglobin A1c, duration of diabetes mellitus, current drinking, current smoking, hypertension, dyslipidemia, coronary heart disease, and stroke.

RESULTS

Higher serum Lp(a) levels were significantly associated with a higher prevalence of diabetic nephropathy: the adjusted odds ratios (95% confidence intervals) for diabetic nephropathy in relation to serum Lp(a) levels of ≤6, 7-15, 16-38, and ≥39mg/dl were 1.00 (reference), 2.74 (1.08-7.00), 3.31 (1.28-8.54), and 4.80 (1.57-14.60), respectively (P for trend=0.004).

CONCLUSIONS

The results suggest that serum Lp(a) levels may be positively associated with diabetic nephropathy among Japanese patients with type 2 diabetes mellitus.

Lipoprotein(a) is not related to markers of insulin resistance in pregnancy

BACKGROUND

Dyslipidemia, a major risk factor for cardiovascular disease is a common finding in patients with type 2 diabetes and among women with gestational diabetes. Elevated levels of lipoprotein(a) [Lp(a)] are linked to increased risk of cardiovascular disease. However, its relationship with insulin resistance, type 2 diabetes and gestational diabetes is controversial and unproven. Here we aimed to clarify whether Lp(a) levels are associated with insulin sensitivity in pregnancy.

METHODS

Sixty-four women with gestational diabetes and 165 with normal glucose tolerance were enrolled in the study. Fasting Lp(a) serum levels were measured in all women at 24-28 weeks of gestation.

RESULTS

In pregnancy, there was no significant difference in serum Lp(a) concentrations between the two groups. Its level did not correlate with markers of insulin resistance (HOMA-IR), insulin sensitivity (HOMA-S%), pancreatic beta-cell function (HOMA-B%) and insulin sensitivity in dynamic conditions (OGIS). In addition, fasting glucose and insulin levels and those throughout an oral glucose tolerance test were independent of Lp(a) concentrations in our study group.

CONCLUSIONS

Lp(a) levels in pregnant women do not differ with respect to the presence or absence of gestational diabetes. Although influenced by some components of the lipid profile, such as triglycerides and HDL-C, insulin resistance in pregnancy is not affected by Lp(a).