How do continuous insulin pumps work and how can hypoglycemia and hypoglycemia unawareness be managed while using one?

Continuous Insulin Pumps: Function and Management of Hypoglycemia and Hypoglycemia Unawareness

Automated insulin delivery (AID) systems are the most effective technology for preventing hypoglycemia and managing hypoglycemia unawareness in people using continuous insulin pumps. 1

How Continuous Insulin Pumps Work

• Continuous subcutaneous insulin infusion (CSII) pumps deliver programmed basal insulin rates and manual boluses through a subcutaneous catheter, providing more precise insulin delivery than multiple daily injections 2
• Basic insulin pumps deliver 50% of daily insulin as basal and 50% as prandial (meal-time) boluses, with typical total daily doses ranging from 0.4 to 1.0 units/kg/day 2
• Modern pump systems integrate with continuous glucose monitoring (CGM) to create sensor-augmented pump (SAP) therapy, which provides real-time glucose readings and trends 2
• Advanced systems include automated features that can suspend insulin delivery when glucose is low (Low Glucose Suspend) or predicted to be low (Predictive Low Glucose Suspend) 1, 2
• Hybrid closed-loop systems (artificial pancreas) automatically adjust basal insulin delivery based on CGM values to maintain target glucose levels 2

Managing Hypoglycemia with Continuous Insulin Pumps

Prevention Strategies

• Use of sensor-augmented pump therapy with CGM has been shown to reduce severe hypoglycemia rates compared to conventional insulin therapy 2
• Automated insulin suspension features can significantly reduce nocturnal hypoglycemia without increasing HbA1c levels 2, 1
• The ASPIRE trial demonstrated that sensor-augmented pump therapy with low glucose suspend function significantly reduced nocturnal hypoglycemia over 3 months without increasing A1C levels 2
• Hybrid closed-loop systems have shown superior protection against hypoglycemia, with greater percentage of time in target glucose range (70-180 mg/dL) 2
• Self-monitoring of blood glucose remains essential despite pump technology; increased frequency of monitoring is recommended for patients at higher risk of hypoglycemia 3

Immediate Management of Hypoglycemia

• Patients must be educated to recognize and manage hypoglycemia symptoms promptly 3
• If hypoglycemia occurs, temporarily suspend insulin delivery using the pump's suspend function 3
• Consume 15-20 grams of fast-acting carbohydrates and recheck glucose in 15 minutes 3
• Resume insulin delivery once glucose levels have stabilized, but consider adjusting basal rates if hypoglycemia is recurrent 2
• Have glucagon available for emergency treatment of severe hypoglycemia 3

Managing Hypoglycemia Unawareness

• Hypoglycemia unawareness significantly increases the risk of severe hypoglycemic events and is associated with reduced adherence to treatment changes 4
• CGM with real-time alerts is particularly beneficial for patients with hypoglycemia unawareness, providing warnings when glucose is trending downward 2, 5
• For patients with hypoglycemia unawareness, AID systems offer the greatest protection by automatically suspending insulin delivery before hypoglycemia occurs 1, 5
• Set higher glucose targets temporarily (aim for 140-180 mg/dL rather than 70-140 mg/dL) to avoid hypoglycemia and help restore awareness 6
• Increase frequency of CGM use to "as close to daily as possible" for maximal benefit in those with hypoglycemia unawareness 2
• Consider using predictive low glucose suspend or hybrid closed-loop systems that can prevent hypoglycemia before it occurs 1, 5

Common Pitfalls and Safety Considerations

• Pump malfunctions, insulin infusion set occlusions, or insulin degradation can rapidly lead to hyperglycemia and ketoacidosis 3
• Patients must be trained to administer insulin by injection and have alternate insulin therapy available in case of pump failure 3
• Never share insulin pumps, cartridges, or infusion sets between patients due to risk of blood-borne pathogen transmission 3
• Replace insulin in the reservoir at least every 7 days to avoid insulin degradation and infusion set occlusion 3
• Change infusion sites regularly (every 2-3 days) to prevent skin irritation and ensure consistent insulin absorption 3
• Even with advanced systems, meal announcements and carbohydrate counting remain necessary for optimal glucose control 1
• Most systems still require manual adjustments for physical activity 1
• Pumps must be removed for certain radiological procedures such as MRI 2

By implementing these strategies with continuous insulin pump therapy, patients can effectively manage hypoglycemia and hypoglycemia unawareness while maintaining optimal glycemic control.