Lower C3d/C3 ratios were found for diabetes (p = 2.87×10−6), higher body mass index (p = 1.00×10−13), the SNPs rs1410996 (p = 0.0001), rs800292 (p = 0.003), rs12144939 (p = 4.60×10−6) in CFH, rs4151667 (p = 1.01×10−5) in CFB and individual haplotypes in CFH and CFB. The linear model revealed a corrected R-square of 0.063 including age, smoking status, gender, and genetic polymorphisms explaining 6.3% of the C3d/C3 ratio. Here, CFH is linked to diabetes mellitus.