Serum uric acid as a predictor of vascular complications in diabetes: an additional case for neuropathy

Serum uric acid and risk of diabetic neuropathy: a genetic correlation and mendelian randomization study

Background

Previous observational studies have indicated an association between serum uric acid (SUA) and diabetic neuropathy (DN), but confounding factors and reverse causality have left the causality of this relationship uncertain.

Methods

Univariate Mendelian randomization (MR), multivariate MR and linkage disequilibrium score (LDSC) regression analysis were utilized to assess the causal link between SUA and DN. Summary-level data for SUA were drawn from the CKDGen consortium, comprising 288,648 individuals, while DN data were obtained from the FinnGen consortium, with 2,843 cases and 271,817 controls. Causal effects were estimated primarily using inverse variance weighted (IVW) analysis, supplemented by four validation methods, with additional sensitivity analyses to evaluate pleiotropy, heterogeneity, and result robustness.

Results

The LDSC analysis revealed a significant genetic correlation between SUA and DN (genetic correlation = 0.293, P = 2.60 × 10-5). The primary methodology IVW indicated that each increase of 1 mg/dL in SUA would increase DN risk by 17% (OR = 1.17, 95% CI 1.02-1.34, P = 0.02), while no causal relationship was found in reverse analysis (OR = 1.00, 95% CI 0.98~1.01, P = 0.97). Multivariate MR further identified that the partial effect of SUA on DN may be mediated by physical activity, low density lipoprotein cholesterol (LDL-C), insulin resistance (IR), and alcohol use.

Conclusion

The study establishes a causal link between elevated SUA levels and an increased risk of DN, with no evidence for a reverse association. This underscores the need for a comprehensive strategy in DN management, integrating urate-lowering interventions with modulations of the aforementioned mediators.

The Ratio of Serum Uric Acid to Glycosylated Haemoglobin as a Predictor of All-Mortality in Elderly Patients with Diabetic Foot Ulcers: A Longitudinal Cohort Study

Aim

To clarify the relationship between serum uric acid (UA) and glycosylated hemoglobin (UA/HbA1c) ratio and all-cause mortality in patients with diabetic foot ulcers (DFUs).

Methods

A total of 172 inpatients with DFUs (PEDIS grades 2-4) were eligible for inclusion in this study from 2018 to 2023. This was a retrospective, longitudinal cohort study. All subjects were followed up every 6 months for a median of 60 months. According to the cutoff value of the UA/HbA1c ratio of 39.07 obtained from ROC analysis, the participants were divided into two groups: low-level (≤ 39.07, n = 107) and high-level (> 39.07, n = 65) groups. The correlation between UA/HbA1c ratio and all-cause mortality was also evaluated by Cox regression analysis TheKaplan-Meier survival curve analysis and Log rank tests were used to assess the incidence rates of all-cause mortality. The contribution rate of risk factors was estimated by the population-attributable risk percentage (PAR%) analysis.

Results

ROC analysis showed that the optimal cutoff values for UA and the UA/HbA1c ratio were 372 μmol/L and 39.07, respectively. Multivariate Cox regression analysis indicated that a high UA/HbA1c ratio (HR =4.63; 95% CI = 2.004-10.7, P < 0.001) was independently associated with a high risk of all-cause mortality in patients with DFUs. Stratified analysis indicated that subjects aged ≥ 60 years had a greater risk of all-cause mortality associated with a high UA/HbA1c ratio (HR = 4.450; 95% CI = 1.711-11.574, P = 0.002). Kaplan-Meier survival analysis showed that all-cause mortality had a significant positive association with a high UA/HbA1c ratio (log-rank, P < 0.001) and a significant negative correlation with the lowered HbA1c level (< 6.5%) after a follow-up of 32 months (log-rank, P < 0.001). The population attributable risk percentage (PAR%) analysis suggested that the contribution rate of the high-level UA/HbA1c ratio to all-cause mortality was 33.7%, which was much greater than the 19.69% of UA.

Conclusion

In brief, our study showed that for every 1.0% increase in the UA/HbA1c ratio, the all-cause mortality rate in elderly patients with DFUs aged ≥ 60 years increased by 3.45-fold. For elderly patients with DFUs, a safe and effective strategy to reduce all-cause mortality is to strictly control serum UA levels to < 372 μmol/L and appropriately loosen the control goal of HbA1c to ≥ 6.5%.

