The effect of uric acid lowering treatment on albuminuria and renal function in Type 1 diabetes: a randomized clinical trial

The Management of Diabetes with Hyperuricemia: Can We Hit Two Birds with One Stone?

Serum urate (SU) is an independent predictor for the incidence of diabetes. In current diabetes treatment regimens, there is insufficient appreciation of the importance of hyperuricemia (HU) in disease control and prevention. To summarize the updated knowledge on the effects of SU on β-cell function, insulin resistance and chronic diabetic complications, as well as to evaluate the management of patients with both HU and diabetes, we searched the MEDLINE PubMed database, and included 285 journal articles. An inverted U-shaped relationship between fasting plasma glucose and SU levels was established in this review. Elevated SU levels may enhance the development of chronic diabetic complications, including macrovascular and microvascular dysfunction. Diet and exercise are essential parts of the lifestyle changes necessary for HU and diabetes management. Glucose- and urate-lowering drug selection and combination should be made with the principle of ameliorating, and at least not deteriorating, diabetes and HU. Medical artificial intelligence technology and monitoring systems can help to improve the effectiveness of long-term management of HU and diabetes through digital healthcare. This study comprehensively reviews and provides a scientific and reliable basis for and viewpoints on the clinical management of diabetes and HU.

Effects of allopurinol on renal function in patients with diabetes: a systematic review and meta-analysis

BACKGROUND/OBJECTIVE

Diabetes mellitus is a common "non-gout" disease with high incidence. Several studies have shown that serum uric acid level in patients with diabetes is higher than that in healthy individuals, and is accompanied by severe albuminuria and high serum creatinine (Scr). Recent clinical studies have found that uric acid-lowering therapy (such as allopurinol) could reduce urinary albumin excretion rates (UAER) and Scr, increase eGFR, and thus reduce kidney damage in patients with diabetes. Therefore, this meta-analysis [PROSPERO CRD42021274465] intended to evaluate the efficacy and safety of allopurinol in patients with diabetes mellitus.

METHODS

We thoroughly searched five electronic resource databases for randomized controlled trials (RCTs) that compared the efficacy and safety of allopurinol versus conventional treatment or placebo for the treatment of patients with diabetes mellitus. Predetermined outcomes were considered continuous variables, mean difference (MD) was used for the determination of effect size (standardized mean difference [SMD] was used to determine the effect size when there were different evaluation criteria in different articles), and the corresponding 95% confidence interval (CI) was calculated. All outcome measures were analyzed using a random-effects model for data analysis.

RESULTS

Ten eligible trials with a total of 866 participants were included in the meta-analysis. Allopurinol was more effective in decreasing serum uric acid (SUA) levels compared with conventional treatment (p = 0.0001) or placebo (p < 0.00001). Moreover, the levels of 24-hour urine protein were significantly lower in the allopurinol group (p < 0.00001). The subgroup analysis of Scr showed that the Scr of patients with an allopurinol treatment duration of fewer than six months was significantly lower than that of the control group (p = 0.03). No significant difference in adverse events (AEs) was identified between the treatment and control groups.

CONCLUSIONS

Our meta-analysis of RCTs showed that oral administration of allopurinol effectively reduced SUA levels in patients with diabetes, and patients' renal function was protected. More RCTs with larger sample sizes and higher quality are needed to clarify the role of allopurinol use in decreasing blood pressure, maintaining blood glucose levels, and improving renal function in patients with diabetes.

The Effect of Allopurinol on Renal Outcomes in Patients with Diabetic Kidney Disease: A Systematic Review and Meta-Analysis

BACKGROUND

Hyperuricemia is an independent risk factor for diabetic kidney disease (DKD) progression. Previous animal and cohort studies have reported that allopurinol administration could be of therapeutic benefit in diabetic subjects. However, there has been controversy regarding the effects of allopurinol on DKD.

