Serum lipoprotein(a) levels are greater in female than male patients with type-2 diabetes

Is inverse association between lipoprotein(a) and diabetes mellitus another paradox in cardiometabolic medicine?

INTRODUCTION

The impact of Type II Diabetes mellitus (T2DM) on cardiovascular disease (CVD) is well-established, while lipoprotein(a) [Lp(a)] has recently emerged as a recognized CVD risk factor. The rising prevalence of T2DM resulting from modern lifestyles and the development of specific Lp(a)-lowering agents brought the association between T2DM and Lp(a) in the forefront.

AREAS COVERED

Despite advancements in T2DM treatment, diabetic patients remain at very-high risk of CVD. Lp(a) may, to some extent, contribute to the persistent CVD risk seen in diabetic patients, and the coexistence of T2DM and elevated Lp(a) levels appears to synergistically amplify overall CVD risk. The relationship between T2DM and Lp(a) is paradoxical. On one hand, high Lp(a) plasma concentrations elevate the risk of diabetic microvascular and macrovascular complications. On the other hand, low Lp(a) plasma concentrations have been linked to an increased risk of developing T2DM.

EXPERT OPINION

Comprehending the association between T2DM and Lp(a) is critical due to the pivotal roles both entities play in overall CVD risk, as well as the unique aspects of their relationship. The mechanisms underlying the inverse association between T2DM and Lp(a) remain incompletely understood, necessitating further meticulous research.

High lipoprotein(a) concentrations are associated with lower type 2 diabetes risk in the Chinese Han population: a large retrospective cohort study

Background

Lipoprotein (a) [Lp(a)] is a proven independent risk factor for coronary heart disease. It is also associated with type 2 diabetes mellitus (T2DM). However, the correlation between Lp(a) and T2DM has not been clearly elucidated.

Methods

This was a retrospective cohort study involving 9248 T2DM patients and 18,496 control individuals (1:2 matched). Patients were randomly selected from among inpatients in the Second Affiliated Hospital of Nanchang University between 2006 and 2017. Clinical characteristics were compared between the two groups. Spearman rank-order correlation coefficients were used to evaluate the strength and direction of monotonic associations of serum Lp(a) with other metabolic risk factors. Binary logistic regression analysis was used to establish the correlation between Lp(a) levels and T2DM risk.

Results

The median Lp(a) concentration was lower in T2DM patients than in controls (16.42 vs. 16.88 mg/dL). Based on four quartiles of Lp(a) levels, there was a decrease in T2DM risk from 33.7% (Q1) to 31.96% (Q4) (P for trend < 0.0001). Then, Lp(a) levels > 28.72 mg/dL (Q4) were associated with a significantly lower T2DM risk in the unadjusted model [0.924 (0.861, 0.992), P = 0.030]. Similar results were obtained in adjusted models 1 [Q4, 0.925 (0.862, 0.993), P = 0.031] and 2 [Q4, 0.919 (0.854, 0.990), P = 0.026]. Furthermore, in the stratified analysis, Q4 of Lp(a) was associated with a significantly lower T2DM risk among men [0.813 (0.734, 0.900), P < 0.001] and those age > 60 years [0.819 (0.737, 0.910), P < 0.001]. In contrast, the low-density lipoprotein cholesterol (LDL-C) levels and coronary heart disease (CHD) did not impact these correlations between Lp(a) and diabetes.

Conclusions

There is an inverse association between Lp(a) levels and T2DM risk in the Chinese population. Male patients, especially those aged more than 60 years with Lp(a) > 28.72 mg/dL, are low-risk T2DM individuals, regardless of LDL-C levels and CHD status.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12944-021-01504-x.

Lipoprotein(a) and coronary artery disease in Chinese postmenopausal female patients: a large cross-sectional cohort study

Background

It has been reported that lipoprotein(a) (Lp(a)) is associated with the risk of cardiovascular disease. The present study aimed to examine the association of Lp(a) levels with the presence and severity of coronary artery disease (CAD) in female patients.

Methods

A total of 3712 female patients who received coronary angiography were consecutively enrolled. The levels of Lp(a) were measured and compared among patients with or without CAD, myocardial infarction and menopause. Spearman correlation analysis and logistic regression analysis were used to examine the association of Lp(a) with the presence of CAD and the severity of coronary atherosclerosis assessed by Gensini score (GS).

Results

The average of Lp(a) levels was elevated as age increased in female subjects. Notably, women after menopause had higher Lp(a) levels compared with that before menopause (16.8 mg/dL (IQR 7.54–41.12 mg/dL) vs 14.7 mg/dL (IQR 6.72–30.82 mg/dL), p=0.002). Furthermore, multiple logistic regression analysis identified that Lp(a)>30 mg/dL was an independent risk factor of CAD in the postmenopausal females (OR: 1.33, 95% CI: 1.08 to 1.63, p=0.007). Finally, Lp(a) had a positive correlation with GS (r=0.11, p<0.001), and Lp(a)>30 mg/dL was an independent risk factor for high GS (OR: 1.43, 95% CI: 1.14 to 1.79, p=0.02) in the postmenopausal females.

