Type 2 diabetes is rapidly increasing globally and has been associated with an increased risk of colorectal cancer. Therefore, the numbers of diabetic patients who will undergo colonoscopic screening are expected to grow exponentially. Colonoscopic preparation entails prolonged fasting, cessation of anti-diabetic medication and ingestion of preparation medications. This may put the diabetic patient at risk of potentially dangerous hypo- or hyperglycemia. However, studies regarding the safety of colonoscopic preparation in diabetic are lacking. In this study, the investigators aim to discover the prevalence of abnormal glucose levels in diabetic patients who undergo colonoscopy. The investigators also aim to find out risk factors for abnormal glucose levels and develop a safe preparation protocol.

1. Type 2 diabetes subjects who will undergo colonoscopy will be prospectively enrolled when visiting the outpatient clinic.
2. Subjects will be instructed to fast from 6pm of the day before colonoscopy.
3. Subjects will be instructed to abstain from diabetes medication while the subjects fast.
4. Subjects who are scheduled to undergo colonoscopy in the morning will take colonoscopy preparation medication (2L (liter) of polyethylene glycol with ascorbic acid) in a split dose (i.e. 1L from 8-10 pm of the day before colonoscopy and 1L 4-6 hours before colonoscopy). Those who will undergo colonoscopy in the afternoon will take 2L of the preparation medication 6 hours before colonoscopy.
5. Subjects will be instructed to take the preparation medication at rate of 250 mL every 10 to 15 minutes.
6. Upon arrival at the endoscopy center of International St. Mary's hospital, subjects will be given a self-administered questionnaire which will ask about their age, gender, duration of diabetes, type of diabetes medication, time of last diabetes medication taken, knowledge of hypo/hyperglycemia symptoms, previous hypo/hyperglycemia experience, self-treatment of hypoglycemia (if done), total amount of colonoscopy preparation medication ingested, total fasting time and time of last preparation medication ingested.
7. Subjects will have vital signs (blood pressure, heart rate) taken and their capillary glucose levels checked using the Accu-Chek Performa.
8. Any subjects with capillary glucose levels <70mg/dL or >250mg/dL will be reported to the attending physician. Those with an initial glucose level <70mg/dL will be given a piece of candy and have their glucose rechecked in 10 mins. Subjects will be asked if the hypoglycemic symptoms (if any) have abated. Those with a glucose level >250mg/dL will undergo hydration with normal saline at 120 ml/Hr. Those who do not respond to treatment or are in critical condition will be moved to the Emergency department for treatment. Subjects who respond to treatment will have their glucose levels checked after colonoscopy before undergoing discharge. Those with abnormal levels upon follow-up testing will be sent to either the endocrinology outpatient clinic or the emergency room depending on their clinical severity.
9. All data will be recorded by initials with patient identities masked. All data will be kept in a locked and secure location by the principal investigator.

Inclusion Criteria:

• Type 2 diabetes
• Between ages of 20-75
• Undergo colonoscopy at International St. Mary's Hospital

Exclusion Criteria:

• Type 1 diabetes patients
• Did not undergo colonoscopy preparation
• Did not meet fasting requirements
• Have known current infectious diseases
• Have known cancer and/or are under cancer treatment
• Are under intravenous fluid therapy during colonoscopy

Adverse event data were collected for 1 month.

Smaller number of subjects than anticipated due to poor enrollment.

Open label