Serum Uric Acid and Diabetes: From Pathophysiology to Cardiovascular Disease

Hyperuricemia, has been traditionally related to nephrolithiasis and gout. However, it has also been associated with the development of type 2 diabetes mellitus (T2DM) and cardiometabolic and cardiovascular diseases. Pathophysiologically, elevated serum uric acid (SUA) levels may be associated with abnormal lipid and glucose metabolism. In this narrative review, we consider the associations between hyperuricemia, hyperglycemia, atherosclerosis and thrombosis. Furthermore, we comment on the available evidence linking elevated SUA levels with the incidence and outcomes of coronary heart disease, stroke, peripheral artery disease and non-alcoholic fatty liver in subjects with T2DM. The effects of antidiabetic drugs (e.g. metformin, pioglitazone, sulfonylureas, dipeptidyl peptidase 4 inhibitors, glucagon-like peptide-1 receptor agonists, sodium-glucose cotransporter 2 inhibitors and insulin) on SUA concentrations are also reviewed.

Α higher ratio of serum uric acid to serum creatinine could predict the risk of total and cause specific mortality- insight from a US national survey

INTRODUCTION

The link between serum uric acid to serum creatinine ratio (SUA/SCr) and mortality has not been studied yet.

METHODS

We prospectively evaluated the association between SUA/SCr and risk of total and cause specific [cardiovascular disease (CVD) and cancer] mortality by applying on the National Health and Nutrition Examination Surveys (NHANES, 1999-2010). Vital status through December 31, 2011 was ascertained. Adjusted Cox proportional hazard regression models were performed to determine the links between SUA/SCr and mortality.

RESULTS

Overall, 20,209 individuals were included (mean age = 47.5 years, 48.9% men) and 3523 deaths occurred during the 76.4 months of follow-up. In a fully adjusted model, individuals in the fourth (Q4) and third (Q3) quartile of SUA/SCr had a 44 and 35% greater risk of total mortality [risk ratio (RR): 1.44 (95% confidence interval, 95%CI: 1.05-1.98) and 1.35 (1.10-1.66), respectively], as well as a 69 and 47% higher risk of CVD death [RR: 1.69 (1.09-2.62) and 1.47 (1.14-1.89), respectively] compared with the lowest (Q1) quartile. With regard to SUA/SCr and cancer mortality, a significant association was found only between participants in Q4 and those in Q1 [RR: 1.12 (1.06-1.19)] in the partially adjusted model, whereas this relationship became non-significant after further adjustments [RR: 1.15 (0.96-1.39)].

CONCLUSIONS

This is the first time that SUA/SCr has been associated with total and cause specific mortality in a large, representative sample of US adults. Further studies are needed to confirm these findings and establish their clinical implications.

Mean platelet volume and coronary artery disease

PURPOSE OF REVIEW

To critically review the literature describing links between mean platelet volume (MPV) and cardiovascular disease (CVD). We will focus on coronary artery disease (CAD). The MPV is measured routinely as part of a routine blood count.

RECENT FINDINGS

There is accumulating evidence showing that the MPV may predict CVD, as well as outcomes in patients with CAD. There is also evidence linking MPV and comorbidities (e.g. diabetes mellitus and impaired glycaemic control) that are expected in patients with CAD. The effect on MPV of drugs commonly used to treat CAD has not been clarified, but there is some evidence that they may exert a beneficial effect on the MPV. More specifically, the MPV may predict the effect of antiplatelet drugs (e.g. clopidogrel). There is also evidence relating MPV to stroke, atrial fibrillation, coronary artery ectasia and periprocedural outcomes after percutaneous coronary intervention (PCI).

SUMMARY

Measuring the MPV may prove useful in CVD risk assessment in patients with established CAD or at risk of developing CAD. Overall, there is evidence pointing to the role of MPV as a contributor rather than simple marker of CVD.

