Association of type 2 diabetes mellitus with pathological grade of prostate cancer and prostate-specific antigen

Objective To investigate the relationship of type 2 diabetes mellitus (T2DM) with prostate cancer (PCa) pathological grade and prostate-specific antigen (PSA). Methods We retrospectively evaluated the data from 1 688 patients who underwent prostate biopsy in Shanghai Tenth People's Hospital from 2012 to 2016. These patients were grouped according to PCa pathological grade (low-grade: Gleason score (GS) ≤6; intermediate-grade: GS=7; high-grade: GS 8-10), diabetes duration (0-5 years, 6-10 years and>10 years) and HbA1c (<6.5%, 6.5%-7.5% and ≥7.5%) for future analysis. The multivariate logistic regression and covariance analysisi were applied to investigate the relationship of T2DM with PCa grade and PSA. Results T2DM was significantly correlated with increased incidence risk of overall (OR=1.41, 95%CI: 1.03-1.93, P=0.032) and high-grade PCa (OR=2.54, 95%CI: 1.49-4.24, P=0.001), but not with low-or intermediate-grade PCa. Also, the risk of high-grade PCa increased with diabetes duration and HbA1c. Serum PSA level in T2DM was lower than that in non-diabetics [(6.5±4.5) vs (8.5±3.7) μg/L, t=-3.380, P=0.001], and the difference increased with duration. Of PCa men, PSA was also lower in diabetics compared to non-diabetics [(18.1±3.5) vs (23.9±3.0) μg/L, t=-2.667, P=0.021]. Conclusions A positive correlation was found between T2DM and PCa. T2DM contributes to lower serum PSA levels, which is more likely to delay and interfere with PCa diagnosis, leading to higher malignant degree of PCa. The current PSA threshold (4 μg/L) may not be suitable for early screening and follow-up of PCa in the T2DM population. Key words: Diabetes mellitus, type 2; Prostatic neoplasms; Prostate-specific antigen