Serum uric acid levels are associated with increased risk of newly developed diabetic retinopathy among Japanese male patients with type 2 diabetes: A prospective cohort study (diabetes distress and care registry at Tenri [DDCRT 13])

Associations of serum uric acid to eGFR ratio with diabetic retinopathy in individuals with type 2 diabetes

Serum uric acid (SUA) is closely associated with diabetes and its complications. The relationship between SUA and diabetic retinopathy (DR) remains unclear, with conflicting results from current studies on SUA in DR Patients. Since uric acid is primarily excreted by the kidneys, the ratio of SUA to eGFR (SUA/eGFR) serves as a renal function-corrected indicator of SUA levels. We tested whether SUA/eGFR might be involved in the pathogenesis and progression of DR. We collected data from 1,399 patients with type 2 diabetes mellitus (T2DM) who were hospitalized between January 2023 and April 2024. They were divided into diabetes without DR (nondiabetic retinopathy, NDR) group (N = 438), non-proliferative diabetic retinopathy (NPDR) group (N = 902) and proliferative diabetic retinopathy (PDR) group (N = 59). Univariate and multivariate logistic regression analyses were used to analyze the relationship between SUA/eGFR and DR and its severity. The SUA/eGFR levels increased with the severity of DR (P<0.05). In the multinomial logistic regression model using patients without DR as the reference, SUA/eGFR was significantly linked with PDR (OR = 1.07, 95%CI 1.00-1.14; P = 0.036), while NPDR group showed no significant difference (P>0.05). In T2DM patients younger than 60 years, SUA/eGFR was positively associated with an increased risk of DR (OR = 1.20, 95%CI 1.05-1.38, P = 0.01). Among T2DM patients with HbA1c > 7%, higher SUA/eGFR levels were linked to a greater risk of DR(OR = 1.10, 95%CI 1.00-1.20, P = 0.045). Stratified analysis by age showed that in T2DM patients younger than 60 years, SUA/eGFR was positively correlated with the severity of DR (NPDR:OR = 1.20, 95%CI 1.04-1.38, P = 0.01; PDR: OR = 1.20, 95%CI 1.04-1.38, P = 0.012). Additionally, stratified analysis by HbA1c levels indicated that among T2DM patients with HbA1c > 7%, those with higher SUA/eGFR levels had an increased risk of DR severity (NPDR:OR = 1.09, 95%CI 1.00-1.19, P = 0.049; PDR: OR = 1.10, 95%CI 1.01-1.20, P = 0.037). Our study reported a positive association between SUA/eGFR and DR and its severity in younger T2DM patients with poorly controlled blood glucose levels. T2DM patients with higher SUA levels had an increased risk of more severe DR (progressing from NPDR to PDR). However, more prospective and high-quality clinical evidence is needed to confirm these current findings.

High levels of serum uric acid are associated with microvascular complications in patients with long-term diabetes

AIMS

To assess the association between serum uric acid (SUA) level and the prevalence of diabetic retinopathy (DR) and chronic kidney disease (CKD) in patients with long-term diabetes.

METHODS

A cross-sectional analysis was conducted involving diabetic patients from Shanghai General hospital during October 2018 and October 2021. Participants underwent measurements of SUA, renal function test and DR assessments via fundus photography. Multivariable ordinal logistic regression models assessed odd ratios (ORs) and 95% confidence intervals (95% CIs) for the progression of DR and CKD. Receiver operating characteristics (ROC) curves identified SUA thresholds, categorizing participants into low and high SUA groups.

RESULTS

Among the 1015 patients with diabetes, SUA levels were higher in individuals with advanced CKD stages (p < 0.001, compared with stage 1 CKD) and vision-threatening diabetic retinopathy (VTDR) (p = 0.019, compared with no diabetic retinopathy (NDR)). In multivariable models adjusted for potential confounders, higher SUA levels were associated with an increased risk of DR (OR: 1.002, 95% CI: 1.001-1.004) and CKD (OR: 1.008, 95% CI: 1.006-1.011). Notably, SUA levels exceeding 354.0 µmol/L (95% CI: 318.9-393.2) and 361.0 µmol/L (339.2-386.3) were associated with 1.571-fold (95% CI: 1.139-2.099, P = 0.006 for DR) and 1.395-fold (95% CI: 1.033-1.885, P = 0.030 for CKD) increased risks, respectively. Gender-specific analyses also demonstrated a positive correlation between higher SUA levels and the incidence of DR and CKD in both males and females.

CONCLUSIONS

Elevated SUA levels are independently coincided with increased risks of DR and CKD, suggesting that SUA may serve as a potential risk marker for diabetic complications.

Association between renal function and diabetic retinopathy: a mediation analysis of geriatric nutritional risk index

BACKGROUND

Diabetes retinopathy (DR) is a prevalent microvascular complication of type 2 diabetes mellitus (T2DM). This study investigated the correlation between renal function and DR, as well as the potential mediating role of the geriatric nutritional risk index (GNRI).

METHOD

We classified 1122 adults with T2DM aged ≥ 40 years from the National Health and Nutrition Examination Survey database (2005-2008) into 2 groups: those with DR and those without DR. We used multivariate logistic regression analysis and restricted cubic spline (RCS) model to explore the relationship between renal function indicators and DR. Additionally, we analyzed the mediating impact of GNRI on renal function and DR.

