What are the steps for initiating an insulin pump in a patient with a current Total Daily Dose (TDD) of 55 units?

Insulin Pump Initiation with TDD of 55 Units

Start with a total basal rate of 22-27.5 units per day (40-50% of current TDD), programmed as a flat rate of approximately 0.9-1.1 units/hour initially, then adjust based on fasting glucose patterns over 2-3 days before fine-tuning individual time blocks. 1

Calculate Initial Pump Settings

Basal Rate Calculation

• Use 40-50% of the current TDD (55 units) for total daily basal insulin = 22-27.5 units per day 1
• The TDD method is the safest presently recommended estimate for pump initiation in both type 1 and type 2 diabetes 1
• Divide the total basal dose by 24 hours to get an initial flat hourly rate: 22-27.5 units ÷ 24 = 0.9-1.1 units/hour 1
• Start with a single flat basal rate across all 24 hours initially, then adjust based on glucose patterns 1

Bolus Insulin Calculation

• Allocate the remaining 50-60% of TDD (27.5-33 units) for bolus insulin divided among meals 2
• Calculate Carbohydrate-to-Insulin Ratio (CR) using the "500 rule": 500 ÷ TDD = 500 ÷ 55 = approximately 1 unit per 9 grams of carbohydrate 3
• Calculate Correction Factor (CF) using the "1800 rule": 1800 ÷ TDD = 1800 ÷ 55 = approximately 1 unit lowers glucose by 33 mg/dL 3

Pre-Initiation Assessment

Patient Readiness Evaluation

• Assess the patient's ability to manage pump independently, including understanding of infusion set changes, troubleshooting occlusions, and recognizing DKA risk 2
• Ensure patient understands that pump failure places them at risk for ketosis and DKA within hours due to lack of long-acting insulin reservoir 2
• Confirm patient has adequate support system and access to supplies 2

Education Requirements Before Starting

• Infusion set complications: Teach recognition of dislodgement and occlusion, which are the primary causes of hyperglycemia and DKA in pump users 2
• Hypoglycemia management: Ensure patient can recognize and treat blood glucose <60 mg/dL with 15-20g oral glucose 4
• Hyperglycemia protocol: If glucose >250 mg/dL, check ketones immediately; if ketones present, contact provider urgently 2
• Site rotation: Educate on changing infusion sites every 2-3 days to prevent lipohypertrophy and infection 2

Transition from Current Regimen

Timing of Pump Start

• If currently on long-acting insulin (glargine/detemir): Start pump 2 hours after the last injection of basal insulin 2
• If currently on NPH: Start pump at the time the next NPH dose would be due 2
• Pump therapy can be successfully started at diagnosis, so no delay is needed for established patients 2

First 24-48 Hours Monitoring

• Check blood glucose every 2-4 hours, including overnight, to establish patterns 4, 5
• Do not make major adjustments to basal rates in the first 24 hours unless severe hypo- or hyperglycemia occurs 1
• Focus on fasting glucose first to optimize basal rates before fine-tuning bolus parameters 2

Basal Rate Optimization

Pattern Analysis Approach

• If fasting glucose is elevated: Increase overnight basal rate by 10-20% 2
• If pre-meal glucose is elevated: Increase basal rate in the 4-6 hours preceding that meal by 10-20% 2
• If hypoglycemia occurs: Decrease basal rate in the 2-4 hours preceding the low by 10-20% 2
• Make only one basal rate change at a time and reassess after 2-3 days 1

Advanced Basal Features

• Once basic basal rates are established, introduce temporary basal rates for exercise (typically 50-80% of usual rate) or illness (typically 120-150% of usual rate) 2
• Consider multiple basal rate time blocks only after establishing that a flat rate is insufficient 1

Bolus Optimization

Carbohydrate Ratio Adjustment

• If post-meal glucose is >180 mg/dL at 2-3 hours: Decrease the CR denominator (give more insulin per gram of carb) 3
• If post-meal hypoglycemia occurs: Increase the CR denominator (give less insulin per gram of carb) 3
• Adjust by 1-2 grams at a time and reassess after 2-3 days 3

Correction Factor Adjustment

• If correction doses fail to bring glucose to target: Decrease the CF number (make insulin more potent) 3
• If correction doses cause hypoglycemia: Increase the CF number (make insulin less potent) 3
• Adjust by 5-10 mg/dL increments 3

Extended Bolus Features

• Introduce extended/square wave bolus for high-fat or high-protein meals after patient masters standard bolusing 2
• Introduce dual wave bolus for mixed meals (e.g., pizza) after patient demonstrates consistent carbohydrate counting 2

Critical Safety Protocols

Emergency Hyperglycemia Management

• If glucose >300 mg/dL: Check ketones immediately; if positive, assume pump failure 2, 4
• Remove pump and infusion set completely 2
• Give correction dose via insulin pen/syringe (not through pump) 2
• Check glucose again in 2 hours; if not improving, seek emergency care 2

Emergency Hypoglycemia Management

• If glucose <60 mg/dL: Give 15-20g oral glucose immediately, even without symptoms 4
• If unconscious or unable to swallow: Give IV glucose immediately 4
• Recheck glucose in 15 minutes; repeat treatment if still <70 mg/dL 4

Pump Failure Recognition

• Unexplained hyperglycemia with ketones = pump/infusion set failure until proven otherwise 2
• Patient must have backup insulin pens/syringes and know their backup basal-bolus regimen 2
• Backup regimen: Give 50% of total pump basal dose as long-acting insulin (glargine/detemir) in 2 divided doses 12 hours apart, plus rapid-acting insulin for meals using same CR and CF 2

Common Pitfalls to Avoid

• Never start with multiple complex basal rate time blocks: Begin with a flat rate and adjust systematically 1
• Never adjust basal and bolus parameters simultaneously: This makes it impossible to determine which change caused the effect 3
• Never ignore the "insulin on board" feature: Ensure patient understands this prevents insulin stacking and hypoglycemia 2
• Never allow patient to disconnect pump for >1 hour without giving replacement insulin: Patients become insulin deficient within 1 hour of disconnection 2
• Never use weight-based calculations alone: The TDD method is significantly safer than weight-based methods for pump initiation 1

Follow-Up Schedule

• First week: Contact patient every 2-3 days to review glucose logs and make adjustments 2
• First month: Weekly follow-up to optimize all pump settings 2
• Ongoing: Follow-up frequency does not influence long-term outcomes, so adjust based on patient stability 2
• Older adults should maintain access to pump therapy with the same follow-up as younger patients 2