Metformin Is Associated with a Lower Incidence of Benign Brain Tumors: A Retrospective Cohort Study in Patients with Type 2 Diabetes Mellitus

Abstract

Background: The risk of benign brain tumors (BBT) associated with metformin use has not received much attention. Therefore, a retrospective cohort study was designed to investigate such an association in patients with type 2 diabetes mellitus (T2DM). Methods: We used the database of Taiwan’s National Health Insurance to enroll 152,176 ever users and 16,120 never users of metformin for the follow-up of incidence of BBT and a more specific outcome of cerebral meningioma. The patients were newly diagnosed with T2DM between 1999 and 2005; and they were followed up from 1 January 2006 until 31 December 2011. Hazard ratios were estimated by Cox regression incorporated with the inverse probability of treatment weighting using propensity score. Results: During follow-up, 111 never users and 557 ever users were diagnosed with BBT. For BBT, the respective incidence rates for never users and ever users were 153.95 per 100,000 person-years and 77.61 per 100,000 person-years. While ever users were compared to never users, the hazard ratio was 0.502 (95% confidence interval: 0.409–0.615). A dose-response pattern was seen when ever users were categorized into tertiles of cumulative duration of metformin therapy (cutoffs: <27.10 months, 27.10–58.27 months and >58.27 months) with respective hazard ratios of 0.910 (0.728–1.138), 0.475 (0.375–0.602) and 0.243 (0.187–0.315). For cerebral meningioma, the overall hazard ratio was 0.506 (0.317–0.808); and the hazard ratios comparing the respective tertiles to never users were 0.895 (0.531–1.508), 0.585 (0.346–0.988) and 0.196 (0.104–0.369). Conclusions: A reduced risk of BBT and cerebral meningioma is observed in metformin users in patients with T2DM.

Bridging the gap: exploring the causal relationship between metformin and tumors

“…Although numerous studies have explored the relationship between metformin and tumors, there seems to be a scarcity of research on benign brain tumors such as meningiomas. A retrospective cohort study investigated the relationship between metformin and benign brain tumors (BBT) and revealed that metformin use reduced the risk of BBT, especially meningiomas, in patients with T2DM ( Tseng, 2021 ). Clinically, there are significantly more female patients with meningioma than male patients, with the ratio ranging from 2 to 3:1 ( Claus et al, 2005 ; Cao et al, 2022 ).…”

DataSheet7.PDF

“…Although numerous studies have explored the relationship between metformin and tumors, there seems to be a scarcity of research on benign brain tumors such as meningiomas. A retrospective cohort study investigated the relationship between metformin and benign brain tumors (BBT) and revealed that metformin use reduced the risk of BBT, especially meningiomas, in patients with T2DM (Tseng, 2021). Clinically, there are significantly more female patients with meningioma than male patients, with the ratio ranging from 2 to 3:1 (Claus et al, 2005;Cao et al, 2022).…”

DataSheet5.CSV

“…Although numerous studies have explored the relationship between metformin and tumors, there seems to be a scarcity of research on benign brain tumors such as meningiomas. A retrospective cohort study investigated the relationship between metformin and benign brain tumors (BBT) and revealed that metformin use reduced the risk of BBT, especially meningiomas, in patients with T2DM (Tseng, 2021). Clinically, there are significantly more female patients with meningioma than male patients, with the ratio ranging from 2 to 3:1 (Claus et al, 2005;Cao et al, 2022).…”