SerpinB1 is an endogenous inhibitor of serine proteases recognized for its anti-inflammatory and host-protective properties. Serum SerpinB1 levels are elevated in patients with type 2 diabetes compared with that in healthy subjects and are negatively correlated with serum LDL-C. serpinB1 as an endogenous protein that can potentially be harnessed to enhance functional beta cell mass in patients with diabetes.