Associations between urate-lowering therapy and the risk of type 2 diabetes mellitus

Background Gout is independently associated with increased risk of type 2 diabetes mellitus (T2DM). Urate-lowering therapy (ULT) might be beneficial in lowering the risks of T2DM. Therefore, we conducted a nested case-control study to evaluate the associations between ULT and T2DM. Methods This study retrieved the data of 29,765 gout patients from the period of 1998-2010 by using data from Taiwan's National Health Insurance Research Database. Controls (n = 59,530) were matched at a 1:2 ratio by age, sex, and region. Multivariate Cox proportional hazards regression were performed to examine the dose-dependent relationship between ULT and T2DM. Results The adjusted Hazard ratio (HR) for the association of T2DM with allopurinol or benzbromarone exposure was 1.17 (95% confidence interval (CI) 1.07-1.28) and1.09 (95% CI 1.03-1.15), respectively. The HR for the cumulative allopurinol dose was 0.87 (95% CI 0.71-1.07) for patients with dose <= 1.3 mg/day and was 1.31 (95% CI 1.13-1.52) for those with a dose >15.2 mg/day. Similarly, the HR for the cumulative benzbromarone dose was 0.85 (95% CI 0.75-0.96) for patients with a dose <= 1.3 mg/day and 1.42 (95% CI 1.30-1.55) for patients with a dose>9.4 mg/day, respectively. Moreover, the average exposure dose of >100 mg/day for allopurinol and >100 mg/day for benzbromarone was associated with a 1.28-fold (95% CI 1.11-1.48) and 1.47-fold (95% CI 1.23-1.76) T2DM risk respectively. The HR for patients in aged >50 years group with cumulative dose <= 1.3 mg/day of allopurinol or benzbromarone had lower risk of T2DM (HR = 0.74, 95% CI 0.58-0.94 for allopurinol; HR = 0.79, 95% CI 0.69-0.90 for benzbromarone). Conclusion Gout patients with prolonged ULT and a high dose of ULT were associated with a significant increase in T2DM risk. Although gout patients with age greater than 50 years and a lower dose of ULT may be beneficial in lowering T2DM risk, further clinical studies need to be confirmed these associations.