WITHDRAWN: Α higher ratio of serum uric acid to serum creatinine could predict the risk of total and cause specific mortality - Insight from a US national survey

This article has been withdrawn at the request of the Publisher. The Publisher apologizes for any inconvenience this may cause. The full Elsevier Policy on Article Withdrawal can be found at https: //www.elsevier.com/about/our-business/policies/article-withdrawal.

Association between serum uric acid and large-nerve fiber dysfunction in type 2 diabetes: a cross-sectional study

Background

Large-nerve fiber dysfunction, as assessed by vibration perception threshold (VPT) predicts risks of ulceration, amputation, and mortality in diabetes. Serum uric acid (UA) is closely associated with various metabolic disorders, especially diabetes. Thus, we sought to investigate the clinical relevance of UA to large-nerve fiber dysfunction, among patients with type 2 diabetes (T2D).

Methods

Medical records of consecutive patients with T2D who were admitted to Beijing Friendship Hospital Pinggu Campus between May 2014 and December 2016 were collected. Data for the 824 eligible patients included in the final analysis were extracted using a structured form. A VPT value ≥15 in either foot was defined as abnormal. We compared the clinical characteristics between patients with abnormal VPT and those with normal VPT (VPT value <15 in both feet) in the overall population and in gender subgroups. Logistic regression analysis was performed to explore the association of abnormal VPT with UA level. One-way analysis of variance was used to compare VPT values across four UA quartiles.

Results

UA levels were significantly lower in T2D patients with abnormal VPT than in those with normal VPT (294.5 ± 84.0 vs. 314.9 ± 92.8 μmol/L, P < 0.01), especially among male patients (311.7 ± 85.2 vs. 336.9 ± 89.6 μmol/L, P < 0.01). From the logistic regression analysis, hyperuricemia (males >420 μmol/L; females >360 μmol/L) was associated with a reduced risk of abnormal VPT (odds ratio [OR], 0.60; 95% confidence interval [CI], 0.39–0.91; P < 0.05). This association was robust in male patients (OR, 0.43; 95% CI, 0.24–0.76; P < 0.01) but not in female patients (OR, 0.92; 95% CI, 0.47–1.82; P = 0.816), even after adjustment for confounding factors. For the younger male subgroup (age <65 years), VPT values decreased as the UA level increased (P for trend = 0.002), but this trend was not significant in older male subgroup (age ≥65 years; P for trend = 0.400).

Conclusions

Low serum UA levels showed a significant association with an increased risk of large-nerve fiber dysfunction in male patients with T2D, but not in female patients with T2D. In addition, in only the younger subgroup of male patients (<65 years), lower levels of UA also correlated with higher VPT values.

Association of ideal cardiovascular health metrics with serum uric acid, inflammation and atherogenic index of plasma: A population-based survey

BACKGROUND AND AIMS

We aimed to evaluate the link between inflammatory score [consisting of C-reactive protein (CRP) and white blood cells], serum uric acid (SUA) and atherogenic index of plasma (AIP) and the cardiovascular health (CVH) score.

METHODS

We used the cross-sectional National Health and Nutrition Examination Survey database. Statistical analyses accounted for the survey design and sample weights.

RESULTS

Overall, there were 23,004 participants (mean age = 47.2 years, 46.5% males). Participants with an ideal CVH level had the highest ratio of poverty to income (3.62%, p < 0.001), as well as lower levels of CRP, SUA and AIP (p < 0.001 for all comparisons). In adjusted linear regression, a significant negative association was observed between inflammatory score (β = -0.052, p < 0.001), SUA (β = -0.041, p < 0.001) and AIP (β = -0.039, p < 0.001) and CVH score, i.e. participants with a better (greater) CVH score had a lower inflammatory score. Results from adjusted logistic regression showed reduction in the likelihood of "high-risk atherosclerosis" (defined as AIP ≥0.21) [intermediate: odds ratio (OR) = 0.90, 95% confidence interval (CI):0.85-0.95, ideal: OR = 0.81, 95%CI: 0.74-0.88] and "high CVD risk" (defined as CRP ≥3 mg/l) [intermediate: OR = 0.86, 95%CI:0.73-0.98, ideal: OR = 0.82, 95%CI:0.69-0.95] across the categories of CVH.

