The forest plot with a random-effects model showed that DM patients with different degree of albuminuria had significantly higher levels of YKL-40 compared with healthy controls (normoalbuminuria: SMD = 1.58, 95% CI 0.59 to 2.56, P = 0.002; microalbuminuria: SMD = 2.57, 95% CI 0.92 to 4.22, P = 0.002; macroalbuminuria: SMD = 2.69, 95% CI 1.40 to 3.98, P = 0.000). The gene discussed is CHI3L1; the disease is diabetes mellitus.