Pathophysiological mechanisms and clinical management of type 2 diabetes mellitus complicated with anal fistula

Background: The comorbidity of type 2 diabetes mellitus (T2DM) and anal fistula is a prevalent global clinical challenge. Anal fistula is the second most common anorectal disease, with an incidence 1.81-2.01 times higher in diabetic patients than in the general population. Diabetic patients face elevated risks of postoperative infection, delayed healing, and recurrence, closely linked to poor preoperative glycemic control. Current strategies are mostly extrapolated from general population guidelines, failing to address the unique metabolic, immune, and microcirculatory abnormalities in this group, leading to suboptimal outcomes. Methods: < 10). We synthesized evidence on surgical optimization, regenerative medicine, and perioperative glycemic management. Results: ① Sphincter-preserving surgeries (LIFT, VAAFT, TROPIS, EAF) reduce incontinence risk; TROPIS achieved 87.6% long-term healing in diabetics, while EAF is well-established for complex fistulas. ② Regenerative therapies (CGF, MSCs) promote healing; autologous MSC-based therapies yielded 68.4%-84.6% healing for complex fistulas, with superior safety/operability vs. allogeneic products. ③ Preoperative HbA1c < 7.0% reduced infection to 8.2%, with perioperative glucose targets of 140-180 mg/dL optimal; once-weekly insulin icodec improved compliance. Conclusions: Individualized multidisciplinary strategies tailored to fistula complexity and glycemic status are essential. Future large-scale RCTs in diabetic patients are needed to validate novel biomaterials and anti-inflammatory agents to optimize outcomes.