The HRs of biguanide use vs. DPP-4 inhibitor use for diabetic retinopathy, nephropathy, neuropathy, and other conditions were 0.93 (0.71–1.22), 0.97 (0.61–1.54), 0.76 (0.34–1.67), and 1.04 (0.59–1.84), indicating no significant difference. This evidence concerns the gene DPP4 and kidney disorder.