Objective: To investigate the effect of L-carnitine combined with alprostadil on patients with diabetic nephropathy and serum inflammatory markers of urinary LAP and PCX levels. Methods: A total of 106 patients with diabetes mellitus that were admitted to our department from August 2016 to October 2017 were enrolled. According to different treatment methods, they were divided into an observation group and a control group, each with 53 cases. The control group received a prostaglandin injection. The observation group was combined with L-carnitine on the basis of the control group, and both groups were treated for 1 month. The blood glucose levels, related renal function indicators and urinary LAP and PCX were measured before and after treatment. The clinical efficacy and adverse reactions of the two groups were observed. Results: After treatment, the total effective rate of clinical treatment was 92.45%, which was significantly higher than that of the control group (69.81%). The difference was statistically significant (P<0.05). FBP, 2 h BG, and 24 h uPro, BUN, Scr, and beta 2-MG were significantly improved in the two groups after treatment, and the difference was statistically significant (P<0.05). The observation group was superior to the control group, and the difference was statistically significant (P<0.05). The levels of urinary LAP and PCX in the observation group were lower than those in the control group, and the difference was statistically significant (P<0.05). The observation group was superior to the control group, and the difference was statistically significant (P<0.05). The total incidence of adverse reactions in the observation group was 7.55%, which is significantly lower than that in the control group (20.75%), and the difference was statistically significant (P<0.05). Thus, the observation group was superior to the control group, and the difference was statistically significant (P<0.05). Conclusion: The clinical efficacy of L-carnitine combined with alprostadil in the treatment of diabetic nephropathy is significant, which can effectively reduce the level of urine LAP and PCX. It is safe and worthy of clinical application.