KEGG enrichment pathway analysis shows that neuroactive ligand–receptor interaction, the calcium signaling pathway, EGFR tyrosine kinase inhibitor resistance, the PI3K–Akt signaling pathway, prostate cancer, the HIF-1 signaling pathway, hepatitis B, the AGE–RAGE signaling pathway in diabetic complications, lipid and atherosclerosis, the cAMP signaling pathway, the Ras signaling pathway, the sphingolipid signaling pathway, the FoxO signaling pathway, endocrine resistance, and insulin resistance are important pathways related to the disease regulation of diabetes. The gene discussed is PIK3CA; the disease is hepatitis B virus infection.