CONCLUSIONS

Our findings highlight that CVH metrics were associated with inflammatory score, SUA and AIP. Furthermore, participants with a better CVH score had a lower CVD risk. These results reinforce the importance of implementing healthy behaviours as proposed by the American Heart Association. If confirmed in clinical trials, this knowledge may have implications for CVD prevention and management.

The relationships among hyperuricemia, body mass index and impaired renal function in type 2 diabetic patients

Chronic kidney disease (CKD) is a common chronic microvascular complication and the major cause of death in diabetic patients. This study was conceived to explore the possible mechanisms of how hyperuricemia and obesity contribute to renal function impairment in type 2 diabetic (T2DM) patients. A cross-sectional study in 609 participants recruited from a T2DM population in North China was conducted. The multiplicative interaction between body mass index (BMI) and uric acid (UA) level was assessed using an interaction term in a logistic regression analysis. Our results indicate that male T2DM patients having higher BMI (OR 1.711, p = 0.038), blood urine nitrogen (BUN) (OR 1.100, p = 0.034), and 24-hour urinary micro-albumin levels (OR 1.004, p = 0.021) were much more likely to have high UA. Whereas, for female T2DM patients, the OR of BMI, BUN, and triglyceride were 1.169 (p = 0.001), 1.337 (p = 0.000), and 1.359 (p = 0.006), respectively. In this study population, obesity and elevated UA work together to increase the risk of renal injury. In vitro experiments indicate that reactive oxygen species (ROS) production increased with UA treatment in human renal glomerular endothelial cells (HRGECs), while endothelial nitric oxide synthase (eNOS) production level dropped. UA also increased monocyte chemotactic protein-1 (MCP-1) expression and nuclear factor kappa B (NF-κB) activation. Taken together, our results indicate that high concentrations of UA lead to endothelial dysfunction through the activation of the inflammatory response and induction of oxidative stress, even in non-obese T2DM patients.

The association and interaction analysis of hypertension and uric acid on cardiovascular autonomic neuropathy

BACKGROUND

The purpose of this study was to evaluate associations among hypertension (HTN) and uric acid (UA) with cardiovascular autonomic neuropathy (CAN), and to estimate the extent to which synergistic effects of HTN and UA affect the outcome in a Chinese population.

METHOD

We conducted a large-scale, population-based study to analyze the association and interaction of the two factors for CAN in a sample of 2092 Chinese people. Univariate and multiple linear regression (MLR) analysis were employed to detect these relationships. Interaction on an additive scale can be calculated by using the relative excess risk due to interaction (RERI), the proportion attributable to interaction (AP), and the synergy index (S).

RESULT

After adjusting for confounding factors, MLR showed that HTN was independently associated with CAN (P < 0.001). A significant interaction effect of UA and HTN on CAN was detected (P = 0.035; RETI = 1.483, 95 % CI 0.415-2.551; AP = 0.360, 95 % CI -0.043 to 0.76 and S = 1.908, 95 % CI 0.152-3.66).

CONCLUSION

Our findings suggest that HTN is independently and significantly associated with CAN and offer evidence to support the hypothesis that HTN and UA have interaction effects to influence the progression of CAN.

Small-Fiber Neuropathy: A Diabetic Microvascular Complication of Special Clinical, Diagnostic, and Prognostic Importance

Damage of small nerve fibers may lead to a large variety of clinical symptoms. Small-fiber neuropathy underlies the symptoms of painful diabetic neuropathy, which may decrease quality of life. It also contributes to the poor prognosis of diabetic neuropathy because it plays a key role in the pathogenesis of foot ulceration and autonomic neuropathy. Impairment of small nerve fibers is considered the earliest alteration in the course of diabetic neuropathy. Therefore, assessment of functional and morphological abnormalities of small nerve fibers may enable timely diagnosis. The definition, symptoms, and clinical significance of small-fiber neuropathy are considered in the present review. An apparently more complex interaction between small-fiber impairment and microcirculation is extensively discussed. Diagnostic modalities include morphometric and functional methods. Corneal confocal microscopy and punch skin biopsy are considered gold standards, but noninvasive functional tests are also diagnostically useful. However, in routine clinical practice, small-fiber neuropathy is diagnosed by its typical clinical presentation. Finally, prompt treatment should be initiated following diagnosis.