Allopurinol and Renal Outcomes in Adults With and Without Type 2 Diabetes: A Retrospective, Population-Based Cohort Study and Propensity Score Analysis

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.

Excess comorbidities in gout: the causal paradigm and pleiotropic approaches to care

Gout is a common hyperuricaemic metabolic condition that leads to painful inflammatory arthritis and a high comorbidity burden, especially cardiometabolic-renal (CMR) conditions, including hypertension, myocardial infarction, stroke, obesity, hyperlipidaemia, type 2 diabetes mellitus and chronic kidney disease. Substantial advances have been made in our understanding of the excess CMR burden in gout, ranging from pathogenesis underlying excess CMR comorbidities, inferring causal relationships from Mendelian randomization studies, and potentially discovering urate crystals in coronary arteries using advanced imaging, to clinical trials and observational studies. Despite many studies finding an independent association between blood urate levels and risk of incident CMR events, Mendelian randomization studies have largely found that serum urate is not causal for CMR end points or intermediate risk factors or outcomes (such as kidney function, adiposity, metabolic syndrome, glycaemic traits or blood lipid concentrations). Although limited, randomized controlled trials to date in adults without gout support this conclusion. If imaging studies suggesting that monosodium urate crystals are deposited in coronary plaques in patients with gout are confirmed, it is possible that these crystals might have a role in the inflammatory pathogenesis of increased cardiovascular risk in patients with gout; removing monosodium urate crystals or blocking the inflammatory pathway could reduce this excess risk. Accordingly, data for CMR outcomes with these urate-lowering or anti-inflammatory therapies in patients with gout are needed. In the meantime, highly pleiotropic CMR and urate-lowering benefits of sodium-glucose cotransporter 2 (SGLT2) inhibitors and key lifestyle measures could play an important role in comorbidity care, in conjunction with effective gout care based on target serum urate concentrations according to the latest guidelines.