RESULT

After accounting for all covariates, the weighted multivariate analysis revealed significant associations between renal function markers and DR. Specifically, creatinine, albumin, blood urea nitrogen, and serum uric acid to creatinine ratio (SUACr) were significantly correlated with DR in serum examination, while creatinine was the only marker correlated with DR in urine. GNRI was negatively correlated with DR (odds ratio 0.94, 95% CI 0.92-0.99). Weighted linear regression showed a negative association between SUACr and GNRI (β = 0.37; 95% CI 0.12-0.62). The RCS analysis showed a nonlinear association between serum creatinine and DR (Pnon-linear = 0.013). GNRI mediated 14.4% of the relationship between SUACr and DR.

CONCLUSION

Our study adds to previous research by analyzing the associations between renal function indicators and DR. Furthermore, we highlight the mediating effect of GNRI, suggesting its potential utility as a predictive and treatment index for assessing renal function and DR.

Causality between serum uric acid and diabetic microvascular complications - a mendelian randomization study

BACKGROUND

The aim of this study was to investigate whether a causal relationship exists between serum uric acid (SUA) and diabetic microvascular complications using a two-sample Mendelian randomization (MR) method.

METHODS

We used the MR approach, utilizing genome-wide association study (GWAS) summary statistics, to estimate the causal effect of SUA on diabetic microvascular complications in European individuals. The summary statistical data of SUA were obtained from the open database (IEU OPEN GWAS PROJECT) (p < 5 × 10- 8), and data on diabetic microvascular complications (diabetic nephropathy, diabetic neuropathy, diabetic retinopathy) were obtained from the FinnGen consortium. F-statistics were calculated to assess the correlation between instrumental variables (IVs) and SUA, and single nucleotide polymorphisms (SNPs) associated with confounders or outcomes were excluded by consulting the PhenoScanner database. Inverse variance weighting (IVW) was used for primary estimation, and MR‒Egger, weighted median (WM), and Mendelian randomization pleiotropy residuals sum and outliers (MR-PRESSO) were used for additional assessment. Heterogeneity was assessed using the Cochran's Q test, and polytropy was assessed using the MR‒Egger intercept.

RESULTS

MR analysis revealed a causal relationship between a genetically predicted increase in SUA and diabetic nephropathy [OR = 1.32, 95%(CI) = 1.07-1.63, p = 0.008]. The results were consistent with those after MR-PRESSO [OR = 1.30, 95%(CI) = 1.07-1.58, p = 0.008]. There was a causal relationship between type 2 diabetes mellitus (T2DM) and renal complication IVW [OR = 1.27, 95%(CI) = 1.00-1.62, p = 0.049]. These results were consistent with those after MR-PRESSO [OR = 1.27, 95%(CI) = 1.00-1.62, p = 0.050]. There was no significant causal relationship between the genetically predicted increase in SUA and diabetic retinopathy [OR 1.09, 95%(CI) = 0.94-1.26, p = 0.249] or diabetic neuropathy [OR = 1.08, 95%(CI) = 0.84-1.40, p = 0.549].

CONCLUSIONS

This MR analysis suggests a causal relationship between genetically predicted uric acid increases and diabetic microvascular complications. A significant causal relationship exists between SUA and diabetic nephropathy but not between SUA and diabetic retinopathy or diabetic neuropathy.

Association between uric acid and referable diabetic retinopathy in patients with type 2 diabetes

Plasmatic uric acid (UA) has been inconsistently associated with diabetic retinopathy (DR). Specific sight-threatening stages of DR have not been studied for their association with UA. Cross-sectional, comparative study. Between 2014 and 2018 we recruited 210 Mexican individuals > 18 years-old with type 2 diabetes (T2D). Clinical, ophthalmological and biochemical assessment was performed with standardized funduscopic examination. Certified readers classified DR stages. The association between DR and UA was assessed by multiple logistic regression analysis, calculating odds ratios (OR) and 95% CI, after adjustment for covariates. Two hundred and ten patients were included, 41 (19.5%) had referable DR. Subjects with referable (severe or worse) DR had longer diabetes duration, 22 (15-28) vs 15 (8-20) years (P < 0.01); higher levels of UA, 6.5 (5.8-8.1) vs 5.4 (4.5-6.6) mg/dL (P < 0.01); higher systolic blood pressure, 130 (120-140) vs 120 (110-130) mmHg (P < 0.01); higher diastolic blood pressure, 78.4 ± 9.7 vs 75.4 ± 9.2 mmHg (P = 0.03); and lower glomerular filtration rate , 54.1 (41.5-69.6) vs 87.3 (66.8-108.3) mL/min/1.73m2 (P < 0.01) compared with those without referable DR. With multiple logistic regression, after adjustment, per each unit of change (mg/dL) in UA the probability of having referable DR increased 45% (OR = 1.45, 95% CI 1.12-1.87, P < 0.01). When UA was evaluated as dichotomous variable, those with levels ≥ 7.8 mg/dL had almost two times (OR = 2.81, 95% CI 1.00-7.9., P = 0.049) the probability of having referable DR compared with those with levels < 7.8 mg/dL. UA may contribute to the microvascular damage in retinal vessels and therefore hyperuricemia could be a therapeutic target to prevent DR progression.

