Assessing the Link between Colonoscopy Preparation Quality and Diabetes Mellitus

Diabetes mellitus, advanced age and male gender are known risk factors for poor bowel preparation for colonoscopy. There is limited literature about the relationship between levels of glycemic control and bowel preparation quality. We studied the association of diabetes-related and demographic variables with quality of bowel preparation for colonoscopy. Retrospective data was obtained for 380 consecutive patients who had HbA1c measured and had colonoscopies within 3 months of this measurement. The outcome variable was colonoscopy preparation quality (good versus poor). Predictors included HbA1c, mean blood glucose concentration, age, sex, and body mass index. The data obtained was further analyzed statistically. The sample was approximately equally distributed between those with good (53.4%) and poor (46.6%) quality colonoscopy preparation. When analyzed based on HbA1c, poor preparations were seen in 46% of the patients with HbA1c ≤ 6.9%, 43% of those with HbA1c between 7% and 9%, and 51% of the patients with HbA1c ≥ 9.1%. Poor preparations were also seen in 47% of the patients with mean blood glucose concentration ≤ 110mg/dL, 40% of those with mean blood glucose concentration between 111mg/dL and140mg/dL, and 51% of the patients with mean blood glucose concentration ≥ 141mg/dL. Gender was the only variable that statistically significantly differed between the groups where males had a greater percentage of poor quality colonoscopy preparation than females (61.6% vs. 38.4%). Patients who had colonoscopies as outpatients were more likely to have poor preparations than those who were inpatients at the time (55% vs. 40%). Ultimately, there was no association between levels of glycemic control, characterized by HbA1c and mean blood glucose concentration, and colonoscopy preparation quality.