How to manage overnight hypoglycemia on a Tandem t:slim (insulin pump) with a basal rate of 1.00 units/hour and an ISF of 50?

Overnight Hypoglycemia Management on Tandem t:slim Insulin Pump

Reduce your basal rate immediately by 10-20% (to 0.8-0.9 units/hour) for overnight hours, as a blood glucose of 82 mg/dL represents clinically significant nocturnal hypoglycemia that requires prompt basal insulin adjustment. 1, 2

Immediate Basal Rate Adjustment

• Decrease your overnight basal rate from 1.00 to 0.8-0.9 units/hour (a 10-20% reduction) starting tonight 1, 2
• If you experience multiple readings <80 mg/dL per week, reduce by the full 20% (to 0.8 units/hour) 2
• Make this adjustment specifically for the hours when hypoglycemia occurs (typically midnight to 6:00 AM) 1

Verify Your Basal Rate is Appropriate

• Your current basal rate of 1.00 units/hour may be supraphysiological (higher than physiologically required), which is a common pitfall where patients run excessive basal rates attempting to lower average glucose 3
• The traditional calculation suggests basal insulin should be approximately 30-50% of your total daily insulin dose (TDD), not the outdated 50% recommendation 3, 1
• If your TDD is 24 units/day, your total basal should be approximately 7.2-12 units/day (0.3-0.5 units/hour), suggesting your current 1.00 units/hour (24 units/day basal) may be excessive 3, 1

Leverage Your Tandem Control-IQ Technology

• Ensure Control-IQ technology is activated, as it automatically suspends insulin delivery when glucose is predicted to go low within 30 minutes, reducing nocturnal hypoglycemia by 3.6% to 2.6% without rebound hyperglycemia 1, 4
• Control-IQ has a dedicated hypoglycemia safety system that should prevent glucose from dropping to 82 mg/dL if properly configured 4, 5
• The system aims for blood glucose levels of approximately 100-120 mg/dL overnight, making 82 mg/dL an inappropriate target 4

Reassess Your Insulin Sensitivity Factor (ISF)

• Your ISF of 50 may be too aggressive, causing overcorrection of elevated glucose that leads to subsequent hypoglycemia 6
• The standard calculation for ISF is 1500÷TDD or 1700÷TDD 2
• If your TDD is 40 units/day, your ISF should be approximately 37.5-42.5 mg/dL per unit, not 50 2
• If correction doses consistently cause hypoglycemia, adjust the ISF upward (to 60-70), not the basal dose 2

Monitor and Titrate Systematically

• Target fasting glucose should be 80-130 mg/dL (4.4-7.2 mmol/L), making 82 mg/dL borderline acceptable but concerning if recurrent 1, 2
• Wait 3 days after each basal rate adjustment before making further changes to assess the full effect 2
• Daily fasting blood glucose monitoring is essential during this titration phase 2

Critical Pitfalls to Avoid

• Do not ignore recurrent readings <80 mg/dL, as 75% of hospitalized patients who experienced hypoglycemia had no insulin dose adjustment before the next administration 1
• Do not continue the same basal rate hoping Control-IQ alone will compensate—the underlying basal rate must be physiologically appropriate 3
• Avoid the temptation to run higher basal rates to compensate for inadequate meal coverage, as this leads to nocturnal hypoglycemia 3, 6
• If you're disconnecting from the pump overnight, this causes relative insulin deficiency within 1 hour and is not an appropriate solution 3

When to Consider Additional Changes

• If hypoglycemia persists after basal reduction, consider whether you're taking correction boluses too close to bedtime that are still active overnight 6
• Evaluate if your carbohydrate-to-insulin ratio (CIR) is appropriate—the formula CIR = 300÷TDD at breakfast or 400÷TDD at other meals may reveal you're taking excessive mealtime insulin 7
• If you have hypoglycemia unawareness, increase monitoring frequency with CGM alerts set at 90 mg/dL to catch trends earlier 6