Evaluation of Macular and Optic Disc Radial Peripapillary Vessel Density Using Optical Coherence Tomography Angiography in Gout Patients

In this cross-sectional study, optical coherence tomography angiography (OCT-A) findings were compared in patients with gout (n = 30) and healthy participants (n = 32). The superficial and deep vessel density variables measured using OCT-A were compared between the groups. The superficial foveal and perifoveal vessel densities of the patient group were lower than those of the healthy participants (p = 0.014 and p = 0.045, respectively). However, all superficial and parafoveal vessel densities were similar in both groups (p = 0.469 and p = 0.284, respectively). The deep capillary plexus density measurements of the whole-zone, foveal, parafoveal, and perifoveal vessel densities using OCT-A revealed no significant differences between the groups (p = 0.251, p = 0.074, p = 0.177, and p = 0.881, respectively). A higher serum uric acid (SUA) level was found to be independently associated with a decreased superficial capillary plexus density and an increased choriocapillary flow deficit in the study population. Men were less sensitive to high SUA levels than women. These findings suggest that an elevated uric acid concentration may play a role in the development and progression of cardiovascular disease through changes in the microvasculature, as shown by the OCT-A parameters.

Nomogram-based prediction of clinically significant macular edema in diabetes mellitus patients

AIMS

The aim of the study was to construct and validate a risk nomogram for clinically significant macular edema (CSME) prediction in diabetes mellitus (DM) patients using systemic variables.

METHODS

In this retrospective study, DM inpatients who underwent routine diabetic retinopathy screening were recruited and divided into training and validation sets according to their admission date. Ninety-three demographic and systemic variables were collected. The least absolute shrinkage and selection operator was used to select the predictive variables from the training set. The selected variables were used to construct the CSME prediction nomogram. Internal and external validations were performed. The C-index, calibration curve and decision curve analysis (DCA) were reported.

RESULTS

A total of 349 patients were divided into the training set (240, 68.77%) and the validation set (109, 31.23%). The presence of diabetic peripheral neuropathy (DPN) symptoms, uric acid, use of insulin only or not for treatment, insulin dosage, urinary protein grade and disease duration were chosen for the nomogram. The C-index of the prediction nomogram was 0.896, 0.878 and 0.837 in the training set, internal validation and external validation, respectively. The calibration curves of the nomogram showed good agreement between the predicted and actual outcomes. DCA demonstrated that the nomogram was clinically useful.

CONCLUSIONS

A nomogram with good performance for predicting CSME using systemic variables was developed. It suggested that DPN symptoms and renal function may be crucial risk factors for CSME. Moreover, this nomogram may be a convenient tool for non-ophthalmic specialists to rapidly recognize CSME in patients and to transfer them to ophthalmologists for early diagnosis and treatment.

Retinal Microvasculature and Choriocapillaris Flow Deficit in Relation to Serum Uric Acid Using Swept-Source Optical Coherence Tomography Angiography

Purpose

To explore the relationship between serum uric acid (SUA) and retinochoroidal microcirculation in the Chinese population.

Methods

This prospective cross-sectional study was conducted among the residents of Guangzhou, southern China. A commercially available optical coherence tomography angiography (OCTA) device was used to obtain the superficial vessel density (SVD) and deep vessel density in the retina and the choriocapillaris flow deficit (CFD) in the macular region. Univariable and multivariable linear regression models were used to assess the association of hyperuricemia and SUA levels with OCTA parameters.

Results

A total of 638 participants with normal SUA and 296 participants with hyperuricemia were included in the study. Parafoveal SVD was significantly reduced among the participants with hyperuricemia compared to participants with normal SUA (P < 0.001), while the parafoveal CFD was higher in hyperuricemic participants than those of normal SUA levels (P = 0.007). After adjusting for potential confounders, greater SUA levels was associated with lower SVD (β = −0.078; P < 0.001) and greater CFD (β = 0.015; P = 0.011). Gender difference analysis indicated that a 10-µmol/L increase in SUA levels among the female participants led to a 0.144 decrease in SVD (P < 0.001), but it was not statistically significant for the male participants (P = 0.653).

Conclusions

An elevated uric acid level and its fluctuations were independently associated with impaired retinal and choroidal microcirculation using OCTA in the study population. Women appear to be more sensitive to high SUA levels than men.

Translational Relevance

Elevating uric acid concentration may play a role in the development and progression of cardiovascular diseases through microvascular alteration, as demonstrated by OCTA parameters.

Uric Acid and Diabetic Retinopathy: A Systematic Review and Meta-Analysis

Background

The relationship between uric acid (UA) and diabetic retinopathy (DR) remains ambiguous, and the results of current studies on the UA levels in patients with DR are conflicting. A meta-analysis was performed to provide a better understanding of the relationship between UA levels and DR.

Methods

PubMed, Web of Science, Embase, and the Cochrane Library databases were searched until December 11, 2021 to identify eligible studies, that compared the UA levels of the case group (patients with DR) and control group (controls with diabetes and healthy participants). The weighted mean difference (WMD) with a 95% confidence interval (CI) was used to evaluate the difference in UA levels between the case and control groups.

Results

Twenty-one studies involving 4,340 patients with DR and 8,595 controls (8,029 controls with diabetes and 566 healthy participants) were included in this meta-analysis. We found that patients with DR had significantly higher UA levels than those in the controls with diabetes (WMD = 36.28; 95% CI: 15.68, 56.89; P < 0.001) and healthy participants (WMD = 70.80; 95% CI: 19.85, 121.75; P = 0.006). There was an obvious heterogeneity among the 21 studies (I² = 97%, P < 0.001). Subgroup analyses of different phases of DR showed that UA levels were significantly increased in participants with proliferative diabetic retinopathy (PDR) (WMD = 46.57; 95% CI: 28.51, 64.63; P < 0.001) than in controls with diabetes; however, the difference is not statistically significant when comparing UA levels in patients with non-proliferative diabetic retinopathy (NPDR) and controls with diabetes (WMD = 22.50; 95% CI: −6.07, 51.08; P = 0.120). In addition, UA levels were higher in participants with a body mass index (BMI) ≥25.0 kg/m² and over 15 years of diabetes. Univariate meta-regression analysis revealed that BMI (P = 0.007, Adj R² = 40.12%) and fasting blood glucose (FBG) (P = 0.040, Adj R² = 29.72%) contributed to between-study heterogeneity.

