All-Cause and Cardiovascular Mortality following Treatment with Metformin or Glyburide in Patients with Type 2 Diabetes Mellitus

Both metformin and sulfonylurea (SU) drugs are among the most widely-used anti-hyperglycemic medications in patients with type 2 diabetes mellitus (T2DM). Previous studies have shown that treatment with SUs might be associated with decreased survival compared with metformin. This study aimed to evaluate all-cause and cardiovascular mortality rates between glyburide and metformin in patients diagnosed with T2DM.
This was a cohort study on 717 patients with T2DM (271 undergoing monotherapy with glyburide and 446 with metformin). Data were gathered from 2001 to 2014. All-cause and cardiovascular mortality were end-points.
During the follow-up, 24 deaths were identified, of which 13 were cardiovascular in nature. The group with glyburide monotherapy had greater all-cause mortality (17 (6.3%) in glyburide vs. 7 (1.6%) in metformin, P = 0.001) and cardiovascular mortality (11 (4.1%) in glyburide vs. 2 (0.4%) in metformin; P = 0.001). Metformin was more protective than glyburide for both all-cause (HR: 0.27 [0.10 – 0.73] P-value = 0.01) and cardiovascular mortality (HR: 0.12 [0.20 – 0.66], P-value = 0.01) after multiple adjustments for cardiovascular risk factors. Among adverse cardiovascular events, non-fatal MI was higher in glyburide compared to metformin monotherapy group (3.2% vs. 0.8%; P-value = 0.03), but not coronary artery bypass grafting (P-value = 0.85), stenting (P-value = 0.69), need for angiography (P-value = 0.24), CCU admission (P-value = 0.34) or cerebrovascular accident (P-value = 0.10).
Treatment with glyburide is associated with increased all-cause and cardiovascular mortality in patients with T2DM.