Effect of high density lipoprotein cholesterol on the relationship of serum iron and hemoglobin with kidney function in diabetes

Association between HDL cholesterol with diabetic retinopathy in diabetic patients: a cross-sectional retrospective study

OBJECTIVE

Diabetic patients are often comorbid with dyslipidemia, however, the relationship between high-density lipoprotein cholesterol(HDL-C) and diabetic retinopathy (DR) in the adult diabetic population remains to be fully elucidated.The aim of this study is to evaluate the associations between HDL-C and DR in the United States adults with diabetes.

METHODS

A total of 1708 participants from the National Health and Nutrition Examination Survey (NHANES) 2005-2008 were enrolled in the present study. Fundus images of all study subjects were captured and evaluated using a digital camera and an ophthalmic digital imaging system, and the diagnosis of DR was made by the severity scale of the Early Treatment Diabetic Retinopathy Study (ETDRS).Roche Diagnostics were used to measure serum HDL-C concentration. The relationship of DR with HDL-C was investigated using multivariable logistic regression. The potential non-line correlation was explored with smooth curve fitting approach.

RESULTS

The fully-adjusted model showed that HDL-C positively correlated with DR(OR:1.69, 95%CI: 1.25-2.31).However, an inverted U-shaped association between them was observed by applying the smooth curve fitted method. The inflection point of HDL-C(1.99mmol/l) was calculated by utilizing the two-piecewise logistic regression model. In the subgroup analysis, the inverted U-shaped nonlinear correlation between HDL-C and DR was also found in female, Non-Hispanic White, and lower age groups.

CONCLUSION

Our study revealed an inverted U-shaped positive relationship between HDL-C and DR.The findings may provide us with a more comprehensive understanding of the association between HDL-C and DR.

Association Between Iron Status and Risk of Chronic Kidney Disease in Chinese Adults

Background: Even though it is well-known that iron deficiency is the result of chronic kidney disease (CKD), whether iron will affect kidney function and disease in the general population is not clear. We thus conducted a nationwide cross-sectional study using data from the China Health and Nutrition Survey (CHNS) to assess the relationship of iron status with estimated glomerular filtration rate (eGFR) and CKD among general adults. Methods: A total of 8,339 adults from the China Health and Nutrition Survey in the wave of 2009 were included to assess the association between iron status and eGFR/CKD. Serum ferritin (SF), transferrin, soluble transferrin receptor (sTfR), and hemoglobin (Hb) were measured. The relationship of iron status and eGFR was evaluated by using multi-variable linear regression model. The effect of iron status on the odds of CKD was calculated by logistic regression model. Results: For the association between iron status and eGFR, every 100 μg/L increase in SF was correlated with 0.26 ml/min per 1.73 m2 (95% CI: 0.08-0.44) decrease in eGFR, and every 5 mg/L increase in sTfR was associated with a decrease of 6.00 ml/min per 1.73 m2 (95% CI: 3.79-8.21) in eGFR. There were no significant associations between Hb or transferrin with eGFR. For the association between iron status and CKD, every 5 g/L increase in sTfR was associated with an odds ratio of 3.72 (95% CI: 2.16-6.13) for CKD. The concentrations of Hb were associated with the odds of CKD in a U-shaped manner, with the lowest risk in the Hb range of 136-141 g/L. There was a positive correlation between SF concentration and CKD prevalence but not in a dose-response manner. The odds of CKD for participants in the highest tertile increased by 28% (98% CI: 1-63%) compared with those in the lowest tertile. Conclusion: The concentration of SF and sTfR was positively correlated with the odds of CKD, and Hb was associated with the odds of CKD in a U-shaped manner. Further large prospective researches are warranted to confirm these findings.

Haptoglobin Phenotype Modulates Lipoprotein-Associated Risk for Preeclampsia in Women With Type 1 Diabetes

CONTEXT

The incidence of preeclampsia (PE) is increased in women with diabetes (∼20% vs ∼5% in the general population), and first trimester lipoprotein profiles are predictive. Haptoglobin (Hp), a protein with functional genetic polymorphisms, has antioxidant, anti-inflammatory, and angiogenic effects. Among people with diabetes, the Hp 2-2 phenotype is associated with cardiorenal disease.

OBJECTIVE

To investigate whether Hp phenotype is associated with PE in type 1 diabetes mellitus (T1DM) and/or modulates lipoprotein-associated risks.

DESIGN AND SETTING

Multicenter prospective study of T1DM pregnancy.

PATIENTS

Pregnant women with T1DM (normal albuminuria, normotensive at enrolment, n = 47) studied at three visits, all preceding PE onset: 12.3 ± 1.9, 21.8 ± 1.5, and 31.5 ± 1.6 weeks' gestation (mean ± SD).

MAIN OUTCOME MEASURES

Hp phenotype and lipoprotein profiles in women with (n = 23) vs without (n = 24) subsequent PE.

RESULTS

Hp phenotype did not predict PE, but lipoprotein associations with subsequent PE were confined to women with Hp 2-2, in whom the following associations with PE were observed: increased low-density lipoprotein (LDL) cholesterol, LDL particle concentration, apolipoprotein B (APOB), triacylglycerol/high-density lipoprotein (HDL) cholesterol ratio, and APOB/apolipoprotein AI (APOA1) ratio; decreased HDL cholesterol, APOA1, large HDL particle concentration, and peripheral lipoprotein lipolysis (all P < 0.05). In women with one or two Hp-1 alleles, no such associations were observed.