Conclusion

Circulating Lp(a) levels were independently associated with the presence and severity of CAD in the postmenopausal females, suggesting that Lp(a) may be useful for prevention and risk-stratification of CAD in female individuals.

High serum osteopontin levels are associated with prevalent fractures and worse lipid profile in post-menopausal women with type 2 diabetes

PURPOSE

Patients with type 2 diabetes (T2DM) have increased fracture risk. Osteopontin (OPN) is a protein involved in bone remodeling and inflammation. The aim of this study was to evaluate the association of OPN with fracture prevalence and with metabolic parameters in post-menopausal women with T2DM.

METHODS

Sixty-four post-menopausal women with T2DM (age 67.0 ± 7.8 years, diabetes duration 8.9 ± 6.7 years), enrolled in a previous study, were followed up (3.6 ± 0.9 years). Previous fragility fractures were recorded. The FRAX score (without BMD) was calculated and biochemical parameters (plasma glucose, HbA1c, lipid profile and renal function) were assessed. Serum 25OH-vitamin D, calcium, PTH and OPN were evaluated at baseline. The association between OPN and fracture prevalence at baseline was evaluated by a logistic model.

RESULTS

OPN levels were higher in patients with previous fractures (n.25) than in patients without previous fractures at baseline (n.39) (p = 0.006). The odds of having fractures at baseline increased by 6.7 (1.9-31.4, 95% CI, p = 0.007) for each increase of 1 ng/ml in OPN levels, after adjustment for vitamin D and HbA1c levels. Fracture incidence was 4.7%. Higher OPN associated with a decrease in HDL-cholesterol (p = 0.048), after adjustment for age, basal HDL-cholesterol, basal and follow-up HbA1c and follow-up duration. 25OH-vitamin D associated with an increase in FRAX-estimated probability of hip fracture at follow-up (p = 0.029), after adjustment for age, 25OH-vitamin D and time.

CONCLUSIONS

In post-menopausal women with T2DM, OPN might be a useful marker of fracture and worse lipid profile.

Lipoprotein(a) in postmenopausal women: assessment of cardiovascular risk and therapeutic options

INTRODUCTION

Lipoprotein(a) [Lp(a)], a low-density lipoprotein (LDL)-like particle, has been independently associated with increased cardiovascular disease (CVD) risk in various populations, such as postmenopausal women. The purpose of this narrative review is to present current data on the role of Lp(a) in augmenting CVD risk in postmenopausal women and focus on the available therapeutic strategies.

METHODS

PubMed was searched for English language publications until November 2015 under the following terms: "therapy" OR "treatment" AND ["lipoprotein (a)" OR "Lp(a)"] AND ("postmenopausal women" OR "menopausal women" OR "menopause").

RESULTS

Only hormone replacement therapy (mainly oral estrogens) and tibolone have been specifically studied in postmenopausal women and can reduce Lp(a) concentrations by up to 44%, although evidence indicating a concomitant reduction in CVD risk associated with Lp(a) is lacking. As alternative treatments for women who cannot, or will not, take hormonal therapies, niacin and the upcoming proprotein convertase subtilisin / kexin type 9 (PCSK-9) inhibitors are effective in reducing Lp(a) concentrations by up to 30%. Statins have minimal or no effect on Lp(a). However, data for these and other promising Lp(a)-lowering therapies including mipomersen, lomitapide, cholesterol-ester-transfer protein inhibitors and eprotirome are derived from studies in the general, mainly high CVD risk, population, and include only subpopulations of postmenopausal women.

CONCLUSIONS

Past, present and emerging therapies can reduce Lp(a) concentrations to a varying extent. Overall, it remains to be proven whether the aforementioned reductions in Lp(a) by these therapeutic options are translated into CVD risk reduction in postmenopausal women.

Lipoprotein (a): impact by ethnicity and environmental and medical conditions

Levels of lipoprotein (a) [Lp(a)], a complex between an LDL-like lipid moiety containing one copy of apoB, and apo(a), a plasminogen-derived carbohydrate-rich hydrophilic protein, are primarily genetically regulated. Although stable intra-individually, Lp(a) levels have a skewed distribution inter-individually and are strongly impacted by a size polymorphism of the LPA gene, resulting in a variable number of kringle IV (KIV) units, a key motif of apo(a). The variation in KIV units is a strong predictor of plasma Lp(a) levels resulting in stable plasma levels across the lifespan. Studies have demonstrated pronounced differences across ethnicities with regard to Lp(a) levels and some of this difference, but not all of it, can be explained by genetic variations across ethnic groups. Increasing evidence suggests that age, sex, and hormonal impact may have a modest modulatory influence on Lp(a) levels. Among clinical conditions, Lp(a) levels are reported to be affected by kidney and liver diseases.

Lipoprotein(a) concentrations, isoform size, and risk of type 2 diabetes: a Mendelian randomisation study

BACKGROUND

Low concentrations of lipoprotein(a) in plasma are associated with increased risk of type 2 diabetes, but whether this association is causal is unclear. Variations in the LPA gene affect lipoprotein(a) isoform size and concentrations in plasma. We therefore did a Mendelian randomisation study to investigate whether large isoform size, low concentrations in plasma, or both, are causally associated with type 2 diabetes.