Conclusions

In conclusion, our study provides evidence that UA levels are higher in patients with DR than those in the controls, but this difference is not statistically significant in the early phases. UA might be a potential biomarker for identifying disease severity in patients with DR, rather than predicting the onset of DR among patients with diabetes. However, more prospective and high-quality clinical evidence is required to confirm these present findings.

Systematic Review Registration

https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=297708.

Serum uric acid levels and diabetic kidney disease in patients with type 2 diabetes mellitus: A dose-response meta-analysis

OBJECTIVE

Our study aimed to assess the existing evidence on whether serum uric acid (SUA) levels are associated with diabetic kidney disease (DKD) in patients with type 2 diabetes mellitus (T2DM).

METHODS

We conducted a systematic search of articles up to October 2021 in Medline, Embase, The Cochrane Library and Web of Science that estimated DKD by SUA levels in patients with T2DM. Pooled relative risks with 95% CI were calculated using random effects models RESULTS: A total of eight cohort studies involving 25,741 T2DM patients were included. Meta-analysis showed that compared the highest with the lowest category of SUA level, the summary risk ratios were 2.04 (95%CI 1.43-2.92, P < 0.001). The linear dose-response analysis revealed that the risk of DKD increased by 24% for each 1 mg/dl increase of SUA. The non-linear dose-response analysis also showed a significant relevance between SUA and the risk of DKD in patients with type 2 diabetes mellitus (P < 0.001).

CONCLUSIONS

Serum uric acid is associated with an increased risk of diabetic kidney disease in patients with type 2 diabetes mellitus. Serum uric acid level could be a good indicator for predicting diabetic kidney disease in patients with type 2 diabetes mellitus.

Association between lncRNAs in plasma exosomes and diabetic retinopathy

BACKGROUND

Long noncoding RNA (lncRNA) in plasma exosomes is a potential non-invasive diagnostic biomarker for diabetic retinopathy (DR). However, the changes in plasma exosomal lncRNAs and diagnostic relevance in patients with DR patients remain unclear.

METHODS

A case-control study with type 2 diabetes mellitus (T2DM) and patients with comorbid DR were enrolled, and their clinical information and blood samples were collected. Plasma exosomes were extracted, and the relative expression levels of representative differentially expressed exosomal lncRNAs were determined. A logistic regression model was used to analyze the relationships of DR with relative lncRNA expression and DR-related factors, and receiver operating characteristic (ROC) curve analysis was used to evaluate the value of exosomal lncRNAs for DR diagnosis.

RESULTS

Sixty-two patients with T2DM and sixty-two patients with DR were matched by age, sex, and disease duration. The fasting blood glucose concentration, glycosylated hemoglobin level (HbA_1c), and relative expression of the plasma exosomal lncRNA DLX6-AS1 were significantly higher in the DR group than in the T2DM group, whereas the 2-h C-peptide concentration and relative expression of the lncRNAs PRINS and FAM190A-3 were lower in the DR group. After adjusting for relevant confounders, the fasting blood glucose concentration, HbA_1c level, 2-h C-peptide concentration, and relative expression of lncRNA DLX6-AS1, PRINS, and FAM190A-3 were found to be associated with DR. Both DLX6-AS1 [area under the curve (AUC): 0.658 (0.562-0.754)], PRINS [AUC: 0.798 (0.722-0.873)], and FAM190A-3 [AUC: 0.603 (0.503-0.702)] expression had predictive value for DR diagnosis. The combination of DLX6-AS1 and PRINS yielded an AUC of 0.813 (0.740-0.886). In males, the combination of DLX6-AS1 and PRINS yielded an AUC of 0.860 (0.780-0.940).

CONCLUSION

The fasting blood glucose concentration, HbA_1c level, and exosomal DLX6-AS1 expression were identified as risk factors for DR, whereas the 2-h C-peptide concentration and exosomal PRINS and FAM190A-3 were identified as protective against DR. The combination of exosomal DLX6-AS1 and PRINS had good diagnostic value for DR in the general population and males. More attention should be paid to the role of exosomal PRINS expression as a predictive and diagnostic DR biomarker in females.

Association of Serum Uric Acid With Retinal Capillary Plexus

BACKGROUND

To determine the association between serum uric acid (SUA) and the retinal capillary plexus (RCP) using optical coherence tomography angiography (OCTA).

METHODS

This cross-sectional study evaluated data from August 2019 to January 2020 from participants recruited from the Jidong community (Tangshan, Hebei, China). All participants completed detailed anthropometrical measurements, laboratory tests and comprehensive ophthalmic examinations. We assessed the vessel density in RCP using OCTA. We used multivariable analysis to evaluate the sex-specific association between SUA and RCP after adjusting for confounders.

RESULTS

A total of 2730 participants were included in this study. The mean age of the participants was 44.0 ± 11.6 years, and 1463 (53.6%) were women. The multivariable βs and 95% confidence intervals (CIs) of superficial RCP vessel density in the second through fourth SUA quartiles compared with the lowest SUA quartiles were -0.27 (-0.56 - 0.03), -0.30 (-0.60 - 0.01), and -0.46 (-0.78 - -0.14) (P for trend = 0.007) in men.

CONCLUSIONS

Higher SUA levels were significantly associated with lower RCP vessel density in men. Our findings provide evidence for the detrimental effect of high SUA levels on the retinal microvasculature and imply the importance of modulating SUA to prevent the microvascular alternation especially for men.

