IGFBP1 and hyperinsulinism: Patients with type 1 diabetes have higher serum IGFBP‐1 concentrations than normoglycemic controls (Suikkari et al., 1988), and acute steady state hyperinsulinemia lowers serum IGFBP‐1 levels by 40–70% in normal individuals (Yeoh & Baxter, 1988; Snyder & Clemmons, 1990).