After adjusting for sex, BMI, smoking status, hypertension, dyslipidaemia, DM, history of stroke, and statin use history, we found that IgM levels were associated with CAD in people younger than 70 years of age (OR: 0.730, 95% CI [0.579–0.921], P = 0.008), but not in people older than 70 years of age (OR: 0.835, 95% CI [0.608–1.147], P = 0.266). Here, CD40LG is linked to diabetes mellitus.