Hypouricaemic and nephroprotective effects of Poria cocos in hyperuricemic mice by up-regulating ATP-binding cassette super-family G member 2

CONTEXT

Poria coco F.A.Wolf (Polyporaceae) dispels dampness and promotes diuresis implying hypouricaemic action.

OBJECTIVE

To examine hypouricaemic action of Poria coco.

MATERIALS AND METHODS

Ethanol extract (PCE) was prepared by extracting the sclerotium of P. cocos with ethanol, and the water extract (PCW) was produced by bathing the remains with water. PCE and PCW (50, 100 and 200 mg/kg, respectively) were orally administered to hyperuricemic Kunming mice (n = 8) to examine its hypouricaemic effect. Also, molecular docking was performed.

RESULTS

P. cocos showed excellent hypouricaemic action, decreasing the serum uric acid of hyperuricaemia (HUA) control (526 ± 112 μmol/L) to 178 ± 53, 153 ± 57 and 151 ± 62 μmol/L (p < 0.01) by PCE and 69 ± 23, 63 ± 15 and 62 ± 20 μmol/L (p < 0.01) by PCW, respectively. According to SCrs, BUNs and H&E staining, PCE and PCW partially attenuated renal dysfunction caused by HUA. They presented no negative effects on ALT, AST and ALP activities. They elevated ABCG2 (ATP-binding cassette super-family G member 2) mRNA and protein expression in comparison to HUA control. In molecular docking, compound 267, 277, 13824, 15730 and 5759 were predicted as the top bioactives of P. cocos against HUA, which even presented better scores than the positive compound, oestrone 3-sulfate.

DISCUSSION AND CONCLUSIONS

This paper demonstrated the hypouricaemic and nephroprotective effects of P. cocos in hyperuricemic mice by up-regulating ABCG2. These results may be useful for the development of a hypouricaemic agent.

Higher Serum Uric Acid Levels Are Associated With an Increased Risk of Vision-Threatening Diabetic Retinopathy in Type 2 Diabetes Patients

Purpose

To investigate the association between serum uric acid (SUA) levels and vision-threatening diabetic retinopathy (VTDR) in patients with type 2 diabetes.

Methods

This cross-sectional study evaluated 3481 patients with type 2 diabetes from four communities in China between 2016 and 2019. VTDR was defined as severe nonproliferative, proliferative diabetic retinopathy, or clinically significant macular edema evaluated by fundus photography and optical coherence tomography. Potential association between SUA and VTDR was examined using multivariable logistic regression. Sub-group analyses based on sex were constructed.

Results

A total of 305 participants had VTDR. Both higher SUA (odds ratio [OR], 1.22 per 100 µmol/L; 95% confidence interval [CI], 1.04–1.44; P = 0.013) and hyperuricemia (OR, 1.47; 95% CI, 1.07–2.04; P = 0.019) were positively associated with VTDR after adjustment for relevant covariates. Compared with those in the lowest SUA quartile, participants in the third (OR, 1.60; 95% CI, 1.07–2.39; P = 0.022) and fourth (OR, 2.05; 95% CI, 1.37–3.08; P = 0.001) sex-specific SUA quartiles showed a significantly increased risk of VTDR after adjustment. No sex-related difference was observed.

Conclusions

Higher SUA levels were associated with an increased risk of VTDR in patients with type 2 diabetes in both sexes, although females seemed to be more sensitive to high SUA than males. Prospective cohort studies are needed to verify SUA as a biomarker for predicting the risk of VTDR. Whether decreased SUA levels could decrease the risk of VTDR also requires further investigation.

Identification of two novel subgroups in patients with diabetes mellitus and their association with clinical outcomes: A two-step cluster analysis

Aims/Introduction

The aim of this study was to determine whether distinct subphenotypes of patients with type 2 diabetes in the European classification exist in Chinese populations, and to further establish novel subphenotypes more suitable for Chinese populations.

Material and Methods

The research retrospectively analyzed 5414 patients with type 2 diabetes from the National Clinical Research Center for Metabolic Diseases Diabetes Center in China, and a two‐step cluster analysis was carried out. First, we confirmed the European classification in Chinese populations by six parameters, including age at disease onset, body mass index, glycosylated hemoglobin, homeostatic model assessment 2 to estimate β‐cell function and insulin resistance, and glutamate decarboxylase antibodies. Furthermore, triglycerides and uric acid were added to refine the cluster analysis, and Cox regression was used to evaluate the risk of diabetic complications.

Results

Just three clusters were replicated in our cohort according to Emma Ahlqvist's European classification. When other variables were added to the cluster analysis, seven subgroups were identified, including five clusters of the European classification and two novel subgroups, namely, uric acid‐related diabetes and inheritance‐related diabetes. Compared with patients with inheritance‐related diabetes, patients with severe insulin‐resistant diabetes showed a higher risk of diabetic peripheral neuropathy, hypertension and chronic kidney disease, and the uric acid‐related diabetes subgroup showed a higher risk of coronary heart disease, cerebral vascular disease and end‐stage renal disease. Patients with severe insulin‐deficient diabetes showed a higher risk of diabetic retinopathy and diabetic foot than those with inheritance‐related diabetes. Furthermore, there were sex‐specific associations between subgroups and clinical outcomes. No significant difference was observed in the prevalence of cancer in each subgroup.

Conclusions

Seven subgroups of type 2 diabetes were identified in Chinese populations, with distinct characteristics and disparate clinical outcomes. This etiology‐based stratification might contribute to the diagnosis and management of type 2 diabetes.

