A large population-based study has shown diabetes to be an independent risk factor for colon cancer compared to the general population. Thus, the completion of an adequately prepped colonoscopy is requisite in providing diabetics with adequate colon cancer screening.

Recent data has shown that diabetic patients have poorer response to bowel cleansing compared to non-diabetics (with a standard PEG prep, only 62% of diabetic patients had their colonoscopy preps rated as good or better vs. 97% of normal patients, p<0.001). This may be due to the fact that a majority of diabetic patients report constipation as a common gastrointestinal complaint.

We postulate that lubiprostone (Amitiza), in combination with PEG, will have additional efficacy over standard PEG preparation, and provide optimal safe and effective colonic cleansing for diabetics.

STUDY DESIGN

This is an investigator-initiated, single site (MCG only), single-blinded prospective study comparing the efficacy of Lubiprostone and 4L PEG (Nulytely) to 4 Liters (4L) PEG alone on preparation quality in patients with known diabetes undergoing colonoscopy. Diabetic outpatients who require a colonoscopy will be randomized to one of the two groups of 60 (total of 120 patients):

Control Group: All patients in the study will receive a standard oral 4L PEG colonoscopy preparation the day prior to their scheduled colonoscopy.

Lubiprostone Group: The lubiprostone group will receive an additional two 24 mcg lubiprostone capsules, which will be taken orally the morning and evening of the day of the 4L PEG prep (before and after the oral 4L PEG preparation).

Randomization Scheme: Subjects will be assigned to the Control Group or Lubiprostone Group, on an odd/even basis. After research informed consent has been obtained, subjects are given a study Identification (ID) numbered 1 through 120. Subjects with an odd number will be assigned to Control Group, and subjects with an even number will be assigned to the Lubiprostone Group. Subjects then will be given a randomization package consisting of the preparation orders, supplies, instructions and the date of their procedure by the investigator obtaining informed consent. The colonoscopist will be blinded to which preparation was given.

Only diabetic patients who require an outpatient colonoscopy by a gastroenterologist at the outpatient MCG Clinic will be eligible for the study. Patients will be presented with a separate consent form for the colonoscopy procedure itself.

Standard of Care Procedures

• Colonoscopy Procedure Consent
• Colonoscopy

Study Procedures

• Research Informed Consent
• Disbursement of randomized preparation order and supplies, instructions, and date of procedure to subjects
• Adverse Events

After the procedure, the physician who performed the colonoscopy will complete a form that rates the quality of the subject's colonoscopy preparation on a 1-5 rating scale.

The subject's study participation duration is two days (day of preparation and day of procedure). No follow-up visits will occur.

Inclusion Criteria:

• Patients with known diabetes (type I or II) undergoing elective colonoscopy at the Medical College of Georgia.
• Patients aged 50 years and older.
• Women must be post-menopausal or surgically sterile.
• Patients able to give a valid, informed consent.

Exclusion Criteria:

• Patients with impaired glucose tolerance.
• Patients with suspected acute or chronic pseudo-obstruction.
• Patients with active gastrointestinal bleeding.
• Patients with known inflammatory bowel disease.
• Patients with chronic diarrhea.
• Patients with prior colonic resection.
• Patients with active diverticulitis.
• Patients with a known colonic mass.
• Patients with clinical evidence of decompensated liver disease.
• Patients with clinical evidence of decompensated renal disease or patients on dialysis.
• Patients currently or previously taking lubiprostone.
• Patients with an allergy to lubiprostone.

1 year