CONCLUSIONS

In women with T1DM, although Hp phenotype did not predict PE risk, lipoprotein-related risks for PE were limited to those with the Hp 2-2 phenotype. Hp phenotype may modulate PE risk in diabetes.

Serum haptoglobin levels are associated with renal function decline in type 2 diabetes mellitus patients in a Chinese Han population

AIMS

We investigated whether serum haptoglobin (Hp) levels play a role in the development and progression of diabetic kidney disease (DKD) in type 2 diabetes mellitus (T2DM) patients in a Chinese Han population, which has not been previously investigated.

METHODS

We recruited 233 participants who had suffered from T2DM for more than 10 years, including 118 subjects with DKD (case) and 115 subjects without DKD (control). Serum Hp levels were measured by an enzyme-linked immunosorbent assay.

RESULTS

Serum Hp levels were significantly higher (P = 0.0258) in case group (2.74 (1.77, 3.48) g/L) than control (2.29 (0.98, 3.48) g/L). The serum Hp level was significantly positively associated with both logarithmically transformed (log-transformed) serum creatinine (r = 0.1663, P = 0.011) and albuminuria levels (r = 0.1793, P = 0.0062) and was negatively associated with the log-transformed estimated glomerular filtration rate (r = -0.1482, P = 0.0237). Multiple linear regression analysis revealed that serum Hp levels were significantly correlated with serum creatinine levels (P = 0.0088) after adjusting for confounding risk factors.

CONCLUSIONS

Our findings suggest that serum Hp levels may be used as a potential biomarker for the early diagnosis and monitoring of DKD in T2DM patients.

Serum Albumin, but not Bilirubin, is Associated with Diabetic Chronic Vascular Complications in a Chinese Type 2 Diabetic Population

To identify the factors associated with serum total bilirubin (STB) and determine whether STB is independently associated with diabetic retinopathy (DR) or diabetic kidney disease (DKD), 1,665 Chinese patients with type 2 diabetes (T2DM) (248 outpatients newly diagnosed with T2DM [NDM] and 1,417 inpatients previously diagnosed with T2DM [PDM]) were studied. Clinical and biochemical information was collected, and a single nucleotide polymorphism (rs6704078) of the UGT1A1 gene was genotyped in 1,059 individuals. Multiple linear regression showed that STB was associated with haemoglobin concentration, platelet count, and serum triglyceride concentration in NDM and PDM patients, and with serum albumin, duration of diabetes, and smoking in PDM patients. In patients with PDM, multiple logistic regression revealed that serum albumin was associated with DR (odds ratio [OR] = 0.92, 95% confidence interval [CI]: 0.87-0.96, p = 0.001) and DKD (OR = 0.93, 95% CI: 0.88-0.98, p = 0.005) after adjustment for STB, STB-related factors, and risk factors for DR and DKD. In addition, patients with the T allele of rs6704078 had higher STB (13.2 [10.4-17.9] μmol/L versus 11.8 (9.4-14.8) μmol/L; p < 0.001) and similar risks of DR or DKD to those without the T allele. Thus, serum albumin, but not STB, is associated with DR and DKD.

Genome-wide association study identifies novel loci for type 2 diabetes-attributed end-stage kidney disease in African Americans

BACKGROUND

End-stage kidney disease (ESKD) is a significant public health concern disproportionately affecting African Americans (AAs). Type 2 diabetes (T2D) is the leading cause of ESKD in the USA, and efforts to uncover genetic susceptibility to diabetic kidney disease (DKD) have had limited success. A prior genome-wide association study (GWAS) in AAs with T2D-ESKD was expanded with additional AA cases and controls and genotypes imputed to the higher density 1000 Genomes reference panel. The discovery analysis included 3432 T2D-ESKD cases and 6977 non-diabetic non-nephropathy controls (N = 10,409), followed by a discrimination analysis in 2756 T2D non-nephropathy controls to exclude T2D-associated variants.

RESULTS

Six independent variants located in or near RND3/RBM43, SLITRK3, ENPP7, GNG7, and APOL1 achieved genome-wide significant association (P < 5 × 10-8) with T2D-ESKD. Following extension analyses in 1910 non-diabetic ESKD cases and 908 non-diabetic non-nephropathy controls, a meta-analysis of 5342 AA all-cause ESKD cases and 6977 AA non-diabetic non-nephropathy controls revealed an additional novel all-cause ESKD locus at EFNB2 (rs77113398; P = 9.84 × 10-9; OR = 1.94). Exclusion of APOL1 renal-risk genotype carriers identified two additional genome-wide significant T2D-ESKD-associated loci at GRAMD3 and MGAT4C. A second variant at GNG7 (rs373971520; P = 2.17 × 10-8, OR = 1.46) remained associated with all-cause ESKD in the APOL1-negative analysis.

CONCLUSIONS

Findings provide further evidence for genetic factors associated with advanced kidney disease in AAs with T2D.