Our present study may be the first to analyze the relationship between serum FABP4 levels and indices of pancreatic α-cell function, and we found that increased serum FABP4 levels were associated with elevated fasting and postchallenge glucagon levels (Gluca0min and AUCgluca) during OGTT in patients with T2D. Here, FABP4 is linked to type 2 diabetes mellitus.