Bowel Preparation for Colonoscopy in Patients with Diabetes Mellitus – a Gap We Have to Bridge: A Review

Colonoscopy is an essential diagnostic and therapeutic tool in gastroenterology, significantly impacting colorectal cancer (CRC) detection and management. Effective bowel preparation is critical for optimal visualization, directly influencing colonoscopy accuracy and patient outcomes. However, diabetic patients frequently encounter challenges achieving adequate bowel preparation, primarily due to gastroparesis, autonomic neuropathy, altered colonic motility, fluid-electrolyte imbalances, and complexities related to antihyperglycemic medication adjustments. This review aims to evaluate current literature on bowel preparation efficacy in diabetic patients undergoing colonoscopy, assess existing guidelines from leading gastroenterological societies, and highlight the necessity for detailed, diabetes-specific recommendations. We conducted a comprehensive PubMed search identifying 20 pertinent studies, including randomized controlled trials, meta-analyses, multicenter studies, cohort studies, and reviews. The findings consistently indicate diabetes as an independent predictor of inadequate bowel preparation. Furthermore, an evaluation of guidelines from the European Society of Gastrointestinal Endoscopy (ESGE), the US Multi-Society Task Force, and the Canadian Association of Gastroenterology revealed either absent or insufficiently detailed diabetes-specific recommendations. Given the rising global prevalence of diabetes and CRC, inadequate bowel preparation significantly impacts the quality of colonoscopy, adenoma detection rates, patient safety, and healthcare costs. This review underscores the urgent need for additional research focusing on tailored bowel preparation strategies for diabetic patients. Ultimately, the implementation of standardized, evidence-based protocols designed explicitly for this high-risk group is essential to enhance diagnostic efficacy, improve patient outcomes, and reduce CRC-related morbidity and mortality.