METHODS

We assessed data for adults from the Danish general population enrolled in the Copenhagen City Heart Study and the Copenhagen General Population Study, with and without type 2 diabetes. Eligible participants had data for lipoprotein(a) concentrations in plasma, LPA kringle IV type 2 (KIV-2) sums of repeats (affecting both isoform size and plasma concentrations), and carrier status for the LPA single-nucleotide polymorphism rs10455872 (mainly affecting concentrations in plasma).

FINDINGS

77,901 individuals had lipoprotein(a) data, of whom 28,567 (36·7%) had all three measurements. Low concentrations of lipoprotein(a) in plasma were associated with risk of type 2 diabetes, with adjusted odds ratios of 1·26 (1·09-1·45), 1·17 (1·01-1·36), 1·04 (0·90-1·21), and 1·05 (95% CI 0·90-1·22), respectively, for quintiles 1-4, compared with quintile 5 concentrations. High KIV-2 sums of repeats were associated with risk of type 2 diabetes (adjusted odds ratio 1·16, 95% CI 1·05-1·28) for KIV-2 quintile 5 versus quintiles 1-4 combined. Being a carrier of rs10455872 did not affect risk of type 2 diabetes. For a halving of lipoprotein(a) concentrations, the instrumental variable estimate of the causal odds ratio for type 2 diabetes was 1·15 (95% CI 1·05-1·27) for KIV-2 sum of repeats and 0·99 (0·95-1·03) for rs10455872 genotype.

INTERPRETATION

Low lipoprotein(a) concentrations alone seem not to be causally associated with type 2 diabetes, but a causal association for large lipoprotein(a) isoform size cannot be excluded.

FUNDING

Danish Heart Foundation, Danish Council for Independent Research-Medical Sciences, IMK Almene Fund, and Johan and Lise Boserup's Fund.

Elevated serum β2-glycoprotein-I-lipoprotein(a) complexes levels are associated with the presence and complications in type 2 diabetes mellitus

AIMS

To examine the serum levels of β2-glycoprotein I-lipoprotein(a) complexes [β2-GPI-Lp(a)] in type 2 diabetes mellitus (T2DM) patients and evaluate the association of the complexes with complications in T2DM.

METHODS

Fifty two T2DM patients (22 with complications and 30 free of complications) and 52 age/gender-matched healthy controls were studied. Serum concentrations of β2-GPI-Lp(a) and ox-Lp(a) were measured by "sandwich" ELISAs and their associations with complications were examined using multiple linear regression.

RESULTS

Mean serum β2-GPI-Lp(a) (1.19 ± 0.30 U/mL vs. 0.89 ± 0.20 U/mL, p<0.001) and ox-Lp(a) concentrations (13.34 ± 11.73 mg/L vs. 5.26 ± 3.34 mg/L, p<0.001) were both significantly higher in T2DM than in controls. The area under the ROC curve (AUC) for β2-GPI-Lp(a) and ox-Lp(a) was 0.725 and 0.738, respectively. β2-GPI-Lp(a) levels were markedly higher in patients with complications than those without complication (1.39 ± 0.28 U/mL vs. 1.04 ± 0.31 U/mL, p<0.01), whereas no marked difference was found in ox-Lp(a). In multivariate regression analysis, the association between β2-GPI-Lp(a) and complications remained significant (β=0.249, p<0.05, respectively) after adjustments were made for other traits.

CONCLUSIONS

Elevated β2-GPI-Lp(a) may reflect chronic underlying pathophysiological processes involved in development of complications of T2DM.

Gender-dependent association of type 2 diabetes with the vasoactive intestinal peptide receptor 1

Type 2 diabetes is characterized by an inadequate pancreatic beta-cell response to the progressive insulin resistance. Its pathogenesis is complex and has been connected with a state of preclinical chronic inflammation. Vasoactive intestinal peptide (VIP) and its receptors play a relevant role in the homeostasis of insulin secretion as well as in the control of inflammation. In particular, VIP receptor 1 (VPAC1) has been found to be down-modulated during inflammation, and to be associated with several diseases. The objective of this study was to compare the distribution of SNPs mapping in the VIP receptor 1 gene in cases with type 2 diabetes and matched controls. Seven hundred cases with type 2 diabetes (423 males and 277 females) and 830 random controls (419 males and 411 females) were analyzed for the distribution of three common SNPs mapping in the VPAC1 gene. The results show a significantly different genotype distribution of the SNP rs9677 in the 3'-UTR of VPAC1 in female cases with type 2 diabetes compared to gender-matched controls (ptrend=6×10(-4)). The rs9677 CC genotype confers the highest risk (OR: 2.1) and correlates with worse clinical parameters such as higher level of total cholesterol, higher LDL/HDL ratio and a higher HbA1c concentration. The genetic association reported here indicates that VIP/VPAC1 signaling can be a relevant pathway in the pathogenesis of type 2 diabetes in females suggesting that at least some aspects of the genetic predisposition to this disease can be gender-specific.