The Effect of Low and Moderate Exercise on Hyperuricemia: Protocol for a Randomized Controlled Study

BACKGROUND

Hyperuricemia (HUA) is a metabolic disease by purine metabolism disorders. It is a risk factor for many chronic diseases, including diabetes, hypertension, and heart disease. Studies have shown that exercise can effectively reduce serum uric acid (SUA), but the optimal exercise dose, intensity, and mode of exercise for improving HUA have not been verified in clinical studies. Therefore, this study aims to explore the effect of different exercise intensities in improving SUA of patients with HUA.

METHODS AND ANALYSIS

A randomized, single-blind, parallel controlled trial will be conducted in this study. 186 HUA patients who meet the inclusion criteria will be randomly divided into a 1:1:1 ratio (1): control group (2), low-intensity exercise group (brisk walking, 57-63% maximum heart rate, 150 min/week, 12 months), and (3) moderate-intensity exercise group (jogging, 64-76% maximum heart rate, 150 min/week, 12 months). The three groups of subjects will receive the same health education and prohibition of high-purine diet during the intervention period. The primary outcomes will be SUA concentration, SUA concentration change (mg/dL), SUA change rate (%), and the proportion of HUA patients. Secondary outcomes will include anthropometric parameters (body weight, waist circumference, hip circumference, BMI); physiological indicators (blood pressure, grip, vital capacity, maximum oxygen); biochemical indicators (blood lipid, blood sugar, liver enzyme, creatinine, and blood urea nitrogen). Each group of patients will go through an assessment at baseline, 3rd, 6th, and 12th months.

DISCUSSION

This study will evaluate the effect of 12-month low-intensity exercise and moderate-intensity exercise on HUA patients. We hypothesize that both low-intensity and moderate-intensity exercise would improve HUA as compared with no-exercise control, and that moderate-intensity exercise would be more effective than low-intensity exercise in improving HUA. These results can provide a basis for the current physical activity guidelines for HUA's healthy lifestyle management.

ETHICS AND DISSEMINATION

This study has been approved by the Ethical Review Committee of the Shanghai University of Sport (approval number: 102772020RT005). Informed consent will be obtained from all participants or their guardians. The authors intend to submit the study findings to peer-reviewed journals or academic conferences to be published.

CLINICAL TRIAL REGISTRATION

Chinese Clinical Trial Registry, identifier ChiCTR2100042643.

Serum uric acid is independently associated with diabetic nephropathy but not diabetic retinopathy in patients with type 2 diabetes mellitus

BACKGROUND

This study aims to investigate the relationship between serum uric acid (SUA) and the severity of diabetic nephropathy (DN) and diabetic retinopathy (DR) in patients with type 2 diabetes mellitus (T2DM).

METHODS

A total of 2961 patients were enrolled in the present cross-sectional study. The severity of DN was determined by 24-hour urinary albumin excretion (UAE), which was classified as normal (UAE <30 mg/24 h), microalbuminuria (UAE: 30-299 mg/24 h), and macroalbuminuria (≥300 mg/24 h). The severity of DR was determined by non-mydriatic retinal photography and was classified as non-diabetic retinopathy (NDR), non-proliferative diabetic retinopathy (NPDR), and proliferative DR (PDR).

RESULTS

Patients with high SUA levels (≥420 μmol/L for males and ≥360 μmol/L for females) had a significantly higher prevalence of DN (UAE ≥30 mg/24 h, 39.3% vs 26.3%; p < 0.001), higher UAE levels (140 ± 297 vs 63 ± 175 mg/24 h; p < 0.001), and lower estimated glomerular filtration rate (eGFR; 79.3 ± 26.8 vs 96.8 ± 19.6 mL/min/1.73 m; p < 0.001), when compared with patients with normal SUA levels. However, the prevalence of DR, NPDR, or PDR did not differ. Furthermore, the concentration of SUA was higher in patients with higher severity of DN (all, p < 0.001) and patients with PDR (compared with NDR or NPDR, p < 0.05). SUA levels were positively associated with male gender, body mass index, the use of diuretics, triglyceride, low-density lipoprotein, and UAE levels, whereas they were negatively correlated with high-density lipoprotein, fasting blood glucose, glycosylated hemoglobin, and eGFR. After adjustment, SUA remained significantly associated with UAE (r = 0.069, p < 0.001).

CONCLUSION

For patients with T2DM, higher SUA levels are associated with higher UAE, lower eGFR, and higher prevalence of DN, but not DR.

A U-shaped association between serum uric acid with all-cause mortality in normal-weight population

BACKGROUND

It is uncertain how serum uric acid (SUA) associated with all-cause mortality among people with normal weight, hence was explored in this study.

METHODS

We enrolled participants from 1999 to 2006 National Health and Nutrition Examination Survey (NHANES) that had mortality status through 31 December 2015. We estimated adjusted hazard ratios (HRs) and 95% confidence intervals (CI) for all-cause mortality using Cox proportional hazard models, and propensity score analyses were performed. We also performed restricted cubic splines to demonstrate the nonlinear relationship, and used subgroup analysis to examine the effect modification.