OBJECTIVES

The aim of our study was to investigate the efficacy of allopurinol on renal function in patients with DKD by meta-analysis of randomized controlled trials.

METHOD

PubMed, EMBASE, and the Cochrane Library were searched from inception to October 2020. The primary outcome was a change in glomerular filtration rate (GFR). The secondary outcome was the change in albuminuria and serum uric acid (UA). Two reviewers independently assessed for risk of bias and extracted data. Standardized mean difference (SMD) or weighted mean difference (WMD) was calculated with random effects models and was reported with corresponding 95% confidence intervals (CIs). Grading of Recommendations Assessment, Development, and Evaluation (GRADE) of the evidence was performed after meta-analysis. International prospective register of systematic reviews registration CRD42020219132.

RESULTS

From 642 potentially relevant citations, 3 studies were ultimately included. Our results showed evident reduction in serum UA after allopurinol intervention (WMD = -103.80, 95% CI -159.05, -48.55, I2 = 76%; p = 0.04), with a high GRADE of evidence. However, allopurinol did not significantly improve GFR (WMD = 1.07, 95% CI -1.68, 3.82, I2 = 33%; p = 0.45), with a moderate GRADE of evidence. There was no significant difference on improvement of albuminuria in patients of allopurinol and those in placebo groups (SMD = -0.26, 95% CI -1.03, 0.52, I2 = 94%; p = 0.52), with a moderate GRADE of evidence.

CONCLUSIONS

The present research showed that allopurinol did not significantly improve renal function and albuminuria in patients with DKD.

Hyperuricemia Predisposes to the Onset of Diabetes via Promoting Pancreatic β-Cell Death in Uricase-Deficient Male Mice

Clinical studies have shown a link between hyperuricemia (HU) and diabetes, while the exact effect of soluble serum urate on glucose metabolism remains elusive. This study aims to characterize the glucose metabolic phenotypes and investigate the underlying molecular mechanisms using a novel spontaneous HU mouse model in which the uricase (Uox) gene is absent. In an attempt to study the role of HU in glycometabolism, we implemented external stimulation on Uox knockout (KO) and wild-type (WT) males with a high-fat diet (HFD) and/or injections of multiple low-dose streptozotocin (MLD-STZ) to provoke the potential role of urate. Notably, while Uox-KO mice developed glucose intolerance in the basal condition, no mice spontaneously developed diabetes, even with aging. HFD-fed Uox-KO mice manifested similar insulin sensitivity compared with WT controls. HU augmented the existing glycometabolism abnormality induced by MLD-STZ and eventually led to diabetes, as evidenced by the increased random glucose. Reduced β-cell masses and increased terminal deoxynucleotidyl TUNEL-positive β-cells suggested that HU-mediated diabetes was cell death dependent. However, urate-lowering therapy (ULT) cannot ameliorate the diabetes incidence or reverse β-cell apoptosis with significance. ULT displayed a significant therapeutic effect of HU-crystal-associated kidney injury and tubulointerstitial damage in diabetes. Moreover, we present transcriptomic analysis of isolated islets, using Uox-KO versus WT mice and streptozotocin-induced diabetic WT (STZ-WT) versus diabetic Uox-KO (STZ-KO) mice. Shared differentially expressed genes of HU primacy revealed Stk17β is a possible target gene in HU-related β-cell death. Together, this study suggests that HU accelerates but does not cause diabetes by inhibiting islet β-cell survival.

Uric acid is not associated with diabetic nephropathy and other complications in type 1 diabetes

BACKGROUND

To examine the association between plasma uric acid (UA) and the presence of diabetic complications including diabetic nephropathy and cardiovascular risk factors in patients with type 1 diabetes.

