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

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.

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.

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.

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.