RESULTS

We enrolled 6169 participants (2905 men and 3264 women, mean age 42.3 ± 21.4 years) and 1060 (17.2%) cases of all-cause mortality occurred during the mean follow-up of 11.9 years. When using the lowest quartile of SUA as referent, the multivariable HRs for all-cause mortality increased in not parallel with the quartiles of SUA (HRs were 0.92 (95%CI: 0.68, 1.23), 1.10 (95%CI: 0.82, 1.47), and 1.08 (95%CI: 0.80, 1.45) from the second to the fourth quartiles, respectively. When treating SUA as continuous variable, the HRs for all-cause mortality were 1.07 (95%CI: 1.00, 1.15; P = 0.046), 1.03 (95%CI: 0.94, 1.12; P = 0.518) and 1.15 (95%CI: 1.01, 1.31; P = 0.032) in all population, male and female subjects, respectively. Elevated SUA was associated with all-cause mortality and the propensity scores analysis showed the similar results. Subgroup analysis showed SUA was an independent risk of all-cause mortality in female (HR1.17, 95%CI: 1.05, 1.31, P = 0.005), people aged <60 years (HR1.18, 95%CI: 1.03, 1.35, P = 0.018), non-diabetic population (HR1.10, 95%CI: 1.02, 1.18, P = 0.017) and people with eGFR<90 (HR1.10, 95%CI: 1.02, 1.19, P = 0.016). Smoothing spline plots suggested the optimal SUA for the lowest risk of all-cause mortality was approximately 4.7 mg/dl.

CONCLUSION

In normal-weight population, SUA was seemed to be a U-shaped relationship with all-cause mortality.

Different associations between serum urate and diabetic complications in men and postmenopausal women

AIMS

The objective of this study was to investigate the different associations of the serum urate (SUA) level with cardiovascular and cerebrovascular diseases (CVD), diabetic kidney disease (DKD) and diabetic retinopathy (DR) in Chinese adults.

METHODS

We analyzed 4767 participants out of 4813 adults with diabetes enrolled from seven communities in a cross-sectional survey. Participants underwent several medical examinations, including the measurement of anthropometric factors, blood pressure, SUA, glucose, lipid profiles, urine albumin/creatinine ratio (ACR) and fundus photographs.

RESULTS

Compared with the first SUA tertile, the third tertile increased the prevalence of CVD by 22% (OR 1.22; 95% CI 1.01, 1.46) (P for trend <0.05) and increased the prevalence of DKD by 59% (OR 1.59; 95% CI 1.28, 1.97) for KDOQI definition. Compared with the first tertile, the OR (95% CI) of the number of diabetic complications, ranging from 0 to 2, associated with SUA level in ordinal logistic regression was 1.75 (1.44, 2.12) for the third tertile (P for trend <0.01). These associations were all fully adjusted. No association was found between the prevalence of DR and the SUA level.

CONCLUSIONS

A higher SUA level was associated with an increased prevalence of CVD and DKD and a variety of diabetic complications, other than DR, in men and postmenopausal women with T2DM. However, the causation remains to be demonstrated.

Total Bilirubin Predicts Severe Progression of Diabetic Retinopathy and the Possible Causal Mechanism

Early detection and treatment are key to delaying the progression of diabetic retinopathy (DR), avoiding loss of vision, and reducing the burden of advanced disease. Our study is aimed at determining if total bilirubin has a predictive value for DR progression and exploring the potential mechanism involved in this pathogenesis. A total of 540 patients with nonproliferative diabetic retinopathy (NPDR) were enrolled between July 2014 and September 2016 and assigned into a progression group (N = 67) or a stable group (N = 473) based on the occurrence of diabetic macular edema (DME), vitreous hemorrhage, retinal detachment, or other conditions that may cause severe loss of vision following a telephonic interview in August 2019. After further communication, 108 patients consented to an outpatient consultation between September and November 2019. Our findings suggest the following: (1) TBIL were significant independent predictors of DR progression (HR: 0.70, 95% CI: 0.54-0.89, p = 0.006). (2) Examination of outpatients indicated that compared to stable group patients, progression group patients had more components of urobilinogen and LPS but a lower concentration of TBIL. The relationship between bilirubin and severe DR was statistically significant after adjusting for sex, age, diabetes duration, type of diabetes, FPG, and HbA1c (OR: 0.70, 95% CI: 0.912-0.986, p = 0.016). The addition of serum LPS and/or urobilinogen attenuated this association. This study concludes that total bilirubin predicts an increased risk of severe DR progression. Decreasing bilirubin might be attributed to the increased levels of LPS and urobilinogen, which may indicate that the change of bilirubin levels is secondary to intestinal flora disorder and/or intestinal barrier destruction. Further prospective investigations are necessary to explore the causal associations for flora disorder, intestinal barrier destruction, and DR.

Rubeosis faciei diabeticorum is not associated with oxidative stress and skin autofluorescence

Background

Rubeosis faciei diabeticorum is a persistent facial erythema in patients with diabetes mellitus. The actual pathogenesis has not been studied. However, it is speculated to be a cutaneous diabetic microangiopathy.

Objective

Examine the correlation between the severity of facial erythema and the possible causes of microvascular diabetic complications, namely oxidative stress, hyperglycemia, and cutaneous accumulation of advanced glycation end-products .

Methods

Patients diagnosed with Type 2 diabetes mellitus (n = 32) were enrolled in the study. The facial erythema index was measured using the Mexameter MX18; cutaneous accumulation of advanced glycation end-products was estimated by measuring skin auto fluorescence with the AGE Reader (DiagnOptics Technologies B.V. – Groningen, Netherlands). Glycated haemoglobin, total antioxidant status, and malondialdehyde were measured in blood by TBARS assay. The correlation between the selected variables was assessed by Spearman's rank test; p ≤ 0.05 was considered statistically significant.

Results

There was a statistically significant correlation between total antioxidant status and the facial erythema index (ρ = 0.398, p = 0.024). Malondialdehyde, skin autofluorescence, glycated haemoglobin, body mass index, duration of diabetes, and age did not demonstrate statistically significant correlation with the facial erythema index.

