What are the management instructions for a patient with diabetes on a Tandem (insulin pump) X-2 and Dexcom (continuous glucose monitoring system) who is required to be Nil Per Os (NPO) while undergoing colonoscopy?

Management of Tandem X-2 Insulin Pump and Dexcom CGM During Colonoscopy While NPO

For a patient with diabetes using a Tandem X-2 insulin pump with Dexcom CGM undergoing colonoscopy, continue the insulin pump with basal rate adjustments (reduce to 80% of usual basal or give 60-80% of usual basal dose) and maintain the Dexcom CGM in place throughout the procedure, with hourly point-of-care glucose monitoring as backup. 1

Pre-Procedure Preparation (Days Before)

Perform a basal rate assessment to confirm the pump settings are optimized for fasting conditions 1:

• The patient should fast overnight (after 5-6 PM meal) and monitor glucose every 2-3 hours
• Blood glucose should not vary by more than 1.7 mmol/L (30 mg/dL) during fasting
• If significant deviations occur, contact the diabetes team to adjust basal rates BEFORE scheduling the procedure 1
• This assessment should ideally cover the time period when the colonoscopy is scheduled 1

Coordinate with the patient's diabetes team early to establish a written management plan with signed patient consent to continue pump therapy perioperatively 1

Verify adequate pump supplies: Ensure the patient brings backup infusion sets, insulin cartridges, batteries, and all necessary equipment to cover the entire hospital stay 1

Day Before Colonoscopy

Insulin pump management during bowel preparation:

• Continue the insulin pump with usual basal rates during the bowel prep phase 1
• The patient can manage their own pump settings if alert and capable 1
• Reduce or hold bolus insulin as oral intake decreases 2, 3
• Monitor for hypoglycemia risk during the fasting period, as bowel preparation increases dehydration risk 2, 3

Dexcom CGM considerations:

• Keep the Dexcom sensor in place throughout preparation 1
• Be aware that dehydration and vasoconstriction during bowel prep may affect CGM accuracy 1
• Confirm point-of-care glucose readings if CGM values seem inconsistent 1

Day of Colonoscopy

Insulin pump settings during NPO period:

• Continue basal insulin at 80% of the usual rate as a temporary basal setting once fasting begins 1
• Alternatively, some protocols recommend 60-80% of usual long-acting insulin equivalent if converting to injections 1
• Do NOT completely discontinue insulin - patients using only rapid-acting insulin in pumps become insulin-deficient within 1-4 hours of cessation, risking hyperglycemia and ketosis 1
• Hold all bolus insulin doses while NPO 1

Glucose monitoring protocol:

• Monitor blood glucose with point-of-care testing every 4-6 hours minimum while NPO 1
• Continue Dexcom CGM for trend monitoring, but do not rely solely on CGM values - always confirm with fingerstick or point-of-care testing 1, 4
• Target glucose range: 80-180 mg/dL (4.4-10.0 mmol/L) perioperatively 1

Infusion site considerations:

• Position the infusion site away from the surgical field (typically abdomen, thighs, or buttocks) 1
• If diathermy will be used, switch to a non-metal infusion set in advance 1
• Ensure the site is accessible to the anesthesia team throughout the procedure 1

During the Colonoscopy Procedure

Pump continuation criteria - the pump can remain on IF 1:

• The patient signed consent for continued pump use
• Hospital policies support inpatient pump use
• The diabetes team is available for consultation
• The procedure is relatively short (colonoscopy typically qualifies)
• The patient will regain consciousness shortly after the procedure

Contraindications requiring pump discontinuation 1:

• Prolonged impaired consciousness beyond brief anesthesia
• Patient inability to self-manage upon awakening
• Lack of trained healthcare providers to manage the pump
• Hyperglycemic crisis (DKA)
• Equipment malfunction or lack of supplies

If pump must be discontinued, convert to basal-bolus subcutaneous insulin using the 24-hour total basal dose from pump settings to calculate long-acting insulin dose 1

CGM management during procedure:

• The Dexcom CGM can remain in place during colonoscopy 1, 4
• Remove CGM only if MRI or specific electromagnetic procedures are planned 1
• Continue hourly point-of-care glucose monitoring during the procedure 1, 4

Post-Procedure Recovery

Resuming normal pump function:

• Return to 100% basal rate once the patient is awake and alert 1
• Resume bolus insulin with the first meal or snack 1
• The patient should resume self-management of pump settings as soon as they are capable 1

Glucose monitoring:

• Continue point-of-care testing every 4-6 hours until oral intake is well-established 1
• The Dexcom CGM provides continuous monitoring but should not replace scheduled fingerstick checks initially 1, 4
• Address hypoglycemia (<70 mg/dL) immediately with 15g fast-acting carbohydrate once oral intake permitted 1
• For hyperglycemia >300 mg/dL (16.7 mmol/L), check for ketones and administer correction bolus via pump 1

Critical Safety Considerations

Common pitfalls to avoid:

• Never completely discontinue insulin in pump users - they have no long-acting insulin on board 1, 5
• Do not rely solely on CGM values during acute physiological changes (dehydration, hypotension) 1
• Avoid removing CGM unnecessarily, as this disrupts the Tandem Control-IQ closed-loop system and may cause prolonged interruption of automated insulin delivery 1, 4
• Do not assume hospital staff can manage the pump - ensure the patient or diabetes team maintains control 1

Emergency protocols:

• If the pump malfunctions, immediately convert to subcutaneous basal-bolus insulin 1
• If severe hyperglycemia (>300 mg/dL) with ketones develops, initiate DKA protocol and discontinue pump 1
• For hypoglycemia during sedation, treat with IV dextrose and reduce basal rate by 20-50% 1

Documentation requirements:

• Written management plan in the medical record 1
• Signed patient consent for continued pump use 1
• Clear handoff communication if patient transfers between care areas 1
• Designated healthcare professional responsible for pump oversight during sedation 1