METHODS

This study, which is cross-sectional in design, included 676 Caucasian type 1 diabetes patients from the Steno Diabetes Center Copenhagen. Participants with UA within the three lowest sex-specific quartiles were compared with participants with levels in the highest quartile. Unadjusted and adjusted linear regression analyses were applied. Adjustment included sex, age, diabetes duration, body mass index, high-density lipoprotein cholesterol, smoking, haemoglobin A1c, 24-h pulse pressure, urinary albumin excretion rate (UAER), estimated glomerular filtration rate (eGFR) and treatment with renin-angiotensin-aldosterone system blockers.

RESULTS

Of the 676 patients, 372 (55%) were male, mean ± SD age was 55 ± 13 years and eGFR was 82 ± 26 mL/min/1.73 m2. The median UA was 0.30 (interquartile range 0.23-0.37) mmol/L. UA in the upper sex-specific quartile was associated with lower eGFR, higher UAER and carotid-femoral pulse wave velocity and lower 24 h and daytime diastolic blood pressure (BP) in unadjusted analyses (P < 0.001). Moreover, UA in the upper sex-specific quartile was associated with higher nighttime systolic BP and the presence of cardiovascular disease in unadjusted analyses (P ≤ 0.01), but significance was lost after adjustment (P ≥ 0.17). UA was higher across the retinopathy groups [nil (n = 142), simplex (n = 277), proliferative (n = 229) and blind (n = 19)] in unadjusted analyses (P < 0.0001), but not after adjustment (P = 0.12). Patients with an accelerated decline in eGFR (≥3 mL/min/year) had significantly higher UA at baseline (P = 0.006) compared with slow decliners (<3 mL/min/year), but significance was lost after adjustment (P = 0.10).

CONCLUSIONS

In type 1 diabetes patients, higher UA was associated with lower kidney function and other diabetic complications. The association between higher UA and lower eGFR and lower diastolic BP was independent of traditional risk factors.

Uric Acid Is an Independent Risk Factor for Decline in Kidney Function, Cardiovascular Events, and Mortality in Patients With Type 1 Diabetes

OBJECTIVE

Previous studies have provided inconclusive results on the role of uric acid (UA) in risk prediction. Here we aimed to improve the power and precision of the predictive value of UA for the risk of decline in kidney function, cardiovascular events (CVEs), and mortality in patients with type 1 diabetes (T1D).

RESEARCH DESIGN AND METHODS

Plasma UA was measured in 670 patients with T1D and various degrees of albuminuria, ranging from normoalbuminuria to macroalbuminuria. Associations of UA with an estimated glomerular filtration rate (eGFR) decline of ≥30%, CVEs, and mortality were analyzed. The median follow-up time was 5.3 years [interquartile range (IQR) 2.7-6.2 years] for a decline in eGFR of ≥30%, 5.8 years (2.5-6.4 years) for progression in albuminuria status, 5.1 years (4.7-5.6 years) for CVE, and 6.2 years (5.8-6.7 years) for mortality. Both univariable and multivariable associations of UA with relevant outcomes and variables were reported. Hazard ratios (HRs) were calculated per doubling of the UA level.

RESULTS

A doubling in UA level was associated with a higher risk of decline in eGFR of ≥30% (n = 89) (HR 3.18 [IQR 1.71-5.93]; P < 0.001), CVE (n = 94) (HR 2.25 [IQR 1.20-4.21]; P = 0.011), and mortality (n = 58) (HR 2.58 [IQR 1.12-5.90]; P = 0.025) in adjusted analyses. Adding UA to the adjusted model including conventional risk factors improved the relative integrated discrimination index by 12.6% for a decline in eGFR of ≥30% (P < 0.001), 6.5% for CVE (P = 0.010), and 11.8% (P = 0.003) for mortality. A doubling in UA level was also associated with a steeper decline in eGFR (P < 0.0026) and a steeper increase in urine albumin-to-creatinine ratio (P < 0.0027) in adjusted analysis.

CONCLUSIONS

In individuals with T1D, a higher UA level is associated with a higher risk of decline in kidney function, CVE, and mortality, independently of other risk factors. Our results suggest that UA has a promising role in risk stratification among individuals with T1D.