Study limitations

This is an observational study. Elevation of total antioxidant status could have been caused by several factors that might have also influenced the development of rubeosis faciei, including hyperbilirubinemia and hyperuricemia.

Conclusions

The results contradicted expectations. Total antioxidant status correlated positively with facial erythema index; however, there was no correlation with oxidative stress and skin autofluorescence. Further investigations should be conducted to reveal the cause of total antioxidant status elevation in patients with rubeosis faciei.

Hyperuricaemia is associated with dyslipidemia but not HbA1c among type 2 diabetes mellitus patients in Botswana

Medical records and residual samples from 334 type 2 diabetes mellitus patients attending a clinic in Gaborone, Botswana, during the period September–December 2016 were analysed for the effects of hyperuricaemia on biochemical markers of adverse outcomes. The patients were stratified as having hyperuricaemia (> 400 µmol/L) or normal serum uric acid (≤ 400 µmol/L). We compared glycated haemoglobin, triglycerides, low-density lipoprotein-cholesterol, high-density lipoprotein-cholesterol, total cholesterol and serum creatinine between the two serum uric acid categories. Hyperuricaemia was detected in 28% of patients (95% confidence interval 23.1–32.9) and was associated with increased serum triglycerides, triglyceride to high-density lipoprotein-cholesterol ratio and creatinine concentration, but not with glycated haemoglobin.

Effects of Uric Acid on Diabetes Mellitus and Its Chronic Complications

With the deepening of the researches on uric acid, especially in the study of metabolic diseases, uric acid has been found to be closely related to obesity, metabolic syndrome, nonalcoholic fatty liver disease, diabetes, and other metabolic diseases. Uric acid causes a series of pathophysiological changes through inflammation, oxidative stress, vascular endothelial injury, and so on and thus subsequently promotes the occurrence and development of diseases. This review confirmed the positive correlation between uric acid and diabetes mellitus and its chronic complications through the pathogenesis and clinical studies aspects.

Current epidemiology of diabetic retinopathy in patients with type 1 diabetes: a national multicenter study in Brazil

BACKGROUND

Diabetic retinopathy is the leading cause of blindness in economically active populations. The aims of this study were to estimate the prevalence and to identify risk factors for diabetic retinopathy in patients with type 1 diabetes in Brazil.

METHODS

This was a nationwide, cross-sectional study conducted between August 2010 and August 2014. The study included 1760 patients with type 1 diabetes. Patients underwent a standard questionnaire, clinical and laboratory analyses and were screened for diabetic retinopathy. To analyze the risk factors related to diabetic retinopathy, two models of logistic regression models were performed, one considering vision-threatening cases and the other with any diabetic retinopathy cases as dependent variables. The group with vision-threatening included patients with severe non-proliferative diabetic retinopathy, proliferative diabetic retinopathy and macular edema.

RESULTS

In total, 1644 patients (mean age, 30.1± 12.0 years; duration of diabetes, 15.3 ± 9.3 years; female, 55.8%) were studied. 35.7% presented diabetic retinopathy and 12% presented vision-threatening diabetic retinopathy. Three risk factors associated with diabetic retinopathy were in common to both groups: longer diabetes duration (OR 1.07; 95% CI, 1.05-1.09), higher levels of HbA1c (OR 1.24; CI, 1.17-1.32) and higher levels of serum uric acid (OR 1.22; CI, 1.13-1.31) (p < 0.001 for all comparisons).

CONCLUSION

The higher rate of vision-threatening retinopathy found in our study highlights the need to improve access to eye care and screening programs for diabetic retinopathy in Brazil. In addition to traditional risk factors, we found an association between serum uric acid levels and diabetic retinopathy. Further studies are needed to address this association.

Hypouricemic Effect of 2,5-Dihydroxyacetophenone, a Computational Screened Bioactive Compound from Ganoderma applanatum, on Hyperuricemic Mice

Searching novel hypouricemic agents of high efficacy and safety has attracted a great attention. Previously, we reported the hypouricemic effect of Ganoderma applanatum, but its bioactives, was not referred. Herein, we report the hypouricemic effect of 2,5-dihydroxyacetophenone (DHAP), a compound screened from Ganoderma applanatum computationally. Serum parameters, such as uric acid (SUA), xanthine oxidase (XOD) activity, blood urea nitrogen (BUN), and creatinine were recorded. Real-time reverse transcription PCR (RT-PCR) and Western blot were exploited to assay RNA and protein expressions of organic anion transporter 1 (OAT1), glucose transporter 9 (GLUT9), uric acid transporter 1 (URAT1), and gastrointestinal concentrative nucleoside transporter 2 (CNT2). DHAP at 20, 40, and 80 mg/kg exerted excellent hypouricemic action on hyperuricemic mice, reducing SUA from hyperuricemic control (407 ± 31 μmol/L, p < 0.01) to 180 ± 29, 144 ± 13, and 139 ± 31 μmol/L, respectively. In contrast to the renal toxic allopurinol, DHAP showed some kidney-protective effects. Moreover, its suppression on XOD activity, in vivo and in vitro, suggested that XOD inhibition may be a mechanism for its hypouricemic effect. Given this, its binding mode to XOD was explored by molecular docking and revealed that three hydrogen bonds may play key roles in its binding and orientation. It upregulated OAT1 and downregulated GLUT9, URAT1, and CNT2 too. In summary, its hypouricemic effect may be mediated by regulation of XOD, OAT1, GLUT9, URAT1, and CNT2.