Association Between Metformin and Sulfonylurea Monotherapies and Cancer Incidence: A Real-World Cohort Study in Shanghai, China

INTRODUCTION: Previous studies have shown that patients with type 2 diabetes mellitus have an increased risk of cancer. The use of antidiabetic medication (ADM) may play an important role in the cancer development. The relationship between oral ADM and cancer incidence has not been investigated in type 2 diabetes mellitus patients in mainland China yet. METHODS: A community-based diabetes cohort was extracted from the Shanghai Community Diabetes Management System database, which is a patient registry from general practices. The cohort included 2353 newly onset type 2 diabetes mellitus patients from 2006 to 2010 aged 35 years or more. Patients were grouped into nonusers of antidiabetic medication (n = 722), metformin monotherapy (n = 374), sulfonylurea monotherapy (n = 653), metformin and sulfonylurea combination therapy (n = 302), and other medication therapies (n = 302) on the basis of initial treatment type at registry entry. Cancer incidence was identified from the Shanghai Cancer Registry Organization. Comparisons between monotherapy and nonuser of medication were conducted using Cox proportional hazards models. RESULTS: A total of 94 cancer cases were identified during 5 years median follow-up. Compared with nonusers, sulfonylurea monotherapy was associated with significantly lower risk of cancer [adjusted HR = 0.50 (95% CI 0.29–0.85)] whereas risk was 49% lower with metformin monotherapy [adjusted HR = 0.51 (95% CI 0.27–0.99)]. CONCLUSION: The real-world evidence suggested that the use of metformin or sulfonylurea was associated with lower risk of cancer incidence in a cohort of newly onset type 2 diabetes mellitus patients.