• Growing evidence suggests a relationship between diabetes and prostate cancer, and men who use metformin may have improved survival outcomes, while men with hyperinsulinemia have worse cancer-specific survival. In this retrospective study, 3217 men with prostate cancer treated with radiation were grouped based on the presence of type 2 diabetes mellitus (T2DM) and treatment received (metformin, another oral agent, insulin, or none). The median follow-up was 50 months. The authors discovered that men who did not receive treatment for T2DM had significantly worse cause-specific mortality (HR, 3.87). Additionally, men with insulin-treated T2DM had worse acute radiation toxicity than those without T2DM (genitourinary, 38% vs 26%; gastrointestinal 21% vs 5%). Likewise, men with untreated or insulin-treated T2DM had significantly worse late toxicities.
  • This study supports the importance of optimizing glycemic control in men with T2DM who are about to undergo radiation therapy. Men who are initiating treatment should be aware that oral medications are preferable to insulin. Further prospective trials are needed, as the study is limited by insufficient information on dosage and adherence.
    Michael Johnson, MD